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The role of conspecific density dependence (CDD) in the maintenance of species richness is a central focus of tropical forest ecology. However, tests of CDD often ignore the integrated effects of CDD over multiple life stages and their long-term impacts on population demography. We combined a 10-year time series of seed production, seedling recruitment and sapling and tree demography of three dominant Southeast Asian tree species that adopt a mast-fruiting phenology. We used these data to construct individual-based models that examine the effects of CDD on population growth rates ( λ ) across life-history stages. Recruitment was driven by positive CDD for all species, supporting the predator satiation hypothesis, while negative CDD affected seedling and sapling growth of two species, significantly reducing λ . This negative CDD on juvenile growth overshadowed the positive CDD of recruitment, suggesting the cumulative effects of CDD during seedling and sapling development has greater importance than the positive CDD during infrequent masting events. Overall, CDD varied among positive, neutral and negative effects across life-history stages for all species, suggesting that assessments of CDD on transitions between just two stages (e.g. seeds seedlings or juveniles mature trees) probably misrepresent the importance of CDD on population growth and stability.

Understanding the drivers of invasive species spread is key to designing optimal management programmes for controlling them. Population models, parameterized from demographic and dispersal data, are useful for simulating invasion when long-term observations are lacking, which is particularly important when invasions are occurring rapidly. We aimed to understand how the spread of Pyracantha angustifolia (an invasive ornamental shrub) is influenced by heterogeneity in local conditions within a dry inter-montane valley in northwestern Argentina that is currently experiencing rapid urban expansion and concomitant reduction in cattle farming. Field surveys demonstrated that individuals growing in shrublands have a higher fecundity than those in grassland and rocky habitats. Furthermore, grazing pressure of cattle and horses substantially reduces fecundity and impacts the relationship between age and fecundity. We incorporated our field-estimated habitat and age-specific fecundities into both analytical integro-difference equation models and individual-based models to predict rates of spread across each habitat type in the presence or absence of grazing pressure. Results indicate that the rate of spread would be substantially higher in shrublands (by up to 33%) and highlight that grazing pressure can, through direct consumption of seeds by livestock, substantially depress the rate of spread (by up to 53%). These results suggest that shrubland areas in the valley are most vulnerable to invasion and that grazing may help to reduce the impact of Pyracantha. This suggests that a synergism between urban expansion and reduction in domestic livestock density contributes to the spread of an invasive species in this environment.

Made available in DSpace on 2022-04-28T19:45:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 Consejo Nacional de Investigaciones Científicas y Técnicas Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Natural Environment Research Council Formulating effective management plans for addressing the impacts of invasive non-native species (INNS) requires the definition of clear priorities and tangible targets, and the recognition of the plurality of societal values assigned to these species. These tasks require a multi-disciplinary approach and the involvement of stakeholders. Here, we describe procedures to integrate multiple sources of information to formulate management priorities, targets, and high-level actions for the management of INNS. We follow five good-practice criteria: justified, evidence-informed, actionable, quantifiable, and flexible. We used expert knowledge methods to compile 17 lists of ecological, social, and economic impacts of lodgepole pines (Pinus contorta) and American mink (Neovison vison) in Chile and Argentina, the privet (Ligustrum lucidum) in Argentina, the yellow-jacket wasp (Vespula germanica) in Chile, and grasses (Urochloa brizantha and Urochloa decumbens) in Brazil. INNS plants caused a greater number of impacts than INNS animals, although more socio-economic impacts were listed for INNS animals than for plants. These impacts were ranked according to their magnitude and level of confidence on the information used for the ranking to prioritise impacts and assign them one of four high-level actions—do nothing, monitor, research, and immediate active management. We showed that it is possible to formulate management priorities, targets, and high-level actions for a variety of INNS and with variable levels of available information. This is vital in a world where the problems caused by INNS continue to increase, and there is a parallel growth in the implementation of management plans to deal with them. School of Biological Sciences University of Aberdeen Instituto de Investigaciones Marinas y Costeras (IIMyC) FCEyN-Universidad Nacional de Mar del Plata-CONICET CC 1260 Instituto de Geología de Costas y del Cuaternario (IGCyC) FCEyN-Universidad Nacional de Mar del Plata-CIC Funes 3350 Instituto de Ecología Regional (IER UNT CONICET) and Facultad de Ciencias Naturales e IMl UNT Residencia Universitaria de Horco Molle, Yerba Buena Business School University of Aberdeen Business School University of Stellenbosch, PO Box 610 Laboratorio de Estudios del Antropoceno (LEA) Facultad de Ciencias Forestales Universidad de Concepción Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Dirección Regional Patagonia Norte de la Administración de Parques Nacionales, O’Connor 1188, 8400-San Carlos de Bariloche Laboratorio de Invasiones Biológicas (LIB) Facultad de Ciencias Forestales Universidad de Concepción Institute of Ecology and Biodiversity (IEB) Servicio Agrícola y Ganadero Gobierno de Chile Lab of Vegetation Ecology Instituto de Biociências Universidade Estadual Paulista (UNESP), Av. 24A Centro de Humedales Río Cruces (CEHUM) Universidad Austral de Chile Grupo de Ecología de Invasiones INIBIOMA CONICET Universidad Nacional del Comahue, Quintral 1250 Department of Biology and Biochemistry University of Houston Programa Patagonia Departamento de Conservación de Aves Argentinas/Asociación Ornitológica del Plata Departamento de Análisis de Sistemas Complejos Fundación Bariloche CONICET, Av. Bustillo 9400 EDGE of Existence-Zoological Society of London Lab of Vegetation Ecology Instituto de Biociências Universidade Estadual Paulista (UNESP), Av. 24A Consejo Nacional de Investigaciones Científicas y Técnicas: -2019-74-APN-DIR#CONICET FAPESP: 2018/14995-8 Natural Environment Research Council: NE/S011641/1

