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Yan-Shih Lin [et al.].- Received 16 August 2014, Accepted 16 January 2015, Published online 02 March 2015, Stomatal conductance (gs) is a key land-surface attribute as it links transpiration, the dominant component of global land evapotranspiration, and photosynthesis, the driving force of the global carbon cycle. Despite the pivotal role of gs in predictions of global water and carbon cycle changes, a global-scale database and an associated globally applicable model of gs that allow predictions of stomatal behaviour are lacking. Here, we present a database of globally distributed gs obtained in the field for a wide range of plant functional types (PFTs) and biomes. We find that stomatal behaviour differs among PFTs according to their marginal carbon cost of water use, as predicted by the theory underpinning the optimal stomatal model1 and the leaf and wood economics spectrum2, 3. We also demonstrate a global relationship with climate. These findings provide a robust theoretical framework for understanding and predicting the behaviour of gs across biomes and across PFTs that can be applied to regional, continental and global-scale modelling of ecosystem productivity, energy balance and ecohydrological processes in a future changing climate.

The Gentianaceae are represented in Peru by 15 genera and nearly 170 species (Brako & Zarucchi, 1993; Ulloa Ulloa et al., 2004; S. Castillo, pers. comm.), mainly herbs and shrubs. Here we recognize 103 endemic species in seven genera. Gentianella and Macrocarpaea are the genera with the largest number of endemic species. Endemic Gentianaceae are found in the Humid and Dry Puna, Paramo and Very Humid Montane Forests regions, between 1000 and 5100 m elevation. We applied IUCN categories and criteria to 99 species. Thirty-three endemic species have been found to date in Peruvian protected areas., La familia Gentianaceae es reconocida en el Perú por presentar alrededor de 15 géneros y aproximadamente de 170 especies (Brako & Zarucchi, 1993; Ulloa Ulloa et al., 2004; S. Castillo, com.pers.), mayormente hierbas y arbustos. En este trabajo se reconoce 103 especies endémicas en siete géneros. Los géneros con mayor número de especies endemicas son Gentianella y Macrocarpaea. Las especies endémicas ocupan principalmente las regiones de la Puna Húmeda y Seca, Páramo y Bosque Muy Húmedo Montano, entre los 1000 y 5100 m de altitud. Se aplicaron las categorías y criterios de la UICN a 99 especies. Treinta y tres especies endémicas se encuentran representadas dentro de un área protegida.

Climate change is affecting the amount and complexity of plant inputs to tropical forest soils. This is likely to influence the carbon (C) balance of these ecosystems by altering decomposition processes e.g., “positive priming effects” that accelerate soil organic matter mineralization. However, the mechanisms determining the magnitude of priming effects are poorly understood. We investigated potential mechanisms by adding 13C labeled substrates, as surrogates of plant inputs, to soils from an elevation gradient of tropical lowland and montane forests. We hypothesized that priming effects would increase with elevation due to increasing microbial nitrogen limitation, and that microbial community composition would strongly influence the magnitude of priming effects. Quantifying the sources of respired C (substrate or soil organic matter) in response to substrate addition revealed no consistent patterns in priming effects with elevation. Instead we found that substrate quality (complexity and nitrogen content) was the dominant factor controlling priming effects. For example a nitrogenous substrate induced a large increase in soil organic matter mineralization whilst a complex C substrate caused negligible change. Differences in the functional capacity of specific microbial groups, rather than microbial community composition per se, were responsible for these substrate-driven differences in priming effects. Our findings suggest that the microbial pathways by which plant inputs and soil organic matter are mineralized are determined primarily by the quality of plant inputs and the functional capacity of microbial taxa, rather than the abiotic properties of the soil. Changes in the complexity and stoichiometry of plant inputs to soil in response to climate change may therefore be important in regulating soil C dynamics in tropical forest soils. Refereed/Peer-reviewed

