320 results on '"John E. Drake"'
Search Results
2. Montane Temperate-Boreal Forests Retain the Leaf Economic Spectrum Despite Intraspecific Variability
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Matthew J. Hecking, Jenna M. Zukswert, John E. Drake, Martin Dovciak, and Julia I. Burton
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climate change ,environmental gradients ,leaf economic spectrum ,functional traits ,trait dimensions ,intraspecific trait variability (ITV) ,Forestry ,SD1-669.5 ,Environmental sciences ,GE1-350 - Abstract
Trait-based analyses provide powerful tools for developing a generalizable, physiologically grounded understanding of how forest communities are responding to ongoing environmental changes. Key challenges lie in (1) selecting traits that best characterize the ecological performance of species in the community and (2) determining the degree and importance of intraspecific variability in those traits. Recent studies suggest that globally evident trait correlations (trait dimensions), such as the leaf economic spectrum, may be weak or absent at local scales. Moreover, trait-based analyses that utilize a mean value to represent a species may be misleading. Mean trait values are particularly problematic if species trait value rankings change along environmental gradients, resulting in species trait crossover. To assess how plant traits (1) covary at local spatial scales, (2) vary across the dominant environmental gradients, and (3) can be partitioned within and across taxa, we collected data on 9 traits for 13 tree species spanning the montane temperate—boreal forest ecotones of New York and northern New England. The primary dimension of the trait ordination was the leaf economic spectrum, with trait variability among species largely driven by differences between deciduous angiosperms and evergreen gymnosperms. A second dimension was related to variability in nitrogen to phosphorous levels and stem specific density. Levels of intraspecific trait variability differed considerably among traits, and was related to variation in light, climate, and tree developmental stage. However, trait rankings across species were generally conserved across these gradients and there was little evidence of species crossover. The persistence of the leaf economics spectrum in both temperate and high-elevation conifer forests suggests that ecological strategies of tree species are associated with trade-offs between resource acquisition and tolerance, and may be quantified with relatively few traits. Furthermore, the assumption that species may be represented with a single trait value may be warranted for some trait-based analyses provided traits were measured under similar light levels and climate conditions.
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- 2022
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3. Integrated Routing and Bridging in Ethernet VPN (EVPN).
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Ali Sajassi, Samer Salam, Samir Thoria, John E. Drake, and Jorge Rabadan
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- 2021
- Full Text
- View/download PDF
4. Patterns of physical, chemical, and metabolic characteristics of sugar maple leaves with depth in the crown and in response to nitrogen and phosphorus addition
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Alexander R Young, Rakesh Minocha, Stephanie Long, John E Drake, and Ruth D Yanai
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Physiology ,Plant Science - Abstract
Few previous studies have described patterns of leaf characteristics in response to nutrient availability and depth in the crown. Sugar maple has been studied for both sensitivity to light, as a shade-tolerant species, and sensitivity to soil nutrient availability, as a species in decline due to acid rain. To explore leaf characteristics from the top to bottom of the canopy, we collected leaves along a vertical gradient within mature sugar maple crowns in a full-factorial nitrogen by phosphorus addition experiment in three forest stands in central New Hampshire, USA. Thirty-two of the 44 leaf characteristics had significant relationships with depth in the crown, with the effect of depth in the crown strongest for leaf area, photosynthetic pigments, and polyamines. Nitrogen addition had a strong impact on the concentration of foliar N, chlorophyll, carotenoids, alanine, and glutamate. For several other elements and amino acids, N addition changed patterns with depth in the crown. Phosphorus addition increased foliar P and B; it also caused a steeper increase of P and B with depth in the crown. Since most of these leaf characteristics play a direct or indirect role in photosynthesis, metabolic regulation, or cell division, studies that ignore the vertical gradient may not accurately represent whole-canopy performance.
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- 2023
5. Oxalate oxidase transgene expression in American chestnut leaves has little effect on photosynthetic or respiratory physiology
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Anuli Onwumelu, William A. Powell, Andrew E. Newhouse, Garrett Evans, Gwen Hilles, Dakota F. Matthews, Vernon Coffey, and John E. Drake
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Forestry - Published
- 2022
6. Foliar chemical composition and respiration rates of sugar maple (Acer saccharum) and American beech (Fagus grandifolia) trees across a gradient of soil acidification
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Arianna Wills, Colin M. Beier, Greg B. Lawrence, and John E. Drake
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Environmental Chemistry ,Earth-Surface Processes ,Water Science and Technology - Published
- 2023
7. Scaling up uncertainties in allometric models: How to see the forest, not the trees
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Jian Lin, Javier G.P. Gamarra, John E. Drake, Anibal Cuchietti, and Ruth D. Yanai
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Forestry ,Management, Monitoring, Policy and Law ,Nature and Landscape Conservation - Published
- 2023
8. Comparative growth and physiological performance of American chestnuts, oaks, hickories, and sugar maple across a silvicultural gradient in overstory retention
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Garrett R. Evans, Julia I. Burton, William A. Powell, and John E. Drake
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Forestry ,Management, Monitoring, Policy and Law ,Nature and Landscape Conservation - Published
- 2023
9. Friend or foe? The role of biotic agents in drought-induced plant mortality
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Katie M. Becklin, Jason D. Fridley, Louis J. Lamit, Robert J. Griffin-Nolan, Joanna I. Lumbsden-Pinto, Jordan R. Stark, John E. Drake, Jordon Tourville, Alexander R. Ebert, Neha Mohanbabu, Douglas A. Frank, Sarah Araldi-Brondolo, Julie LeVonne, and Hannah Roden
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0106 biological sciences ,Abiotic component ,Ecology ,media_common.quotation_subject ,fungi ,Drought tolerance ,Biodiversity ,food and beverages ,Biota ,Plant Science ,Biology ,010603 evolutionary biology ,01 natural sciences ,Competition (biology) ,Plant ecology ,Habitat ,Ecosystem ,010606 plant biology & botany ,media_common - Abstract
Plant mortality is a complex process influenced by both biotic and abiotic factors. In recent decades, widespread mortality events have been attributed to increasing drought severity, which has motivated research to examine the physiological mechanisms of drought-induced mortality, particularly hydraulic failure. Drought-based mortality mechanisms are further influenced by plant interactions with biota such as neighboring plants, insect pests, and microbes. In this review, we highlight some of the most influential papers addressing these biotic interactions and their influence on plant mortality. Plant–plant interactions can be positive (facilitation), neutral, or negative (competition), depending on drought intensity and neighbor identity. For example, stand-scale mortality likely increases with basal area (an index of competition). However, the diversity of forest stands matters, as more diverse forests suffer less mortality from drought than species-poor forests. Dense forest stands also increase bark beetle attack frequency, which can exacerbate drought stress and mortality, particularly for fast-growing species with lower defense allocation. In some cases, however, drought stress can alleviate biotic attack, depending on feedbacks between plant and pest physiology. Finally, plant interactions with beneficial microorganisms can increase drought tolerance, reduce the likelihood of mortality, and even extend plant distributions into drier habitats. Our review suggests more work is needed in natural herbaceous plant communities as well as dry tropical ecosystems where mortality mechanisms are less understood. Overall, relatively few studies directly link biotic interactions with the physiological mechanisms of mortality. Simultaneous manipulations of biotic interactions and measurements of physiological thresholds (e.g., xylem cavitation) are needed to fully represent biotic interactions in predictive models of plant mortality.
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- 2021
10. Water availability drives fine root dynamics in a Eucalyptus woodland under elevated atmospheric CO 2 concentration
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Sally A. Power, Mark G. Tjoelker, John E. Drake, Raúl Ochoa-Hueso, and Juan Piñeiro
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Agronomy ,Co2 concentration ,Woodland ,Biology ,Eucalyptus ,Water content ,Ecology, Evolution, Behavior and Systematics ,Carbon cycle - Published
- 2020
11. No evidence of homeostatic regulation of leaf temperature in Eucalyptus parramattensis trees: integration of CO 2 flux and oxygen isotope methodologies
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John E. Drake, Margaret M. Barbour, Richard Harwood, Craig V. M. Barton, Peter B. Reich, Mark G. Tjoelker, and Angelica Vårhammar
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0106 biological sciences ,0301 basic medicine ,Physiology ,Vapour Pressure Deficit ,Chemistry ,Plant Science ,Thermoregulation ,Photosynthesis ,Atmospheric sciences ,01 natural sciences ,Degree (temperature) ,Carbon cycle ,03 medical and health sciences ,Light intensity ,030104 developmental biology ,Poikilotherm ,Homeothermy ,010606 plant biology & botany - Abstract
Thermoregulation of leaf temperature (Tleaf ) may foster metabolic homeostasis in plants, but the degree to which Tleaf is moderated, and under what environmental contexts, is a topic of debate. Isotopic studies inferred the temperature of photosynthetic carbon assimilation to be a constant value of c. 20°C; by contrast, leaf biophysical theory suggests a strong dependence of Tleaf on environmental drivers. Can this apparent disparity be reconciled? We continuously measured Tleaf and whole-crown net CO2 uptake for Eucalyptus parramattensis trees growing in field conditions in whole-tree chambers under ambient and +3°C warming conditions, and calculated assimilation-weighted leaf temperature (TL-AW ) across 265 d, varying in air temperature (Tair ) from -1 to 45°C. We compared these data to TL-AW derived from wood cellulose δ18 O. Tleaf exhibited substantial variation driven by Tair , light intensity, and vapor pressure deficit, and Tleaf was strongly linearly correlated with Tair with a slope of c. 1.0. TL-AW values calculated from cellulose δ18 O vs crown fluxes were remarkably consistent; both varied seasonally and in response to the warming treatment, tracking variation in Tair . The leaves studied here were nearly poikilothermic, with no evidence of thermoregulation of Tleaf towards a homeostatic value. Importantly, this work supports the use of cellulose δ18 O to infer TL-AW , but does not support the concept of strong homeothermic regulation of Tleaf.
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- 2020
12. The temperature optima for tree seedling photosynthesis and growth depend on water inputs
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Belinda E. Medlyn, Angelica Vårhammar, Dushan Kumarathunge, Sebastian Pfautsch, Rosana López, Mark G. Tjoelker, and John E. Drake
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0106 biological sciences ,Global and Planetary Change ,Biomass (ecology) ,010504 meteorology & atmospheric sciences ,Ecology ,biology ,Specific leaf area ,Global warming ,Plant physiology ,Photosynthesis ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Indirect effect ,Agronomy ,Seedling ,Respiration ,Environmental Chemistry ,Environmental science ,0105 earth and related environmental sciences ,General Environmental Science - Abstract
Understanding how tree growth is affected by rising temperature is a key to predicting the fate of forests in future warmer climates. Increasing temperature has direct effects on plant physiology, but there are also indirect effects of increased water limitation because evaporative demand increases with temperature in many systems. In this study, we experimentally resolved the direct and indirect effects of temperature on the response of growth and photosynthesis of the widely distributed species Eucalyptus tereticornis. We grew E. tereticornis in an array of six growth temperatures from 18 to 35.5°C, spanning the climatic distribution of the species, with two watering treatments: (a) water inputs increasing with temperature to match plant demand at all temperatures (Wincr ), isolating the direct effect of temperature; and (b) water inputs constant for all temperatures, matching demand for coolest grown plants (Wconst ), such that water limitation increased with growth temperature. We found that constant water inputs resulted in a reduction of temperature optima for both photosynthesis and growth by ~3°C compared to increasing water inputs. Water limitation particularly reduced the total amount of leaf area displayed at Topt and intermediate growth temperatures. The reduction in photosynthesis could be attributed to lower leaf water potential and consequent stomatal closure. The reduction in growth was a result of decreased photosynthesis, reduced total leaf area display and a reduction in specific leaf area. Water availability had no effect on the response of stem and root respiration to warming, but we observed lower leaf respiration rates under constant water inputs compared to increasing water inputs at higher growth temperatures. Overall, this study demonstrates that the indirect effect of increasing water limitation strongly modifies the potential response of tree growth to rising global temperatures.