1. Revealing the mechanisms of environmental niche partitioning within lowland tropical forests is important for understanding the drivers of current species distributions and potential vulnerability to environmental change. Tropical forest structure and species composition change across edaphic gradients in Borneo over short distances. However, our understanding of how edaphic conditions affect tree physiology and whether these relationships drive niche partitioning within Bornean forests remains incomplete. 2. This study evaluated how leaf physiological function changes with nutrient availability across a fine-scale edaphic gradient and whether these relationships vary according to tree height. Furthermore, we tested whether intraspecific leaf trait variation allows generalist species to populate a wider range of environments. 3. We measured leaf traits of 218 trees ranging in height from 4 to 66 m from 13 dipterocarp species within four tropical forest types (alluvial, mudstone, sandstone and kerangas) occurring along an

Trade-offs in wood anatomical characteristics reflect different strategies used by trees to deal with water transport in response to variation in environmental conditions. To study vascular strategies for Bornean rainforest trees, we compared water transport-related anatomical characteristics in branch wood between the common tree species Vatica dulitensis (Dipterocarpaceae) from old-growth forest and the common pioneer tree species Macaranga gigantea (Euphorbiaceae) from selectively logged forest. We hypothesised that the vessel traits of the pioneer species would reflect the need to capture and transport resources to support its fast growth rate (resource-acquisitive strategy), while the species of the old-growth forest would display more conservative vessel traits (resource-conservative strategy). We found that M. gigantea had significantly greater vessel area, hydraulically weighted diameter, vessel area to number ratio, and potential hydraulic conductivity than V. dulitensis. These results suggest that vessel traits of the common old-growth species would ensure high hydraulic safety during occasional drought when soil moisture is limited, while the common species of selectively logged forest possesses an efficient water transport system but its vessels would confer lower hydraulic safety during drought conditions. These contrasting vascular strategies highlight the potential for divergent responses of species of Bornean forest trees to future climatic extremes.

• Fine-scale topographic–edaphic gradients are common in tropical forests and drive species spatial turnover and marked changes in forest structure and function. We evaluate how hydraulic traits of tropical tree species relate to vertical and horizontal spatial niche specialization along such a gradient. • Along a topographic–edaphic gradient with uniform climate in Borneo, we measured six key hydraulic traits in 156 individuals of differing heights in 13 species of Dipterocarpaceae. We investigated how hydraulic traits relate to habitat, tree height and their interaction on this gradient. • Embolism resistance increased in trees on sandy soils but did not vary with tree height. By contrast, water transport capacity increased on sandier soils and with increasing tree height. Habitat and height only interact for hydraulic efficiency, with slope for height changing from positive to negative from the clay-rich to the sandier soil. Habitat type influenced trait–trait relationships for all traits except wood density. • Our data reveal that variation in the hydraulic traits of dipterocarps is driven by a combination of topographic–edaphic conditions, tree height and taxonomic identity. Our work indicates that hydraulic traits play a significant role in shaping forest structure across topographic–edaphic and vertical gradients and may contribute to niche specialization among dipterocarp species.

Forest degradation through logging is pervasive throughout the world’s tropical forests, leading to changes in the three‐dimensional canopy structure that have profound consequences for wildlife, microclimate and ecosystem functioning. Quantifying these structural changes is fundamental to understanding the impact of degradation, but is challenging in dense, structurally complex forest canopies. We exploit discrete‐return airborne LiDAR surveys across a gradient of logging intensity in Sabah, Malaysian Borneo, and assess how selective logging has affected canopy structure (Plant Area Index, PAI, and its vertical distribution within the canopy). LiDAR products compared well to independent, analogue models of canopy structure produced from detailed ground‐based inventories undertaken in forest plots, demonstrating the potential for airborne LiDAR to quantify the structural impacts of forest degradation at landscape scale, even in some of the world’s tallest and most structurally complex tropical forests. PAI estimates across the plot network exhibited a strong linear relationship with stem basal area (R2 = 0.95). After at least 11‐14 years of recovery, PAI was ~28% lower in moderately logged plots and ~52% lower in heavily logged plots than in old‐growth forest plots. These reductions in PAI are associated with near‐complete lack of trees >30‐m tall, which has not been fully compensated for by increasing plant area lower in the canopy. This structural change drives a marked reduction in the diversity of canopy environments, with the deep, dark understory conditions characteristic of old‐growth forests far less prevalent in logged sites, with full canopy recovery likely to take decades. Synthesis and Applications. Effective management and restoration of tropical forests requires detailed monitoring of the forest and its environment. We demonstrate that airborne LiDAR can effectively map the canopy architecture of the complex tropical forests of Borneo, capturing the three‐dimensional impact of degradation on canopy structure at landscape scales, therefore facilitating efforts to restore and conserve these ecosystems.

Arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) associations are critical for host-tree performance. However, how mycorrhizal associations correlate with the latitudinal tree beta-diversity remains untested. Using a global dataset of 45 forest plots representing 2,804,270 trees across 3840 species, we test how AM and EcM trees contribute to total beta-diversity and its components (turnover and nestedness) of all trees. We find AM rather than EcM trees predominantly contribute to decreasing total beta-diversity and turnover and increasing nestedness with increasing latitude, probably because wide distributions of EcM trees do not generate strong compositional differences among localities. Environmental variables, especially temperature and precipitation, are strongly correlated with beta-diversity patterns for both AM trees and all trees rather than EcM trees. Results support our hypotheses that latitudinal beta-diversity patterns and environmental effects on these patterns are highly dependent on mycorrhizal types. Our findings highlight the importance of AM-dominated forests for conserving global forest biodiversity., The relationship of mycorrhizal associations with latitudinal gradients in tree beta-diversity is unexplored. Using a global dataset approach, this study examines how trees with arbuscular mycorrhizal and ectomycorrhizal associations contribute to latitudinal beta-diversity patterns and the environmental controls of these patterns.

The decline in species richness at higher latitudes is among the most fundamental patterns in ecology. Whether changes in species composition across space (beta-diversity) contribute to this gradient of overall species richness (gamma-diversity) remains hotly debated. Previous studies that failed to resolve the issue suffered from a well-known tendency for small samples in areas with high gamma-diversity to have inflated measures of beta-diversity. Here, we provide a novel analytical test, using beta-diversity metrics that correct the gamma-diversity and sampling biases, to compare beta-diversity and species packing across a latitudinal gradient in tree species richness of 21 large forest plots along a large environmental gradient in East Asia. We demonstrate that after accounting for topography and correcting the gamma-diversity bias, tropical forests still have higher beta-diversity than temperate analogues. This suggests that beta-diversity contributes to the latitudinal species richness gradient as a component of gamma-diversity. Moreover, both niche specialization and niche marginality (a measure of niche spacing along an environmental gradient) also increase towards the equator, after controlling for the effect of topographical heterogeneity. This supports the joint importance of tighter species packing and larger niche space in tropical forests while also demonstrating the importance of local processes in controlling beta-diversity.

Logging and conversion of tropical forests in Southeast Asia have resulted in the expansion of landscapes containing a mosaic of habitats that may vary in their ability to sustain local biodiversity. However, the complexity of these landscapes makes it difficult to assess abundance and distribution of some species using ground-based surveys alone. Here, we deployed a combination of ground-transects and aerial surveys to determine drivers of the critically endangered Bornean Orangutan (Pongo pygmaeus morio) distribution across a large multiple-use landscape in Sabah, Malaysian Borneo. Ground-transects and aerial surveys using drones were conducted for orangutan nests and hemi-epiphytic strangler fig trees (Ficus spp.) (an important food resource) in 48 survey areas across 76 km², within a study landscape of 261 km². Orangutan nest count data were fitted to models accounting for variation in land use, above-ground carbon density (ACD, a surrogate for forest quality), strangler fig density, and elevation (between 117 and 675 m). Orangutan nest counts were significantly higher in all land uses possessing natural forest cover, regardless of degradation status, than in monoculture plantations. Within these natural forests, nest counts increased with higher ACD and strangler fig density, but not with elevation. In logged forest (ACD 14–150 Mg ha⁻¹), strangler fig density had a significant, positive relationship with orangutan nest counts, but this relationship disappeared in a forest with higher carbon content (ACD 150–209 Mg ha⁻¹). Based on an area-to-area comparison, orangutan nest counts from ground transects were higher than from counts derived from aerial surveys, but this did not constitute a statistically significant difference. Although the difference in nest counts was not significantly different, this analysis indicates that both methods under-sample the total number of nests present within a given area. Aerial surveys are, therefore, a useful method for assessing the orangutan habitat use over large areas. However, the under-estimation of nest counts by both methods suggests that a small number of ground surveys should be retained in future surveys using this technique, particularly in areas with dense understory vegetation. This study shows that even highly degraded forests may be a suitable orangutan habitat as long as strangler fig trees remain intact after areas of forest are logged. Enrichment planting of strangler figs may, therefore, be a valuable tool for orangutan conservation in these landscapes. Published version This research was funded by the Government of Malaysia-UNDP-GEF project on biodiversity conservation in multiple-use forest landscapes in Sabah, Sub-Contract SC-6B.