Background: Tropical montane cloud forests (TMCF) are unique ecosystems with high biodiversity and large carbon reservoirs. To date there have been limited descriptions of the carbon cycle of TMCF. Aims: We present results on the production, allocation and cycling of carbon for two mid-elevation (1500–1750 m) tropical montane cloud forest plots in San Pedro, Kosnipata Valley, Peru. Methods: We repeatedly recorded the components of net primary productivity (NPP) using biometric measurements, and autotrophic (R a) and heterotrophic (R h) respiration, using gas exchange measurements. From these we estimated gross primary productivity (GPP) and carbon use efficiency (CUE) at the plot level. Results: The plot at 1500 m was found very productive, with our results comparable with the most productive lowland Amazonian forests. The plot at 1750 m had significantly lower productivity, possibly because of greater cloud immersion. Both plots had similar patterns of NPP allocation, a substantial seasonality in NPP com...

Background: The forests of western Amazonia are known to be more dynamic that the better-studied forests of eastern Amazonia, but there has been no comprehensive description of the carbon cycle of a western Amazonian forest. Aims: We present the carbon budget of two forest plots in Tambopata in south-eastern Peru, western Amazonia. In particular, we present, for the first time, the seasonal variation in the detailed carbon budget of a tropical forest. Methods: We measured the major components of net primary production (NPP) and total autotrophic respiration over 3–6 years. Results: The NPP for the two plots was 15.1 ± 0.8 and 14.2 ± 1.0 Mg C ha−1 year−1, the gross primary productivity (GPP) was 35.5 ± 3.6 and 34.5 ± 3.5 Mg C ha−1 year−1, and the carbon use efficiency (CUE) was 0.42 ± 0.05 and 0.41 ± 0.05. NPP and CUE showed a large degree of seasonality. Conclusions: The two plots were similar in carbon cycling characteristics despite the different soils, the most notable difference being high allocation ...

The functional role of herbivores in tropical rainforests remains poorly understood. We quantified the magnitude of, and underlying controls on, carbon, nitrogen and phosphorus cycled by invertebrate herbivory along a 2800 m elevational gradient in the tropical Andes spanning 12°C mean annual temperature. We find, firstly, that leaf area loss is greater at warmer sites with lower foliar phosphorus, and secondly, that the estimated herbivore-mediated flux of foliar nitrogen and phosphorus from plants to soil via leaf area loss is similar to, or greater than, other major sources of these nutrients in tropical forests. Finally, we estimate that herbivores consume a significant portion of plant carbon, potentially causing major shifts in the pattern of plant and soil carbon cycling. We conclude that future shifts in herbivore abundance and activity as a result of environmental change could have major impacts on soil fertility and ecosystem carbon sequestration in tropical forests.

Background: In tropical montane cloud forests (TMCFs) fires can be a frequent source of disturbance near the treeline. Aims: To identify how forest structure and tree species composition change in response to fire and to identify fire-tolerant species, and determine which traits or characteristics are associated with fire tolerance. Methods: Shifts in forest structure and diversity were assessed on 15 paired plots in burnt and unburnt (control) forests, along a fire chronosequence. Species were classified as fire-sensitive, fire survivors or fire thrivers, using a fire tolerance index. Regression and tree analyses were used to determine which traits contributed to the fire tolerance of species. Results: There were more small- and medium-sized trees in the burnt plots independent of time since the last fire. There were shifts in family importance value and in species diversity among the plots. Of the 73 species analysed there were 39 fire-sensitive species, 19 fire survivors and 14 fire thrivers. Sprouting ability and biomass showed a positive relationship with the fire tolerance of species. Conclusions: There were immediate as well as long-term (up to 15 years) effects of fire on forest structure and species composition, suggesting that TMCFs take more than 15 years to regenerate from a fire. Long-term studies are needed to fully understand regeneration patterns of TMCFs after fires. Keywords: bark thickness; fire sensitivity; Peruvian Andes; species diversity; sprouting, tree size; wood density