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- 2020
13. An extreme heatwave enhanced the xanthophyll de-epoxidation state in leaves of Eucalyptus trees grown in the field
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Namraj Dhami, John E. Drake, Mark G. Tjoelker, David T. Tissue, and Christopher I Cazzonelli
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0106 biological sciences ,0301 basic medicine ,chemistry.chemical_classification ,Physiology ,Global warming ,Plant physiology ,Plant Science ,15. Life on land ,Biology ,Photosynthesis ,01 natural sciences ,Acclimatization ,Zeaxanthin ,03 medical and health sciences ,chemistry.chemical_compound ,Horticulture ,030104 developmental biology ,chemistry ,13. Climate action ,Xanthophyll ,Molecular Biology ,Carotenoid ,010606 plant biology & botany ,Violaxanthin - Abstract
Heatwaves are becoming more frequent with climate warming and can impact tree growth and reproduction. Eucalyptus parramattensis can cope with an extreme heatwave in the field via transpiratory cooling and enhanced leaf thermal tolerance that protected foliar tissues from photo-inhibition and photo-oxidation during natural midday irradiance. Here, we explored whether changes in foliar carotenoids and/or the xanthophyll cycle state can facilitate leaf acclimation to long-term warming and/or an extreme heatwave event. We found that leaves had similar carotenoid levels when grown for one year under ambient and experimental long-term warming (+ 3 °C) conditions in whole tree chambers. Exposure to a 4-day heatwave (> 43 °C) significantly altered the xanthophyll de-epoxidation state of carotenoids revealing one mechanism by which trees could minimise foliar photo-oxidative damage. The levels of zeaxanthin were significantly higher in both young and old leaves during the heatwave, revealing that violaxanthin de-epoxidation and perhaps de novo zeaxanthin synthesis contributed to enhancement of the xanthophyll cycle state. In a future climate of long-term warming and increased heatwave events, leaves of E. parramattensis will be able to utilise biochemical strategies to alter the xanthophyll cycle state and cope with extreme temperatures under natural solar irradiation.
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- 2020
14. Management trade-offs between forest carbon stocks, sequestration rates and structural complexity in the central Adirondacks
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Ry M. Patton, Diane H. Kiernan, Julia I. Burton, and John E. Drake
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Forestry ,Management, Monitoring, Policy and Law ,Nature and Landscape Conservation - Published
- 2022
15. No evidence for triose phosphate limitation of light‐saturated leaf photosynthesis under current atmospheric CO2concentration
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Mark G. Tjoelker, Dushan Kumarathunge, John E. Drake, Alistair Rogers, and Belinda E. Medlyn
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0106 biological sciences ,0301 basic medicine ,biology ,Physiology ,ved/biology ,ved/biology.organism_classification_rank.species ,RuBisCO ,Biosphere ,Plant Science ,Phosphate ,Photosynthesis ,01 natural sciences ,Tundra ,C3 photosynthesis ,03 medical and health sciences ,chemistry.chemical_compound ,030104 developmental biology ,chemistry ,Co2 concentration ,Environmental chemistry ,Terrestrial plant ,biology.protein ,010606 plant biology & botany - Abstract
The triose phosphate utilization (TPU) rate has been identified as one of the processes that can limit terrestrial plant photosynthesis. However, we lack a robust quantitative assessment of TPU limitation of photosynthesis at the global scale. As a result, TPU, and its potential limitation of photosynthesis, is poorly represented in terrestrial biosphere models (TBMs). In this study, we utilized a global data set of photosynthetic CO2 response curves representing 141 species from tropical rainforests to Arctic tundra. We quantified TPU by fitting the standard biochemical model of C3 photosynthesis to measured photosynthetic CO2 response curves and characterized its instantaneous temperature response. Our results demonstrate that TPU does not limit leaf photosynthesis at the current ambient atmospheric CO2 concentration. Furthermore, our results showed that the light-saturated photosynthetic rates of plants growing in cold environments are not more often limited by TPU than those of plants growing in warmer environments. In addition, our study showed that the instantaneous temperature response of TPU is distinct from temperature response of the maximum rate of Rubisco carboxylation. The new formulations of the temperature response of TPU derived in this study may prove useful in quantifying the biochemical limits to terrestrial plant photosynthesis and improve the representation of plant photosynthesis in TBMs.
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- 2019
16. Carbon isotopic tracing of sugars throughout whole‐trees exposed to climate warming
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Elise Pendall, Andreas Richter, Julia Wiesenbauer, John E. Drake, and Morgan E. Furze
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0106 biological sciences ,0301 basic medicine ,Canopy ,Time Factors ,Carbohydrate transport ,Physiology ,Climate Change ,chemistry.chemical_element ,Plant Science ,Root system ,Phloem ,Plant Roots ,01 natural sciences ,Trees ,03 medical and health sciences ,Sugar ,Isotope analysis ,Carbon Isotopes ,Eucalyptus ,Global warming ,Carbon ,Dilution ,Plant Leaves ,030104 developmental biology ,Agronomy ,chemistry ,Environmental science ,Sugars ,010606 plant biology & botany - Abstract
Trees allocate C from sources to sinks by way of a series of processes involving carbohydrate transport and utilization. Yet these dynamics are not well characterized in trees, and it is unclear how these dynamics will respond to a warmer world. Here, we conducted a warming and pulse-chase experiment on Eucalyptus parramattensis growing in a whole-tree chamber system to test whether warming impacts carbon allocation by increasing the speed of carbohydrate dynamics. We pulse-labelled large (6-m tall) trees with 13 C-CO2 to follow recently fixed C through different organs by using compound-specific isotope analysis of sugars. We then compared concentrations and mean residence times of individual sugars between ambient and warmed (+3°C) treatments. Trees dynamically allocated 13 C-labelled sugars throughout the aboveground-belowground continuum. We did not, however, find a significant treatment effect on C dynamics, as sugar concentrations and mean residence times were not altered by warming. From the canopy to the root system, 13 C enrichment of sugars decreased, and mean residence times increased, reflecting dilution and mixing of recent photoassimilates with older reserves along the transport pathway. Our results suggest that a locally endemic eucalypt was seemingly able to adjust its physiology to warming representative of future temperature predictions for Australia.
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- 2019
17. Climate warming and tree carbon use efficiency in a whole‐tree 13 <scp>CO</scp> 2 tracer study
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Elise Pendall, Craig V. M. Barton, John E. Drake, Yolima Carrillo, Mark G. Tjoelker, and Morgan E. Furze
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2. Zero hunger ,0106 biological sciences ,0301 basic medicine ,Biomass (ecology) ,Physiology ,Global warming ,Heterotrophic respiration ,chemistry.chemical_element ,Primary production ,Plant Science ,15. Life on land ,01 natural sciences ,Acclimatization ,03 medical and health sciences ,030104 developmental biology ,chemistry ,Agronomy ,13. Climate action ,TRACER ,Respiration ,Environmental science ,Carbon ,010606 plant biology & botany - Abstract
Autotrophic respiration is a major driver of the global C cycle and may contribute a positive climate warming feedback through increased atmospheric concentrations of CO2 . The extent of this feedback depends on plants' ability to acclimate respiration to maintain a constant carbon use efficiency (CUE). We quantified respiratory partitioning of gross primary production (GPP) and CUE of field-grown trees in a long-term warming experiment (+3°C). We delivered a 13 C-CO2 pulse to whole tree crowns and chased that pulse in the respiration of leaves, whole crowns, roots, and soil. We also measured the isotopic composition of soil microbial biomass and the respiration rates of leaves and whole crowns. We documented homeostatic respiratory acclimation of foliar and whole-crown respiration rates; the trees adjusted to experimental warming such that leaf-level respiration rates were not increased. Experimental warming had no detectable impact on respiratory partitioning or mean residence times. Of the 13 C label acquired by the trees, aboveground respiration consumed 10%, belowground respiration consumed 40%, and the remaining 50% was retained. Experimental warming of +3°C did not alter respiratory partitioning at the scale of entire trees, suggesting that complete acclimation of respiration to warming is likely to dampen a positive climate warming feedback.
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- 2019
18. The partitioning of gross primary production for young Eucalyptus tereticornis trees under experimental warming and altered water availability
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Michael J. Aspinwall, Peter B. Reich, Mark G. Tjoelker, Craig V. M. Barton, Sebastian Pfautsch, and John E. Drake
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0106 biological sciences ,0301 basic medicine ,Maintenance respiration ,Physiology ,Primary production ,Plant Science ,15. Life on land ,01 natural sciences ,Acclimatization ,Accelerated Growth ,03 medical and health sciences ,030104 developmental biology ,Agronomy ,Soil water ,Respiration ,Environmental science ,Ecosystem ,Precipitation ,010606 plant biology & botany - Abstract
The allocation of carbon (C) is an important component of tree physiology that influences growth and ecosystem C storage. Allocation is challenging to measure, and its sensitivity to environmental changes such as warming and altered water availability is uncertain. We exposed young Eucalyptus tereticornis trees to +3°C warming and elimination of summer precipitation in the field using whole-tree chambers. We calculated C allocation terms using detailed measurements of growth and continuous whole-crown CO2 and water exchange measurements. Trees grew from small saplings to nearly 9 m height during this 15-month experiment. Warming accelerated growth and leaf area development, and it increased the partitioning of gross primary production (GPP) to aboveground respiration and growth while decreasing partitioning below ground. Eliminating summer precipitation reduced C gain and growth but did not impact GPP partitioning. Trees utilized deep soil water and avoided strongly negative water potentials. Warming increased growth respiration, but maintenance respiration acclimated homeostatically. The increasing growth in the warmed treatment resulted in higher rates of respiration, even with complete acclimation of maintenance respiration. Warming-induced stimulations of tree growth likely involve increased C allocation above ground, particularly to leaf area development, whereas reduced water availability may not stimulate allocation to roots.
- Published
- 2019
19. COSORE: A community database for continuous soil respiration and other soil‐atmosphere greenhouse gas flux data
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Dennis D. Baldocchi, Kadmiel Maseyk, Yuji Kominami, Nadine K. Ruehr, Patrick M. Crill, John E. Drake, Mioko Ataka, Anya M. Hopple, Haiming Kan, Samaneh Ashraf, Matthew Saunders, Zhuo Pang, Daphne Szutu, Stephanie C. Pennington, Whendee L. Silver, Scott T. Miller, Cecilio Oyonarte, David A. Lipson, Naishen Liang, Masahito Ueyama, Thomas Wutzler, Michael L. Goulden, Järvi Järveoja, Jiye Zeng, Wu Sun, Debjani Sihi, Takashi Hirano, Nina Buchmann, Amir AghaKouchak, Peter S. Curtis, Ruth K. Varner, Greg Winston, Munemasa Teramoto, Mark G. Tjoelker, Susan E. Trumbore, Kathleen Savage, Omar Gutiérrez del Arroyo, Asko Noormets, Mats Nilsson, Catriona A. Macdonald, Carolyn Monika Görres, M. Altaf Arain, Alexandre A. Renchon, Joseph Verfaillie, James W. Raich, Masahiro Takagi, Jason P. Kaye, Quan Zhang, Hamidreza Norouzi, Ulli Seibt, Melanie A. Mayes, Jinsong Wang, Juan J. Armesto, Marion Schrumpf, Tianshan Zha, Mirco Migliavacca, Chelcy Ford Miniat, Jin-Sheng He, Enrique P. Sánchez-Cañete, Michael Gavazzi, Tarek S. El-Madany, T. A. Black, H. Hughes, Elise Pendall, Christopher M. Gough, Jillian W. Gregg, Guofang Miao, Junliang Zou, Avni Malhotra, Russell L. Scott, D. S. Christianson, Marguerite Mauritz, Steve McNulty, Juying Wu, Jinshi Jian, K. C. Mathes, Tana E. Wood, Rodrigo Vargas, Jennifer Goedhart Nietz, Christoph S. Vogel, Claire L. Phillips, Mariah S. Carbone, Kentaro Takagi, Shih-Chieh Chang, Jorge F. Perez-Quezada, Richard P. Phillips, Hassan Anjileli, Eric A. Davidson, Ankur R. Desai, Christine S. O’Connell, Matthias Peichl, Bruce Osborne, Ben Bond-Lamberty, and Rachhpal S. Jassal
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0106 biological sciences ,010504 meteorology & atmospheric sciences ,Nitrous Oxide ,Climate change ,open data ,computer.software_genre ,Greenhouse gas ,010603 evolutionary biology ,01 natural sciences ,Database design ,soil respiration ,Soil respiration ,Greenhouse Gases ,Soil ,11. Sustainability ,greenhouse gases ,open science ,ddc:550 ,Environmental Chemistry ,Biology ,Ecosystem ,0105 earth and related environmental sciences ,General Environmental Science ,Global and Planetary Change ,Database ,Ecology ,Atmosphere ,carbon dioxide ,methane ,Respiration ,Reproducibility of Results ,15. Life on land ,Biological Sciences ,Climate Action ,Earth system science ,Ancillary data ,Chemistry ,Earth sciences ,Technical Advance ,13. Climate action ,Soil water ,Environmental science ,Ecosystem respiration ,computer ,Environmental Sciences - Abstract
Globally, soils store two to three times as much carbon as currently resides in the atmosphere, and it is critical to understand how soil greenhouse gas (GHG) emissions and uptake will respond to ongoing climate change. In particular, the soil‐to‐atmosphere CO2 flux, commonly though imprecisely termed soil respiration (R S), is one of the largest carbon fluxes in the Earth system. An increasing number of high‐frequency R S measurements (typically, from an automated system with hourly sampling) have been made over the last two decades; an increasing number of methane measurements are being made with such systems as well. Such high frequency data are an invaluable resource for understanding GHG fluxes, but lack a central database or repository. Here we describe the lightweight, open‐source COSORE (COntinuous SOil REspiration) database and software, that focuses on automated, continuous and long‐term GHG flux datasets, and is intended to serve as a community resource for earth sciences, climate change syntheses and model evaluation. Contributed datasets are mapped to a single, consistent standard, with metadata on contributors, geographic location, measurement conditions and ancillary data. The design emphasizes the importance of reproducibility, scientific transparency and open access to data. While being oriented towards continuously measured R S, the database design accommodates other soil‐atmosphere measurements (e.g. ecosystem respiration, chamber‐measured net ecosystem exchange, methane fluxes) as well as experimental treatments (heterotrophic only, etc.). We give brief examples of the types of analyses possible using this new community resource and describe its accompanying R software package., Here we describe the lightweight, open source COSORE (COntinuous SOil REspiration) database and software. COSORE focuses on automated, continuous and long‐term greenhouse gas flux datasets, and is intended to serve as a community resource for earth sciences, climate change syntheses and model evaluation.