© 2020 John Wiley & Sons Ltd Aim: Mapping tree species richness across the tropics is of great interest for effective conservation and biodiversity management. In this study, we evaluated the potential of full-waveform lidar data for mapping tree species richness across the tropics by relating measurements of vertical canopy structure, as a proxy for the occupation of vertical niche space, to tree species richness. Location: Tropics. Time period: Present. Major taxa studied: Trees. Methods: First, we evaluated the characteristics of vertical canopy structure across 15 study sites using (simulated) large-footprint full-waveform lidar data (22 m diameter) and related these findings to in-situ tree species information. Then, we developed structure–richness models at the local (within 25–50 ha plots), regional (biogeographical regions) and pan-tropical scale at three spatial resolutions (1.0, 0.25 and 0.0625 ha) using Poisson regression. Results: The results showed a weak structure–richness relationship at the local scale. At the regional scale (within a biogeographical region) a stronger relationship between canopy structure and tree species richness across different tropical forest types was found, for example across Central Africa and in South America [R2 ranging from.44–.56, root mean squared difference as a percentage of the mean (RMSD%) ranging between 23–61%]. Modelling the relationship pan-tropically, across four continents, 39% of the variation in tree species richness could be explained with canopy structure alone (R2 =.39 and RMSD% = 43%, 0.25-ha resolution). Main conclusions: Our results may serve as a basis for the future development of a set of structure–richness models to map high resolution tree species richness using vertical canopy structure information from the Global Ecosystem Dynamics Investigation (GEDI). The value of this effort would be enhanced by access to a larger set of field reference data for all tropical regions. Future research could also support the use of GEDI data in frameworks using environmental and spectral information for modelling tree species richness across the tropics.

Conservation planning tends to focus on protecting species' ranges or landscape connectivity but seldom both-particularly in the case of diverse taxonomic assemblages and multiple planning goals. Therefore, information on potential trade-offs between maintaining landscape connectivity and achieving other conservation objectives is lacking. We developed an optimization approach to prioritize the maximal protection of species' ranges, ecosystem types, and forest carbon stocks, while also including habitat connectivity for range-shifting species and dispersal corridors to link protected area. We applied our approach to Sabah, Malaysia, where the state government mandated an increase in protected-area coverage of approximately 305,000 ha but did not specify where new protected areas should be. Compared with a conservation planning approach that did not incorporate the 2 connectivity features, our approach increased the protection of dispersal corridors and elevational connectivity by 13% and 21%, respectively. Coverage of vertebrate and plant species' ranges and forest types were the same whether connectivity was included or excluded. Our approach protected 2% less forest carbon and 3% less butterfly range than when connectivity features were not included. Hence, the inclusion of connectivity into conservation planning can generate large increases in the protection of landscape connectivity with minimal loss of representation of other conservation targets.Incorporación de la Conectividad a la Planeación de la Conservación para la Representación Óptima de Especies Múltiples y Servicios Ambientales Resumen Las tendencias de planeación de la conservación tienden a enfocarse en la protección de la distribución geográfica de las especies o en la conectividad de paisajes, pero rara vez se enfocan en ambas - particularmente para el caso de los ensamblajes taxonómicos y las metas múltiples de planeación. Por lo tanto, hay carencias en la información sobre las compensaciones potenciales entre mantener la conectividad de los paisajes y alcanzar otros objetivos de conservación. Desarrollamos una estrategia de optimización para priorizar la protección máxima de la distribución de las especies, los tipos de ecosistemas y los stocks de carbono de los bosques, a la vez que incluimos la conectividad del hábitat para las especies que modifican su distribución y los corredores de dispersión para conectar el área protegida. Aplicamos nuestra estrategia en Sabah, Malasia, en donde el gobierno estatal ordenó un incremento de ∼305, 000 ha en la cobertura de áreas protegidas sin especificar la ubicación de las nuevas áreas protegidas. En comparación con una estrategia de planeación de la conservación que no incorporó las dos características de la conectividad, nuestra estrategia incrementó la protección de los corredores de dispersión y la conectividad altitudinal en un 13% y 21% respectivamente. La cobertura de la distribución de las especies de plantas y vertebrados y de los tipos de bosque fue la misma con o sin la inclusión de la conectividad. Nuestra estrategia protegió 2% menos del carbono forestal y 3% menos de la distribución de mariposas que cuando no se incluyeron las características de conectividad en la estrategia. Por lo tanto, incluir a la conectividad en la planeación de la conservación puede generar grandes incrementos en la protección de la conectividad del paisaje con una pérdida mínima de representación para los demás objetivos de conservación.