1. The Andes are predicted to warm by 3–5 °C this century with the potential to alter the processes regulating carbon (C) cycling in these tropical forest soils. This rapid warming is expected to stimulate soil microbial respiration and change plant species distributions, thereby affecting the quantity and quality of C inputs to the soil and influencing the quantity of soil-derived CO2 released to the atmosphere. 2. We studied tropical lowland, premontane and montane forest soils taken from along a 3200-m elevation gradient located in south-east Andean Peru. We determined how soil microbial communities and abiotic soil properties differed with elevation. We then examined how these differences in microbial composition and soil abiotic properties affected soil C-cycling processes, by amending soils with C substrates varying in complexity and measuring soil heterotrophic respiration (RH). 3. Our results show that there were consistent patterns of change in soil biotic and abiotic properties with elevation. Microbial biomass and the abundance of fungi relative to bacteria increased significantly with elevation, and these differences in microbial community composition were strongly correlated with greater soil C content and C:N (nitrogen) ratios. We also found that RH increased with added C substrate quality and quantity and was positively related to microbial biomass and fungal abundance. 4. Statistical modelling revealed that RH responses to changing C inputs were best predicted by soil pH and microbial community composition, with the abundance of fungi relative to bacteria, and abundance of gram-positive relative to gram-negative bacteria explaining much of the model variance. 5. Synthesis. Our results show that the relative abundance of microbial functional groups is an important determinant of RH responses to changing C inputs along an extensive tropical elevation gradient in Andean Peru. Although we do not make an experimental test of the effects of climate change on soil, these results challenge the assumption that different soil microbial communities will be ‘functionally equivalent’ as climate change progresses, and they emphasize the need for better ecological metrics of soil microbial communities to help predict C cycle responses to climate change in tropical biomes.

Mostly herbs and vines, the Alstroemeriaceae are represented in Peru with 85 species in two genera, Alstroemeria and Bomarea (Brako & Zarucchi, 1993; Ulloa Ulloa et al., 2004). Here we recognize 22 endemic taxa, all in the genus Bomarea. These endemic taxa occupy several ecological regions, from Humid Montane Forest to the Dry and Humid Puna, between 1000 and 4600 m elevation. Approximately a third of the species are known only from their type localities, located in isolated mountain ranges o in basins that had received scarce attention from botanists over the last 80 years, as in the case of the Monzón. Nine of these species have been recorded in Peru’s protected areas network., La familia Alstroemeriaceae es reconocida en el Perú con dos géneros, Alstroemeria y Bomarea, y 85 especies (Brako & Zarucchi, 1993; Ulloa Ulloa et al., 2004), básicamente hierbas y enredaderas. En este trabajo reconocemos 22 endemismos en el género Bomarea. Estos taxones endémicos ocupan varias regiones ecológicas, incluyendo la del Bosque Húmedo Montano y de la Puna Seca y Húmeda, entre los 1000 y 4600 m de altitud. Aproximadamente un tercio de esas especies, son conocidas solamente de sus localidades tipo, ubicadas en cadenas montañosas aisladas o en cuencas que han recibido escasa herborización los últimos 80 años, como la del Monzón. Nueve de estas especies están representadas en áreas naturales protegidas.

Summary •We present the results from a litter translocation experiment along a 2800-m elevation gradient in Peruvian tropical forests. The understanding of the environmental factors controlling litter decomposition is important in the description of the carbon and nutrient cycles of tropical ecosystems, and in predicting their response to long-term increases in temperature. •Samples of litter from 15 species were transplanted across all five sites in the study, and decomposition was tracked over 448 d. •Species’ type had a large influence on the decomposition rate (k), most probably through its influence on leaf quality and morphology. When samples were pooled across species and elevations, soil temperature explained 95% of the variation in the decomposition rate, but no direct relationship was observed with either soil moisture or rainfall. The sensitivity of the decay rate to temperature (κT) varied seven-fold across species, between 0.024 and 0.169°C−1, with a mean value of 0.118 ± 0.009°C−1 (SE). This is equivalent to a temperature sensitivity parameter (Q10) for litter decay of 3.06 ± 0.28, higher than that frequently assumed for heterotrophic processes. •Our results suggest that the warming of approx. 0.9°C experienced in the region in recent decades may have increased decomposition and nutrient mineralization rates by c. 10%.