- Published
- 2020
20. Whole-tree mesophyll conductance reconciles isotopic and gas-exchange estimates of water-use efficiency
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Craig V. M. Barton, Courtney E. Campany, Mark G. Tjoelker, Nerea Ubierna, John D. Marshall, John E. Drake, and Teresa E. Gimeno
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0106 biological sciences ,0301 basic medicine ,Physiology ,Plant Science ,Photosynthesis ,01 natural sciences ,Trees ,03 medical and health sciences ,Respiration ,Water cycle ,Water-use efficiency ,Carbon Isotopes ,Direct effects ,Conductance ,Water ,15. Life on land ,Carbon Dioxide ,Eucalyptus ,Plant Leaves ,030104 developmental biology ,Agronomy ,13. Climate action ,Environmental science ,Phloem ,Mesophyll Cells ,010606 plant biology & botany - Abstract
Photosynthetic water-use efficiency (WUE) describes the link between terrestrial carbon (C) and water cycles. Estimates of intrinsic WUE (iWUE) from gas exchange and C isotopic composition (δ13 C) differ due to an internal conductance in the leaf mesophyll (gm ) that is variable and seldom computed. We present the first direct estimates of whole-tree gm , together with iWUE from whole-tree gas exchange and δ13 C of the phloem (δ13 Cph ). We measured gas exchange, online 13 C-discrimination, and δ13 Cph monthly throughout spring, summer, and autumn in Eucalyptus tereticornis grown in large whole-tree chambers. Six trees were grown at ambient temperatures and six at a 3°C warmer air temperature; a late-summer drought was also imposed. Drought reduced whole-tree gm . Warming had few direct effects, but amplified drought-induced reductions in whole-tree gm . Whole-tree gm was similar to leaf gm for these same trees. iWUE estimates from δ13 Cph agreed with iWUE from gas exchange, but only after incorporating gm . δ13 Cph was also correlated with whole-tree 13 C-discrimination, but offset by -2.5 ± 0.7‰, presumably due to post-photosynthetic fractionations. We conclude that δ13 Cph is a good proxy for whole-tree iWUE, with the caveats that post-photosynthetic fractionations and intrinsic variability of gm should be incorporated to provide reliable estimates of this trait in response to abiotic stress.
- Published
- 2020
21. The fate of carbon in a mature forest under carbon dioxide enrichment
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Belinda E. Medlyn, Kristine Y. Crous, Sally A. Power, Peter B. Reich, Teresa E. Gimeno, Catriona A. Macdonald, Bruna Marques dos Santos, Scott N. Johnson, Brajesh K. Singh, David S. Ellsworth, Riikka Rinnan, Elise Pendall, Luke Collins, Andrew N. Gherlenda, Jinyan Yang, Yolima Carrillo, Elizabeth H.J. Neilson, Ian C. Anderson, Mark G. Tjoelker, Laura Castañeda-Gómez, Sönke Zaehle, Uffe N. Nielsen, John E. Drake, K. Mahmud, Sarah L. Facey, Raúl Ochoa-Hueso, Craig V. M. Barton, Agnieszka Wujeska-Klause, Benjamin Smith, Remko A. Duursma, Jeff R. Powell, Paul D. Rymer, Matthias M. Boer, Jennifer K. M. Walker, Kathryn M. Emmerson, Nam Jin Noh, Loïc Nazaries, Shun Hasegawa, Juan Piñeiro, Johanna Pihlblad, Varsha S. Pathare, Martin G. De Kauwe, Roberto L. Salomón, Ülo Niinemets, Mingkai Jiang, Markus Riegler, Alexandre A. Renchon, Astrid Kännaste, and Ben D. Moore
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0106 biological sciences ,Carbon Sequestration ,010504 meteorology & atmospheric sciences ,chemistry.chemical_element ,Forests ,Carbon sequestration ,Global Warming ,Models, Biological ,010603 evolutionary biology ,01 natural sciences ,Trees ,Carbon cycle ,Soil respiration ,Soil ,chemistry.chemical_compound ,Biomass ,Photosynthesis ,0105 earth and related environmental sciences ,Eucalyptus ,Carbon dioxide in Earth's atmosphere ,Multidisciplinary ,Atmosphere ,Carbon sink ,Carbon Dioxide ,chemistry ,Agronomy ,Carbon dioxide ,Environmental science ,New South Wales ,Ecosystem respiration ,Carbon - Abstract
Atmospheric carbon dioxide enrichment (eCO2) can enhance plant carbon uptake and growth1–5, thereby providing an important negative feedback to climate change by slowing the rate of increase of the atmospheric CO2 concentration6. Although evidence gathered from young aggrading forests has generally indicated a strong CO2 fertilization effect on biomass growth3–5, it is unclear whether mature forests respond to eCO2 in a similar way. In mature trees and forest stands7–10, photosynthetic uptake has been found to increase under eCO2 without any apparent accompanying growth response, leaving the fate of additional carbon fixed under eCO2 unclear4,5,7–11. Here using data from the first ecosystem-scale Free-Air CO2 Enrichment (FACE) experiment in a mature forest, we constructed a comprehensive ecosystem carbon budget to track the fate of carbon as the forest responded to four years of eCO2 exposure. We show that, although the eCO2 treatment of +150 parts per million (+38 per cent) above ambient levels induced a 12 per cent (+247 grams of carbon per square metre per year) increase in carbon uptake through gross primary production, this additional carbon uptake did not lead to increased carbon sequestration at the ecosystem level. Instead, the majority of the extra carbon was emitted back into the atmosphere via several respiratory fluxes, with increased soil respiration alone accounting for half of the total uptake surplus. Our results call into question the predominant thinking that the capacity of forests to act as carbon sinks will be generally enhanced under eCO2, and challenge the efficacy of climate mitigation strategies that rely on ubiquitous CO2 fertilization as a driver of increased carbon sinks in global forests. Carbon dioxide enrichment of a mature forest resulted in the emission of the excess carbon back into the atmosphere via enhanced ecosystem respiration, suggesting that mature forests may be limited in their capacity to mitigate climate change.
- Published
- 2020
22. No evidence of homeostatic regulation of leaf temperature in Eucalyptus parramattensis trees: integration of CO
- Author
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John E, Drake, Richard, Harwood, Angelica, Vårhammar, Margaret M, Barbour, Peter B, Reich, Craig V M, Barton, and Mark G, Tjoelker
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Plant Leaves ,Eucalyptus ,Temperature ,Homeostasis ,Carbon Dioxide ,Oxygen Isotopes ,Photosynthesis ,Trees - Abstract
Thermoregulation of leaf temperature (T
- Published
- 2019
23. Photosynthetic capacity and leaf nitrogen decline along a controlled climate gradient in provenances of two widely distributed Eucalyptus species
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Oula Ghannoum, Kristine Y. Crous, John E. Drake, Robert E. Sharwood, Michael J. Aspinwall, and Mark G. Tjoelker
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0106 biological sciences ,010504 meteorology & atmospheric sciences ,Nitrogen ,Acclimatization ,Climate ,Climate Change ,Ribulose-Bisphosphate Carboxylase ,Climate change ,Subtropics ,Biology ,Photosynthesis ,01 natural sciences ,Trees ,Temperate climate ,Environmental Chemistry ,0105 earth and related environmental sciences ,General Environmental Science ,Eucalyptus ,Global and Planetary Change ,Ecology ,Global warming ,Temperature ,Tropics ,15. Life on land ,Environment, Controlled ,Photosynthetic capacity ,Plant Leaves ,Agronomy ,13. Climate action ,010606 plant biology & botany - Abstract
Climate is an important factor limiting tree distributions and adaptation to different thermal environments may influence how tree populations respond to climate warming. Given the current rate of warming, it has been hypothesized that tree populations in warmer, more thermally stable climates may have limited capacity to respond physiologically to warming compared to populations from cooler, more seasonal climates. We determined in a controlled environment how several provenances of widely distributed Eucalyptus tereticornis and E. grandis adjusted their photosynthetic capacity to +3.5°C warming along their native distribution range (~16-38°S) and whether climate of seed origin of the provenances influenced their response to different growth temperatures. We also tested how temperature optima (Topt ) of photosynthesis and Jmax responded to higher growth temperatures. Our results showed increased photosynthesis rates at a standardized temperature with warming in temperate provenances, while rates in tropical provenances were reduced by about 40% compared to their temperate counterparts. Temperature optima of photosynthesis increased as provenances were exposed to warmer growth temperatures. Both species had ~30% reduced photosynthetic capacity in tropical and subtropical provenances related to reduced leaf nitrogen and leaf Rubisco content compared to temperate provenances. Tropical provenances operated closer to their thermal optimum and came within 3% of the Topt of Jmax during the daily temperature maxima. Hence, further warming may negatively affect C uptake and tree growth in warmer climates, whereas eucalypts in cooler climates may benefit from moderate warming.
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- 2018
24. Three years of soil respiration in a mature eucalypt woodland exposed to atmospheric CO2 enrichment
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Peter B. Reich, Catriona A. Macdonald, David S. Ellsworth, John E. Drake, Mark G. Tjoelker, Brajesh K. Singh, and Ian C. Anderson
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0106 biological sciences ,010504 meteorology & atmospheric sciences ,Q10 ,Primary production ,Atmospheric sciences ,010603 evolutionary biology ,01 natural sciences ,Carbon cycle ,Soil respiration ,chemistry.chemical_compound ,chemistry ,Soil water ,Carbon dioxide ,Environmental Chemistry ,Environmental science ,Ecosystem ,Precipitation ,0105 earth and related environmental sciences ,Earth-Surface Processes ,Water Science and Technology - Abstract
The rate of CO2 diffusion from soils to the atmosphere (soil CO2 efflux, soil respiration; Rsoil) reflects the integrated activity of roots and microbes and is among the largest fluxes of the terrestrial global C cycle. Most experiments have demonstrated that Rsoil increases by 20–35% following the exposure of an ecosystem to an atmosphere enriched in CO2 (i.e., eCO2), but such experiments have largely been performed in young and N-limited ecosystems. Here, we exposed a mature and phosphorus-limited eucalypt woodland to eCO2 and measured Rsoil across three full years with a combination of manual surveys and automated measurements. We also implemented an empirical model describing the dependence of Rsoil on volumetric soil water content (θ) and soil temperature (Tsoil) to produce annual Rsoil flux estimates. Rsoil varied strongly with Tsoil, θ, and precipitation in complex and interacting ways. The realized long-term (weeks to years) temperature dependence (Q10) of Rsoil increased from ~ 1.6 at low θ up to ~ 3 at high θ. Additionally, Rsoil responded strongly and rapidly to precipitation events in a manner that depended on the conditions of θ and Tsoil at the beginning of the rain event; Rsoil increased by up to 300% within 30 min when rain fell on dry soil that had not experience rain in the preceding week, but Rsoil was rapidly reduced by up to 70% when rain fell on wet soil, leading to flooding. Repeated measures analysis of Rsoil observations over 3 years indicated no significant change in response to CO2 enrichment (P = 0.7), and elevated CO2 did not alter the dependence of Rsoil on Tsoil or θ. However, eCO2 increased Rsoil observations by ~ 10% under some constrained and moderate environmental conditions. Annual Rsoil flux sums estimated with an empirical model were ~ 7% higher in eCO2 plots than in aCO2 plots, but this difference was not statistically significant. The lack of a large eCO2 effect on Rsoil is consistent with recent evidence that aboveground net primary production was not stimulated by eCO2 in this ecosystem. The C budget of this mature woodland may be less affected by eCO2 than the young N-limited ecosystems that have been studied previously.
