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Riparian woodlands are hotspots of productivity and biodiversity on dryland landscapes, yet riparian tree species are also extremely vulnerable to catastrophic hydraulic damage caused by hydroclimatic change. Root zone water subsidies from shallow groundwater facilitate the high levels of productivity seen in riparian woodlands. Shallow groundwater provides a persistent source of root zone soil moisture that is somewhat decoupled from the local precipitation regime. As a result, riparian tree species are able to avoid water stress and maximize productivity throughout the prolonged summer dry seasons that are common in the southwestern United States. Groundwater declines caused by extreme drought conditions threaten the health and function of dryland riparian woodlands. If groundwater elevations drop below the root zones of riparian tree species, it is likely that riparian woodlands will experience widespread stress and mortality. However, the sensitivity of riparian tree species to changes in root zone water availability remains poorly constrained. This dissertation combines remote sensing, flux tower measurements, and ecological modeling to examine vegetation cover, evapotranspiration, and photosynthesis in riparian woodlands under changing environmental conditions. It also identifies critical physiological thresholds that are needed to maintain ecosystem structure and function under anthropogenic climate change.In the first chapter, I combine remote sensing data with measurements from groundwater monitoring wells to identify critical groundwater thresholds that are needed to maintain the health and function of riparian woodlands. The analysis examines the Santa Clara River in southern California, which experienced widespread groundwater declines during an extreme drought from 2012 to 2019. Spectral mixture analysis was used to estimate the fractional cover of green vegetation and non-photosynthetic vegetation (i.e., dead and woody plant material) in six riparian woodlands. The groundwater depth was characterized for each woodland using data from groundwater monitoring wells. The analysis revealed that riparian woodlands experience substantial decreases in green vegetation cover and substantial increases in dead/woody vegetation cover when the depth to groundwater exceeds ca. 5 m. The analysis also revealed a coherent spatial and temporal trend of riparian woodland mortality that proceeded downstream over six years and mirrored trends in groundwater elevation over space and time. The findings reveal that riparian woodlands depend on shallow groundwater access to maintain health and function, and that they experience substantial stress and mortality when they lose access to root zone water subsidies from shallow groundwater aquifers.In the second chapter, I develop a novel theoretical model to predict leaf temperature as a function of evapotranspiration. The model reveals that the difference between leaf temperature and air temperature varies as a linear function of the evaporative fraction. The model also reveals that leaf temperature converges to air temperature when the evaporative fraction equals one. The model predictions were validated using flux tower measurements from a riparian woodland and an upland savanna in southeastern Arizona. The flux tower measurements reveal that evaporative cooling reduced leaf temperature by ca. 1-5 °C in the middle of the growing season. Evaporative cooling also resulted in a ca. 15% reduction in leaf respiration. The impact of evaporative cooling on leaf carbon cycling represents a novel connection between plant water and carbon cycles via leaf energy balance that has received little attention in literature.In the third chapter, I develop a novel modeling framework to predict the vertical profiles of radiation and wind speed within forest canopies based on known physical principles. The predictions are then used to estimate the vertical profiles of leaf temperature and net photosynthesis for five flux tower sites spanning a large latitudinal gradient in North and South America. The model predictions reveal that leaf temperature decreases exponentially downward through forest canopies, and that the difference between top-of-canopy leaf temperature and bottom-of-canopy leaf temperature can exceed 7 °C. Unexpectedly, in many forest biomes, the highest levels of net photosynthesis often occur in the middle of the canopy. The analysis helps uncover the mechanistic basis for this behavior. The analysis also identifies the combinations of environmental conditions that result in critical leaf temperatures that cause irreversible damage to leaf photosynthetic infrastructure. Two different data sets provide evidence of trait coordination between leaf size and stomatal conductance to avoid critical leaf temperatures across global forest biomes.