Understanding functional trait-environment relationships (TERs) may improve predictions of community assembly. However, many empirical TERs have been weak or lacking conceptual foundation. TERs based on leaf venation networks may better link individuals and communities via hydraulic constraints. We report measurements of vein density, vein radius, and leaf thickness for more than 100 dominant species occurring in ten forest communities spanning a 3,300 m Andes-Amazon elevation gradient in Peru. We use these data to measure the strength of TERs at community scale and to determine whether observed TERs are similar to those predicted by physiological theory. We found strong support for TERs between all traits and temperature, as well weaker support for a predicted TER between maximum abundance-weighted leaf transpiration rate and maximum potential evapotranspiration. These results provide one approach for developing a more mechanistic trait-based community assembly theory. Fil: Blonder, Benjamin. University of Oxford; Reino Unido Fil: Salinas, Norma. University of Oxford; Reino Unido. Pontificia Universidad Católica de Perú; Perú Fil: Patrick Bentley, Lisa. University of Oxford; Reino Unido Fil: Shenkin, Alexander. University of Oxford; Reino Unido Fil: Chambi Porroa, Percy O.. Universidad Nacional San Antonio Abad del Cusco; Perú Fil: Valdez Tejeira, Yolvi. Universidad Nacional San Antonio Abad del Cusco; Perú Fil: Violle, Cyrille. Université de Montpellier. Centre d’Ecologie Fonctionnelle et Evolutive; Francia Fil: Fyllas, Nikolaos M.. University of Oxford; Reino Unido Fil: Goldsmith, Gregory R.. Paul Scherrer Institute. Ecosystem Fluxes Group. Laboratory for Atmospheric Chemistry; Suiza Fil: Martin, Robert E.. Carnegie Institution for Science. Department of Global Ecology; Estados Unidos Fil: Asner, Gregory P.. Carnegie Institution for Science. Department of Global Ecology; Estados Unidos Fil: Díaz, Sandra Myrna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Enquist, Brian J.. Arizona State University; Estados Unidos Fil: Malhi, Yadvinder. University of Oxford; Reino Unido

Soil enzymes are catalysts of organic matter depolymerisation, which is of critical importance for ecosystem carbon (C) cycling. Better understanding of the sensitivity of enzymes to temperature will enable improved predictions of climate change impacts on soil C stocks. These impacts may be especially large in tropical montane forests, which contain large amounts of soil C. We determined the temperature sensitivity (Q 10) of a range of hydrolytic and oxidative enzymes involved in organic matter cycling from soils along a 1900 m elevation gradient (a 10 °C mean annual temperature gradient) of tropical montane forest in the Peruvian Andes. We investigated whether the activity (V max) of selected enzymes: (i) exhibited a Q 10 that varied with elevation and/or soil properties; and (ii) varied among enzymes and according to the complexity of the target substrate for C-degrading enzymes. The Q 10 of V max for β-glucosidase and β-xylanase increased with increasing elevation and declining mean annual temperature. For all other enzymes, including cellobiohydrolase, N-acetyl β-glucosaminidase and phosphomonoesterase, the Q 10 of V max did not vary linearly with elevation. Hydrolytic enzymes that degrade more complex C compounds had a greater Q 10 of V max, but this pattern did not apply to oxidative enzymes because phenol oxidase had the lowest Q 10 value of all enzymes studied here. Our findings suggest that regional differences in the temperature sensitivities of different enzyme classes may influence the terrestrial C cycle under future climate warming.