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- 2018
25. Stomatal and non-stomatal limitations of photosynthesis for four tree species under drought: A comparison of model formulations
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Sally A. Power, Danielle Creek, Michael J. Aspinwall, Remko A. Duursma, Sebastian Pfautsch, Chelsea Maier, John E. Drake, Derek Eamus, Mark G. Tjoelker, Renee Smith, Belinda E. Medlyn, Brendan Choat, and David T. Tissue
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0106 biological sciences ,Atmospheric Science ,Global and Planetary Change ,Stomatal conductance ,010504 meteorology & atmospheric sciences ,Empirical modelling ,Forestry ,Biology ,Rainout ,Photosynthesis ,Atmospheric sciences ,01 natural sciences ,Photosynthetic capacity ,Botany ,Soil water ,Ecosystem ,Water-use efficiency ,Agronomy and Crop Science ,010606 plant biology & botany ,0105 earth and related environmental sciences - Abstract
Drought strongly influences terrestrial C cycling via its effects on plant H2O and CO2 exchange. However, the treatment of photosynthetic physiology under drought by many ecosystem and earth system models remains poorly constrained by data. We measured the drought response of four tree species and evaluated alternative model formulations for drought effects on photosynthesis (A). We implemented a series of soil drying and rewetting events (i.e. multiple droughts) with four contrasting tree species in large pots (75 L) placed in the field under rainout shelters. We measured leaf-level gas exchange, predawn and midday leaf water potential (Ψpd and Ψmd), and leaf isotopic composition (δ13C) and calculated discrimination relative to the atmosphere (Δ). We then evaluated eight modeling frameworks that simulate the effects of drought in different ways. With moderate reductions in volumetric soil water content (θ), all species reduced stomatal conductance (gs), leading to an equivalent increase in water use efficiency across species inferred from both leaf gas exchange and Δ, despite a small reduction in photosynthetic capacity. With severe reductions in θ, all species strongly reduced gs along with a coincident reduction in photosynthetic capacity, illustrating the joint importance of stomatal and non-stomatal limitations of photosynthesis under strong drought conditions. Simple empirical models as well as complex mechanistic model formulations were equally successful at capturing the measured variation in A and gs, as long as the predictor variables were available from direct measurements (θ, Ψpd, and Ψmd). However, models based on leaf water potential face an additional challenge, as we found that Ψpd was substantially different from Ψsoil predicted by standard approaches based on θ. Modeling frameworks that combine gas exchange and hydraulic traits have the advantage of mechanistic realism, but sacrificed parsimony without an improvement in predictive power in this comparison. Model choice depends on the desired balance between simple empiricism and mechanistic realism. We suggest that empirical models implementing stomatal and non-stomatal limitations based on θ are highly predictive simple models. Mechanistic models that incorporate hydraulic traits have excellent potential, but several challenges currently limit their widespread implementation.
- Published
- 2017
26. Rhizosphere-driven increase in nitrogen and phosphorus availability under elevated atmospheric CO2 in a mature Eucalyptus woodland
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Raúl Ochoa-Hueso, John E. Drake, Sally A. Power, Mark G. Tjoelker, John Hughes, Juan Piñeiro, and Manuel Delgado-Baquerizo
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0106 biological sciences ,chemistry.chemical_classification ,Rhizosphere ,Chemistry ,Phosphorus ,Soil organic matter ,Soil Science ,chemistry.chemical_element ,Plant Science ,Woodland ,010603 evolutionary biology ,01 natural sciences ,Nutrient ,Agronomy ,Terrestrial ecosystem ,Organic matter ,Ecosystem ,010606 plant biology & botany - Abstract
Rhizosphere processes are integral to carbon sequestration by terrestrial ecosystems in response to rising concentrations of atmospheric CO2. Yet, the nature and magnitude of rhizosphere responses to elevated CO2, particularly in nutrient and water-limited forest ecosystems, remain poorly understood. We investigated rhizosphere responses (enzyme activities and nutrient availability) to atmospheric CO2 enrichment (ambient +150 μmol CO2 mol−1) in a phosphorus-limited mature eucalypt woodland in south-eastern Australia (the EucFACE experiment). Following 17 months of treatment, the activity of rhizosphere soil exoenzymes related to starch and cellulose degradation decreased between 0 and 10 cm and increased from 10 to 30 cm depth under elevated CO2. This response was concurrent with increases in nitrogen and phosphorus availability and smaller C:P nutrient ratios in rhizosphere soil under elevated CO2. This nutrient-poor eucalypt woodland exhibited rhizosphere responses to atmospheric CO2 enrichment that increased nutrient availability in rhizosphere soil and suggest accelerated rates of soil organic matter decomposition, both of which may, in turn, promote plant growth under elevated CO2 concentrations.
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- 2017
27. The fate of carbon in a mature forest under carbon dioxide enrichment
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Benjamin Smith, David S. Ellsworth, Jinyan Yang, Mark G. Tjoelker, Teresa E. Gimeno, Ben D. Moore, John E. Drake, Belinda E. Medlyn, Matthias M. Boer, Kristine Y. Crous, Sally A. Power, Ian C. Anderson, Brajesh K. Singh, Jeff R. Powell, Roberto L. Salomón, Peter B. Reich, Paul D. Rymer, Jennifer K. M. Walker, Remko A. Duursma, Kathryn M. Emmerson, Craig V. M. Barton, Yolima Carrillo, Agnieszka Wujeska-Klause, Nam Jin Noh, Sönke Zaehle, Juan Piñeiro, Varsha S. Pathare, Andrew N. Gherlenda, K. Mahmud, Markus Riegler, Laura Castañeda-Gómez, Martin G. De Kauwe, Catriona A. Macdonald, Sarah L. Facey, Elise Pendall, Raúl Ochoa-Hueso, Shun Hasegawa, Loïc Nazaries, Mingkai Jiang, Alexandre A. Renchon, Luke Collins, Uffe N. Nielsen, and Scott N. Johnson
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0303 health sciences ,Carbon dioxide in Earth's atmosphere ,Primary production ,Carbon sink ,Biomass ,chemistry.chemical_element ,04 agricultural and veterinary sciences ,15. Life on land ,Carbon sequestration ,Soil respiration ,03 medical and health sciences ,chemistry.chemical_compound ,chemistry ,13. Climate action ,Environmental chemistry ,Carbon dioxide ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,Environmental science ,Carbon ,030304 developmental biology - Abstract
Atmospheric carbon dioxide enrichment (eCO2) can enhance plant carbon uptake and growth1,2,3,4,5, thereby providing an important negative feedback to climate change by slowing the rate of increase of the atmospheric CO2concentration6. While evidence gathered from young aggrading forests has generally indicated a strong CO2fertilization effect on biomass growth3,4,5, it is unclear whether mature forests respond to eCO2in a similar way. In mature trees and forest stands7,8,9,10, photosynthetic uptake has been found to increase under eCO2without any apparent accompanying growth response, leaving an open question about the fate of additional carbon fixed under eCO24, 5, 7,8,9,10,11. Here, using data from the first ecosystem-scale Free-Air CO2Enrichment (FACE) experiment in a mature forest, we constructed a comprehensive ecosystem carbon budget to track the fate of carbon as the forest responds to four years of eCO2exposure. We show that, although the eCO2treatment of ambient +150 ppm (+38%) induced a 12% (+247 gCm-2yr-1) increase in carbon uptake through gross primary production, this additional carbon uptake did not lead to increased carbon sequestration at the ecosystem level. Instead, the majority of the extra carbon was emitted back into the atmosphere via several respiratory fluxes, with increased soil respiration alone contributing ∼50% of the total uptake surplus. Our results call into question the predominant thinking that the capacity of forests to act as carbon sinks will be generally enhanced under eCO2, and challenge the efficacy of climate mitigation strategies that rely on CO2fertilization as a driver of increased carbon sinks in standing forests and afforestation projects.
- Published
- 2019
- Full Text
- View/download PDF
28. An extreme heatwave enhanced the xanthophyll de-epoxidation state in leaves of
- Author
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Namraj, Dhami, John E, Drake, Mark G, Tjoelker, David T, Tissue, and Christopher I, Cazzonelli
- Subjects
Research Article - Abstract
Heatwaves are becoming more frequent with climate warming and can impact tree growth and reproduction. Eucalyptus parramattensis can cope with an extreme heatwave in the field via transpiratory cooling and enhanced leaf thermal tolerance that protected foliar tissues from photo-inhibition and photo-oxidation during natural midday irradiance. Here, we explored whether changes in foliar carotenoids and/or the xanthophyll cycle state can facilitate leaf acclimation to long-term warming and/or an extreme heatwave event. We found that leaves had similar carotenoid levels when grown for one year under ambient and experimental long-term warming (+ 3 °C) conditions in whole tree chambers. Exposure to a 4-day heatwave (> 43 °C) significantly altered the xanthophyll de-epoxidation state of carotenoids revealing one mechanism by which trees could minimise foliar photo-oxidative damage. The levels of zeaxanthin were significantly higher in both young and old leaves during the heatwave, revealing that violaxanthin de-epoxidation and perhaps de novo zeaxanthin synthesis contributed to enhancement of the xanthophyll cycle state. In a future climate of long-term warming and increased heatwave events, leaves of E. parramattensis will be able to utilise biochemical strategies to alter the xanthophyll cycle state and cope with extreme temperatures under natural solar irradiation.
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- 2019
29. Acclimation and adaptation components of the temperature dependence of plant photosynthesis at the global scale
- Author
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Kelsey R. Carter, Nicholas G. Smith, Martijn Slot, Michael J. Aspinwall, Lina M. Mercado, Belinda E. Medlyn, Danielle A. Way, Qingmin Han, Francisco Javier Cano, Jeffrey Q. Chambers, Molly A. Cavaleri, David S. Ellsworth, Eric L. Kruger, Mark G. Tjoelker, Oula Ghannoum, Göran Wallin, Lasse Tarvainen, Peter B. Reich, Johan Uddling, David T. Tissue, Edgard Siza Tribuzy, Dushan Kumarathunge, Dylan N. Dillaway, Jeff W. G. Kelly, Michael Battaglia, Lucas A. Cernusak, Erwin Dreyer, Anna M. Jensen, Kouki Hikosaka, John E. Drake, Yusuke Onoda, Angelica Vårhammar, Martin G. De Kauwe, Kristine Y. Crous, Alistair Rogers, Jeffrey M. Warren, Henrique Furstenau Togashi, Western Sydney University, New York University, New York University [New York] (NYU), NYU System (NYU)-NYU System (NYU), University of North Florida [Jacksonville] (UNF), Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Michigan Technological University (MTU), James Cook University (JCU), University of California [Berkeley], University of California, University of New South Wales [Sydney] (UNSW), Thomashow Learning Laboratories, Partenaires INRAE, SILVA (SILVA), Institut National de la Recherche Agronomique (INRA)-Université de Lorraine (UL)-AgroParisTech, Forestry and Forest Products Research Institute (FFPRI), Tohoku University [Sendai], Linnaeus University, University of Washington [Seattle], University of Wisconsin-Madison, University of Exeter, Centre for Ecology and Hydrology, Kyoto University [Kyoto], Brookhaven National Laboratory [Upton, NY] (BNL), U.S. Department of Energy [Washington] (DOE)-UT-Battelle, LLC-Stony Brook University [SUNY] (SBU), State University of New York (SUNY)-State University of New York (SUNY), Smithsonian Tropical Research Institute, TexasTech University, Swedish University of Agricultural Sciences (SLU), Macquarie University, Universidade Federal do Oeste do Pará, University of Gothenburg (GU), Oak Ridge National Laboratory, University of Western Ontario (UWO), and Duke University [Durham]
- Subjects
0106 biological sciences ,0301 basic medicine ,Stomatal conductance ,Physiology ,[SDV]Life Sciences [q-bio] ,Acclimatization ,Ribulose-Bisphosphate Carboxylase ,maximum electron transport rate ,Cell Respiration ,Plant Science ,Photosynthesis ,Atmospheric sciences ,01 natural sciences ,Models, Biological ,growth temperature ,Ecology and Environment ,Electron Transport ,03 medical and health sciences ,Ecosystem ,climate of origin ,global vegetation models (GVMs) ,maximum carboxylation capacity ,ACi curves ,Temperature ,Vegetation ,15. Life on land ,Carbon Dioxide ,Plants ,Tundra ,Plant Leaves ,030104 developmental biology ,13. Climate action ,J max ,Linear Models ,Environmental science ,Adaptation ,V cmax ,010606 plant biology & botany ,Tropical rainforest - Abstract
International audience; The temperature response of photosynthesis is one of the key factors determining predicted responses to warming in global vegetation models (GVMs). The response may vary geographically, owing to genetic adaptation to climate, and temporally, as a result of acclimation to changes in ambient temperature. Our goal was to develop a robust quantitative global model representing acclimation and adaptation of photosynthetic temperature responses. We quantified and modelled key mechanisms responsible for photosynthetic temperature acclimation and adaptation using a global dataset of photosynthetic CO2 response curves, including data from 141 C3 species from tropical rainforest to Arctic tundra. We separated temperature acclimation and adaptation processes by considering seasonal and common‐garden datasets, respectively. The observed global variation in the temperature optimum of photosynthesis was primarily explained by biochemical limitations to photosynthesis, rather than stomatal conductance or respiration. We found acclimation to growth temperature to be a stronger driver of this variation than adaptation to temperature at climate of origin. We developed a summary model to represent photosynthetic temperature responses and showed that it predicted the observed global variation in optimal temperatures with high accuracy. This novel algorithm should enable improved prediction of the function of global ecosystems in a warming climate.