Актуальность. Сегодня в разработку вводится большое количество нефтяных месторождений с трудноизвлекаемыми запасами, в частности, с низкопроницаемыми коллекторами. При проницаемости менее 1 мД система поддержания пластового давления имеет низкую эффективность, а добывающие скважины имеют высокие темпы падения и низкие дебиты даже при наличии гидроразрыва пласта. Помочь в решении данной проблемы может новая технология - водный Huff and Puff. Данная технология представляет собой циклическую закачку воды, остановку и последующий отбор жидкости на добывающей нефтяной скважине. Она позволяет инициировать процесс капиллярной пропитки в малодебитных безводных скважинах в низкопроницаемом коллекторе и увеличить добычу нефти. Цель: проанализировать мировой опыт применения и лабораторные исследования технологии Huff and Puff, определить ключевые параметры ее эффективности, сформулировать критерии применимости технологии. Объекты: процесс капиллярной пропитки в низкопроницаемом нефтенасыщенном коллекторе, результаты лабораторных исследований, отчеты о применении технологии на нефтяных месторождениях. Методы: оценка и анализ существующих лабораторных исследований технологии на керне, анализ условий и методик проведения экспериментов и их результатов, сравнение с аналогичными исследованиями, выявление общих зависимостей; обзор опыта применения технологии в США, КНР и России, сравнение их результатов с результатами лабораторных исследований. Результаты. В процессе анализа лабораторных исследований выявлены ключевые параметры эффективности применения технологии - наличие трещин в коллекторе, низкая проницаемость, гидрофильность и маленький характерный размер поровых каналов. Анализ мирового опыта применения водного Huff and Puff показал, что технология успешно применяется в КНР на малопроницаемых гидрофильных пластах на скважинах с многостадийным гидроразрывом пласта, что подтверждает лабораторные исследования. Опыт применения в США не был успешным из-за гидрофобности коллекторов. Опыт в России имеет неоднозначные результаты - из-за гидрофильности и низкой проницаемости пласта эффект капиллярной пропитки присутствует, но из-за конструкции скважин и отсутствия раскрытых трещин гидроразрыва пласта значительного эффекта не было. Результаты опыта применения согласуются с данными лабораторных испытаний. В результате данного анализа были сформированы критерии применимости технологии водного Huff and Puff. The relevance. Today, a large number of oil fields with hard-to-recover reserves, in particular, with low-permeability reservoirs, are in exploration. With a permeability of less than 1 mD, the formation pressure flow system has low efficiency, and production wells have high decline rates and low flow rates even in the presence of hydraulic fracturing. A new technology, water Huff and Puff, can help solve this problem. This technology is a cyclic water injection, shutdown and subsequent withdrawal of fluid during an oil well production. It allows us to initiate the process of capillary imbibition in marginal waterless wells in a low-permeability reservoir and increase oil production. The main aim: to analyze the world experience in the application and laboratory studies of the Huff and Puff technology, to determine the key parameters of its effectiveness, to formulate criteria for the applicability of the technology. Objects: capillary imbibition in a low-permeability oil-saturated reservoir, the results of laboratory studies, reports on the application of the technology in oil fields. Methods: evaluation and analysis of existing laboratory studies of technology on core, analysis of the conditions and methods for conducting experiments and their results, comparison with similar studies, identification of common dependencies; review of the experience of applying the technology in the USA, China and Russia, comparing their results with the results of laboratory studies. Results. During the analysis of laboratory studies, the key parameters of the effectiveness of the technology application - the presence of fractures in the reservoir, low permeability, hydrophilicity and small characteristic size of pore channels - were identified. An analysis of the world experience in the use of water Huff and Puff showed that the technology is successfully used in China in low-permeability hydrophilic formations in wells with multi-stage hydraulic fracturing, which is confirmed by laboratory studies. The US experience has not been successful due to the hydrophobicity of the reservoirs. The experience in Russia has mixed results - due to the hydrophilicity and low permeability of the reservoir, the effect of capillary impregnation is present, but due to the design of the wells and the absence of open hydraulic fractures, there was no significant effect. The results of the application experience are consistent with laboratory test data. As a result of this analysis, criteria for the applicability of water Huff and Puff technology were formed.

Characterizing variability in the global water cycle is fundamental to predicting impacts of future climate change; understanding the role of the Pacific Walker circulation (PWC) in the regional expression of global water cycle changes is critical to understanding this variability. Water isotopes are ideal tracers of the role of the PWC in global water cycling because they retain information about circulation-dependent processes including moisture source, transport, and delivery. We collated publicly available measurements of precipitationδ18O (δ18OP) and used novel data processing techniques to synthesize long (34 yr), globally distributed composite records from temporally discontinuousδ18OPmeasurements. We investigated relationships between global-scaleδ18OPvariability and PWC strength, as well as other possible drivers of globalδ18OPvariability—including El Niño–Southern Oscillation (ENSO) and global mean temperature—and used isotope-enabled climate model simulations to assess potential biases arising from uneven geographical distribution of the observations or our data processing methodology. Covariability underlying theδ18OPcomposites is more strongly correlated with the PWC (r= 0.74) than any other index of climate variability tested. We propose that the PWC imprint in globalδ18OParises from multiple complementary processes, including PWC-related changes in moisture source and transport length, and a PWC- or ENSO-driven “amount effect” in tropical regions. The clear PWC imprint in globalδ18OPimplies a strong PWC influence on the regional expression of global water cycle variability on interannual to decadal time scales, and hence that uncertainty in the future state of the PWC translates to uncertainties in future changes in the global water cycle.

The pyrite-type FeO2 and FeO2H were synthesized at the pressure-temperature conditions relevant to Earth’s deep lower mantle. Through the water-iron reaction, the pyrite-phase is a good candidate to explain the chemical heterogeneities and seismological anomalies at the bottom of the mantle. The solid solution of pyrite-type FeO2 and FeO2H, namely the FeO2Hx (0 ​≤ ​x ​≤ ​1), is particularly interesting and introduces puzzling chemical states for both the O and H atoms in the deep mantle. While the role of H in the FeO2–FeO2H system has been primarily investigated, discrepancies remain. In this work, we summarize recent progress on the pyrite-phase, including FeO2, FeO2H, and FeO2Hx, which is critical for understanding the water cycling, redox equilibria, and compositional heterogenicities in the deep lower mantle.

