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Landslides are a central component of tropical montane forest disturbance regimes, including in the tropical Andes biodiversity hotspot, one of the most biodiverse ecosystems in the world. Technological developments in remote sensing have made landscape-scale landslide studies possible, unlocking new avenues for understanding montane biodiversity, ecosystem functioning, and the future effects of climate change. Here, we outline three axes of inquiry for future landslide ecology research in Andean tropical montane forest. We focus exclusively on the Andes due to the vast floral diversity and high endemicity of the tropical Andes biodiversity hotspot, and its importance for global biodiversity and regional ecosystem service provisioning; the broad elevational, latitudinal, and topographic gradients across which landslide dynamics play out; and the existence of long-term plot networks that provide the necessary baseline data on mature forest structure, composition, and functioning to contextualize disturbance impacts. The three lines of study we outline, which draw heavily on remote sensing data and techniques, will deepen scientific understanding of tropical montane forest biodiversity and ecosystem functioning, and the potential impacts of climate change on both. They are: (1) tracking landslide biodiversity dynamics across time and space with high spatial and temporal resolution satellite and unoccupied aerial vehicle imagery; (2) assessing the ecological influence of landslides through the lens of plant functional diversity with imaging spectroscopy; and (3) understanding current and predicting future landslide regimes at scale by building a living landslide inventory spanning the tropical Andes. The research findings from these three axes of inquiry will shed light on the role of landslides and the process of forest recovery from them in both the Andes and worldwide.

Funding: Floristic identification in plots in the RAINFOR forest monitoring network have been supported by the Natural Environment Research Council (grants NE/B503384/1, NE/ D01025X/1, NE/I02982X/1, NE/F005806/1, NE/D005590/1 and NE/I028122/1) and the Gordon and Betty Moore Foundation. In a time of rapid global change, the question of what determines patterns in species abundance distribution remains a priority for understanding the complex dynamics of ecosystems. The constrained maximization of information entropy provides a framework for the understanding of such complex systems dynamics by a quantitative analysis of important constraints via predictions using least biased probability distributions. We apply it to over two thousand hectares of Amazonian tree inventories across seven forest types and thirteen functional traits, representing major global axes of plant strategies. Results show that constraints formed by regional relative abundances of genera explain eight times more of local relative abundances than constraints based on directional selection for specific functional traits, although the latter does show clear signals of environmental dependency. These results provide a quantitative insight by inference from large-scale data using cross-disciplinary methods, furthering our understanding of ecological dynamics. Publisher PDF

Recent studies have demonstrated that ecological processes that shape community structure and dynamics change along environmental gradients. However, much less is known about how the emergence of the gradients themselves shape the evolution of species that underlie community assembly. In this study, we address how the creation of novel environments leads to community assembly via two nonmutually exclusive processes: immigration and ecological sorting of pre-adapted clades (ISPC), and recent adaptive diversification (RAD). We study these processes in the context of the elevational gradient created by the uplift of the Central Andes. We develop a novel approach and method based on the decomposition of species turnover into within- and among-clade components, where clades correspond to lineages that originated before mountain uplift. Effects of ISPC and RAD can be inferred from how components of turnover change with elevation. We test our approach using data from over 500 Andean forest plots. We found that species turnover between communities at different elevations is dominated by the replacement of clades that originated before the uplift of the Central Andes. Our results suggest that immigration and sorting of clades pre-adapted to montane habitats is the primary mechanism shaping tree communities across elevations.

Species interactions generating consistent landscape or seascape patterns are important to ecosystem health and function. One widely-documented pattern in shallow, tropical reefscapes is sand “halos” that separate coral patches from surrounding vegetation. Multiple hypotheses for this pattern have been proposed, but individual explanations are rarely integrated to reflect the complexity of systems where halos occur. To evaluate and synthesize multiple hypotheses of halo formation and maintenance into a single model, connect the halo pattern with similar terrestrial phenomena, and identify targets to guide future research and conservation. We reviewed halo accounts from over fifty years in the scientific literature and combined them with related research on marine nutrients, bioturbation, analogous terrestrial processes, and new field measurements to create a conceptual model of halo formation and maintenance. Though halos are widely attributed to herbivory, grazing alone cannot explain patterns at all locations. Nutrients have large effects on tropical reefscapes but remain understudied for halos. Coupling nutrients and grazing explains a variety of observed halo patterns. Fish and invertebrate bioturbators also appear important. We combine these factors to explain pattern variability and present a framework for more comprehensive halo research. Explanations for halos to date have been overly simplistic. Halos are common patterns with complex underlying causes, including foraging behavior and nutrient cycling. Not all halo-like patterns may be created or maintained by the same mechanism(s). Our integrated model provides a more complete understanding of factors contributing to these patterns, a framework for ecological interpretations, and a guide for conservation.

International audience; Despite its importance for forest regeneration, food webs, and human economies, changes in tree fecundity with tree size and age remain largely unknown. The allometric increase with tree diameter assumed in ecological models would substantially overestimate seed contributions from large trees if fecundity eventually declines with size. Current estimates are dominated by overrepresentation of small trees in regression models. We combined global fecundity data, including a substantial representation of large trees. We compared size–fecundity relationships against traditional allometric scaling with diameter and two models based on crown architecture. All allometric models fail to describe the declining rate of increase in fecundity with diameter found for 80% of 597 species in our analysis. The strong evidence of declining fecundity, beyond what can be explained by crown architectural change, is consistent with physiological decline. A downward revision of projected fecundity of large trees can improve the next generation of forest dynamic models.

Fine roots constitute a significant component of the net primary productivity (NPP) of forest ecosystems but are much less studied than aboveground NPP. Comparisons across sites and regions are also hampered by inconsistent methodologies, especially in tropical areas. Here, we present a novel dataset of fine root biomass, productivity, residence time, and allocation in tropical old-growth rainforest sites worldwide, measured using consistent methods, and examine how these variables are related to consistently determined soil and climatic characteristics. Our pantropical dataset spans intensive monitoring plots in lowland (wet, semi-deciduous, and deciduous) and montane tropical forests in South America, Africa, and Southeast Asia (n = 47). Large spatial variation in fine root dynamics was observed across montane and lowland forest types. In lowland forests, we found a strong positive linear relationship between fine root productivity and sand content, this relationship was even stronger when we considered the fractional allocation of total NPP to fine roots, demonstrating that understanding allocation adds explanatory power to understanding fine root productivity and total NPP. Fine root residence time was a function of multiple factors: soil sand content, soil pH, and maximum water deficit, with longest residence times in acidic, sandy, and water-stressed soils. In tropical montane forests, on the other hand, a different set of relationships prevailed, highlighting the very different nature of montane and lowland forest biomes. Root productivity was a strong positive linear function of mean annual temperature, root residence time was a strong positive function of soil nitrogen content in montane forests, and lastly decreasing soil P content increased allocation of productivity to fine roots. In contrast to the lowlands, environmental conditions were a better predictor for fine root productivity than for fractional allocation of total NPP to fine roots, suggesting that root productivity is a particularly strong driver of NPP allocation in tropical mountain regions. © 2021 The Authors. Global Change Biology published by John Wiley & Sons Ltd. This study is a product of the Global Ecosystem Monitoring network (GEM), Andes Biodiversity and Ecosystem Research Group (ABERG), Amazon Forest Inventory Network (RAINFOR), Stability of Altered Forest Ecosystem (SAFE), and Instituto de Investigaciones de la Amazonia Peruana (IIAP). WHH was funded by Peruvian FONDECYT/CONCYTEC (grant contract number 213-2015-FONDECYT). The GEM network was supported by a European Research Council Advanced Investigator Grant to YM (GEM-TRAITS: 321131) under the European Union's Seventh Framework Programme (FP7/2007-2013). The field data collection was funded NERC Grants NE/D014174/1 and NE/J022616/1 for in Peru, BALI (NE/K016369/1) for work in Malaysia, the Royal Society-Leverhulme Africa Capacity Building Programme for work in Ghana and Gabon and ESPA-ECOLIMITS (NE/1014705/1) in Ghana and Ethiopia. Plot inventories in South America were supported by funding from the US National Science Foundation Long-Term Research in Environmental Biology program (LTREB; DEB 1754647) and the Gordon and Betty Moore Foundation Andes-Amazon Program. GEM data in Gabon were collected under authorization to YM and supported by the Gabon National Parks Agency. Y.M. is supported by the Jackson Foundation. We would like to acknowledge the GEM team across the tropical regions and countries of Bolivia, Brazil, Ghana, Gabon, Ethiopia, Malaysia, and Peru.

Aims: Terrestrial ecosystems are changing in biodiversity, species composition and functional trait composition. To understand the underlying causes of these changes and predict the long-term resilience of the ecosystem to withstand future disturbances, we can evaluate changes in diversity and composition from fossil pollen records. Although diversity can be well estimated from pollen in temperate ecosystems, this is less clear for the hyperdiverse tropics. Moreover, it remains unknown whether functional composition of plant assemblages can be accurately predicted from pollen assemblage composition. Here, we evaluate how community-weighted mean (CWM) traits and diversity indices change along elevation.Location: Amazon–Andes elevation gradient in Peru.Methods: We used 82 modern pollen samples and 59 vegetation plots along the elevation gradient, and calculated CWM traits and diversity indices for each pollen sample and vegetation plot. We also quantified the degree to which taxa are over- or underrepresented by their pollen, by dividing the relative pollen abundance by the relative basal area abundance in the nearby vegetation survey plots (i.e. the R-rel values).Results: We found that CWM wood density increased, and CWM adult height and leaf area decreased with elevation. This change was well predicted by pollen assemblages, indicating that CWM trait–environment relationships based on pollen abundance data provide meaningful results. Diversity (richness, Shannon and Simpson) decreased with elevation for vegetation plots, but these trends could not be observed from pollen assemblages.Conclusions: Our results demonstrate that more research is needed to develop methods that lead to accurate diversity estimates from pollen data in these tropical ecosystems, but that CWM traits can be calculated from pollen data to assess spatial shifts in functional composition. This opens opportunities to calculate CWM traits from fossil pollen data sets in the tropics, with broad implications for improving our understanding and predictions of forest dynamics, functioning and resilience through time.