The decline in species richness at higher latitudes is among the most fundamental patterns in ecology. Whether changes in species composition across space (beta-diversity) contribute to this gradient of overall species richness (gamma-diversity) remains hotly debated. Previous studies that failed to resolve the issue suffered from a well-known tendency for small samples in areas with high gamma-diversity to have inflated measures of beta-diversity. Here, we provide here a novel analytical test, using beta-diversity metrics that correct the gamma-diversity and sampling biases, to compare beta-diversity and species packing across a latitudinal gradient in tree species richness of 21 large forest plots along a large environmental gradient in East Asia. We demonstrate that after accounting for topography and correcting the gamma-diversity bias, tropical forests still have higher beta-diversity than temperate analogs. This suggests that beta-diversity contributes to the latitudinal species richness gradient as a component of gamma-diversity. Moreover, both niche specialization and niche marginality (a measure of niche spacing along an environmental gradient) also increase towards the equator, after controlling for the effect of topographic heterogeneity. This supports the joint importance of tighter species packing and larger niche space in tropical forests while also demonstrating the importance of local processes in controlling beta-diversity.

Background: The spatial structure of tree species diversity may identify the relative importance of positive, negative and neutral interactions among species and the processes that maintain high sp...

We thank Scottish Natural Heritage for funding this work via a PhD studentship to JM. The National Trust for Scotland provided the field site and fenced the experiment. In particular we thank Kate Sampson and Lindsay Mackinlay at NTS staff for their assistance in establishing this experiment. RJM and RJP were funded through the 2011-2016 and 2016-2021 Strategic Research Programmes of the Scottish Government.

A growing awareness of the destructive effects of non-native invasive species has led to a massive increase in removal programmes around the world. However, little is generally known about what happens to sites following the removal of the invasives and the implicit assumption that the native community will return, unaided, to pre-invasion conditions is often left untested. We assessed recovery of the native understorey plant community following removal of the non-native invasive Rhododendron ponticum L. from Scottish Atlantic oak woodland. We recorded understorey community composition in sites covering a gradient of increasing R. ponticum density, and across a separate series of sites covering a chronosequence of time since R. ponticum removal. We then compared both of these series to the target community found in uninvaded sites. We also analysed differences in soil chemistry between the sites to test for chemical legacy effects of invasion in the soil. Native understorey cover declined as R. ponticum density increased, with bryophytes dropping to less than a third of the cover present in uninvaded sites and forbs and grasses being completely extirpated under dense stands. Cleared sites showed no evidence of returning to the target community, even after 30 years of recovery, and instead formed a bryophyte-dominated “novel community,” containing few of the typical oak woodland vascular plants. Contrary to expectation, soil pH, C:N ratio and nutrient concentrations (N, P, K, Ca and Mg) were not affected by the invasion of R. ponticum, and chemical legacy effects in the soil were not responsible for the failure of the native community to revert to pre-invasion conditions. Instead, we hypothesise that the rapid formation of a bryophyte mat, coupled with the often substantial distances to potential seed sources, hindered vascular plant recolonisation. Synthesis and applications. Clear evidence of invasion history can be detected in the understorey plant community even decades after the successful removal of the invasive Rhododendron ponticum L. This finding demonstrates that native communities may be unable to recover effectively of their own accord following invasive species removal, and will require further management interventions in order to achieve restoration goals.

The soil seed bank plays an important role in determining what plant species emerge following the removal of monodominant invasive species. A depleted seed bank may provide a substantial barrier to site restoration, however, little is known about what changes occur in the seed bank during invasion and following clearance. This study used greenhouse germination trials to quantify and compare the seed bank present in 30 Scottish Atlantic oak woodland sites under three treatments: (1) sites featuring dense stands of the non-native invasive shrub Rhododendron ponticum; (2) sites that had been previously subject to dense R. ponticum stands but which had been cleared; and (3) uninvaded control sites. Seed banks of densely invaded and cleared sites had significantly lower species richness than those of uninvaded control sites with a lower abundance of graminoid, and to a lesser extent forb seeds than the uninvaded controls. The seed bank community composition differed significantly between the three site types. Uninvaded sites featured a wide array of species, densely invaded sites were dominated by R. ponticum seeds and cleared sites were dominated by birch (Betula sp.) seeds. Cleared sites contained very few R. ponticum seeds indicating that once effective clearance had been achieved, re-invasion would be unlikely to occur from the soil seed bank. Our findings revealed that the soil seed bank present in cleared sites was very different from the seed bank of uninvaded control sites, with clear implications for site restoration.