Rainfall partitioning is a key process in forest ecosystems, affecting evaporation, transpiration and water storage in the canopy, litter and soil. Although rainfall partitioning has been well studied in forest ecosystems, less is known about how rainfall partitioning is modified by tree species diversity. To disentangle the effects of tree species identity and diversity on rainfall partitioning, we installed 128 rain gauges in an experimental plantation, located in Zedelgem (Belgium), part of a large, multi-site forest diversity experiment in Belgium (FORBIO). With these rain gauges, we monitored throughfall for a full year, with a temporal resolution of two weeks. Based on these data, we analysed identity (i.e. whether throughfall is species-specific), non-additive (i.e. whether throughfall in mixtures is different from the expected amounts based on monocultures) and richness effects (i.e. how species richness affects throughfall). First of all, we found that rainfall partitioning highly differed between tree species, due to pronounced species identity effects. The presence of Pinus sylvestris [pine] was always associated with lower throughfall. Year-round throughfall was, for example, the lowest in mixtures of pine and Tilia cordata [lime] (43.8 +/- 14.5% of the open-field rainfall) and monocultures of pine (48.6 +/- 11.8%). Addi-tionally, non-additive effects were significant, leading to a 10% decrease of rainfall reaching the forest floor in mixtures compared to the expected throughfall based on measurements in monocultures. Tree species richness effects on rainfall partitioning acted indirectly, mostly via an increased basal area in mixed stands. Our findings suggest that mixing tree species leads to a higher than expected reduction in throughfall, which lowered soil moisture in mixed plots. Whether this reduced throughfall and soil moisture affects ecosystem functioning re-mains to be quantified.

A primary source of uncertainty in terrestrial biosphere model (TBM) projection of carbon uptake and water cycling from ecosystems is the relationship between CO2 assimilation (A) and wa...

Subduction-induced deep hydration and water cycling may play significant roles in the modification and destruction of the overriding cratonic lithosphere. Two contrasting modes are generally propos...

Pre-print (óritrýnt handrit), Oceanic crust is a major transport medium of water into the mantle wedge and the convecting mantle. Yet, the water content of the oceanic crust remains uncertain. Active geothermal systems situated at on-land spreading centers provide a unique opportunity to study the hydration of the oceanic crust, with well constrained systems and boreholes reaching depths of >4 km. Here, we present hydrogen isotope data of geothermal fluids and altered basalt for three Icelandic geothermal systems: the meteoric water fed system at Krafla and the seawater fed systems at Reykjanes and Surtsey. The bulk rock δD values of altered and hydrated basalts from these localities, which exhibit significantly higher water contents (up to 8.9 wt.%) than magmatic (non-hydrated) basalts, vary greatly from −125 to −96 at Krafla, from −80 to −46 at Reykjanes and from −78 to −46 at Surtsey. The corresponding fluids have δD values of −84.1 to −81.1 at Krafla, −23.1 to −14.9 at Reykjanes and +2.1 to +4.3 at Surtsey. Comparison of isotope modeling results to the natural data reveals that hydration of the Icelandic crust and corresponding hydrogen isotopic characteristics are controlled by (1) the isotope composition of the source fluid, (2) isotope fractionation between the aqueous geothermal fluids and the alteration minerals formed, and (3) the type and quantity of alteration minerals formed. These factors in turn depend on the extent of fluid-rock interaction and temperature. Using the same modeling approach and expanding it to datasets available for the oceanic crust, we assessed the hydration state and δD values of the oceanic crust as a function of depth. We show that 1400 to 1650 Tg H2O/yr is added to the igneous oceanic crust upon alteration by seawater and that the upper part (, This project was financially supported by NordVulk, the International Continental Scientific Drilling Program (ICDP) through a grant to the SUSTAIN project, and the Icelandic Research Fund (project number: 163083-051). SAH acknowledges support from the Icelandic Research Fund (project number: 196139-051). HS Orka and Landsvirkjun kindly provided access to the drill cuttings. J. Cullen, T. Larson, R. Ólafsdóttir and Á.E. Sveinbjörnsdóttir are thanked for assistance during sample preparation and data acquisition. BIK is particularly grateful of being part of this project as without the project-related lab work she would have never met her future husband E.W. Marshall IV. We thank four anonymous reviewers for their constructive comments and suggestions to an earlier version of this manuscript. Louis Derry is thanked for careful editorial handling of this study.