SummaryBiogeographic events occurring in the deep past can contribute to the structure of modern ecological communities. However, little is known about how the emergence of environmental gradients shape the evolution of species that underlie community assembly. In this study, we address how the creation of novel environments lead to community assembly via two non-mutually exclusive processes: 1) the immigration and ecological sorting of pre-adapted clades (ISPC), and 2) recent adaptive diversification (RAD). We study these processes in the context of the elevational gradient created by the uplift of the Central Andes.We develop a novel approach and method based on the decomposition of species turnover into within- and among-clade components, where clades correspond to lineages that originated before mountain uplift. Effects of ISPC and RAD can be inferred from how components of turnover change with elevation. We test our approach using data from over 500 Andean forest plots.We found that species turnover between communities at different elevations is dominated by the replacement of clades that originated before the uplift of the Central Andes.Our results suggest that immigration and sorting of clades pre-adapted to montane habitats is the primary mechanism shaping communities across elevations.

The sizes and shapes of tree crowns are of fundamental importance in ecology, yet understanding the forces that determine them remains elusive. A cardinal question facing ecologists is the degree to which general and non-specific versus ecological and context-dependent processes are responsible for shaping tree crowns. Here, we test this question for the first time across diverse tropical ecosystems. Using trees from 20 plots varying in elevation, precipitation, and ecosystem type (savanna-forest transitions) across the paleo- and neo-tropics, we test the relationship between crown dimensions and tree size. By analyzing these scaling relationships across environmental gradients, biogeographic regions, and phylogenetic distance, we extend Metabolic Scaling Theory (MST) predictions to include how local selective pressures shape variation in crown dimensions. Across all sites, we find strong agreement between mean trends and MST predictions for the scaling of crown size and shape, but large variation around the mean. While MST explained approximately half of the observed variation in tree crown dimensions, we find that local, ecosystem, and phylogenetic predictors account for the half of the residual variation. Crown scaling does not change significantly across regions, but does change across ecosystem types, where savanna tree crowns grow more quickly with tree girth than forest tree crowns. Crowns of legumes were wider and more voluminous than those of other taxa. Thus, while MST can accurately describe the central tendency of tree crown size, local ecological conditions and evolutionary history appear to modify the scaling of crown shape. Importantly, our extension of MST incorporating these differences accounts for the mechanisms driving variation in the scaling of crown dimensions across the tropics. We present allometric equations for the prediction of crown dimensions across tropical ecosystems. These results are critical when scaling the function of individual trees to larger spatial scales or incorporating the size and shape of tree crowns in global biogeochemical models.

Understanding how evolutionary constraints shape the elevational distributions of tree lineages provides valuable insight into the future of tropical montane forests under global change. With narrow elevational ranges, high taxonomic turnover, frequent habitat specialisation, and exceptional levels of endemism, tropical montane forests and trees are predicted to be highly sensitive to environmental change. Using plot census data from a gradient traversing >3000 m in elevation on the Amazonian flank of the Peruvian Andes, we employ phylogenetic approaches to assess the influence of evolutionary heritage on distribution trends of trees at the genus level. We find that closely related lineages tend to occur at similar mean elevations, with sister genera pairs occurring a mean 254 m in elevation closer to each other than the mean elevational difference for all genera pairs. We also demonstrate phylogenetic clustering both above and below 1750 m a.s.l, corresponding roughly to the cloud-base ecotone. Belying these general trends, some lineages occur across many different elevations. However, these highly plastic lineages are not phylogenetically clustered. Overall, our findings suggest that tropical montane forests are home to unique tree lineage diversity, constrained by their evolutionary heritage and vulnerable to substantial losses under environmental changes, such as rising temperatures or an upward shift of the cloud base.

Remote sensing of trait-based ecology can improve our understanding of the effect of trait diversity on ecosystem functioning., Spatially continuous data on functional diversity will improve our ability to predict global change impacts on ecosystem properties. We applied methods that combine imaging spectroscopy and foliar traits to estimate remotely sensed functional diversity in tropical forests across an Amazon-to-Andes elevation gradient (215 to 3537 m). We evaluated the scale dependency of community assembly processes and examined whether tropical forest productivity could be predicted by remotely sensed functional diversity. Functional richness of the community decreased with increasing elevation. Scale-dependent signals of trait convergence, consistent with environmental filtering, play an important role in explaining the range of trait variation within each site and along elevation. Single- and multitrait remotely sensed measures of functional diversity were important predictors of variation in rates of net and gross primary productivity. Our findings highlight the potential of remotely sensed functional diversity to inform trait-based ecology and trait diversity-ecosystem function linkages in hyperdiverse tropical forests.

Worldwide demand for gold has caused increased extractive activities in the Western Amazon, resulting in a wide-scale transformation of the Madre de Dios river basin (Peru) due to Artisanal and Small-scale Gold Mining (ASGM). These impactful activities profoundly affect the natural landscape and hydroscape as terra firme forest and floodplain habitats are deforested leaving a vast landscape of abandoned ponds that are subsequently colonized from surrounding water bodies. However, the metacommunity dynamics of these emergent networks of connected wetlands and their environmental drivers remain virtually unknown. Here, we present a one-year (May 2017–May 2018) study conducted to assess the composition, abundance and trophic structure of fish assemblages in three abandoned ASGM ponds and their interactions in relation to those of other freshwater groups (macroinvertebrates, phytoplankton and zooplankton). We aimed to determine the influence of environmental parameters on community composition, focused on flood pulse influence (FPI), seasonality, and to identify indicators for predicting aquatic communities’ assemblages. A remarkably abundance and diversity were found totaling 4601 sampled fish from 6 orders, 27 families, 68 genera and 103 species, as well as 87 macoinvertebrate, 71 phytoplankton and 44 zooplankton taxa. The two FPI ponds showed a more stable fish trophic structure throughout the year than the unique non-FPI, probably due to the floods provision of buffer against the lack of resources that occurs during the dry season. Conversely, fish of higher trophic levels were not detected during the dry and transition-to-wet seasons in the non-FPI pond surveyed. Community trajectory analysis showed greater stability of fish assemblages in the non-FPI pond compared to the FPI ponds, which experienced larger disturbance of environmental parameters and biotic inputs during flooding events. Detrended correspondence analysis showed floods as the key factor influencing aquatic communities and species accumulation. However, whereas floods had a large influence on fish and macroinvertebrates, seasonality was the main driver for plankton. FPI ponds showed six-fold higher fish and macroinvertebrate species richness than non-FPI ones, while plankton showed an opposite trend. FPI was the main factor determining the taxonomic composition of fish, followed by dissolved oxygen. Macroinvertebrates were also affected by FPI together with pH and the presence of grassed banks, while conductivity determined phytoplankton composition. Our study presents novel evidence on the highly heterogeneous communities of ASGM abandoned ponds, highlighting their important ecological value and potential role in providing of ecosystem services currently overlooked from conservation policies and management of the aquatic resources.

Amazonian forests support high biodiversity and provide valuable ecosystem services. Unfortunately, these forests are under extreme pressure from land use change and other anthropogenic disturbances. A recent study combined data from an Amazon-wide network of forest inventory plots with spatially explicit deforestation models to predict that by 2050, 36% or 57% of species will be ‘globally threatened’, as defined by IUCN Red List criteria, due to deforestation under Increased-Governance or Business-As-Usual scenarios, respectively. It was also predicted that the number of threatened species will drop by 29–44% if no deforestation occurs within protected areas. However, even the best-protected areas of the Amazon may still be susceptible to the effects of climate change and rising temperatures. To illustrate the potential dangers of climate change for Amazonian parks, we calculated the percentage of land area within all officially designated protected areas of tropical South America that will or will not have future temperature analogs under various scenarios of temperature change and park connectivity. We show that depending on the rate of warming and degree of connectivity, about 19–67% of protected areas will not have any temperature analogs in the near future (2050s). These results help to emphasize that protected areas are not immune to the effects of climate change and that large portions of Amazonian protected areas include ‘disappearing climates’. In the face of these disappearing climates, the biggest determinant of many species’ extinction risks may be their ability to migrate through non-protected habitats.

Liverworts and mosses are a major component of the epiphyte flora of tropical montane forest ecosystems. Canopy access was used to analyse the distribution and vertical stratification of bryophyte epiphytes within tree crowns at nine forest sites across a 3400 m elevational gradient in Peru, from the Amazonian basin to the high Andes. The stable isotope compositions of bryophyte organic material (13C/12C and18O/16O) are associated with surface water diffusive limitations and, along with C/N content, provide a generic index for the extent of cloud immersion. From lowland to cloud forest δ13C increased from −33‰ to −27‰, while δ18O increased from 16.3‰ to 18.0‰. Epiphytic bryophyte and associated canopy soil biomass in the cloud immersion zone was estimated at up to 45 t dry mass ha−1, and overall water holding capacity was equivalent to a 20 mm precipitation event. The study emphasizes the importance of diverse bryophyte communities in sequestering carbon in threatened habitats, with stable isotope analysis allowing future elevational shifts in the cloud base associated with changes in climate to be tracked.