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- 2019
- Full Text
- View/download PDF
30. Using plant, microbe and soil fauna traits to improve the predictive power of biogeochemical models
- Author
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John E. Drake, Benjamin G. Jackson, Nil Alvarez, Sara Hortal, David W. Johnson, Richard D. Bardgett, Elizabeth M. Baggs, Jocelyn M. Lavallee, Shun Hasegawa, Mingkai Jiang, Brajesh K. Singh, Ellen L. Fry, Pete Smith, Jennifer M. Rhymes, Yolima Carrillo, Mathilde Chomel, Belinda E. Medlyn, Jonathan R. De Long, Lucía Álvarez Garrido, Ian C. Anderson, Laura Castañeda-Gómez, Marta Dondini, Terrestrial Ecology (TE), Producció Animal, and Aigües Marines i Continentals
- Subjects
0106 biological sciences ,Biogeochemical cycle ,intra- and interspecific variation ,Soil biology ,Biodiversity ,Climate change ,010603 evolutionary biology ,01 natural sciences ,above-belowground interactions ,carbon and nitrogen cycling ,mycorrhizae ,Biological sciences ,Ecology, Evolution, Behavior and Systematics ,biodiversity ,effect and response traits ,2. Zero hunger ,Ecology ,010604 marine biology & hydrobiology ,Ecological Modeling ,Plant microbe ,15. Life on land ,climate change ,Work (electrical) ,13. Climate action ,international ,Predictive power ,Environmental science ,community weighted means - Abstract
Process‐based models describing biogeochemical cycling are crucial tools to understanding long‐term nutrient dynamics, especially in the context of perturbations, such as climate and land‐use change. Such models must effectively synthesize ecological processes and properties. For example, in terrestrial ecosystems, plants are the primary source of bioavailable carbon, but turnover rates of essential nutrients are contingent on interactions between plants and soil biota. Yet, biogeochemical models have traditionally considered plant and soil communities in broad terms. The next generation of models must consider how shifts in their diversity and composition affect ecosystem processes. One promising approach to synthesize plant and soil biodiversity and their interactions into models is to consider their diversity from a functional trait perspective. Plant traits, which include heritable chemical, physical, morphological and phenological characteristics, are increasingly being used to predict ecosystem processes at a range of scales, and to interpret biodiversity–ecosystem functional relationships. There is also emerging evidence that the traits of soil microbial and faunal communities can be correlated with ecosystem functions such as decomposition, nutrient cycling, and greenhouse gas production. Here, we draw on recent advances in measuring and using traits of different biota to predict ecosystem processes, and provide a new perspective as to how biotic traits can be integrated into biogeochemical models. We first describe an explicit trait‐based model framework that operates at small scales and uses direct measurements of ecosystem properties; second, an integrated approach that operates at medium scales and includes interactions between biogeochemical cycling and soil food webs; and third, an implicit trait‐based model framework that associates soil microbial and faunal functional groups with plant functional groups, and operates at the Earth‐system level. In each of these models, we identify opportunities for inclusion of traits from all three groups to reduce model uncertainty and improve understanding of biogeochemical cycles. These model frameworks will generate improved predictive capacity of how changes in biodiversity regulate biogeochemical cycles in terrestrial ecosystems. Further, they will assist in developing a new generation of process‐based models that include plant, microbial, and faunal traits and facilitate dialogue between empirical researchers and modellers. info:eu-repo/semantics/acceptedVersion
- Published
- 2019
31. No evidence for triose phosphate limitation of light-saturated leaf photosynthesis under current atmospheric CO
- Author
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Dushan P, Kumarathunge, Belinda E, Medlyn, John E, Drake, Alistair, Rogers, and Mark G, Tjoelker
- Subjects
Plant Leaves ,Light ,Atmosphere ,Trioses ,Temperature ,Carbon Dioxide ,Photosynthesis ,Phosphates - Abstract
The triose phosphate utilization (TPU) rate has been identified as one of the processes that can limit terrestrial plant photosynthesis. However, we lack a robust quantitative assessment of TPU limitation of photosynthesis at the global scale. As a result, TPU, and its potential limitation of photosynthesis, is poorly represented in terrestrial biosphere models (TBMs). In this study, we utilized a global data set of photosynthetic CO
- Published
- 2019
32. Drought response strategies and hydraulic traits contribute to mechanistic understanding of plant dry-down to hydraulic failure
- Author
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Michael J. Aspinwall, John E. Drake, Belinda E. Medlyn, Sebastian Pfautsch, Chris J. Blackman, Chelsea Maier, Brendan Choat, Danielle Creek, David T. Tissue, Sylvain Delzon, Anthony P. O'Grady, Hawkesbury Institute for the Environment, Western Sydney University, University of North Florida [Jacksonville] (UNF), Forest and Natural Resources Management, Partenaires INRAE, Land and Water, Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Biodiversité, Gènes & Communautés (BioGeCo), and Institut National de la Recherche Agronomique (INRA)-Université de Bordeaux (UB)
- Subjects
0106 biological sciences ,Stomatal conductance ,pinus ,Physiology ,Range (biology) ,[SDV]Life Sciences [q-bio] ,Drought tolerance ,hydraulics ,Plant Science ,drought ,Biology ,01 natural sciences ,Trees ,03 medical and health sciences ,recovery ,Magnoliopsida ,Stress, Physiological ,rainfall exclusion ,rainout shelter ,030304 developmental biology ,0303 health sciences ,Biomass (ecology) ,Eucalyptus ,Plant Stems ,Water stress ,fungi ,Xylem ,food and beverages ,NSCs ,15. Life on land ,mortality ,Droughts ,Plant Leaves ,Agronomy ,Plant Stomata ,010606 plant biology & botany ,Woody plant - Abstract
Drought-induced tree mortality alters forest structure and function, yet our ability to predict when and how different species die during drought remains limited. Here, we explore how stomatal control and drought tolerance traits influence the duration of drought stress leading to critical levels of hydraulic failure. We examined the growth and physiological responses of four woody plant species (three angiosperms and one conifer) representing a range of water-use and drought tolerance traits over the course of two controlled drought–recovery cycles followed by an extended dry-down. At the end of the final dry-down phase, we measured changes in biomass ratios and leaf carbohydrates. During the first and second drought phases, plants of all species closed their stomata in response to decreasing water potential, but only the conifer species avoided water potentials associated with xylem embolism as a result of early stomatal closure relative to thresholds of hydraulic dysfunction. The time it took plants to reach critical levels of water stress during the final dry-down was similar among the angiosperms (ranging from 39 to 57 days to stemP88) and longer in the conifer (156 days to stemP50). Plant dry-down time was influenced by a number of factors including species stomatal-hydraulic safety margin (gsP90 – stemP50), as well as leaf succulence and minimum stomatal conductance. Leaf carbohydrate reserves (starch) were not depleted at the end of the final dry-down in any species, irrespective of the duration of drought. These findings highlight the need to consider multiple structural and functional traits when predicting the timing of hydraulic failure in plants.
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- 2019
33. Range size and growth temperature influence Eucalyptus species responses to an experimental heatwave
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Malcolm Possell, Steven C. Van Sluyter, Siobhan Dennison, Owen K. Atkin, John E. Drake, Angelica Vårhammar, Mark G. Tjoelker, David T. Tissue, Peter B. Reich, Michael J. Aspinwall, Paul D. Rymer, and Sebastian Pfautsch
- Subjects
0106 biological sciences ,Thermotolerance ,Stomatal conductance ,010504 meteorology & atmospheric sciences ,Range (biology) ,Climate Change ,Large range ,Biology ,Forests ,Photosynthesis ,010603 evolutionary biology ,01 natural sciences ,chemistry.chemical_compound ,Species Specificity ,Environmental Chemistry ,Isoprene ,0105 earth and related environmental sciences ,General Environmental Science ,Global and Planetary Change ,Eucalyptus ,Ecology ,Plant Dispersal ,Global warming ,Temperature ,15. Life on land ,Plant Leaves ,Horticulture ,chemistry ,13. Climate action ,Tree species ,Heat-Shock Response - Abstract
Understanding forest tree responses to climate warming and heatwaves is important for predicting changes in tree species diversity, forest C uptake, and vegetation-climate interactions. Yet, tree species differences in heatwave tolerance and their plasticity to growth temperature remain poorly understood. In this study, populations of four Eucalyptus species, two with large range sizes and two with comparatively small range sizes, were grown under two temperature treatments (cool and warm) before being exposed to an equivalent experimental heatwave. We tested whether the species with large and small range sizes differed in heatwave tolerance, and whether trees grown under warmer temperatures were more tolerant of heatwave conditions than trees grown under cooler temperatures. Visible heatwave damage was more common and severe in the species with small rather than large range sizes. In general, species that showed less tissue damage maintained higher stomatal conductance, lower leaf temperatures, larger increases in isoprene emissions, and less photosynthetic inhibition than species that showed more damage. Species exhibiting more severe visible damage had larger increases in heat shock proteins (HSPs) and respiratory thermotolerance (Tmax ). Thus, across species, increases in HSPs and Tmax were positively correlated, but inversely related to increases in isoprene emissions. Integration of leaf gas-exchange, isoprene emissions, proteomics, and respiratory thermotolerance measurements provided new insight into mechanisms underlying variability in tree species heatwave tolerance. Importantly, warm-grown seedlings were, surprisingly, more susceptible to heatwave damage than cool-grown seedlings, which could be associated with reduced enzyme concentrations in leaves. We conclude that species with restricted range sizes, along with trees growing under climate warming, may be more vulnerable to heatwaves of the future.