Water infiltration is commonly recommended as an indicator of soil dynamic properties and water cycling on rangelands. We investigated the utility of a two-trial single-ring infiltration test by evaluating the relationship between the first and second trial, the spatial variation in infiltration rates within and between sampling locations, and the relationship between water infiltration and bulk density and soil organic carbon (SOC) in the context of texture and water content. We measured water infiltration rates at 156 sites in 14 counties in California. We found a strong correlation between first and second infiltration trials. In pairwise correlations, both first and second trials were significantly correlated with SOC and bulk density. However, we did not find a significant relationship between water infiltration and either initial water content or soil texture. Model comparison revealed that in the context of soil texture, infiltration can serve as an indicator of bulk density and SOC; shorter water infiltration time (i.e., faster rate) is associated with decreased bulk density and increased SOC. Our results suggest that a single-ring infiltration test can be a useful, but imprecise, indicator of soil dynamic properties such as SOC and bulk density.

Quantifying forest evapotranspiration (ET) is essential for understanding of climatic response of forest carbon and water cycling. However, there are still large uncertainties in forest ET predictions, especially in plant transpiration (PT). The poor estimations of forest ET and PT are largely attributed to the neglect of wet canopy evaporation and uncertainties in the stomatal conductance. Thus, by coupling a revised Ball—Woodrow–Berry (BWB) model, a precipitation intercepted algorithm and the gross primary production (GPP) model to Shuttleworth–Wallace (SW) model, this study introduced a modified SW ${\rm{(SW}}_{{\rm{m}}})$ model. The performances of this model were subsequently tested in three different forest sites with long-term observed records. Compared with previous models, ${\rm{SW}}_{{\rm{m}}}$ had a canopy stomatal scheme with stronger ecological significance and simpler GPP estimation scheme. Our analyses reveal the following. 1) ${\rm{SW}}_{{\rm{m}}}$ evidently improves the agreements between estimated and measured ET compared to original SW ( R 2 increasing by 0.19–0.68). ${\rm{SW}}_{{\rm{m}}}$ could more accurately partition PT and evaporation, when compared with an earlier BWB-based SW ( R 2 increasing by ∼0.03). This finding also supports the use of Lohammer function in semiempirical model of stomatal conductance. 2) Accurate predictions of GPP are helpful for improving ET estimations in ${\rm{SW}}_{{\rm{m}}}\,(r\,= \,{\text{0.73,\,p}}\, , suggesting that carbon and water fluxes are inherently linked. 3) In addition to GPP, leaf area index evidently affects the performances of estimated ET in ${\rm{SW}}_{{\rm{m}}}$ . These results suggest that critically coupling carbon and water cycling are very important for improving forest ET prediction.

Transpiration from the Amazon rainforest generates an essential water source at a global and local scale. However, changes in rainforest function with climate change can disrupt this process, causing significant reductions in precipitation across Amazonia, and potentially at a global scale. We report the only study of forest transpiration following a long-term (>10 year) experimental drought treatment in Amazonian forest. After 15 years of receiving half the normal rainfall, drought-related tree mortality caused total forest transpiration to decrease by 30%. However, the surviving droughted trees maintained or increased transpiration because of reduced competition for water and increased light availability, which is consistent with increased growth rates. Consequently, the amount of water supplied as rainfall reaching the soil and directly recycled as transpiration increased to 100%. This value was 25% greater than for adjacent non-droughted forest. If these drought conditions were accompanied by a modest increase in temperature (e.g. 1.5°C), water demand would exceed supply, making the forest more prone to increased tree mortality. This article is protected by copyright. All rights reserved.

To improve predictions of the future of ecosystems in a changing world, it is necessary to consider fine-scale processes. We propose that for the Mediterranean region (a hotspot of climate change and biodiversity), there are three local processes that have often been overlooked in predictive models and that are key to understanding vegetation changes: rural abandonment that increases wildlands, population changes that boost fire ignitions, and coastal degradation that enhances drought. These processes are not directly driven by global warming and act in different directions (greening and browning). The current balance is still toward greening, because land abandonment is buffering the browning drivers; however, it is likely to switch with increasing warming. The challenge is to mitigate the browning processes. Given that climatic warming is not directly driving these processes, local management can make a difference in reducing the overall impact on the landscape and society

Among the most critical processes in simulating terrestrial ecosystem performance is the regulatory role of sto- mata in carbon and water cycles. Compared with field measurements, the changes in stomatal slope caused by the biophysical environment provide a simple but effective synthetic framework for studying climate-related carbon and water cycling, due to its sensitivity to CO2, vapor pressure deficit, and photosynthesis. It is also crucial in un- derstanding the effects of climate change on photosynthesis and water use efficiency. Endeavored by numerous scholastic efforts, stomatal conductance models have been improved based on experimental, semi-experimental, and mechanical processes. However, the underlying biological mechanisms and the dynamics of key parameters in these models remain unexplored, especially regarding the changes in stomatal slope. By improving the under- s tanding of the stomata's regulatory role, we reduced the uncertainty of stomatal conductance simulation. We then synthesized the recent developments and lessons in optimal stomatal behavior theory to simulate stomatal con- ductance and included an introduction to widely used stomatal conductance models and parameters, the main fac- tors influencing stomatal slopes, and applications of the mechanical stomatal conductance models in different ecosystems. Based on our literature review, we proposed that future research is needed on the optimal stomatal