Our knowledge about the structure and function of Andean forests at regional scales remains limited. Current initiatives to study forests over continental or global scales still have important geographical gaps, particularly in regions such as the tropical and subtropical Andes. In this study, we assessed patterns of structure and tree species diversity along ~ 4000 km of latitude and ~ 4000 m of elevation range in Andean forests. We used the Andean Forest Network (Red de Bosques Andinos, https://redbosques.condesan.org/) database which, at present, includes 491 forest plots (totaling 156.3 ha, ranging from 0.01 to 6 ha) representing a total of 86,964 identified tree stems ≥ 10 cm diameter at breast height belonging to 2341 identified species, 584 genera and 133 botanical families. Tree stem density and basal area increases with elevation while species richness decreases. Stem density and species richness both decrease with latitude. Subtropical forests have distinct tree species composition compared to those in the tropical region. In addition, floristic similarity of subtropical plots is between 13 to 16% while similarity between tropical forest plots is between 3% to 9%. Overall, plots ~ 0.5-ha or larger may be preferred for describing patterns at regional scales in order to avoid plot size effects. We highlight the need to promote collaboration and capacity building among researchers in the Andean region (i.e., South-South cooperation) in order to generate and synthesize information at regional scale. Fil: Malizia, Agustina. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina Fil: Blundo, Cecilia Mabel. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina Fil: Carilla, Julieta. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina Fil: Osinaga Acosta, Oriana. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina Fil: Cuesta, Francisco. Universidad de Las Américas; Ecuador. Consorcio para el Desarrollo Sostenible de la Ecorregión Andina; Ecuador Fil: Duque, Alvaro. Universidad Nacional de Colombia. Sede Medellín; Colombia Fil: Aguirre, Nikolay. Universidad Nacional de Loja. Centro de Investigaciones Tropicales del Ambiente y la Biodiversidad; Ecuador Fil: Aguirre, Zhofre. Universidad Nacional de Loja. Centro de Investigaciones Tropicales del Ambiente y la Biodiversidad; Ecuador Fil: Ataroff, Michele. Universidad de Los Andes; Venezuela Fil: Baez, Selene. Escuela Politécnica Nacional; Ecuador Fil: Calderón Loor, Marco. Universidad de Las Américas; Ecuador. Deakin University; Australia Fil: Cayola, Leslie. Herbario Nacional de Bolivia; Bolivia. Missouri Botanical Garden; Estados Unidos Fil: Cayuela, Luis. Universidad Rey Juan Carlos; España Fil: Ceballos, Sergio Javier. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina Fil: Cedillo, Hugo. Universidad de Cuenca; Ecuador Fil: Farfán Ríos, William. Universidad Nacional de San Antonio Abad del Cusco. Herbario Vargas; Perú Fil: Feeley, Kenneth J.. University of Miami; Estados Unidos Fil: Fuentes, Alfredo Fernando. Herbario Nacional de Bolivia; Bolivia. Missouri Botanical Garden; Estados Unidos Fil: Gámez Álvarez, Luis E.. Universidad de Los Andes; Venezuela Fil: Grau, Hector Ricardo. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina Fil: Homeier, Juergen. Universität Göttingen; Alemania Fil: Jadan, Oswaldo. Universidad de Cuenca; Ecuador Fil: Llambi, Luis Daniel. Escuela Politécnica Nacional; Ecuador Fil: Loza Rivera, María Isabel. University of Missouri; Estados Unidos. Herbario Nacional de Bolivia; Bolivia. Missouri Botanical Garden; Estados Unidos Fil: Macía, Manuel J.. Universidad Autónoma de Madrid; España Fil: Malhi, Yadvinder. University of Oxford; Reino Unido Fil: Malizia, Lucio Ricardo. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias; Argentina Fil: Peralvo, Manuel. Consorcio para el Desarrollo Sostenible de la Ecorregión Andina; Ecuador Fil: Pinto, Esteban. Consorcio para el Desarrollo Sostenible de la Ecorregión Andina; Ecuador Fil: Tello, Sebastián. Missouri Botanical Garden; Estados Unidos Fil: Silman, Miles. Center for Energy, Environment and Sustainability; Estados Unidos Fil: Young, Kenneth R.. University of Texas at Austin; Estados Unidos

Made available in DSpace on 2018-12-11T17:17:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-12-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Ministério da Ciência, Tecnologia e Inovação Ministério da Educação Species distribution models (SDMs) are widely used in ecology and conservation. Presence-only SDMs such as MaxEnt frequently use natural history collections (NHCs) as occurrence data, given their huge numbers and accessibility. NHCs are often spatially biased which may generate inaccuracies in SDMs. Here, we test how the distribution of NHCs and MaxEnt predictions relates to a spatial abundance model, based on a large plot dataset for Amazonian tree species, using inverse distance weighting (IDW). We also propose a new pipeline to deal with inconsistencies in NHCs and to limit the area of occupancy of the species. We found a significant but weak positive relationship between the distribution of NHCs and IDW for 66% of the species. The relationship between SDMs and IDW was also significant but weakly positive for 95% of the species, and sensitivity for both analyses was high. Furthermore, the pipeline removed half of the NHCs records. Presence-only SDM applications should consider this limitation, especially for large biodiversity assessments projects, when they are automatically generated without subsequent checking. Our pipeline provides a conservative estimate of a species' area of occupancy, within an area slightly larger than its extent of occurrence, compatible to e.g. IUCN red list assessments. Coordenação de Botânica Museu Paraense Emílio Goeldi, Av. Magalhães Barata 376, C.P. 399 Programa de Pós-Graduação em Ciência Ambientais Universidade Federal Do Pará, Rua Augusto Corrêa 01 Biodiversity Dynamics Naturalis Biodiversity Center, PO Box 9517 Marine and Coastal Management, Deltares, Boussinesqweg 1 Coordenação de Biodiversidade Instituto Nacional de Pesquisas da Amazônia - INPA, Av. André Araújo 2936 EMBRAPA Centro de Pesquisa Agroflorestal de Roraima, BR 174 km 8, Distrito Industrial Herbario Amazónico Colombiano Instituto SINCHI, Calle 20 No 5-44 Department of Integrative Biology University of California Universidad San Francisco de Quito Colegio de Ciencias Biológicas Diego de Robles y Vía Interoceánica Coordenação de Pesquisas em Ecologia Instituto Nacional de Pesquisas da Amazônia - INPA, Av. André Araújo 2936 School of Geography University of Leeds, Woodhouse Lane Department of Wetland Ecology Institute of Geography and Geoecology Karlsruhe Institute of Technology - KIT, Josefstr 1 Biogeochemistry Max Planck Institute for Chemistry, Hahn-Meitner Weg 1 Departamento de Botânica Instituto de Pesquisas Científicas e Tecnológicas Do Amapá - IEPA Campus Do IEPA da Fazendinha, Rodovia JK Km 10 AMAP IRD Cirad CNRS INRA Université de Montpellier, TA A-51/PS2, Bd. de la Lironde Science and Education Field Museum, 1400 S. Lake Shore Drive Coordenação de Dinâmica Ambiental Instituto Nacional de Pesquisas da Amazônia - INPA, Av. André Araújo 2936 Jardín Botánico de Missouri Departamento de Ecologia Universidade Estadual Paulista - UNESP Instituto de Biociências - IB, Av. 24 A 1515 Centro de Biociências Departamento de Ecologia Universidade Federal Do Rio Grande Do Norte, Av. Senador Salgado Filho 3000 Divisao de Sensoriamento Remoto - DSR Instituto Nacional de Pesquisas Espaciais - INPE, Av. dos Astronautas 1758 Herbario Vargas Universidad Nacional de San Antonio Abad Del Cusco, Avenida de la Cultura, Nro 733 Departamento de Geografia Universidade Estadual Paulista - UNESP Instituto de Geociências e Ciências Extas - IGCe Departamento de Biologia Universidade Federal de Rondônia, Rodovia BR 364 s/n Km 9.5 Center for Tropical Conservation Duke University Nicholas School of the Environment Programa de Pós-Graduação em Biodiversidade e Biotecnologia - PPG-Bionorte Universidade Federal de Rondônia Campus Porto Velho, Km 9.5 Instituto Boliviano de Investigacion Forestal Santa Cruz, Av. 6 agosto 28 Km 14,Doble via La Guardia Casilla, 6204 Programa de Pós-Graduação em Ecologia e Conservação Universidade Do Estado de Mato Grosso Instituto de Investigaciones de la Amazonía Peruana - IIAP, Av. A. Quiñones km 2.5 Geography College of Life and Environmental Sciences University of Exeter Departamento de Ciencias Forestales Universidad Nacional de Colombia, Calle 64 x Cra 65 Agteca-Amazonica Facultad de Ciencias Agrícolas Universidad Autónoma Gabriel René Moreno Santa Cruz Prédio da Botânica e Ecologia Embrapa Recursos Genéticos Biotecnologia Parque Estação Biológica, Av. W5 Norte Projeto Dinâmica Biológica de Fragmentos Florestais Instituto Nacional de Pesquisas da Amazônia - INPA, Av. André Araújo 2936 Centre for Tropical Environmental and Sustainability Science College of Science and Engineering James Cook University Laboratório de Ecologia de Doenças Transmissíveis da Amazônia (EDTA) Instituto Leônidas e Maria Deane Fiocruz, Rua Terezina 476 Programa de Pós-graduação em Biodiversidade Saúde Instituto Oswaldo Cruz IOC/FIOCRUZ Pav. Arthur Neiva, Térreo Av. Brasil 4365 Centro de Investigaciones Ecológicas de Guayana Universidad Nacional Experimental de Guayana Calle Chile, urbaniz Chilemex Laboratorio de Ecología de Bosques Tropicales y Primatología Universidad de Los Andes, Carrera 1 # 18a- 10 Programa de Pós-Graduação em Biologia (Botânica) Instituto Nacional de Pesquisas da Amazônia - INPA, Av. André Araújo 2936 Institute of Biodiversity and Ecosystem Dynamics University of Amsterdam, Sciencepark 904 Programa de Ciencias Del Agro y El Mar Herbario Universitario (PORT) UNELLEZ-Guanare Endangered Species Coalition, 8530 Geren Rd MAUA Working Group Instituto Nacional de Pesquisas da Amazônia - INPA, Av. André Araújo 2936 Inventory and Monitoring Program National Park Service, 120 Chatham Lane Center for Conservation Education Sustainability Smithsonian Conservation Biology Institute, 1100 Jefferson Dr. SW, Suite 3123 Biologia Vegetal Universidade Estadual de Campinas, Caixa Postal 6109 Institute of Molecular Plant Sciences University of Edinburgh, Mayfield Rd Royal Botanic Garden Edinburgh, 20a Inverleith Row Programa de Pós-Graduação em Ecologia Instituto Nacional de Pesquisas da Amazônia - INPA, Av. André Araújo 2936 Forest Ecology and Forest Management Group Wageningen University Wageningen University and Research, Droevendaalsesteeg 3, P.O. Box 47 Natural Capital and Plant Health Royal Botanic Gardens Kew Ecosistemas Biodiversidad y Conservación de Especies Universidad Estatal Amazónica, Km. 2 1/2 vía a Tena (Paso Lateral) Museo de Historia Natural Noel Kempff Mercado Universidad Autónoma Gabriel Rene Moreno Santa Cruz, Avenida Irala 565 Casilla Postal 2489 Centro de Biociências Departamento de Botânica e Zoologia Universidade Federal Do Rio Grande Do Norte Campus Universitário Department of Biology University of Miami Coral Fairchild Tropical Botanic Garden Coral Instituto de Biociências Dept. Ecologia Universidade de Sao Paulo - USP, Rua do Matão, Trav. 14, no. 321 Diretoria de Pesquisas Científicas Instituto de Pesquisas Jardim Botânico Do Rio de Janeiro Escuela de Biología Herbario Alfredo Paredes Universidad Central, Ap. Postal 17.01.2177 International Center for Tropical Botany (ICTB) Department of Biological Sciences Florida International University, 11200 SW 8th Street, OE 243 Grupo de Ecología de Ecosistemas Terrestres Tropicales Universidad Nacional de Colombia Sede Amazonía Institute of Biological and Health Sciences Federal University of Alagoas, Av. Lourival Melo Mota, s/n Museu Universitário Centro de Ciências Biológicas e da Natureza Laboratório de Botânica e Ecologia Vegetal Universidade Federal Do Acre Universidad Regional Amazónica IKIAM, Km 7 via Muyuna Cirad UMR Ecofog AgrosParisTech CNRS INRA Univ Guyane Campus Agronomique Iwokrama International Programme for Rainforest Conservation Department of Biological Sciences Humboldt State University, 1 Harpst Street New York Botanical Garden, 2900 Southern Blvd Servicios de Biodiversidad EIRL, Jr. Independencia 405 Herbario Nacional de Bolivia Universitario UMSA, Casilla 10077 Correo Central Missouri Botanical Garden, P.O. Box 299 School of Environmental Sciences University of East Anglia Laboratoire Evolution et Diversité Biologique CNRS Université Paul Sabatier UMR 5174 EDB Department of Forestry Management Universidad Nacional Agraria la Molina, Avenido La Molina, Apdo. 456 School of Geosciences University of Edinburgh, 201 Crew Building, King's Buildings Biology Department Center for Energy Environment and Sustainability Wake Forest University, 1834 Wake Forest Rd Department of Anthropology University of Texas at Austin, SAC 5.150, 2201 Speedway Stop C3200 Andes to Amazon Biodiversity Program Madre de Dios Fundación Puerto Rastrojo, Cra 10 No. 24-76 Oficina 1201 Colegio de Ciencias Biológicas y Ambientales-COCIBA Galapagos Institute for the Arts and Sciences-GAIAS Universidad San Francisco de Quito-USFQ Department of Wildlife Ecology Conservation University of Florida, 110 Newins-Ziegler Hall Fundación Estación de Biología, Cra 10 No. 24-76 Oficina 1201 Embrapa Amazônia Oriental Trav. Dr. Enéas Pinheiro S/no Instituto de Ciencias Naturales Universidad Nacional de Colombia, Apartado, 7945 Amazon Conservation Team, Doekhieweg Oost #24 Facultad de Ciencias Forestales y Medio Ambiente Universidad Nacional de San Antonio Abad Del Cusco, Jirón San Martín 451 Laboratory of Human Ecology Instituto Venezolano de Investigaciones Científicas - IVIC, Ado 20632 Departement EV Muséum National d'Histoire Naturelle de Paris, 16 rue Buffon Instituto de Ciência Agrárias Universidade Federal Rural da Amazônia, Av. Presidente Tancredo Neves 2501 PROTERRA Instituto de Investigaciones de la Amazonía Peruana (IIAP), Av. A. Quiñones km 2 5 ACEER Foundation, Jirón Cusco No 370 Universidad Autónoma Del Beni José Ballivián Campus Universitario Final, Av. Ejercito Regional Norte Amazónico Centro de Investigación y Promoción Del Campesinado, C/Nicanor Gonzalo Salvatierra No 362 Environmental Change Institute Oxford University Centre for the Environment Dyson Perrins Building, South Parks Road School of Agriculture and Food Sciences ARC Centre of Excellence for Environmental Decisions CEED University of Queensland Instituto de Investigaciones para El Desarrollo Forestal (INDEFOR) Universidad de Los Andes, Conjunto Forestal, C.P. 5101 School of Environmental and Forest Sciences University of Washington University of Nottingham, University Park Geography and the Environment University of Texas at Austin, 305 E. 23rd Street, CLA building Laboratório de Ciências Ambientais Universidade Estadual Do Norte Fluminense, Av. Alberto Lamego 2000 Department of Biology University of Maryland GeoIS, El Día 369 y El Telégrafo, 3o Piso Environmental Science and Policy Northern Arizona University FOMABO Manejo Forestal en Las Tierras Tropicales de Bolivia Escuela de Ciencias Forestales (ESFOR) Universidad Mayor de San Simon (UMSS) Agricultural Services Ministry of Agro-Industry and Food Security Agricultural Services Ministry of Agro-Industry and Food Security Mauritius Herbarium Department of Bioscience Aarhus University, Building 1540 Ny Munkegade Ciencias Biológicas Universidad de Los Andes, Carrera 1 # 18a- 10 Medio Ambiente PLUSPRETOL Center for Conservation Education and Sustainability Smithsonian's National Zoo Conservation Biology Institute, National Zoological Park, 3001 Connecticut Ave Tropenbos International, Lawickse Allee 11 PO Box 232 Instituto de Biodiversidade e Floresta Universidade Federal Do Oeste Do Pará Campus Tapajós, Rua Vera Paz Department of Biology University of Missouri Facultad de Biologia Universidad Nacional de la Amazonia Peruana, Pevas 5ta cdra School of Anthropology and Conservation University of Kent, Marlowe Building Herbario Nacional Del Ecuador Universidad Técnica Del Norte Ecology and Biodiversity Group Utrecht University, Padualaan 8 Systems Ecology Free University, De Boelelaan 1087 Departamento de Ecologia Universidade Estadual Paulista - UNESP Instituto de Biociências - IB, Av. 24 A 1515 Departamento de Geografia Universidade Estadual Paulista - UNESP Instituto de Geociências e Ciências Extas - IGCe CAPES: 407232/2013-3-PVE CNPq: 407232/2013-3-PVE Ministério da Ciência, Tecnologia e Inovação: 407232/2013-3-PVE Ministério da Educação: 407232/2013-3-PVE