- Published
- 2018
34. Stoichiometry constrains microbial response to root exudation- insights from a model and a field experiment in a temperate forest
- Author
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B. A. Darby, John E. Drake, Richard P. Phillips, Adrien C. Finzi, Marc-André Giasson, and Mark A. Kramer
- Subjects
chemistry.chemical_classification ,Exudate ,Nutrient cycle ,Rhizosphere ,Soil organic matter ,lcsh:QE1-996.5 ,lcsh:Life ,Mineralization (soil science) ,Biology ,lcsh:Geology ,chemistry.chemical_compound ,lcsh:QH501-531 ,chemistry ,lcsh:QH540-549.5 ,Botany ,medicine ,biology.protein ,Lignin ,Exoenzyme ,Organic matter ,lcsh:Ecology ,medicine.symptom ,Ecology, Evolution, Behavior and Systematics ,Earth-Surface Processes - Abstract
Plant roots release a wide range of chemicals into soils. This process, termed root exudation, is thought to increase the activity of microbes and the exoenzymes they synthesize, leading to accelerated rates of carbon (C) mineralization and nutrient cycling in rhizosphere soils relative to bulk soils. The nitrogen (N) content of microbial biomass and exoenzymes may introduce a stoichiometric constraint on the ability of microbes to effectively utilize the root exudates, particularly if the exudates are rich in C but low in N. We combined a theoretical model of microbial activity with an exudation experiment to test the hypothesis that the ability of soil microbes to utilize root exudates for the synthesis of additional biomass and exoenzymes is constrained by N availability. The field experiment simulated exudation by automatically pumping solutions of chemicals often found in root exudates ("exudate mimics") containing C alone or C in combination with N (C : N ratio of 10) through microlysimeter "root simulators" into intact forest soils in two 50-day experiments. The delivery of C-only exudate mimics increased microbial respiration but had no effect on microbial biomass or exoenzyme activities. By contrast, experimental delivery of exudate mimics containing both C and N significantly increased microbial respiration, microbial biomass, and the activity of exoenzymes that decompose low molecular weight components of soil organic matter (SOM, e.g., cellulose, amino sugars), while decreasing the activity of exoenzymes that degrade high molecular weight SOM (e.g., polyphenols, lignin). The modeling results were consistent with the experiments; simulated delivery of C-only exudates induced microbial N-limitation, which constrained the synthesis of microbial biomass and exoenzymes. Exuding N as well as C alleviated this stoichiometric constraint in the model, allowing for increased exoenzyme production, the priming of decomposition, and a net release of N from SOM (i.e., mineralization). The quantity of N released from SOM in the model simulations was, under most circumstances, in excess of the N in the exudate pulse, suggesting that the exudation of N-containing compounds can be a viable strategy for plant-N acquisition via a priming effect. The experimental and modeling results were consistent with our hypothesis that N-containing compounds in root exudates affect rhizosphere processes by providing substrates for the synthesis of N-rich microbial biomass and exoenzymes. This study suggests that exudate stoichiometry is an important and underappreciated driver of microbial activity in rhizosphere soils.
- Published
- 2018
35. Supplementary material to 'Examining the evidence for sustained transpiration during heat extremes'
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Martin G. De Kauwe, Belinda E. Medlyn, Andrew J. Pitman, John E. Drake, Anna Ukkola, Anne Griebal, Elise Pendall, Suzanne Prober, and Michael Roderick
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- 2018
36. Examining the evidence for sustained transpiration during heat extremes
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Michael L. Roderick, Elise Pendall, Anne Griebal, Martin G. De Kauwe, Andrew J. Pitman, Anna M. Ukkola, Suzanne M. Prober, Belinda E. Medlyn, and John E. Drake
- Subjects
Work (thermodynamics) ,Vapour Pressure Deficit ,Latent heat ,Environmental science ,Ecosystem ,Climate model ,Decoupling (cosmology) ,Photosynthesis ,Atmospheric sciences ,Transpiration - Abstract
Recent experimental evidence suggests that during heat extremes, wooded ecosystems may decouple photosynthesis and transpiration: reducing photosynthesis to near zero but increasing transpiration into the boundary layer. This feedback may act to dampen, rather than amplify, heat extremes in wooded ecosystems. We examined eddy-covariance databases (OzFlux and FLUXNET2015) to identify whether there was field-based evidence to support these experimental findings. We focused on two types of heat extremes: (i) the three days leading up to a temperature extreme, defined as including a daily maximum temperature > 37 °C (similar to the widely used TXx metric) and (ii) heatwaves, defined as three or more consecutive days above 35 °C. When focussing on (i), we found some evidence of reduced photosynthesis and sustained or increased latent heat fluxes in seven Australian evergreen wooded flux sites. However, when considering the role of vapour pressure deficit and focusing on (ii), we were unable to conclusively disentangle the decoupling between photosynthesis and latent heat flux from the effect of increasing vapour pressure deficit. Outside of Australia, the Tier-1 FLUXNET2015 database provided limited scope to tackle this issue as it does not sample sufficient high temperature events with which to probe the physiological response of trees to extreme heat. Thus, further work is required to determine whether this photosynthetic decoupling occurs widely, ideally by matching experimental species with those found at eddy-covariance towers sites. Such measurements would allow this decoupling mechanism to be probed experimentally and at the ecosystem scale. Transpiration during heatwaves remains a key issue to resolve, as no land surface model includes a decoupling mechanism, and any potential dampening of the land-atmosphere amplification is thus not included in climate model projections.
- Published
- 2018
37. Responses of respiration in the light to warming in field-grown trees: a comparison of the thermal sensitivity of the Kok and Laisk methods
- Author
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Danielle A. Way, Michael J. Aspinwall, Kristine Y. Crous, Courtney E. Campany, Oula Ghannoum, John E. Drake, David T. Tissue, and Mark G. Tjoelker
- Subjects
0106 biological sciences ,0301 basic medicine ,Light ,Physiology ,Chemistry ,Cell Respiration ,Phosphoenolpyruvate carboxylase activity ,Temperature ,Plant Science ,15. Life on land ,Carbon Dioxide ,Darkness ,01 natural sciences ,Acclimatization ,Degree (temperature) ,Mitochondria ,Trees ,03 medical and health sciences ,Horticulture ,030104 developmental biology ,13. Climate action ,Respiration ,Plant Stomata ,Mesophyll Cells ,010606 plant biology & botany - Abstract
The Kok and Laisk techniques can both be used to estimate light respiration Rlight . We investigated whether responses of Rlight to short- and long-term changes in leaf temperature depend on the technique used to estimate Rlight . We grew Eucalyptus tereticornis in whole-tree chambers under ambient temperature (AT) or AT + 3°C (elevated temperature, ET). We assessed dark respiration Rdark and light respiration with the Kok (RKok ) and Laisk (RLaisk ) methods at four temperatures to determine the degree of light suppression of respiration using both methods in AT and ET trees. The ET treatment had little impact on Rdark , RKok or RLaisk . Although the thermal sensitivities of RKok or RLaisk were similar, RKok was higher than RLaisk . We found negative values of RLaisk at the lowest measurement temperatures, indicating positive net CO2 uptake, which we propose may be related to phosphoenolpyruvate carboxylase activity. Light suppression of Rdark decreased with increasing leaf temperature, but the degree of suppression depended on the method used. The Kok and Laisk methods do not generate the same estimates of Rlight or light suppression of Rdark between 20 and 35°C. Negative rates of RLaisk imply that this method may become less reliable at low temperatures.
- Published
- 2018
38. Trees tolerate an extreme heatwave via sustained transpirational cooling and increased leaf thermal tolerance
- Author
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Peter B. Reich, John E. Drake, Dushan Kumarathunge, Angelica Vårhammar, Chris J. Blackman, Rosana López, Owen K. Atkin, Kristine Y. Crous, Brendan Choat, Belinda E. Medlyn, Remko A. Duursma, Sebastian Pfautsch, Martin G. De Kauwe, Adrienne B. Nicotra, Craig V. M. Barton, Michael J. Aspinwall, David T. Tissue, Mingkai Jiang, Mark G. Tjoelker, Andrea Leigh, Hawkesbury Institute for the Environment, Western Sydney University, SUNY College of Environmental Science and Forestry (SUNY-ESF), State University of New York (SUNY), Department of Forest Resources, University of Minnesota [Twin Cities] (UMN), University of Minnesota System-University of Minnesota System, School of Life Sciences, University of Technology Sydney (UTS), Laboratoire de Physique et Physiologie Intégratives de l’Arbre en environnement Fluctuant (PIAF), Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut National de la Recherche Agronomique (INRA), University of North Florida [Jacksonville] (UNF), University of New South Wales [Sydney] (UNSW), Australian National University (ANU), Australian Research Council Discovery DP140103415, and New South Wales Climate Action Grant NSW T07/CAG/016
- Subjects
0106 biological sciences ,Canopy ,Irrigation ,Hot Temperature ,010504 meteorology & atmospheric sciences ,warming ,Climate Change ,[SDV]Life Sciences [q-bio] ,Climate change ,Forests ,Photosynthesis ,Atmospheric sciences ,01 natural sciences ,thermal tolerance ,Trees ,heatwave ,Environmental Chemistry ,0105 earth and related environmental sciences ,General Environmental Science ,Transpiration ,Eucalyptus parramattensis ,Global and Planetary Change ,Eucalyptus ,photosynthesis ,Ecology ,Global warming ,temperature ,Plant Transpiration ,Vegetation ,15. Life on land ,Plant Leaves ,climate change ,13. Climate action ,latent cooling ,[SDE]Environmental Sciences ,Environmental science ,Climate model ,010606 plant biology & botany - Abstract
International audience; Heatwaves are likely to increase in frequency and intensity with climate change, which may impair tree function and forest C uptake. However, we have little information regarding the impact of extreme heatwaves on the physiological performance of large trees in the field. Here, we grew Eucalyptus parramattensis trees for 1 year with experimental warming (+ 3 degrees C) in a field setting, until they were greater than 6 m tall. We withheld irrigation for 1 month to dry the surface soils and then implemented an extreme heatwave treatment of 4 consecutive days with air temperatures exceeding 43 degrees C, while monitoring whole-canopy exchange of CO2 and H2O, leaf temperatures, leaf thermal tolerance, and leaf and branch hydraulic status. The heatwave reduced midday canopy photosynthesis to near zero but transpiration persisted, maintaining canopy cooling. A standard photosynthetic model was unable to capture the observed decoupling between photosynthesis and transpiration at high temperatures, suggesting that climate models may underestimate a moderating feedback of vegetation on heatwave intensity. The heatwave also triggered a rapid increase in leaf thermal tolerance, such that leaf temperatures observed during the heatwave were maintained within the thermal limits of leaf function. All responses were equivalent for trees with a prior history of ambient and warmed (+ 3 degrees C) temperatures, indicating that climate warming conferred no added tolerance of heatwaves expected in the future. This coordinated physiological response utilizing latent cooling and adjustment of thermal thresholds has implications for tree tolerance of future climate extremes as well as model predictions of future heatwave intensity at landscape and global scales.
- Published
- 2018
39. Photosynthesis and carbon allocation are both important predictors of genotype productivity responses to elevated CO2 in Eucalyptus camaldulensis
- Author
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David T. Tissue, Víctor Resco de Dios, Renee Smith, Paul D. Rymer, Mark G. Tjoelker, Chris J. Blackman, John E. Drake, Florian A. Busch, Michael J. Aspinwall, Michael E. Loik, and Sebastian Pfautsch
- Subjects
0106 biological sciences ,Genotype ,Physiology ,Nitrogen ,Ribulose-Bisphosphate Carboxylase ,Plant Science ,Photosynthesis ,010603 evolutionary biology ,01 natural sciences ,Trees ,chemistry.chemical_compound ,Dry weight ,Biomass ,Plant Proteins ,Biomass (ecology) ,Eucalyptus ,biology ,RuBisCO ,Australia ,food and beverages ,Carbon sink ,Carbon Dioxide ,Carbon ,Plant Leaves ,Horticulture ,Eucalyptus camaldulensis ,chemistry ,Productivity (ecology) ,Carbon dioxide ,biology.protein ,010606 plant biology & botany - Abstract
Intraspecific variation in biomass production responses to elevated atmospheric carbon dioxide (eCO2) could influence tree species' ecological and evolutionary responses to climate change. However, the physiological mechanisms underlying genotypic variation in responsiveness to eCO2 remain poorly understood. In this study, we grew 17 Eucalyptus camaldulensis Dehnh. subsp. camaldulensis genotypes (representing provenances from four different climates) under ambient atmospheric CO2 and eCO2. We tested whether genotype leaf-scale photosynthetic and whole-tree carbon (C) allocation responses to eCO2 were predictive of genotype biomass production responses to eCO2. Averaged across genotypes, growth at eCO2 increased in situ leaf net photosynthesis (Anet) (29%) and leaf starch concentrations (37%). Growth at eCO2 reduced the maximum carboxylation capacity of Rubisco (-4%) and leaf nitrogen per unit area (Narea, -6%), but Narea calculated on a total non-structural carbohydrate-free basis was similar between treatments. Growth at eCO2 also increased biomass production and altered C allocation by reducing leaf area ratio (-11%) and stem mass fraction (SMF, -9%), and increasing leaf mass area (18%) and leaf mass fraction (5%). Overall, we found few significant CO2 × provenance or CO2 × genotype (within provenance) interactions. However, genotypes that showed the largest increases in total dry mass at eCO2 had larger increases in root mass fraction (with larger decreases in SMF) and photosynthetic nitrogen-use efficiency (PNUE) with CO2 enrichment. These results indicate that genetic differences in PNUE and carbon sink utilization (in roots) are both important predictors of tree productivity responsiveness to eCO2.