Increased awareness of the negative impacts of invasive non-native species has led to a rapid increase in clearance programs around the world. One of the main goals of clearance is the restoration of native communities that were present pre-invasion. Little monitoring is typically carried out, however, to verify that native communities return without further management intervention in the years following invasive species removal. We investigated whether the epiphytic plant community of Atlantic oak woodlands, which principally consists of bryophyte species, returned after up to thirty years of recovery following the removal of the invasive non-native shrub Rhododendron ponticum . This community is of international conservation value and is particularly threatened by invasive Rhododendron . We revealed that the epiphytic plant community was able to recover effectively in sites that had been clear from Rhododendron for over fifteen years. This recovery included several species of particular conservation interest with highly restricted European distributions (i.e. ‘Atlantic species’ such as Plagiochila heterophylla ). Total cover and species richness both returned to similar or even higher levels to those found in uninvaded control plots by fifteen or more years following clearance, despite being highly reduced within dense Rhododendron thickets. Overall community composition also recovered to resemble uninvaded control plots in the years following Rhododendron removal. These findings present an encouraging message that at least some native communities can return naturally in the years following invasive species removal and may not require further management interventions to speed their return.

The last few decades have seen an increasing interest and strong development in spatial point process methodology, and associated software that facilitates model fitting has become available. A lot of this progress has made these approaches more accessible to users, through freely available software. However, in the ecological user community the methodology has only been slowly picked up despite its obvious relevance to the field. This paper reflects on this development, highlighting mutual benefits of interdisciplinary dialogue for both statistics and ecology. We detail the contribution point process methodology has made to research on biodiversity theory as a result of this dialogue and reflect on reasons for the slow take-up of the methodology. This primarily concerns the current lack of consideration of the usability of the approaches, which we discuss in detail, presenting current discussions as well as indicating future directions. Publisher PDF

Logging, pervasive across the lowland tropics, affects millions of hectares of forest, yet its influence on nutrient cycling remains poorly understood. One hypothesis is that logging influences phosphorus (P) cycling, because this scarce nutrient is removed in extracted timber and eroded soil, leading to shifts in ecosystem functioning and community composition. However, testing this is challenging because P varies within landscapes as a function of geology, topography and climate. Superimposed upon these trends are compositional changes in logged forests, with species with more acquisitive traits, characterized by higher foliar P concentrations, more dominant. It is difficult to resolve these patterns using traditional field approaches alone. Here, we use airborne light detection and ranging‐guided hyperspectral imagery to map foliar nutrient (i.e. P, nitrogen [N]) concentrations, calibrated using field measured traits, over 400 km2 of northeastern Borneo, including a landscape‐level disturbance gradient spanning old‐growth to repeatedly logged forests. The maps reveal that canopy foliar P and N concentrations decrease with elevation. These relationships were not identified using traditional field measurements of leaf and soil nutrients. After controlling for topography, canopy foliar nutrient concentrations were lower in logged forest than in old‐growth areas, reflecting decreased nutrient availability. However, foliar nutrient concentrations and specific leaf area were greatest in relatively short patches in logged areas, reflecting a shift in composition to pioneer species with acquisitive traits. N:P ratio increased in logged forest, suggesting reduced soil P availability through disturbance. Through the first landscape scale assessment of how functional leaf traits change in response to logging, we find that differences from old‐growth forest become more pronounced as logged forests increase in stature over time, suggesting exacerbated phosphorus limitation as forests recover., Soil nutrients that come from rocks are critical for tree growth but rare in tropical forests. Logging removes these nutrients in quantities that could change plant life there. We mapped leaf nutrients in pristine and logged forests in Malaysia using cutting edge remote sensing combined with field measurements and found fewer nutrients in logged forests after controlling for other variables. Nutrients were most scarce in logged forests that had recovered with time after logging, raising concerns that they are changed permanently in terms of the species that live there and the nutrients available to them.

The data set contains images of leaf venation networks obtained from tree species in Malaysian Borneo. The data set contains 726 leaves from 295 species comprising 50 families, sampled from eight forest plots in Sabah. Image extents are approximately 1 × 1 cm, or 50 megapixels. All images contain a region of interest in which all veins have been hand traced. The complete data set includes over 30 billion pixels, of which more than 600 million have been validated by hand tracing. These images are suitable for morphological characterization of these species, as well as for training of machine‐learning algorithms that segment biological networks from images. Data are made available under the Open Data Commons Attribution License. You are free to copy, distribute, and use the database; to produce works from the database; and to modify, transform, and build upon the database. You must attribute any public use of the database, or works produced from the database, in the manner specified in the license. For any use or redistribution of the database, or works produced from it, you must make clear to others the license of the database and keep intact any notices on the original database.