More than 200 years ago, Alexander von Humboldt reported that tropical plant species richness decreased with increasing elevation and decreasing temperature. Surprisingly, coordinated patterns in plant, bacterial, and fungal diversity on tropical mountains have not yet been observed, despite the central role of soil microorganisms in terrestrial biogeochemistry and ecology. We studied an Andean transect traversing 3.5 km in elevation to test whether the species diversity and composition of tropical forest plants, soil bacteria, and fungi follow similar biogeographical patterns with shared environmental drivers. We found coordinated changes with elevation in all three groups: species richness declined as elevation increased, and the compositional dissimilarity among communities increased with increased separation in elevation, although changes in plant diversity were larger than in bacteria and fungi. Temperature was the dominant driver of these diversity gradients, with weak influences of edaphic properties, including soil pH. The gradients in microbial diversity were strongly correlated with the activities of enzymes involved in organic matter cycling, and were accompanied by a transition in microbial traits towards slower‐growing, oligotrophic taxa at higher elevations. We provide the first evidence of coordinated temperature‐driven patterns in the diversity and distribution of three major biotic groups in tropical ecosystems: soil bacteria, fungi, and plants. These findings suggest that interrelated and fundamental patterns of plant and microbial communities with shared environmental drivers occur across landscape scales. These patterns are revealed where soil pH is relatively constant, and have implications for tropical forest communities under future climate change.

Analyses of forest loss and protected areas suggest that 36 to 57% of Amazonian tree flora may qualify as “globally threatened.”, Estimates of extinction risk for Amazonian plant and animal species are rare and not often incorporated into land-use policy and conservation planning. We overlay spatial distribution models with historical and projected deforestation to show that at least 36% and up to 57% of all Amazonian tree species are likely to qualify as globally threatened under International Union for Conservation of Nature (IUCN) Red List criteria. If confirmed, these results would increase the number of threatened plant species on Earth by 22%. We show that the trends observed in Amazonia apply to trees throughout the tropics, and we predict that most of the world’s >40,000 tropical tree species now qualify as globally threatened. A gap analysis suggests that existing Amazonian protected areas and indigenous territories will protect viable populations of most threatened species if these areas suffer no further degradation, highlighting the key roles that protected areas, indigenous peoples, and improved governance can play in preventing large-scale extinctions in the tropics in this century.

Aim The aim was to test competing hypotheses regarding migration of the Andean timberline within the last 2000 years. Location The upper forest limit in Manu National Park, Peru. Methods A randomized stratified design provided 21 soil profiles from forested sites just below the timberline, 15 from puna grassland sites just above the timberline and 15 from the transitional habitat at the puna–forest boundary. From each profile a surface sample (hereafter modern) and a sample from the base of the organic horizon (hereafter historical) were collected. Pollen and charcoal were analysed from the modern and historical layers of the 51 soil profiles. A chronological framework was provided by 24 14C dates. Data were ordinated as modern and historical groups and the temporal trends illustrated by Procrustes rotation. Results The organic layer from the soil profiles represented the last 600–2000 years. Fire was much more abundant in all habitat types (puna, transitional and forested) in the modern compared with the historical groups. Samples that had historically been in puna just above the timberline showed encroachment by woody species. Samples that had been forested were still classified as forest but their composition had become more transitional. Sites that were transitional appeared to represent a new or expanded class of sites that was far less abundant historically. Main conclusions Our results are consistent with ongoing warming causing an upslope migration of species, although not necessarily of the timberline. Weedy fire-tolerant species are spreading upslope, creating a transitional forest, softening the boundary between forest and puna. Simultaneously, fire introduced to improve grazing outside the park has increasingly penetrated the forest and is causing the upper timberline to shift towards more fire-tolerant and weedy species. Consequently, both the form of the ecotone between forest and grassland and the species composition of these forests is changing and is expected to continue to change, representing a shifting baseline for what is considered to be natural.