The use of water production as a pressure mitigation tool in the context of CO2 storage is widely studied but the impact it might have on the migration behaviour of a buoyant CO2 plume is less well reported. To investigate this further two different scenarios were modelled. In the first, a single water production well was used to draw CO2 along the strike of an open aquifer with a regional dip. Large rates of water production (5–10 times the volume of injected CO2) were required to achieve only small displacements of the CO2 plume. The second scenario investigated to what extent an induced hydraulic gradient might spill CO2 already stored in a structural trap. Here the effects were more pronounced with over 90% of the CO2 being spilled at a water cycling rate of 10 Mt per year (corresponding to a hydraulic gradient of 1.28 bar/km). The modelling was tested by the real case at Sleipner where CO2 migration in the Utsira Sand is potentially impacted by water production at the nearby Volve field. Simulations concluded that the CO2 plume at Sleipner should not be materially affected by water production from Volve and this is supported by the time-lapse seismics.

御手洗水試験流域は、福岡県糟屋郡篠栗町の九州大学農学部附属演習林内に設置されており、2003年以降、流量および気象データが継続的に観測されている。本試験流域の地質は三郡変成岩類中層部の緑色片岩と北部九州に分布する三郡変成岩帯に部分的に含まれる蛇紋岩である。本試験地はヒノキ人工林および常緑・落葉の混交二次林で覆われており、ヒノキ人工林では2012年1月～3月にかけて本数間伐率50%の強度間伐が行われた。本試験流域の観測結果は2003年から2007年の5年分についてはすでに公開されており、本報告は間伐後の1年間を含む2008年から2012年の日単位の流量データ、気象データを取りまとめたものである。, This report presents daily meteorological and stream flow data for the Ochozu Experimental Watershed located in the Kasuya Research Forest. This watershed is covered with a plantation forest of Japanese cypress (Chamaecyparis obtusa) and underlain by green schist and serpentinite. Fifty percent thinning was conducted and stand density was reduced to halfin January 2012. Daily meteorological and stream flow data from 2003 to 2008 have already been published. This report presents the data from 2008 to 2012, including a year post-thinning.

On the Ground • Goal-driven ecologically based grazing management moved a ranching operation from negative economic returns to profit. • Management adaptively manipulated the duration, seasonality, and frequency of grazing with a goal to recruit cool-season midgrasses. A change to recovery periods based on plant physiology of goal species was a key adaptation. • Recruitment of both cool- and warm-season mid-grasses improved water cycling, extended the grazing season, and eventually increased sustainable stocking rates. • Flexible stocking rates were central to improved profit.

Coal is the major energy in China, which always account for more than 70% in the structure of consumer demand for primary energy. on the one hand, coal mining provides us with the main energy, on the other hand, it gives a tremendous pressure on ecology in the mining process. Comparative analysis of ecological pressure between open-pit and underground coal mine with using the method of ecological burden. The result shows, the total ecological burden and the coefficient of ecological burden of open-pit are 4.31 to 11.36 times and 2.77 to 7.74 times of underground coal mine's respectively. Meanwhile, It is the main method by adopt measures such as pay attention to the mining section and improving technology to reduce the amount of stripping and tunneling, and lower the electricity consumption and improve the water cycling utilization ratio, as well as adopt the clean energy and biological energy to reduce the ecological pressure of coal mine. Underground coal mining is recommended if the two mining methods are allowed.

Estimation and economic valuation of the forest retention capacities Based on results concerning the forest impact on water cycling an attempt was undertaken to evaluate water retention in forests. The economic value of water retention was established assuming the cost of water storage in small reservoirs built in forest areas. Calculations did not account for differences resulting from different functions of naturally retained water and that stored with the use of technical methods. Considering volume and time of water retention in forests, the annual value of natural water retention in forests calculated per average hectare of the country area was estimated at 800 zł.

Obtaining the d-excess parameter from oxygen and hydrogen stable isotope composition of meteoric waters has the potential power to reconstruct changes in atmospheric water pools (e,g. sources, origins and overall balance) and the climatic conditions that prevail during surface evaporation. Recently, plant and ecosystem scientists turned their attention using d-excess information to inform questions at these scales. Here, we use the d-excess parameter to evaluate the influence of forest canopies on atmospheric humidity within a mixed evergreen forest in coastal California. We found that during the day, when transpiration was at a maximum, the d-excess of atmospheric water vapour exceeded model predictions for the background atmosphere into which the ecosystem evapotranspiration mixes. At night when transpiration was minor, the d-excess of atmospheric water vapour was on average less than model predictions for an ocean derived water vapour source. The observed diurnal fluctuations around the d-excess of the modelled background water vapour provided a strong evidence that during the day as the land surface warms and the boundary layer grows plants alter the isotope composition of atmospheric humidity via non-steady state isotope effects. In contrast, at night equilibrium isotope effects dominate as the atmosphere stabilizes. These day and nighttime fluctuations around the d-excess of ocean derived water vapour highlight the importance of plant transpiration for the isotope hydrology of near surface humidity and subsequently for the isotope composition of condensate like dew, an important water input to this ecosystem. © 2013 John Wiley & Sons, Ltd.