- Published
- 2017
40. Traits and trade-offs in whole-tree hydraulic architecture along the vertical axis of Eucalyptus grandis
- Author
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John E. Drake, Mark G. Tjoelker, Frederic Lens, Rob Langelaan, David T. Tissue, Sebastian Pfautsch, Larissa Chacon-Doria, and Michael J. Aspinwall
- Subjects
0106 biological sciences ,Eucalyptus grandis ,Apical dominance ,Hydraulic conductivity ,Plant Science ,Biology ,Stem water potential ,010603 evolutionary biology ,01 natural sciences ,Light and electron microscopy ,Trees ,Microscopy, Electron, Transmission ,Xylem ,Vessel taper ,Intervessel pit membranes ,Eucalyptus ,Water transport ,Plant Stems ,Water ,Original Articles ,Tree height ,Tree (graph theory) ,Apex (geometry) ,Plant Leaves ,Horticulture ,Tree water use ,Vessel anatomy ,Whole-tree assessment ,Water use ,010606 plant biology & botany - Abstract
• Background and Aims Sapwood traits like vessel diameter and intervessel pit characteristics play key rolesin maintaining hydraulic integrity of trees. Surprisingly little is known about how sapwood traits covary with treeheight and how such trait-based variation could affect the efficiency of water transport in tall trees. This studypresents a detailed analysis of structural and functional traits along the vertical axes of tall Eucalyptus grandis trees. • Methods To assess a wide range of anatomical and physiological traits, light and electron microscopy wasused, as well as eld measurements of tree architecture, water use, stem water potential and leaf area distribution. • Key Results Strong apical dominance of water transport resulted in increased volumetric water supply per unitleaf area with tree height. This was realized by continued narrowing (from 250 to 20 μm) and an exponentialincrease in frequency (from 600 to 13 000 cm−2) of vessels towards the apex. The widest vessels were detected atleast 4 m above the stem base, where they were associated with the thickest intervessel pit membranes. In addition,this study established the lower limit of pit membrane thickness in tall E. grandis at ~375 nm. This minimumthickness was maintained over a large distance in the upper stem, where vessel diameters continued to narrow.• Conclusions The analyses of xylem ultrastructure revealed complex, synchronized trait covariation and trade-offs with increasing height in E. grandis. Anatomical traits related to xylem vessels and those related to architectureof pit membranes were found to increase efficiency and apical dominance of water transport. This study underlinesthe importance of studying tree hydraulic functioning at organismal scale. Results presented here will improveunderstanding height-dependent structure–function patterns in tall trees.
- Published
- 2017
41. Elevated CO2 does not increase eucalypt forest productivity on a low-phosphorus soil
- Author
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Andrew N. Gherlenda, Peter B. Reich, Kristine Y. Crous, David S. Ellsworth, Teresa E. Gimeno, Catriona A. Macdonald, John E. Drake, Mark G. Tjoelker, Julia Cooke, Jeff R. Powell, Ian C. Anderson, Belinda E. Medlyn, Hawkesbury Institute for the Environment [Richmond] (HIE), Western Sydney University (UWS), School of Environment, Earth and Ecosystem Sciences [Milton Keynes], The Open University [Milton Keynes] (OU), Interactions Sol Plante Atmosphère (ISPA), Institut National de la Recherche Agronomique (INRA)-Ecole Nationale Supérieure des Sciences Agronomiques de Bordeaux-Aquitaine (Bordeaux Sciences Agro), Department of Forest Resources, University of Minnesota [Twin Cities], University of Minnesota System-University of Minnesota System, Western Sydney University, Faculty of Science, Technology, Engineering and Mathematics [Milton Keynes], The Open University [Milton Keynes] (OU)-The Open University [Milton Keynes] (OU), Interactions Sol Plante Atmosphère (UMR ISPA), and University of Minnesota [Twin Cities] (UMN)
- Subjects
0106 biological sciences ,010504 meteorology & atmospheric sciences ,Ecology ,Phosphorus ,[SDV]Life Sciences [q-bio] ,productivité forestière ,Tropics ,chemistry.chemical_element ,Vegetation ,15. Life on land ,Environmental Science (miscellaneous) ,Evergreen ,Carbon sequestration ,carbone atmosphérique ,01 natural sciences ,Productivity (ecology) ,chemistry ,13. Climate action ,Soil water ,photosynthèse foliaire ,Temperate climate ,Environmental science ,Social Sciences (miscellaneous) ,010606 plant biology & botany ,0105 earth and related environmental sciences - Abstract
Experimental evidence from a mature, phosphorous-limited, eucalypt forest finds that aboveground productivity was not significantly stimulated by elevated CO2. Findings suggest that this effect may be limited across much of the tropics. Rising atmospheric CO2 stimulates photosynthesis and productivity of forests, offsetting CO2 emissions1,2. Elevated CO2 experiments in temperate planted forests yielded ∼23% increases in productivity3 over the initial years. Whether similar CO2 stimulation occurs in mature evergreen broadleaved forests on low-phosphorus (P) soils is unknown, largely due to lack of experimental evidence4. This knowledge gap creates major uncertainties in future climate projections5,6 as a large part of the tropics is P-limited. Here, we increased atmospheric CO2 concentration in a mature broadleaved evergreen eucalypt forest for three years, in the first large-scale experiment on a P-limited site. We show that tree growth and other aboveground productivity components did not significantly increase in response to elevated CO2 in three years, despite a sustained 19% increase in leaf photosynthesis. Moreover, tree growth in ambient CO2 was strongly P-limited and increased by ∼35% with added phosphorus. The findings suggest that P availability may potentially constrain CO2-enhanced productivity in P-limited forests; hence, future atmospheric CO2 trajectories may be higher than predicted by some models. As a result, coupled climate–carbon models should incorporate both nitrogen and phosphorus limitations to vegetation productivity7 in estimating future carbon sinks.
- Published
- 2017
42. Seasonal plasticity in the temperature sensitivity of microbial activity in three temperate forest soils
- Author
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John E. Drake, Marc-André Giasson, K. J. Spiller, and Adrien C. Finzi
- Subjects
Ecology ,biology ,Soil organic matter ,Q10 ,Temperate forest ,Mineralization (soil science) ,Seasonality ,biology.organism_classification ,Atmospheric sciences ,medicine.disease ,Tsuga ,Snowmelt ,Soil water ,medicine ,Environmental science ,Ecology, Evolution, Behavior and Systematics - Abstract
The temperature sensitivity of soil organic matter (SOM) decomposition has been a source of much debate, given the potential feedbacks with climate warming. Here, we evaluated possible seasonal variation in the temperature sensitivity of microbially mediated soil fluxes related to decomposition (net N mineralization, net nitrification, proteolysis, the maximum velocity (Vmax) of proteolysis, microbial respiration, and the Vmax of four soil exo-enzymes) across forests dominated by eastern hemlock (Tsuga canadensis), white ash (Fraxinus americana), and red oak (Quercus rubra) in central Massachusetts, USA. We asked two simple questions: (1) do temperature sensitivities vary across forest types or different steps of the decomposition process, and (2) do temperature sensitivities display plasticity on a seasonal time frame? We observed substantial variation in temperature sensitivities (Q10 and R10 values) across the different fluxes and forest types. The ash soils exhibited the strongest temperature sensitivities and the mineral-N fluxes exhibited higher temperature sensitivities relative to the proteolytic fluxes or microbial respiration. The Vmax of soil exo-enzymes varied considerably in an interactive manner across forests and time, and the response of some enzymes was consistent with the thermal plasticity. The enzymatic kinetic properties Vmax and Km (half-saturation constant) were strongly correlated with slopes that differed across enzymes, reflecting an enzyme-specific tradeoff between maximum catalytic rate and substrate-binding efficiency. Generally, Q10 values were largely constant, but R10 values varied in a manner consistent with distinct seasonal plasticity. There was a consistent seasonal shift in R10 values coincident with snowmelt, suggesting that the time following snowmelt is a particularly interesting and dynamic period of microbial activity in these temperate forests.
- Published
- 2013
43. PUTTING THE PUZZLE TOGETHER: INVESTIGATING HYDRAULIC FUNCTIONING AND WATER TRANSPORT AT HIGH SPATIAL RESOLUTION IN TALL TREES
- Author
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Sebastian Pfautsch, Michael J. Aspinwall, John E. Drake, Brendan Choat, T Burykin, David T. Tissue, and Mark G. Tjoelker
- Subjects
Hydrology ,Engineering ,Stomatal conductance ,Water transport ,Moisture ,business.industry ,Water flow ,Microclimate ,Horticulture ,Evergreen ,business ,Eucalyptus ,Water use - Abstract
Understanding of tree water use ranging from individual to ecosystem scale has greatly progressed over past decades. However, studies that integrate measurements of tree water use, physiological functioning, wood anatomy and whole-tree architecture are scarce, and are needed for developing a holistic perspective on plant function and responses to environmental drivers. Here we introduce the experimental design of a research project (December 2012 - March 2013) to provide novel insights to whole-tree hydraulic function of tall trees (>20 m). The study focuses on Eucalyptus grandis , an evergreen angiosperm native to eastern Australia. The experiment used a large number of sap flow sensors distributed among 12 trees in a forest plantation at different levels of intensity – the most intensively studied tree had 52 sap flow sensors installed along its vertical axis and in all branches of the lower-, mid- and top-canopy. Parameters describing stem and branch architecture have been recorded. In addition, we operated a number of other sensor types at various heights within the trees (dendrometers, psychrometers, linPAR sensors, microclimate loggers) and belowground (soil temperature and moisture) to further complete information about the movement of water and key environmental variables. Leaf water potential, net photosynthesis and stomatal conductance were measured for three full diel cycles during early-, mid- and late-summer 2012-2013. At the termination of the experiment, trees were felled to facilitate assessment of branch traits (e.g., SLA, total branch leaf area). Wood was extracted from all locations of sap flow measurement to determine anatomical characteristics of vessels and to allow reconstruction of water conducting networks. Finally, all streams of information (hydraulic, physiological, anatomical, environmental) were merged to systematically reconstruct the tree in virtual space, developing a 3-dimensional representation of in situ water flow through vessel networks under varying natural environmental conditions. INTRODUCTION
- Published
- 2013
44. Root carbon inputs to the rhizosphere stimulate extracellular enzyme activity and increase nitrogen availability in temperate forest soils
- Author
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Adrien C. Finzi, Edward R. Brzostek, John E. Drake, and Alison Greco
- Subjects
chemistry.chemical_classification ,Rhizosphere ,Soil organic matter ,Bulk soil ,Temperate forest ,Biology ,Enzyme assay ,Soil respiration ,chemistry ,Agronomy ,Botany ,biology.protein ,Environmental Chemistry ,Organic matter ,Nitrogen cycle ,Earth-Surface Processes ,Water Science and Technology - Abstract
The exudation of carbon (C) by tree roots stimulates microbial activity and the production of extracellular enzymes in the rhizosphere. Here, we investigated whether the strength of rhizosphere processes differed between temperate forest trees that vary in soil organic matter (SOM) chemistry and associate with either ectomycorrhizal (ECM) or arbuscular mycorrhizal (AM) fungi. We measured rates of root exudation, microbial and extracellular enzyme activity, and nitrogen (N) availability in samples of rhizosphere and bulk soil influenced by four temperate forest tree species (i.e., to estimate a rhizosphere effect). Although not significantly different between species, root exudation ranged from 0.36 to 1.10 g C m−2 day−1, representing a small but important transfer of C to rhizosphere microbes. The magnitude of the rhizosphere effects could not be easily characterized by mycorrhizal associations or SOM chemistry. Ash had the lowest rhizosphere effects and beech had the highest rhizosphere effects, representing one AM and one ECM species, respectively. Hemlock and sugar maple had equivalent rhizosphere effects on enzyme activity. However, the form of N produced in the rhizosphere varied with mycorrhizal association. Enhanced enzyme activity primarily increased amino acid availability in ECM rhizospheres and increased inorganic N availability in AM rhizospheres. These results show that the exudation of C by roots can enhance extracellular enzyme activity and soil-N cycling. This work suggests that global changes that alter belowground C allocation have the potential to impact the form and amount of N to support primary production in ECM and AM stands.