Aim Tropical elevation gradients are natural laboratories to assess how changing climate can influence tropical forests. However, there is a need for theory and integrated data collection to scale from traits to ecosystems. We assess predictions of a novel trait-based scaling theory, including whether observed shifts in forest traits across a broad tropical temperature gradient are consistent with local phenotypic optima and adaptive compensation for temperature. Location An elevation gradient spanning 3,300 m and consisting of thousands of tropical tree trait measures taken from 16 1-ha tropical forest plots in southern Peru, where gross and net primary productivity (GPP and NPP) were measured. Time period April to November 2013. Major taxa studied Plants; tropical trees. Methods We developed theory to scale from traits to communities and ecosystems and tested several predictions. We assessed the covariation between climate, traits, biomass and GPP and NPP. We measured multiple traits linked to variation in tree growth and assessed their frequency distributions within and across the elevation gradient. We paired these trait measures across individuals within 16 forests with simultaneous measures of ecosystem net and gross primary productivity. Results Consistent with theory, variation in forest NPP and GPP primarily scaled with forest biomass, but the secondary effect of temperature on productivity was much less than expected. This weak temperature dependence appears to reflect directional shifts in several mean community traits that underlie tree growth with decreases in site temperature. Main conclusions The observed shift in traits of trees that dominate in more cold environments is consistent with an ‘adaptive/acclimatory’ compensation for the kinetic effects of temperature on leaf photosynthesis and tree growth. Forest trait distributions across the gradient showed overly peaked and skewed distributions, consistent with the importance of local filtering of optimal growth traits and recent shifts in species composition and dominance attributable to warming from climate change. Trait-based scaling theory provides a basis to predict how shifts in climate have and will influence the trait composition and ecosystem functioning of tropical forests.

The Anthropocene is characterized as an epoch when human influence has begun to fundamentally alter many aspects of the Earth system and many of the planet's biomes. Here, we review and synthesize our understanding of Anthropocene changes in tropical forests. Key facets include deforestation driven by agricultural expansion, timber and wood extraction, the loss of fauna that maintain critical ecological connections, the spread of fire, landscape fragmentation, the spread of second-growth forests, new species invasion and pathogen spread, increasing CO2, and climate change. The patterns of change are spatially heterogeneous, are often characterized by strong interactions among different drivers, can have both large-scale and remote effects, and can play out through ecological cascades over long timescales. As a consequence, most tropical forests are on a trajectory to becoming altered ecosystems, with the degree of alteration dependent on the intensity and duration of the current bottleneck of human-induced pressures. We highlight the importance of this understanding to develop the strategies necessary for shaping the transition of tropical forests through the early Anthropocene, as well as highlight the opportunities and challenges for the tropical forest science community in the coming decades.

Solar irradiance and precipitation are the most likely drivers of the seasonal variation of net primary productivity (NPP) in tropical forests. Since their roles remain poorly understood, we use litter traps, dendrometer bands and census data collected from one hectare permanent plots to quantify the seasonality of above-groundNPPcomponents and weather parameters in 13 sites distributed along a 2800-m altitudinal gradient ranging from lowland Amazonia to the high Andes. We combine canopy leaf area index and litterfall data to describe the seasonality of canopy production. We hypothesize that solar irradiance is the primary driver of canopy phenology in wetter sites, whereas precipitation drives phenology in drier systems. The seasonal rhythm of canopyNPPcomponents is in synchrony with solar irradiance at all altitudes. Leaf litterfall peaks in the late dry season, both in lowland (averaging 0.54 ± 0.08 Mg C ha y−1, n = 5) and montane forests (averaging 0.29 ± 0.04 Mg C ha y−1, n = 8). Peaks in above-ground coarse woodyNPPappears to be triggered by the onset of rainfall in seasonal lowland rain forests (averaging 0.26 ± 0.04 Mg C ha y−1, n = 5, in November), but not in montane cloud forests.

Research to date on Amazonian swamps has reinforced the impression that tree communities there are dominated by a small, morphologically specialized subset of the regional flora capable of surviving physiologically challenging conditions. In this paper, using data from a large-scale tree inventory in upland, floodplain, and mixed palm swamp forests in Amazonian Ecuador, we report that tree communities growing on well-drained and saturated soils are more similar than previously appreciated. While our data support the traditional view of Amazonian swamp forests as low-diversity tree communities dominated by palms, they also reveal four patterns that have not been well documented in the literature to date: 1) tree communities in these swamp forests are dominated by a phylogenetically diverse oligarchy of 30 frequent and common species; 2) swamp specialists account for 80%) also occur in adjacent well-drained forest types; and 4) many tree species present in swamps are common in well-drained forests (e.g. upland oligarchs account for 34.1% of all swamp stems). These observations imply that, as in the temperate zone, the composition and structure of Amazonian swamp vegetation are determined by a combination of local-scale environmental filters (e.g. plant survival in permanently saturated soils) and landscape-scale patterns and processes (e.g. the composition and structure of tree communities in adjacent non-swamp habitats, the dispersal of propagules from those habitats to swamps). We conclude with suggestions for further research to quantify the relative contributions of these factors in structuring tree communities in Amazonian swamps.

Global climate models suggest enhanced warming of the tropical mid and upper troposphere, with larger temperature rise rates at higher elevations. Changes in fire activity are amongst the most significant ecological consequences of rising temperatures and changing hydrological properties in mountainous ecosystems, and there is a global evidence of increased fire activity with elevation. Whilst fire research has become popular in the tropical lowlands, much less is known of the tropical high Andean region (2000 masl, from Colombia to Bolivia). This study examines fire trends in the high Andes for three ecosystems, the Puna, the Paramo and the Yungas, for the period 1982-2006. We pose three questions: (i) is there an increased fire response with elevation? (ii) does the El Niño- Southern Oscillation control fire activity in this region? (iii) are the observed fire trends human driven (e.g., human practices and their effects on fuel build-up) or climate driven? We did not find evidence of increased fire activity with elevation but, instead, a quasicyclic and synchronous fire response in Ecuador, Peru and Bolivia, suggesting the influence of high-frequency climate forcing on fire responses on a subcontinental scale, in the high Andes. ENSO variability did not show a significant relation to fire activity for these three countries, partly because ENSO variability did not significantly relate to precipitation extremes, although it strongly did to temperature extremes. Whilst ENSO did not individually lead the observed regional fire trends, our results suggest a climate influence on fire activity, mainly through a sawtooth pattern of precipitation (increased rainfall before fire-peak seasons (t-1) followed by drought spells and unusual low temperatures (t0), which is particularly common where fire is carried by low fuel loads (e.g., grasslands and fine fuel). This climatic sawtooth appeared as the main driver of fire trends, above local human influences and fuel build-up cyclicity.

Aim: To examine variation in the phylogenetic diversity (PD) of tree communities across geographical and environmental gradients in Amazonia. Location: Two hundred and eighty-three c. 1 ha forest inventory plots from across Amazonia. Methods: We evaluated PD as the total phylogenetic branch length across species in each plot (PDss), the mean pairwise phylogenetic distance between species (MPD), the mean nearest taxon distance (MNTD) and their equivalents standardized for species richness (ses.PDss, ses.MPD, ses.MNTD). We compared PD of tree communities growing (1) on substrates of varying geological age; and (2) in environments with varying ecophysiological barriers to growth and survival. Results: PDss is strongly positively correlated with species richness (SR), whereas MNTD has a negative correlation. Communities on geologically young- and intermediate-aged substrates (western and central Amazonia respectively) have the highest SR, and therefore the highest PDss and the lowest MNTD. We find that the youngest and oldest substrates (the latter on the Brazilian and Guiana Shields) have the highest ses.PDss and ses.MNTD. MPD and ses.MPD are strongly correlated with how evenly taxa are distributed among the three principal angiosperm clades and are both highest in western Amazonia. Meanwhile, seasonally dry tropical forest (SDTF) and forests on white sands have low PD, as evaluated by any metric. Main conclusions: High ses.PDss and ses.MNTD reflect greater lineage diversity in communities. We suggest that high ses.PDss and ses.MNTD in western Amazonia results from its favourable, easy-to-colonize environment, whereas high values in the Brazilian and Guianan Shields may be due to accumulation of lineages over a longer period of time. White-sand forests and SDTF are dominated by close relatives from fewer lineages, perhaps reflecting ecophysiological barriers that are difficult to surmount evolutionarily. Because MPD and ses.MPD do not reflect lineage diversity per se, we suggest that PDss, ses.PDss and ses.MNTD may be the most useful diversity metrics for setting large-scale conservation priorities. © 2015 John Wiley & Sons Ltd.

Th is paper revisits various hypotheses about oligarchic patterns in Amazonian tree communities put forward by Pitman et al. (2001). Together, these hypotheses predict that most lowland sites in the Amazon are located within large patches of relatively homogeneous edaphic and other environmental conditions, where an oligarchy of common, frequent tree species accounts for a majority of trees. To assess the degree to which these hypotheses have been corroborated or refuted over the last ten years, we reviewed � 200 studies published since 2001. We found overwhelming support for the hypothesis that large-scale oligarchies of common and frequent species are a common feature of Amazonian tree communities. At least 22 studies have documented oligarchies in Amazonian woody plant communities to date, and no studies have looked for oligarchies as defi ned by Pitman et al. (2001) and failed to fi nd them. We argue that six publications that off er critiques of the oligarchy hypothesis do not constitute valid tests. Th e other hypotheses in Pitman et al. (2001) – one regarding the specifi c oligarchic taxa that dominate forests near the eastern base of the Andes and one that attempts to explain why oligarchic species exist – are less well supported by the literature, in large part because they have not been subjected to many tests. We discuss links between these hypotheses and other well-known patterns and hypotheses in ecology (the abundance – occupancy relationship, the Janzen – Connell hypothesis, the niche-environment hypothesis, and the niche breadth hypothesis), and provide additional detail to facilitate rigorous tests in the future. Th e paper concludes by presenting remote sensing evidence that large patches of relatively homogeneous environmental conditions account for most of the upland forest landscape across Amazonian Peru.