Data Availability Statement:: Airborne data are available via the CEDA archive (project code MA14/21); plot data is archived on forestplots (Lopez‐Gonzalez et al., 2011) (codes SEP‐03, 04, 05, 07, 08, 09, 10, 11, 12) and from the Figshare Repository: https://doi.org/10.6084/m9.figshare.8427998.v1. Acknowledgements: We are grateful to the Sabah Forestry Department and the Sabah Biodiversity Centre for allowing us to conduct our research in Sepilok as well as to the South East Asia Rainforest Research Partnership for the logistical support. This work was supported by a grant through the Human Modified Tropical Forests programme of NERC (NE/K016377/1) as well as a Cambridge NERC-DTP studentship. Resurvey of the field plots was supported by an ERC Advanced Grant (291585, T-FORCES) awarded to O.L.P. S.E.D.T was supported by the Joint Imperial-NUS PhD Scholarship. J.R. was supported by fellowships from the Natural Environment Research Council (NERC) (NE/I021179, NE/L011611/1). We thank members of the NERC Airborne Research Facility and Data Analysis Node for the collection and processing of the data (project code MA14/21). Data processing was aided by the NERCs JASMIN computing cluster and the Imperial College London computing facilities. We would also like to thank Felix May for his advice during the early stages of this study. The quality of this manuscript was greatly improved by the comments of Gabriel Arellano and two other anonymous Reviewers.

Here we report the recent discovery of the world's tallest tropical tree (Shorea faguetiana), possibly the world's tallest angiosperm (flowering plant), located in the rainforests of Sabah, Malaysian Borneo. In addition, we provide a novel three-dimensional exploration of the dimensions of this remarkable tree and use these data to speculate on what drives the limits of tree height. Through consideration of both mechanical (risk of wind damage) and ecophysiological constraints we argue that this tree is close to the maximum height possible for angiosperms, around 100 m, and discuss more broadly what the nature and location of this tree imply about the limits to tree height. We propose to name this remarkable tree “Menara,” Malay for “tower.”This tall tree (“Menara”) was first identified during an airborne Light Detection and Ranging (LiDAR) survey conducted in 2014. The tree is located in the Danum Valley Conservation Area (DVCA) in Sabah, which also holds the previous record holder for tallest tropical tree1. This tree is located at an elevation of 436 m a.s.l on a slope of 33° and an aspect of 72°. Because airborne LiDAR is prone to significant errors when used to estimate heights of individual trees (Wan Mohd Jaafar et al., 2018), and because hilly topography will likely exacerbate those errors, record claims need to verified by reliable and calibrated instruments (such as Terrestrial Laser Scanning [TLS]) and, ideally, manual tape measurement. Hence, following the airborne identification, researchers returned in August 2018 to manually measure trunk diameter and conduct TLS scans and a drone flight to construct a detailed 3D model (Figure 1) and to calculate tree height and other dimensions. A further visit was conducted in January 2019, during which the tree was climbed to the top of its crown so the height could be directly verified with a measuring tape (Figure 2).

In a context of both long-term climatic changes and short-term climatic shocks, temporal dynamics profoundly influence ecosystems and societies. In low income contexts in the Tropics, where both exposure and vulnerability to climatic fluctuations is high, the frequency, duration, and trends in these fluctuations are important determinants of socio-ecological resilience. In this paper, the dynamics of six diverse socio-ecological systems (SES) across the Tropics – ranging from agricultural and horticultural systems in Africa and Oceania to managed forests in South East Asia and coastal systems in South America – are examined in relation to the 2015–16 El Niño, and the longer context of climatic variability in which this short-term ‘event’ occurred. In each case, details of the socio-ecological characteristics of the systems and the climate phenomena experienced during the El Niño event are described and reflections on the observed impacts of, and responses to it are presented. Drawing on these cases, we argue that SES resilience (or lack of) is, in part, a product of both long-term historical trends, as well as short-term shocks within this history. Political and economic lock-ins and dependencies, and the memory and social learning that originates from past experience, all contribute to contemporary system resilience. We propose that the experiences of climate shocks can provide a window of insight into future ecosystem responses and, when combined with historical perspectives and learning from multiple contexts and cases, can be an important foundation for efforts to build appropriate long-term resilience strategies to mediate impacts of changing and uncertain climates.

Background: Tree species composition at the landscape scale is often tightly associated with underlying soil type in tropical forests. Changes in soil type may have effects on forest structure that drive changes in both light and soil resource availability, since light availability in the understorey tends to be lower in more fertile sites. Plant functional traits may determine species distributions across gradients of light and soil resource availability.Aims: To test whether tree species with contrasting distributions exhibit leaf traits that reflect adaptation to the resources most limiting in their native environment.Methods: We measured foliar nutrient concentrations, stomatal density, leaf δ13C values, leaf mass per area, and leaf lifespan for saplings of nine common dipterocarp species at Sepilok Forest Reserve, Malaysian Borneo, possessing varying associations to soil resource habitats.Results: Species specialised in their adult distribution to nutrient-poor sandstone soils had traits indicative o...

Background: Logging and habitat fragmentation of tropical rain forests may disrupt patterns of gene flow and genetic diversity. Consequently, inbreeding in tree populations may reduce fitness and increase extinction risks, especially among species that are predominantly outcrossing, dependent on biotic pollination and/or display limited seed dispersal such as species of the Dipterocarpaceae.Aims: To test the hypothesis that heterozygosity of individual progeny affects their likelihood of germination and the growth and survival of seedlings.Methods: Standardised measure of multilocus heterozygosity (sMLH) was estimated from seven microsatellite loci for individual progeny collected from 18 mother trees of the large dipterocarp Parashorea tomentella. The relationships among sMLH, germination and seedling growth and survival were determined for the progeny.Results: Seedling survival over 18 months increased with greater sMLH and fresh fruit weight. This result was expressed under all experimentally controlle...