Old-growth forest ecosystems comprise a mosaic of patches in different successional stages, with the fraction of the landscape in any particular state relatively constant over large temporal and spatial scales. The size distribution and return frequency of disturbance events, and subsequent recovery processes, determine to a large extent the spatial scale over which this old-growth steady state develops. Here, we characterize this mosaic for a Central Amazon forest by integrating field plot data, remote sensing disturbance probability distribution functions, and individual-based simulation modeling. Results demonstrate that a steady state of patches of varying successional age occurs over a relatively large spatial scale, with important implications for detecting temporal trends on plots that sample a small fraction of the landscape. Long highly significant stochastic runs averaging 1.0 Mg biomass⋅ha−1⋅y−1 were often punctuated by episodic disturbance events, resulting in a sawtooth time series of hectare-scale tree biomass. To maximize the detection of temporal trends for this Central Amazon site (e.g., driven by CO2 fertilization), plots larger than 10 ha would provide the greatest sensitivity. A model-based analysis of fractional mortality across all gap sizes demonstrated that 9.1–16.9% of tree mortality was missing from plot-based approaches, underscoring the need to combine plot and remote-sensing methods for estimating net landscape carbon balance. Old-growth tropical forests can exhibit complex large-scale structure driven by disturbance and recovery cycles, with ecosystem and community attributes of hectare-scale plots exhibiting continuous dynamic departures from a steady-state condition.

Stable isotope analysis is a powerful tool for assessing plant carbon and water relations and their impact on biogeochemical processes at different scales. Our process-based understanding of stable isotope signals, as well as technological developments, has progressed significantly, opening new frontiers in ecological and interdisciplinary research. This has promoted the broad utilisation of carbon, oxygen and hydrogen isotope applications to gain insight into plant carbon and water cycling and their interaction with the atmosphere and pedosphere. Here, we highlight specific areas of recent progress and new research challenges in plant carbon and water relations, using selected examples covering scales from the leaf to the regional scale. Further, we discuss strengths and limitations of recent technological developments and approaches and highlight new opportunities arising from unprecedented temporal and spatial resolution of stable isotope measurements.

In Arabidopsis thaliana, the cryptochrome (CRY) blue light photoreceptors and the phytochrome (phy) red/far-red light photoreceptors mediate a variety of light responses. COP1, a RING motif-containing E3 ubiquitin ligase, acts as a key repressor of photomorphogenesis. Production of stomata, which mediate gas and water vapor exchange between plants and their environment, is regulated by light and involves phyB and COP1. Here, we show that, in the loss-of-function mutants of CRY and phyB, stomatal development is inhibited under blue and red light, respectively. In the loss-of-function mutant of phyA, stomata are barely developed under far-red light. Strikingly, in the loss-of-function mutant of either COP1 or YDA, a mitogen-activated protein kinase kinase kinase, mature stomata are developed constitutively and produced in clusters in both light and darkness. CRY, phyA, and phyB act additively to promote stomatal development. COP1 acts genetically downstream of CRY, phyA, and phyB and in parallel with the leucine-rich repeat receptor-like protein TOO MANY MOUTHS but upstream of YDA and the three basic helix-loop-helix proteins SPEECHLESS, MUTE, and FAMA, respectively. These findings suggest that light-controlled stomatal development is likely mediated through a crosstalk between the cryptochrome-phytochrome-COP1 signaling system and the mitogen-activated protein kinase signaling pathway.

The Meridiani Planum region on Mars is rich in minerals derived from evaporation, but lacks a topography consistent with standing water. Do the deposits stem from upwelling groundwater early in the planet's history?

In long term studies the following climatological characteristics were measured or calculated: air and soil temperature, sunshine, wind speed, vapor pressure, saturation deficit, precipitation, humidity, incoming and reflected solar energy, energy emitted by active surfaces and primary production. Taking into account the relationships between climatological characteristics, the growth stages of vegetation, and relations between heat balance components, the fluxes of energy used for evapotranspiration, air, and soil heating were estimated in various ecosystems composing the agricultural landscape. The energy contained in biomass production of various crops was estimated also. Aggregate estimates of energy flow connected with evapotranspiration, and soil and air heating were calculated for eight model landscapes which differed by the plant cover structure. A higher variability of energy fluxes was observed for individual ecosystems than for agricultural landscapes. It was shown that the structure of the plant cover has an important bearing on energy flow and water cycling both by direct and indirect influences. Shelterbelts are especially important in their influence on energy flow and water cycling. &nbsp