One of the major challenges in ecology is to understand how ecosystems respond to changes inenvironmental conditions, and how taxonomic and functional diversity mediate these changes. Inthis study, we use a trait-spectra and individual-based model, to analyse variation in forest primaryproductivity along a 3.3 km elevation gradient in the Amazon-Andes. The model accuratelypredicted the magnitude and trends in forest productivity with elevation, with solar radiation andplant functional traits (leaf dry mass per area, leaf nitrogen and phosphorus concentration, andwood density) collectively accounting for productivity variation. Remarkably, explicit representationof temperature variation with elevation was not required to achieve accurate predictions offorest productivity, as trait variation driven by species turnover appears to capture the effect oftemperature. Our semi-mechanistic model suggests that spatial variation in traits can potentiallybe used to estimate spatial variation in productivity at the landscape scale. Fil: Fyllas, Nikolaos M.. University of Oxford; Reino Unido Fil: Patrick Bentley, Lisa. University of Oxford; Reino Unido Fil: Shenkin, Alexander. University of Oxford; Reino Unido Fil: Asner, Gregory P.. Carnegie Institution for Science. Department of Global Ecology; Reino Unido Fil: Atkin, Owen K.. The Australian National University. ARC Centre of Excellence in Plant Energy Biology. Research School of Biology; Australia 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: Farfan Rios, William. University Wake Forest; Estados Unidos Fil: Gloor, Emanuel. University of Leeds; Reino Unido Fil: Guerrieri, Rossella. Universitat Autònoma de Barcelona; España. University of Edinburgh; Reino Unido Fil: Huaraca Huasco, Walter. Universidad Nacional de San Antonio Abad del Cusco; Perú Fil: Ishida, Yoko. James Cook University; Australia Fil: Martin, Roberta E.. Carnegie Institution for Science. Department of Global Ecology; Estados Unidos Fil: Meir, Patrick. University of Edinburgh; Reino Unido. The Australian National University. Research School of Biology. Division of Plant Sciences; Australia Fil: Phillips, Oliver. University of Leeds; Reino Unido Fil: Salinas, Norma. University of Oxford; Reino Unido. Pontificia Universidad Católica de Perú; Perú Fil: Silman, Miles. University Wake Forest; Estados Unidos Fil: Weerasinghe, Lasantha K.. The Australian National University. Research School of Biology. Division of Plant Sciences; Australia Fil: Zaragoza Castells, Joana. The Australian National University. Research School of Biology. Division of Plant Sciences; Australia. University of Exeter; Reino Unido Fil: Malhi, Yadvinder. University of Oxford; Reino Unido

Aim The aim of this study was to assess the effect of Holocene fire activity and drought on the mesic forests of the Upper Beni and the extent of ecotone migration in south-western Amazonia during the mid-Holocene. An additional goal was to address the hypothesis of Amazonia as a manufactured landscape prior to the arrival of European colonizers in the New World in ad 1492. Location Lakes Chalalan and Santa Rosa, Upper Beni, Bolivian Amazon. Methods Holocene vegetation and fire activity were reconstructed based on pollen and microcharcoal records from sediments of lakes Chalalan and Santa Rosa. Chronologies were based on accelerator mass spectrometry radiocarbon analyses, and vegetation changes were summarized using detrended correspondence analysis. The normalized difference vegetation index was used to classify and determine the extent of the modern savanna–forest ecotone using MODIS satellite image data. Results Mesic evergreen forests persisted in the Upper Beni throughout the Holocene. Fire was frequent during the early and mid-Holocene and temporally consistent in both records. Ordination of pollen data showed an increase in forest change during the late Holocene when fire activity was asynchronous in the two records. Main conclusions The Upper Beni sites were not reached by expanding savannas during periods of major environmental change, suggesting forest resilience and a degree of ecotone stability. We associated the largest observed change in these forests with late Holocene fires that were most probably ignited by humans. We found little evidence supporting widespread pre-1491 cultural landscapes.

Aim Understanding patterns of species turnover along environmental gradients and their consistency across taxonomic groups is central to the study of biodiversity. We may expect congruence in diversity patterns across groups whose ranges could be influenced by species interactions. We explore associations between bird and vegetation communities in the tropical Andes to determine whether patterns of species richness and turnover in birds and trees are congruent with elevation, and whether tree species composition, vegetation structure, elevation, or a combination of these best predicts bird species composition. Location A forested 2600-m elevational gradient on the eastern slope of the Peruvian Andes. Methods Bird surveys and vegetation measurements were conducted at 172 points, and a subset of these were spatially matched with fourteen 1-ha tree inventory plots. Diversity patterns were described for trees, birds, and avian foraging guilds. We used dissimilarity matrices to examine patterns of turnover and nestedness. Turnover of birds and trees was examined by comparing compositional change of adjacent plots along the gradient. Multiple regression on distance matrices was employed to determine contributions of tree species composition, vegetation structure and elevation to explaining variation in bird species composition. Results Species richness was higher for trees than for birds, and whereas diversity in both taxa decreased with elevation, tree richness showed a low-elevation plateau before declining at higher elevations. Tree species had narrower distributions compared to birds, but patterns of turnover were largely congruent between taxa. Nestedness contributed much less to dissimilarity than turnover, although birds showed higher nestedness, particularly at high elevations. Tree species composition, elevation and vegetation structure were all important predictors of bird species composition; the best model explained 78% of bird dissimilarity across plots. Tree species composition was always included in the best models, for all birds and foraging guilds. Main conclusions Our assessment of Andean bird and vegetation communities suggests strong correspondence, perhaps due to direct interactions or similar underlying drivers. We hypothesize that with climate change, range shifts in these groups may not occur independently. Rather, birds may have delayed upslope shifts or may be limited to high-elevation patches where appropriate vegetation communities exist.

Aim To determine if recurrent fire accounts for bamboo-dominated forests that cover about 180,000 km2 of western Amazonia. Location Western Amazonia, including Los Amigos and Cocha Cashu, Peru, and Acre, Brazil. Methods We identified bamboo (B+) and closed-canopy forests (B−) using a combination of MODIS imagery, Landsat TM imagery and field surveys. Local-scale and landscape-scale patterns of historical bamboo dynamics were analysed by collecting soil cores from B+ and B− sites across three regions. Soil charcoal within cores was used to document previous fire, and phytoliths were employed to reconstruct vegetational patterns through time. Results Fire occurred in B+ and B− sites with approximately equal frequencies in each region sampled. Between regions, fire signals were most prevalent at Los Amigos, with Cocha Cashu and Acre sites typically containing only trace amounts of charcoal. Vegetational state remained constant through time in both B+ and B− forests of Cocha Cashu and Acre. The persistence of bamboo through time is less clear at Los Amigos, with bamboo presence changing both spatially and temporally. Main conclusions Fire does not appear to be the driving mechanism behind current bamboo distributions, although it may facilitate bamboo invasion. Once established in an area, bamboo persistently dominates the vegetation structure over historical time-scales at some sites (Cocha Cashu and Acre), but not at others (Los Amigos), which is likely to be a function of patch origin. Increasing human activity, including fire and deforestation, combined with predicted Amazonian drought, may allow bamboo to expand from its current distribution and replace typical Amazonian closed-canopy forests. These structural changes in the forests have important implications for carbon storage, as Amazonian forests are currently the largest terrestrial carbon sink in the world.

Tree growth response across environmental gradients is fundamental to understanding species distributional ecology and forest ecosystem ecology and to predict future ecosystem services. Cross-sectional patterns of ecosystem properties with respect to climatic gradients are often used to predict ecosystem responses to global change. Across sites in the tropics, primary productivity increases with temperature, suggesting that forest ecosystems will become more productive as temperature rises. However, this trend is confounded with a shift in species composition and so may not reflect the response of in situ forests to warming. In this study, we simultaneously studied tree diameter growth across the altitudinal ranges of species within a single genus across a geographically compact temperature gradient, to separate the direct effect of temperature on tree growth from that of species compositional turnover. Using a Bayesian state space modeling framework we combined data from repeated diameter censuses and dendrometer measurements from across a 1700-m altitudinal gradient collected over six years on over 2400 trees in Weinmannia, a dominant and widespread genus of cloud forest trees in the Andes. Within species, growth showed no consistent trend with altitude, but higher-elevation species had lower growth rates than lower-elevation species, suggesting that species turnover is largely responsible for the positive correlation between productivity and temperature in tropical forests. Our results may indicate a significant difference in how low- and high-latitude forests will respond to climate change, since temperate and boreal tree species are consistently observed to have a positive relationship between growth and temperature. If our results hold for other tropical species, a positive response in ecosystem productivity to increasing temperatures in the Andes will depend on the altitudinal migration of tree species. The rapid pace of climate change, and slow observed rates of migration, suggest a slow, or even initially negative response of ecosystem productivity to warming. Finally, this study shows how the observed scale of biological organization can affect conclusions drawn from studies of ecological phenomena across environmental gradients, and calls into question the common practice in tropical ecology of lumping species at higher taxonomic levels.

Tropical forests are threatened by many human disturbances – two of the most important of which are deforestation and climate change. To mitigate the impacts of these disturbances, it is important to understand their potential effects on the distributions of species. In the tropics, such understanding has been hindered by poor knowledge of the current distributions and range limits of most species. Here, we use herbarium collection records to model the current and future distributions of ca. 3000 Amazonian plant species. We project these distributions into the future under a range of different scenarios related to the magnitude of climate change and extent of deforestation as well as the response of species to changes in temperature, precipitation, and atmospheric concentrations of CO2 . We find that the future of Amazonian diversity will be dependant primarily on the ability of species to tolerate or adapt to rising temperatures. If the thermal niches of tropical plant species are fixed and incapable of expanding under rapid warming, then the negative effects of climate change will overshadow the effects of deforestation, greatly reducing the area of suitable habitat available to most species and potentially leading to massive losses of biodiversity throughout the Amazon. If tropical species are generally capable of tolerating warmer temperatures, rates of habitat loss will be greatly reduced but many parts of Amazonia may still experience rapid losses of diversity, with the effects of enhanced seasonal water stress being similar in magnitude to the effects of deforestation.

The history of landscape alteration in Amazonia by humans prior to the arrival of Europeans remains poorly understood. Estimates of human population size at the time of European contact vary by several million, and the trajectories of cultural and agricultural development are equally uncertain. The extent to which human populations altered Amazonian ecosystems is a function of population size, land management style, radius of influence of each subpopulation, and the temporal development of settlements. Here we report evidence that relates to the temporal and spatial scales of human disturbance in western Amazonia. Three lake sediment records and 94 terrestrial soil cores located 0–12 km from the adjacent lake were used to examine scales of pre-Columbian human impacts at two sites in western Amazonian forests. Lake sediment and soil charcoal records indicate discontinuous and localized burning around the study areas. Terrestrial soil phytolith and nutrient analyses reveal a range in disturbance intensity between the two sites but contain no evidence of large-scale forest clearing or anthropogenic soil enrichment. Our data suggest that while all of the settings examined were occupied or used, the halo of influence around each was limited. It should not be assumed that intensive landscape transformations by prehistoric human populations occurred throughout Amazonia or that Amazonian forests were resilient in the face of heavy historical disturbance.