The net primary productivity (NPP) of tropical forests is one of the most important and least quantified components of the global carbon cycle. Most relevant studies have focused particularly on the quantification of the above-ground coarse wood productivity, and little is known about the carbon fluxes involved in other elements of the NPP, the partitioning of total NPP between its above- and below-ground components and the main environmental drivers of these patterns. In this study we quantify the above- and below-ground NPP of ten Amazonian forests to address two questions: (1) How do Amazonian forests allocate productivity among its above- and below-ground components? (2) How do soil and leaf nutrient status and soil texture affect the productivity of Amazonian forests? Using a standardized methodology to measure the major elements of productivity, we show that NPP varies between 9.3±1.3 Mg C ha−1 yr−1 (mean±standard error), at a white sand plot, and 17.0±1.4 Mg C ha−1 yr−1 at a very fertile Terra Preta site, with an overall average of 12.8±0.9 Mg C ha−1 yr−1. The studied forests allocate on average 64±3% and 36±3% of the total NPP to the above- and below-ground components, respectively. The ratio of above-ground and below-ground NPP is almost invariant with total NPP. Litterfall and fine root production both increase with total NPP, while stem production shows no overall trend. Total NPP tends to increase with soil phosphorus and leaf nitrogen status. However, allocation of NPP to below-ground shows no relationship to soil fertility, but appears to decrease with the increase of soil clay content.

Background: The slopes of the eastern Andes harbour some of the highest biodiversity on Earth and a high proportion of endemic species. However, there have been only a few and limited descriptions of carbon budgets in tropical montane forest regions. Aims: We present the first comprehensive data on the production, allocation and cycling of carbon for two high elevation (ca. 3000 m) tropical montane cloud forest plots in the Kosñipata Valley, Peruvian Andes. Methods: We measured the main components and seasonal variation of net primary productivity (NPP), autotrophic (Ra) and heterotrophic (Rh) respiration to estimate gross primary productivity (GPP) and carbon use efficiency (CUE) in two 1-ha plots. Results:NPP for the two plots was estimated to be 7.05 ± 0.39 and 8.04 ± 0.47 Mg C ha−1 year−1, GPP to be 22.33 ± 2.23 and 26.82 ± 2.97 Mg C ha−1 year−1 and CUE was 0.32 ± 0.04 and 0.30 ± 0.04. Conclusions: We found strong seasonality in NPP and moderate seasonality of Ra, suggesting that forest NPP is driven by changes in photosynthesis and highlighting the importance of variation in solar radiation. Our findings imply that trees invest more in biomass production in the cooler season with lower solar radiation and more in maintenance during the warmer and high solar radiation period.

Owen K. Atkin [et al.].- Received: 8 July 2014, Accepted: 29 November 2014, Leaf dark respiration (Rdark) is an important yet poorly quantified component of the global carbon cycle. Given this, we analyzed a new global database of Rdark and associated leaf traits., Data for 899 species were compiled from 100 sites (from the Arctic to the tropics). Several woody and nonwoody plant functional types (PFTs) were represented. Mixed-effects models were used to disentangle sources of variation in Rdark., Area-based Rdark at the prevailing average daily growth temperature (T) of each site increased only twofold from the Arctic to the tropics, despite a 20°C increase in growing T (8–28°C). By contrast, Rdark at a standard T (25°C, Rdark25) was threefold higher in the Arctic than in the tropics, and twofold higher at arid than at mesic sites. Species and PFTs at cold sites exhibited higher Rdark25 at a given photosynthetic capacity (Vcmax25) or leaf nitrogen concentration ([N]) than species at warmer sites. Rdark25 values at any given Vcmax25 or [N] were higher in herbs than in woody plants., The results highlight variation in Rdark among species and across global gradients in T and aridity. In addition to their ecological significance, the results provide a framework for improving representation of Rdark in terrestrial biosphere models (TBMs) and associated land-surface components of Earth system models (ESMs).