The Arctic and Subarctic regions are of particular importance to the global climate change and are now experiencing a climate warming that is higher than the global average. Around 50% of the global soil carbon is stored in high latitude soils, especially in permafrost and peatland soils. Permafrost thawing, speeding up the decomposition of previously frozen soil carbon, is expected to result in strongly positive feedbacks to global warming. Meanwhile, increased air temperature may strongly impact vegetation growth and distributions in this region. Dynamic ecosystem models are powerful tools to study climate change influences on ecosystem processes and also to quantify ecosystem feedbacks to the atmosphere. However, these models often focus on the vertical transfer of carbon and water between the atmosphere, the land surface vegetation and soils. Therefore, they generally do not consider the horizontal water and soluble carbon flows between the modelled spatial units (grid cells), which could result in an incomplete estimation of water and carbon budgets, especially for climatically sensitive high latitude regions. In this thesis, we aim to overcome this limitation by implementing spatial topographical indices into a state-of-the-art dynamic ecosystem model, LPJ-GUESS, and to incorporate water and carbon (mainly dissolved organic carbon, DOC) interactions between the grid cells. Modelling approaches and algorithms developed in this thesis were applied to study the subarctic Stordalen catchment, located in northern Sweden, and to explore the potential influence on the model’s hydrological and ecological estimations. Extensive sets of observation data were used for model evaluation throughout. We proposed a distributed hydrological (DH) approach to dynamically simulate water flow from cell to cell within the catchment and compared the hydrological and ecological impacts resulting from different flow routing algorithms. The results indicate an improved accuracy of runoff estimation when using the proposed DH scheme in the Stordalen catchment. They also show that the choice of flow algorithm can have strong impacts on water and carbon flux estimations in this region. Furthermore, a complete estimation of the catchment carbon budget was assessed using our developed model. We found that the catchment is a carbon sink at present and could become a stronger sink in the near future, a result which is, however, very dependent on future atmospheric CO2 concentrations and methane (CH4) emissions from the peatlands. Additionally, the model was further extended to dynamically model soil water DOC and the lateral transport of DOC across the landscape. The modelled outputs suggest that DOC production and mineralization largely contribute to DOC fluxes and that wet fen peatland is and will be a hotspot for DOC export. In conclusion, this thesis demonstrates the feasibility of implementing topographical indices into LPJ-GUESS to describe water flows, and the importance of considering spatial heterogeneity in hydrological conditions when modelling carbon dynamics at high latitudes. Furthermore, the integration of vertical and horizontal carbon fluxes at high spatial resolutions can be used to provide more accurate estimations of a complete carbon budget and can dynamically simulate the fate of different carbon components in response to climate change. De arktiska och subarktiska regionerna är av särskild betydelse för den globala klimatförändringen, och genomgår nu en klimatuppvärmning som är högre än genomsnittshöjningen på jorden. Omkring 50 % av världens markkol är lagrat i nordliga jordar (på höga latituder), och där främst i permafrost- och torvjordar. Upptiningen av permafrost påskyndar nedbrytningen, och därmed frigöring, av tidigare fryst markkol, vilket förväntas ha kraftiga effekter på den globala uppvärmningen. Samtidigt kan en ökad lufttemperatur påtagligt påverka tillväxt och utbredning av vegetation i dessa regioner. Dynamiska ekosystemmodeller är effektiva verktyg för att studera klimatförändringars påverkan på ekosystemprocesser, inklusive kvantifiering av återkopplingar från olika ekosystem till atmosfären. Dessa