Aim Species distribution models (SDMs) use the locations of collection records to map the distributions of species, making them a powerful tool in conservation biology, ecology and biogeography. However, the accuracy of range predictions may be reduced by temporally autocorrelated biases in the data. We assess the accuracy of SDMs in predicting the ranges of tropical plant species on the basis of different sample sizes while incorporating real-world collection patterns and biases. Location Tropical South American moist forests. Methods We use dated herbarium records to model the distributions of 65 Amazonian and Andean plant species. For each species, we use the first 25, 50, 100, 125 and 150 records collected and available for each species to analyse changes in spatial aggregation and climatic representativeness through time. We compare the accuracy of SDM range estimates produced using the time-ordered data subsets to the accuracy of range estimates generated using the same number of collections but randomly subsampled from all available records. Results We find that collections become increasingly aggregated through time but that additional collecting sites are added resulting in progressively better representations of the species’ full climatic niches. The range predictions produced using time-ordered data subsets are less accurate than predictions from random subsets of equal sample sizes. Range predictions produced using time-ordered data subsets consistently underestimate the extent of ranges while no such tendency exists for range predictions produced using random data subsets. Main conclusions These results suggest that larger sample sizes are required to accurately map species ranges. Additional attention should be given to increasing the number of records available per species through continued collecting, better distributed collecting, and/or increasing access to existing collections. The fact that SDMs generally under-predict the extent of species ranges means that extinction risks of species because of future habitat loss may be lower than previously estimated.

Fire in tropical montane cloud forests (TMCFs) is not as rare as once believed. Andean TMCFs sit immediately below highly flammable, high-altitude grasslands (Puna/Paramo) that suffer from recurrent anthropogenic fire. This treeline is a zone of climatic tension where substantial future warming is likely to force upward tree migrations, while increased fire presence and fire impacts are likely to force it downwards. TMCFs contain large carbon stocks in their peat soils and their loss through fire is a currently unaccounted for regional source of CO2. This study, conducted in the southern Peruvian Andes (>2800 m), documents differences in live tree biomass, fine root biomass, fallen and standing dead wood, and soil organic carbon in 4 paired-sample plots (burned versus control) following the severe ground fires that occurred during the 2005 Andean drought. Peat soils contributed the most to biomass burning emissions, with lower values corresponding to an 89% mean stock difference compared to the controls (mean ± SE) (54.1 ± 22.3 vs. 5.8 ± 5.3 MgC ha−1). Contrastingly, carbon stocks from live standing trees differed by a non-significant 37% lower value in the burned plots compared to the controls, largely compensated by vigorous resprouting (45.5 ± 17.4 vs. 69.2 ± 13.4 MgC ha−1). Both standing dead trees and fallen dead wood were significantly higher in the burned plots with a three-fold difference from the controls: dead Trees 45.2 ± 9.4 vs. 16.4 ± 4.4 MgC ha−1, and ca. a 2 fold difference for the fallen dead wood: 11.2 ± 5 vs. 6.7 ± 3.2 MgC ha−1 for the burned plots versus their controls. A preliminary estimate of the regional contribution of biomass burning emissions from Andean TMCFs for the period 2000–2008, resulted in mean carbon emission rates of 1.3 TgC yr−1 (max-min: 1.8–0.8 TgC yr−1). This value is in the same order of magnitude than South American annual fire emissions (300 TgC yr−1) suggesting the need for further research on Andean forest fires. On-going projects on the region are working on the promotion of landowner participation in TMCFs conservation through REDD+ mechanism. The heart of the proposed initiative is reforestation of degraded lands with green fire breaks enriched with economically valuable Andean plant species. The cultivation of these species may contribute to reduce deforestation pressure on the Amazonian cloud forest by providing an alternative income to local communities, at the same time that they prevent the spread of fire into Manu National Park and adjacent community-held forests, protecting forest and reducing CO2 emissions.

Developing countries are required to produce robust estimates of forest carbon stocks for successful implementation of climate change mitigation policies related to reducing emissions from deforestation and degradation (REDD). Here we present a “benchmark” map of biomass carbon stocks over 2.5 billion ha of forests on three continents, encompassing all tropical forests, for the early 2000s, which will be invaluable for REDD assessments at both project and national scales. We mapped the total carbon stock in live biomass (above- and belowground), using a combination of data from 4,079 in situ inventory plots and satellite light detection and ranging (Lidar) samples of forest structure to estimate carbon storage, plus optical and microwave imagery (1-km resolution) to extrapolate over the landscape. The total biomass carbon stock of forests in the study region is estimated to be 247 Gt C, with 193 Gt C stored aboveground and 54 Gt C stored belowground in roots. Forests in Latin America, sub-Saharan Africa, and Southeast Asia accounted for 49%, 25%, and 26% of the total stock, respectively. By analyzing the errors propagated through the estimation process, uncertainty at the pixel level (100 ha) ranged from ±6% to ±53%, but was constrained at the typical project (10,000 ha) and national (>1,000,000 ha) scales at ca . ±5% and ca . ±1%, respectively. The benchmark map illustrates regional patterns and provides methodologically comparable estimates of carbon stocks for 75 developing countries where previous assessments were either poor or incomplete.

Question: How accurately do Amazonian montane forest pollen spectra reflect the vegetation? Can compositional changes observed in the vegetation along environmental gradients be identified in the pollen spectra? How well do herbarium collection data and bioclimatic envelopes represent abundance changes along elevation gradients? Location: Amazonian montane forests, Peru. Methods: Moss polsters collected along five altitudinal transects spanning over 3000 m a.s.l. were used to characterize pollen spectra. Vegetation plot data from a network of 15 1-ha permanent plots were used to correlate pollen spectra with present-day vegetation. Probability density functions (PDFs) fitted to pollen and plot data allowed comparisons using Spearman correlation coefficients. Ordination analyses were used to summarize changes in pollen spectra. Correlations between pollen-based PDFs and previously-published herbarium collection PDFs were also evaluated. Results: Pollen spectra closely reflected changes in species composition along elevation gradients. A mid-elevation shift in pollen spectra was identified using ordination analyses. Pollen spectra from the driest forest in our data set were statistically different from those of wet forests. Pollen abundance PDFs along the altitudinal gradient were significantly correlated (P

The elevational gradient in plant and animal diversity is one of the most widely documented patterns in ecology and, although no consensus explanation exists, many hypotheses have been proposed over the past century to explain these patterns. Historically, research on elevational diversity gradients has focused almost exclusively on plant and animal taxa. As a result, we do not know whether microbes exhibit elevational gradients in diversity that parallel those observed for macroscopic taxa. This represents a key knowledge gap in ecology, especially given the ubiquity, abundance, and functional importance of microbes. Here we show that, across a montane elevational gradient in eastern Peru, bacteria living in three distinct habitats (organic soil, mineral soil, and leaf surfaces) exhibit no significant elevational gradient in diversity (r2 0.1 in all cases), in direct contrast to the significant diversity changes observed for plant and animal taxa across the same montane gradient (r2 > 0.75, P < 0.001 in all cases). This finding suggests that the biogeographical patterns exhibited by bacteria are fundamentally different from those of plants and animals, highlighting the need for the development of more inclusive concepts and theories in biogeography to explain these disparities.

Three pollen and charcoal records from three lakes lying at 3400 m elevation in southern Peru provided a record of landscape change spanning the last ca.18 000 cal. a BP. The tree line lay close to the site between ca. 16 000 and 12 000 cal. a BP, with Polylepis woodlands growing near the lakes. Progressively drying conditions led to increased fire after 12 000 cal. a BP, coinciding with a decline in Polylepis cover and Andean forest relicts as puna grasslands expanded. A strong decrease in the rate of sediment deposition between ca. 12 000 and ca. 4400 cal. a BP was interpreted to indicate the presence of sedimentary hiatuses. With the return of wet conditions after 4400 cal. a BP, forests did not reassemble around the lakes. Instead, fire-maintained grasslands dominated the landscape. Humans probably induced the intensified fire activity during the late Holocene and thereby deflected local successions. The modern fragmented landscape, with Polylepsis woodlands existing in fire-resistant pockets above the general limit of the Andean tree line, resulted from the intensification of human land use practices during the last 4400 cal. a BP. Copyright # 2011 John Wiley & Sons, Ltd.

Aim Climate change causes shifts in species distributions, or ‘migrations’. Despite the centrality of species distributions to biodiversity conservation, the demonstrated large migration of tropical plant species in response to climate change in the past, and the expected sensitivity of species distributions to modern climate change, no study has tested for modern species migrations in tropical plants. Here we conduct a first test of the hypothesis that increasing temperatures are causing tropical trees to migrate to cooler areas. Location Tropical Andes biodiversity hotspot, south-eastern Peru, South America. Methods We use data from repeated (2003/04–2007/08) censuses of 14 1-ha forest inventory plots spanning an elevational gradient from 950 to 3400 m in Manu National Park in south-eastern Peru, to characterize changes in the elevational distributions of 38 Andean tree genera. We also analyse changes in the genus-level composition of the inventory plots through time. Results We show that most tropical Andean tree genera shifted their mean distributions upslope over the study period and that the mean rate of migration is approximately 2.5–3.5 vertical metres upslope per year. Consistent with upward migrations we also find increasing abundances of tree genera previously distributed at lower elevations in the majority of study plots. Main conclusions These findings are in accord with the a priori hypothesis of upward shifts in species ranges due to elevated temperatures, and are potentially the first documented evidence of present-day climate-driven migrations in a tropical plant community. The observed mean rate of change is less than predicted from the temperature increases for the region, possibly due to the influence of changes in moisture or non-climatic factors such as substrate, species interactions, lags in tree community response and/or dispersal limitations. Whatever the cause(s), continued slower-than-expected migration of tropical Andean trees would indicate a limited ability to respond to increased temperatures, which may lead to increased extinction risks with further climate change.