Background: The slopes of the eastern Andes harbour some of the highest biodiversity on Earth and a high proportion of endemic species. However, there have been only a few and limited descriptions of carbon budgets in tropical montane forest regions. Aims: We present the first comprehensive data on the production, allocation and cycling of carbon for two high elevation (ca. 3000 m) tropical montane cloud forest plots in the Kosñipata Valley, Peruvian Andes. Methods: We measured the main components and seasonal variation of net primary productivity (NPP), autotrophic (Ra) and heterotrophic (Rh) respiration to estimate gross primary productivity (GPP) and carbon use efficiency (CUE) in two 1-ha plots. Results:NPP for the two plots was estimated to be 7.05 ± 0.39 and 8.04 ± 0.47 Mg C ha−1 year−1, GPP to be 22.33 ± 2.23 and 26.82 ± 2.97 Mg C ha−1 year−1 and CUE was 0.32 ± 0.04 and 0.30 ± 0.04. Conclusions: We found strong seasonality in NPP and moderate seasonality of Ra, suggesting that forest NPP is driven by changes in photosynthesis and highlighting the importance of variation in solar radiation. Our findings imply that trees invest more in biomass production in the cooler season with lower solar radiation and more in maintenance during the warmer and high solar radiation period.

Los Andes están considerados como los puntos calientes más diversos de los trópicos, dentro de estos se encuentra el Parque Nacional del Manu, cuyas complejas condiciones climáticas y fisiográficas albergan una mega-diversidad y endemismo. En el presente trabajo se presenta una lista anotada de especies arbóreas y afines a lo largo de un gradiente de elevación desde los bosques submontanos a 800 m hasta la línea de bosque a 3625 m en la Reserva de Biosfera del Manu. En base a una red de 21 parcelas permanentes de una hectárea y exploraciones botánicas se sistematiza la información florística por rangos de elevación, distribución geográfica y endemismo. Estos resultados preliminares se traducen en 1108 especies de las cuales el 39.7% son morfoespecies, el 43% de las especies determinadas son registros nuevos para la región del Cusco, 15 especies son nuevos registros para la flora peruana, 40 especies son endémicas para Perú y 30 son potenciales especies nuevas para la ciencia. Adicionalmente, se resalta la expansión del rango altitudinal para el 45.2% de las especies determinadas (302 especies). Estos resultados son una muestra de la alta diversidad arbórea y afines en estos ecosistemas montañosos registrados en tan solo ~20 km de distancia geográfica, además muestra lo escasamente colectados y poco estudiados que se encuentran. Mas colecciones botánicas son necesarias - estos estudios básicos de florística son imperativos para un mejor entendimiento de la distribución de especies y la función del ecosistemas, además ayudará a responder una de las grandes preguntas en la ecología global moderna, ¿Cómo responderán los bosques tropicales al cambio climático global?, The tropical Andes and adjacent Amazon are Earth’s highest biodiversity hotspot. Manu National Park in southeastern Peru encompasses an entire watershed, ranging from Andean highlands to Amazonian lowlands, and is a megadiverse landscape on the Andes to Amazon transition. Here we present an annotated checklist of trees and related species is along an elevation gradient in the Manu Biosphere Reserve that runs from sub-montane forests at 800 m elevation up to the tree line at 3625 m. Based on a network of 21 1-hectare permanent tree plots and botanical explorations, the floristic information is systematized by elevation ranges, geographical distribution and endemism. These preliminary results show 1108 species. Of these, 43% are new records for the region of Cusco, 15 species are new records for the Peruvian flora, 40 species are endemics for Peru, and 30 are potential new species for science. Another 39.7% are identified to genus or family level and remain morphospecies. Additionally, we show altitudinal range expansion for 45.2% of identified species (302 species). These results were found in a transect of plots spanning only 20 km of geographic distance, and are a sample of the high tree diversity in these mountainous ecosystems. The data show how poorly collected and understudied these ecosystems are. Basic floristic studies and collections are imperative for a better understanding of species distribution and function of ecosystems, and the basic biodiversity of the tropical Andes. They will also help to answer a major, unresolved question in modern global ecology of how tropical forests will respond to global climate change.