modeller fokuserar emellertid främst på det vertikala utbytet av kol och vatten mellan atmosfär, landyta, vegetation och mark. Därför tar de i allmänhet inte hänsyn till de horisontella vatten- och kolflödena som förekommer mellan de modellerade rumsliga enheterna (jmf gridceller i en rasterkarta eller pixlar i en bild). Denna förenkling kan leda till en ofullständig uppskattning av vatten- och kolbudgetar, och då i synnerhet för de klimatkänsliga regionerna på de höga latituderna. Denna avhandling syftar till att reducera ovan nämnda begränsningar genom att implementera rumsliga topografiska index i den dynamiska ekosystemmodellen LPJ-GUESS, samt att inkorporera interaktioner mellan vatten och kol (huvudsakligen löst organiskt kol, DOC) över ytan (mellan gridcellerna i kartan). De modeller som utvecklats inom denna studie har implementerats i det subarktiska Stordalens avrinningsområde, beläget i norra Sverige. Där har modellernas eventuella inverkan på hydrologiska och ekologiska simuleringar analyserats och dokumenterats. För utvärdering av modellerna har omfattande observationsdata använts. Vidare föreslås en distribuerad hydrologisk (DH) metod för att dynamiskt simulera vattentransport från cell till cell inom Stordalens avrinningsområde, och jämförande studier av de hydrologiska och ekologiska effekterna beroende på olika algoritmer för modellering av vattenflöden har genomförts. Resultaten visar att den föreslagna DH-metoden kan modellera avrinningen i Stordalens avrinningsområde bättre än tidigare föreslagna metoder. Vidare kan det konstateras att valet av flödesalgoritm har en stor inverkan på modelleringen av vatten- och kolflöden i regionen. Den utvecklade metoden användes även för att utföra en fullständig uppskattning av kolbudgeten i avrinningsområdet. I denna delstudie kom det fram att upptagningsområdet idag är en kolsänka, och att det inom en snar framtid sannolikt kommer att bli en ännu starkare sänka. Detta förlopp är emellertid starkt beroende av framtida atmosfäriska CO2-koncentrationer och metanutsläpp från torvmarkerna. Den sista delen av avhandlingen behandlar ytterligare utveckling av modellen för att dynamiskt kunna modellera DOC i markvatten, samt den laterala (horisontella) transporten av DOC i landskapet. Resultaten visar att produktion och mineralisering av DOC i stor utsträckning bidrar till DOC-flöden, samt att våta torvmarker är och kommer att vara hetfläckar (även kallade hotspots) för DOC-export. Sammanfattningsvis visar denna avhandling möjligheterna att implementera topografiska index och vattenflöden (lateralt och vertikalt) i LPJ-GUESS. Den demonstrerar också vikten av att ta hänsyn till rumslig heterogenitet i hydrologiska förhållanden vid modellering av koldynamik på höga latituder. Avhandlingsarbetet har gjort det möjligt att genom integrering av vertikala och laterala kolflöden vid höga rumsliga upplösningar noggrannare skatta en fullständig kolbudget, samt att dynamiskt simulera vilken påverkan klimatförändringarna har på olika kolkomponenter. 北极和亚北极地区对全球气候变化影响尤为重要。目前，北极地区正面临着变暖速度高于全球平均的现状。全球大约有50%的土壤碳储存在高纬度地区的土壤里，这些土壤碳主要分布于冻土层和泥炭层中。冻土层的解冻会使原先被冻结的土壤碳加速分解，产生温室气体，从而对全球变暖形成一个强烈的正反馈。与此同时，气温的增加可能会很大程度地影响植被在这些地区的生长和分布。动态生态系统模型是一种非常强大的工具，被用来研究气候变化对生态系统的影响，并且可以量化生态系统对大气的反馈信息。然而这些模型通常只关注大气、地表植被和土壤之间的水和碳的纵向转移，从而忽略了其在模型空间单元中的横向移动。这样可能会导致模型对于水和碳平衡的计算不够准确和全面，尤其在气候敏感的高纬度极地地区，这种偏差可能会更大。 本论文旨在解决动态生态系统模型中的这个局限性问题。基于目前最先进的动态生态系统模型LPJ-GUESS，我们利用和结合空间地形指数实现了模拟水和碳（主要是土壤溶解性有机碳）在空间单元中的相互作用。文中所提出来的建模方法和算法被应用到坐落于亚北极地区，瑞典北部的Stordalen流域，以探索模型新方法对估算水文和生态过程的潜在影响。在整个应用过程中，我们采用了大量的观测数据集来进行模型评估。 我们提出了一种基于网格单元对网格单元的分布式水文（DH）方法来动态模拟流域内的水流。我们进一步比较了不同的流量路径算法对于模拟水文和生态过程的影响。结果表明，当我们在Stordalen流域内使用结合了分布式水文方法的模型时，该模型对于径流估算的精度比以往有所提高。同时实验结果也表明了流量路径算法的选择会对研究区域内水通量和碳通量的估算产生重大的影响。基于以上结果，我们（在高空间分辨率下）利用该模型对流域内的碳预算有了一个更为完整的估算。我们发现，Stordalen流域现在是一个碳汇，并且在不久的将来有可能成为一个更大的碳汇。然而这一预测结果非常地依赖于空气中二氧化碳浓度的增加对流域内植被固碳能力的影响，同时还受流域内泥炭地里甲烷的排放量的影响。除此之外，该模型进一步扩展了对土壤水中的溶解性有机碳（DOC）的含量及其空间横向传输的动态模拟。模拟的输出表明，土壤中DOC的动态变化主要受DOC 的产生量和矿化作用的影响，潮湿的沼泽泥炭地在现在和将来都会是土壤DOC输出的热点区域。 总而言之，本论文展示了在LPJ-GUESS模型中加入用以描述水流的地形指数的可行性，同时证明了在高纬度地区模拟碳动态变化时对于水文条件的空间异质性的考量的重要性。此外，本论文还说明了在高空间分辨率下，综合考虑垂直和水平碳通量可以提供更准确和更完整的碳预算的估计，也可以动态地模拟不同的碳成分在应对气候变化时产生的不同结果。