Conserving biodiversity in the face of climate change requires a predictive ecology of species distributions. Nowhere is this need more acute than in the tropics, which harbor the majority of Earth’s species and face rapid and large climate and land-use changes. However, the study of species distributions and their responses to climate change in high diversity tropical regions is potentially crippled by a lack of basic data. We analyzed a database representing more than 800 000 unique geo-referenced natural history collections to determine what fraction of tropical plant species has sufficient numbers of available collections for use in the habitat or niche models commonly used to predict species responses to climate change. We found that more than nine out of 10 species from the three principle tropical realms are so poorly collected (no20 records) that they are essentially invisible to modern modeling and conservation tools. In order to predict the impact of climate change on tropical species, efforts must be made to increase the amount of data available from tropical countries through a combination of collecting new specimens and digitizing existing records.

Improved management of carbon storage by terrestrial biomes has significant value for mitigating climate change. The carbon value of such management has the potential to provide additional income to rural communities and provide biodiversity and climate adaptation co-benefits. Here, we quantify the carbon stores in a 49,300-ha landscape centered on the cloud forest–grassland transition of the high Andes in Manu National Park, Peru. Aboveground carbon densities were measured across the landscape by field sampling of 70 sites above and below the treeline. The forest near the treeline contained 63.4 ± 5.2 Mg C ha−1 aboveground, with an additional 13.9 ± 2.8 Mg C ha−1 estimated to be stored in the coarse roots, using a root to shoot ratio of 0.26. Puna grasslands near the treeline were found to store 7.5 ± 0.7 Mg C ha−1 in aboveground biomass. Comparing our result to soil data gathered by Zimmermann and others (Ecosystems 13:62–74, 2010), we found the ratio of belowground:aboveground carbon decreased from 15.8 on the puna to 8.6 in the transition zone and 2.1 in the forest. No significant relationships were found between carbon densities and slope, altitude or fire disturbance history, though grazing (for puna) was found to reduce aboveground carbon densities significantly. We scaled our study sites to the study region with remote sensing observations from Landsat. The carbon sequestration potential of improved grazing management and assisted upslope treeline migration was also estimated. Afforestation of puna at the treeline could generate revenues of US $1,374 per ha over the project lifetime via commercialization of the carbon credits from gains in aboveground carbon stocks. Uncertainties in the fate of the large soil carbon stocks under an afforestation scenario exist.

Aim To investigate the palaeoecological changes associated with the last ice age, subsequent deglaciation and human occupation of the central Andes. Location Lake Pacucha, Peruvian Andes (13� 36¢26¢¢ S, 73� 19¢42¢¢ W; 3095 m elevation). Methods Vegetation assemblages were reconstructed for the last 24 cal. kyr bp (thousand calibrated 14 C years before present), based on pollen analysis of sediments from Lake Pacucha. An age model was established using 14 C accelerator mass spectrometry dates on bulk sediment. Fossil pollen and sedimentological analyses followed standard methodologies. Results Puna brava replaced the Andean forest at the elevation of Lake Pacucha at the Last Glacial Maximum (LGM). Deglaciation proceeded rapidly after 16 cal. kyr bp, and near-modern vegetation was established by c. 14 cal. kyr bp. The deglacial was marked by the range expansion of forest taxa as grassland taxa receded in importance. The mid-Holocene was marked by a lowered lake level but relatively unchanged vegetation. Quinoa and maize pollen were found in the latter half of the Holocene. Main conclusions Temperatures were about 7‐8 � C colder than present at this site during the LGM. The pattern of vegetation change was suggestive of microrefugial expansion rather than simple upslope migration. The midHolocene droughts were interrupted by rainfall events sufficiently frequent to allow vegetation to survive largely unchanged, despite lowering of the lake level. Human activity at the lake included a 5500-year history of quinoa cultivation and 3000 years of maize cultivation.

Predicted climate change in the Andes will require plant species to migrate upslope to avoid extinction. Central to predictions of species responses to climate change is an understanding of species distributions along environmental gradients. Environmental gradients are frequently modelled as abiotic, but biotic interactions can play important roles in setting species distributions, abundances, and life history traits. Biotic interactions also have the potential to influence species responses to climate change, yet they remain mostly unquantified. An important interaction long studied in tropical forests is postdispersal seed predation which has been shown to affect the population dynamics, community structure, and diversity of plant species in time and space. This paper presents a comparative seed predation study of 24 species of tropical trees across a 2.5 km elevation gradient in the Peruvian Andes and quantifies seed predation variation across the elevational gradient. We then use demographic modelling to assess effects of the observed variation in seed predation on population growth rates in response to observed increasing temperatures in the area. We found marked variation among species in total seed predation depending on the major seed predator of the species and consistent changes in seed predation across the gradient. There was a significant increase in seed survival with increasing elevation, a trend that appears to be driven by regulation of seed predators via top-down forces in the lowlands giving way to bottom-up (productivity) regulation at mid- to high elevations, resulting in a ninefold increase in effective fecundity for trees at high elevations. This potential increase in seed crop size strongly affects modelled plant population growth and seed dispersal distances, increasing population migration potential in the face of climate change. These results also indicate that species interactions can have effects on par with climate in species responses to global change.

Understory herb communities in the Southern Appalachians are among the highest biodiversity plant communities in North America. In the mid-1990s, a debate began over whether understory herb communities recover to their pre-disturbance states following logging. Studies showing reduced herb-layer diversity in previously logged forests were criticized for not accounting for intersite environmental heterogeneity. More recent studies have addressed environmental heterogeneity, but have neglected long-term recovery by using “mature forests” as young as 80 years old as the benchmark for diversity comparison, even though old growth stands have disturbance return intervals exceeding 500 years. Here we address concerns clouding previous studies of high-diversity Appalachian herb communities and investigate their long-term recovery by comparing paired sites of old growth forest and forest logged 100–150 years ago. We found that species richness and individual abundance is greater in old growth forests than mature forests and that species composition differed significantly between the two. Turnover in species among old growth and mature forests accounted for 11% of the total species richness and was significantly greater than expected. Species turnover at intermediate (5–50 m) and landscape-scales (>10 km) contributed the most towards total species richness. Herb communities in rich cove forests have successional trajectories that exceed 150 years, with important community changes still occurring long after the forest returns to what has been previously termed a “mature” state. To conserve the diverse herb layer, we conclude that mature forest stands are too young to serve as baselines for recovery, landscape-scale preservation of multiple forest stands is needed to maximize species richness, and maintaining 100–150-year logging rotations will likely lead to loss of biodiversity.

The net primary productivity, carbon (C) stocks and turnover rates (i.e. C dynamics) of tropical forests are an important aspect of the global C cycle. These variables have been investigated in lowland tropical forests, but they have rarely been studied in tropical montane forests (TMFs). This study examines spatial patterns of above- and belowground C dynamics along a transect ranging from lowland Amazonia to the high Andes in SE Peru. Fine root biomass values increased from 1.50 Mg C ha−1 at 194 m to 4.95 ± 0.62 Mg C ha−1 at 3020 m, reaching a maximum of 6.83 ± 1.13 Mg C ha−1 at the 2020 m elevation site. Aboveground biomass values decreased from 123.50 Mg C ha−1 at 194 m to 47.03 Mg C ha−1 at 3020 m. Mean annual belowground productivity was highest in the most fertile lowland plots (7.40 ± 1.00 Mg C ha−1 yr−1) and ranged between 3.43 ± 0.73 and 1.48 ± 0.40 Mg C ha−1 yr−1 in the premontane and montane plots. Mean annual aboveground productivity was estimated to vary between 9.50 ± 1.08 Mg C ha−1 yr−1 (210 m) and 2.59 ± 0.40 Mg C ha−1 yr−1 (2020 m), with consistently lower values observed in the cloud immersion zone of the montane forest. Fine root C residence time increased from 0.31 years in lowland Amazonia to 3.78 ± 0.81 years at 3020 m and stem C residence time remained constant along the elevational transect, with a mean of 54 ± 4 years. The ratio of fine root biomass to stem biomass increased significantly with increasing elevation, whereas the allocation of net primary productivity above- and belowground remained approximately constant at all elevations. Although net primary productivity declined in the TMF, the partitioning of productivity between the ecosystem subcomponents remained the same in lowland, premontane and montane forests.

Aim Species distribution models are a potentially powerful tool for predicting the effects of global change on species distributions and the resulting extinction risks. Distribution models rely on relationships between species occurrences and climate and may thus be highly sensitive to georeferencing errors in collection records. Most errors will not be caught using standard data filters. Here we assess the impacts of georeferencing errors and the importance of improved data filtering for estimates of the elevational distributions, habitat areas and predicted relative extinction risks due to climate change of nearly 1000 Neotropical plant species. Location The Amazon basin and tropical Andes, South America. Methods We model the elevational distributions, or ‘envelopes’, of 932 Amazonian and Andean plant species from 35 families after performing standard datafiltering,andagainusingonlydatathathavepassedthroughanadditionallayer ofdatafiltering.Wetestforagreementintheelevationsrecordedwiththecollection and the elevation inferred from a digital elevation model (DEM) at the collection coordinates. From each dataset we estimate species range areas and extinction risks due to the changes in habitat area caused by a 4.5 � C increase in temperature. Results Amazonian and Andean plant species have a median elevational range of 717 m. Using only standard data filters inflates range limits by a median of 433 m (55%). This is equivalent to overestimating the temperature tolerances of species by over 3 � C ‐ only slightly less than the entire regional temperature change predicted over the next 50‐100 years. Georeferencing errors tend to cause overestimates in the amount of climatically suitable habitat available to species and underestimates in species extinction risks due to global warming. Georeferencing error artefacts are sometimes so great that accurately predicting whether species habitat areas will decrease or increase under global warming is impossible. The drawback of additional data filtering is large decreases in the number of species modelled, with Andean species being disproportionately eliminated. Main conclusions Even with rigorous data filters, distribution models will mischaracterize the climatic conditions under which species occur due to errors in the collection data. These errors affect predictions of the effects of climate change on species ranges and biodiversity, and are particularly problematic in mountainous areas. Additional data filtering reduces georeferencing errors but eliminates many species due to a lack of sufficient ‘clean’ data, thereby limiting our ability to predict the effects of climate change in many ecologically important and sensitive regions such as the Andes Biodiversity Hotspot.