- Published
- 2012
45. Trenching reduces soil heterotrophic activity in a loblolly pine ( Pinus taeda ) forest exposed to elevated atmospheric [CO 2 ] and N fertilization
- Author
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Marc-André Giasson, A. C. Oishi, Kurt H. Johnsen, Adrien C. Finzi, John E. Drake, and Ram Oren
- Subjects
Atmospheric Science ,Global and Planetary Change ,Soil organic matter ,Proteolytic enzymes ,Heterotroph ,Forestry ,Mineralization (soil science) ,Biology ,Soil respiration ,Agronomy ,Soil water ,Nitrification ,Autotroph ,Agronomy and Crop Science - Abstract
Forests return large quantities of C to the atmosphere through soil respiration ( R soil ), which is often conceptually separated into autotrophic C respired by living roots ( R root ) and heterotrophic decomposition ( R het ) of soil organic matter (SOM). Live roots provide C sources for microbial metabolism via exudation, allocation to fungal associates, sloughed-off cells, and secretions such as mucilage production, suggesting a coupling between the activity of roots and heterotrophs. We addressed the strength of root effects on the activity of microbes and exo-enzymes by removing live-root-C inputs to areas of soil with a trenching experiment. We examined the extent to which trenching affected metrics of soil heterotrophic activity (proteolytic enzyme activity, microbial respiration, potential net N mineralization and nitrification, and exo-enzyme activities) in a forest exposed to elevated atmospheric [CO 2 ] and N fertilization, and used automated measurements of R soil in trenched and un-trenched plots to estimate R root and R het components. Trenching decreased many metrics of heterotrophic activity and increased net N mineralization and nitrification, suggesting that the removal of root-C inputs reduced R het by exacerbating microbial C limitation and stimulating waste-N excretion. This trenching effect was muted by N fertilization alone but not when N fertilization was combined with elevated CO 2 , consistent with known patterns of belowground C allocation at this site. Live-root-C inputs to soils and heterotrophic activity are tightly coupled, so root severing techniques like trenching are not likely to achieve robust quantitative estimates of R root or R het .
- Published
- 2012
46. Convergent acclimation of leaf photosynthesis and respiration to prevailing ambient temperatures under current and warmer climates in Eucalyptus tereticornis
- Author
-
John E. Drake, Peter B. Reich, David T. Tissue, Oula Ghannoum, Mark G. Tjoelker, Michael J. Aspinwall, Angelica Vårhammar, and Courtney E. Campany
- Subjects
0106 biological sciences ,010504 meteorology & atmospheric sciences ,Light ,Physiology ,Nitrogen ,Acclimatization ,Climate ,Cell Respiration ,Carbohydrates ,Climate change ,Plant Science ,Photosynthesis ,01 natural sciences ,Eucalyptus tereticornis ,Trees ,Botany ,Respiration ,0105 earth and related environmental sciences ,Analysis of Variance ,Eucalyptus ,biology ,AMAX ,Global warming ,Temperature ,15. Life on land ,Carbon Dioxide ,biology.organism_classification ,Plant Leaves ,Horticulture ,13. Climate action ,Linear Models ,010606 plant biology & botany - Abstract
Summary Understanding physiological acclimation of photosynthesis and respiration is important in elucidating the metabolic performance of trees in a changing climate. Does physiological acclimation to climate warming mirror acclimation to seasonal temperature changes? We grew Eucalyptus tereticornis trees in the field for 14 months inside 9-m tall whole-tree chambers tracking ambient air temperature (Tair) or ambient Tair + 3°C (i.e. ‘warmed’). We measured light- and CO2-saturated net photosynthesis (Amax) and night-time dark respiration (R) each month at 25°C to quantify acclimation. Tree growth was measured, and leaf nitrogen (N) and total nonstructural carbohydrate (TNC) concentrations were determined to investigate mechanisms of acclimation. Warming reduced Amax and R measured at 25°C compared to ambient-grown trees. Both traits also declined as mean daily Tair increased, and did so in a similar way across temperature treatments. Amax and R (at 25°C) both increased as TNC concentrations increased seasonally; these relationships appeared to arise from source–sink imbalances, suggesting potential substrate regulation of thermal acclimation. We found that photosynthesis and respiration each acclimated equivalently to experimental warming and seasonal temperature change of a similar magnitude, reflecting a common, nearly homeostatic constraint on leaf carbon exchange that will be important in governing tree responses to climate warming.
- Published
- 2016
47. Using models to guide field experiments:a prioripredictions for the CO2response of a nutrient- and water-limited native Eucalypt woodland
- Author
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Bernard Pak, Teresa E. Gimeno, Anthony P. Walker, Richard J. Norby, K. A. Luus, John E. Drake, Belinda E. Medlyn, Martin G. De Kauwe, Catriona A. Macdonald, Mikhail Mishurov, Sönke Zaehle, Ying-Ping Wang, Remko A. Duursma, Kristine Y. Crous, Sally A. Power, Xiaojuan Yang, David S. Ellsworth, Mark G. Tjoelker, Benjamin Smith, Hawkesbury Institute for the Environment, Western Sydney University, Department of Biological Sciences, Macquarie University, Max Planck Institute for Biogeochemistry (MPI-BGC), Max-Planck-Gesellschaft, Oak Ridge National Laboratory, Lund University [Lund], Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Interactions Sol Plante Atmosphère (UMR ISPA), and Institut National de la Recherche Agronomique (INRA)-Ecole Nationale Supérieure des Sciences Agronomiques de Bordeaux-Aquitaine (Bordeaux Sciences Agro)
- Subjects
0106 biological sciences ,010504 meteorology & atmospheric sciences ,Climate Change ,[SDV]Life Sciences [q-bio] ,Climate change ,ecosystem model ,Woodland ,drought ,Forests ,01 natural sciences ,Carbon Cycle ,Ecosystem model ,Environmental Chemistry ,Ecosystem ,Photosynthesis ,phosphorus ,0105 earth and related environmental sciences ,General Environmental Science ,2. Zero hunger ,Hydrology ,Eucalyptus ,Global and Planetary Change ,Data collection ,Ecology ,Water ,Primary production ,carbon dioxide ,Vegetation ,15. Life on land ,Eucalyptus tereticornis ,13. Climate action ,[SDE]Environmental Sciences ,Environmental science ,Terrestrial ecosystem ,010606 plant biology & botany - Abstract
International audience; The response of terrestrial ecosystems to rising atmospheric CO2 concentration (C-a), particularly under nutrient-limited conditions, is a major uncertainty in Earth System models. The Eucalyptus Free-Air CO2 Enrichment (EucFACE) experiment, recently established in a nutrient- and water-limited woodland presents a unique opportunity to address this uncertainty, but can best do so if key model uncertainties have been identified in advance. We applied seven vegetation models, which have previously been comprehensively assessed against earlier forest FACE experiments, to simulate a priori possible outcomes from EucFACE. Our goals were to provide quantitative projections against which to evaluate data as they are collected, and to identify key measurements that should be made in the experiment to allow discrimination among alternative model assumptions in a postexperiment model intercomparison. Simulated responses of annual net primary productivity (NPP) to elevated C-a ranged from 0.5 to 25% across models. The simulated reduction of NPP during a low-rainfall year also varied widely, from 24 to 70%. Key processes where assumptions caused disagreement among models included nutrient limitations to growth; feedbacks to nutrient uptake; autotrophic respiration; and the impact of low soil moisture availability on plant processes. Knowledge of the causes of variation among models is now guiding data collection in the experiment, with the expectation that the experimental data can optimally inform future model improvements.
- Published
- 2016
48. Does physiological acclimation to climate warming stabilize the ratio of canopy respiration to photosynthesis?
- Author
-
Craig V. M. Barton, Michael J. Aspinwall, Belinda E. Medlyn, John E. Drake, Remko A. Duursma, Peter B. Reich, and Mark G. Tjoelker
- Subjects
0106 biological sciences ,Canopy ,Time Factors ,010504 meteorology & atmospheric sciences ,Physiology ,Acclimatization ,Climate Change ,Cell Respiration ,Plant Science ,Photosynthesis ,Atmospheric sciences ,01 natural sciences ,Trees ,chemistry.chemical_compound ,Respiration ,Botany ,0105 earth and related environmental sciences ,Analysis of Variance ,Global warming ,Diurnal temperature variation ,Temperature ,Primary production ,15. Life on land ,Carbon Dioxide ,Wood ,Circadian Rhythm ,Plant Leaves ,chemistry ,13. Climate action ,Organ Specificity ,Carbon dioxide ,Environmental science ,010606 plant biology & botany - Abstract
Given the contrasting short-term temperature dependences of gross primary production (GPP) and autotrophic respiration, the fraction of GPP respired by trees is predicted to increase with warming, providing a positive feedback to climate change. However, physiological acclimation may dampen or eliminate this response. We measured the fluxes of aboveground respiration (Ra ), GPP and their ratio (Ra /GPP) in large, field-grown Eucalyptus tereticornis trees exposed to ambient or warmed air temperatures (+3°C). We report continuous measurements of whole-canopy CO2 exchange, direct temperature response curves of leaf and canopy respiration, leaf and branch wood respiration, and diurnal photosynthetic measurements. Warming reduced photosynthesis, whereas physiological acclimation prevented a coincident increase in Ra . Ambient and warmed trees had a common nonlinear relationship between the fraction of GPP that was respired above ground (Ra /GPP) and the mean daily temperature. Thus, warming significantly increased Ra /GPP by moving plants to higher positions on the shared Ra /GPP vs daily temperature relationship, but this effect was modest and only notable during hot conditions. Despite the physiological acclimation of autotrophic respiration to warming, increases in temperature and the frequency of heat waves may modestly increase tree Ra /GPP, contributing to a positive feedback between climate warming and atmospheric CO2 accumulation.
- Published
- 2015
49. Impact of a reduced winter snowpack on litter arthropod abundance and diversity in a northern hardwood forest ecosystem
- Author
-
Andrew F. Schiller, Pamela H. Templer, Thomas H. Kunz, John E. Drake, Anne M. Socci, Nathan W. Fuller, and John Campbell
- Subjects
Forest floor ,Ecology ,Soil biology ,Soil Science ,Growing season ,Experimental forest ,Biology ,Microbiology ,Agronomy ,Abundance (ecology) ,Forest ecology ,Litter ,Species richness ,Agronomy and Crop Science - Abstract
Projected changes in climate for the northeastern USA over the next 100 years include a reduction in the depth and duration of the winter snowpack, which could affect soil temperatures and frost regimes. We conducted a snow-removal experiment in a northern hardwood forest at the Hubbard Brook Experimental Forest in central New Hampshire over 2 years to induce soil freezing and evaluate its effect on the abundance, richness, and diversity of soil arthropods during the growing season. Snow removal at the beginning of winter increased the depth and duration of soil frost, decreased soil temperatures, and led to a reduced abundance of some arthropod taxa, including Araneae (reduced by 57%; P=0.0001), Pseudoscorpionida (75%; P
- Published
- 2011
50. Increases in the flux of carbon belowground stimulate nitrogen uptake and sustain the long-term enhancement of forest productivity under elevated CO2
- Author
-
Seth G. Pritchard, M. Luke McCormack, Richard P. Phillips, Sharon A. Billings, Kurt S. Johnsen, John E. Drake, Kirsten S. Hofmockel, Ram Oren, Robert B. Jackson, David J. P. Moore, Emily S. Bernhardt, John Lichter, Evan H. DeLucia, Sari Palmroth, Kathleen K. Treseder, Jeffrey S. Pippen, Adrien C. Finzi, Heather R. McCarthy, William H. Schlesinger, and Anne Gallet-Budynek
- Subjects
0106 biological sciences ,2. Zero hunger ,Biogeochemical cycle ,010504 meteorology & atmospheric sciences ,Ecology ,Chemistry ,Primary production ,15. Life on land ,Carbon sequestration ,Photosynthesis ,01 natural sciences ,Carbon cycle ,chemistry.chemical_compound ,13. Climate action ,Carbon dioxide ,Ecosystem ,Nitrogen cycle ,Ecology, Evolution, Behavior and Systematics ,010606 plant biology & botany ,0105 earth and related environmental sciences - Abstract
The earth’s future climate state is highly dependent upon changes in terrestrial C storage in response to rising concentrations of atmospheric CO2. Here we show that consistently enhanced rates of net primary production (NPP) are sustained by a C-cascade through the root-microbe-soil system; increases in the flux of C belowground under elevated CO2 stimulated microbial activity, accelerated the rate of soil organic matter decomposition and stimulated tree uptake of N bound to this SOM. This process set into motion a positive feedback maintaining greater C gain under elevated CO2 as a result of increases in canopy N content and higher photosynthetic N-use efficiency. The ecosystem-level consequence of the enhanced requirement for N and the exchange of plant C for N belowground is the dominance of C storage in tree biomass but the preclusion of a large C sink in the soil.
- Published
- 2011
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