International audience; Farmers worldwide regularly plant trees to obtain provisioning and other ecosystem services. This practice has come under scrutiny by conservationists who perceive a reduction of biodiversity due to preferential planting of exotic trees. In order to reverse this preference for exotic trees it is necessary to identify the key drivers of exotic species planting and propose alternative species of interest to farmers. We examined this question in a coffee agroforestry landscape of the Western Ghats, India, a global biodiversity hotspot. We interviewed farmers regarding tree planting behaviour, preferences and constraints, and assessed the relative performance and value of native versus exotic species. Multivariateanalyses were used with six species-level characteristics and four farm-level characteristics, to reveal the most significant predictors of planting frequency.The exotic species Grevillea robusta was planted 5.4 times more often than native trees. Individual species’ planting frequencies were most strongly related to their realised economic values, which was highest for G. robusta. Native trees with greater multipurpose utility value and stature were also more likely to be planted. Farm-level characteristics related to increased planting efforts were increasing climatic dryness, increased land area with native tree tenurial rights and farm size. However, farmers with a greater proportion of land under secure tree tenure planted fewer trees.We conclude that although native trees had higher multipurpose utility and potential economic value than the exotic G. robusta, the latter is grown more often due to existing legal frameworks that restrict private ownership and realising monetary value from native species. If current laws were amended to increase the economic benefits obtained from native trees, they are likely to be planted more often by farmers. We propose that our results can help in implementation of the recent National Agroforestry Policy of India, as well as inform agroforestry policies and practice elsewhere.

Topography is a key driver of tropical forest structure and composition, as it constrains local nutrient and hydraulic conditions within which trees grow. Yet, we do not fully understand how changes in forest physiognomy driven by topography impact other emergent properties of forests, such as their aboveground carbon density (ACD). Working in Borneo – at a site where 70‐m‐tall forests in alluvial valleys rapidly transition to stunted heath forests on nutrient‐depleted dip slopes – we combined field data with airborne laser scanning and hyperspectral imaging to characterise how topography shapes the vertical structure, wood density, diversity and ACD of nearly 15 km2 of old‐growth forest. We found that subtle differences in elevation – which control soil chemistry and hydrology – profoundly influenced the structure, composition and diversity of the canopy. Capturing these processes was critical to explaining landscape‐scale heterogeneity in ACD, highlighting how emerging remote sensing technologies can provide new insights into long‐standing ecological questions.

This study was part of the Stability of Altered Forest Ecosystem (SAFE) Project, funded by the Sime Darby Foundation, and the Biodiversity And Land‐use Impacts on tropical ecosystem function (BALI) Project (NE/K016377/1) within the NERC Human‐Modified Tropical Forests Programme. This paper is also a product of the GEM network (gem.tropicalforests.ox.ac.uk). We are grateful to Rostin Jantan, SAFE Carbon Team and SAFE Project staff, Alexander Karolus and the Danum 50 ha plot team, and Xyxtus Tan, Nasir Muhi and Abilano Deres for fieldwork assistance. We thank Bernadus Bala Ola and Dr Bill McDonald for the tree species identification. Dr. Reuben Nilus and Dr. Robert Ong at the Forest Research Centre, Sabah Forestry Department, kindly helped us access the historical forest inventory records. Maliau Basin and Danum Valley Management Committees, Royal Society South East Asia Rainforest Research Partnership (SEARRP), Sabah Foundation, Benta Wawasan, the State Secretary, Sabah Chief Minister's Departments, Sabah Forestry Department, Sabah Biodiversity Council, and the Economic Planning Unit are acknowledged for their support and access to the sites in Sabah. The sites in Lambir were supported by the Malaysian Palm Oil Board (MPOB) and Centre for Tropical Forest Science (CTFS) in collaboration with HSBC Climate Partnership. The 52 ha Long‐Term Ecological Research Project in Lambir is a collaborative project of the Forest Department of Sarawak, Malaysia, the Center for Tropical Forest Science of the Smithsonian Tropical Research Institute, USA (NSF awards DEB‐9107247 and DEB‐9629601), and Osaka City, Ehime & Kyoto Universities, Japan (Monbusho grants 06041094, 08NP0901 and 09NP0901). The Danum 50 ha plot is a core project of SEARRP. We thank HSBC Malaysia and the University of Zurich for funding and CTFS for support. YM is supported by the Jackson Foundation and European Research Council Advanced Investigator Grant, GEM‐TRAIT (321131). This article is a contribution to Imperial College's Grand Challenges in Ecosystems and the Environment Initiative.

Partitioning of soil phosphorus (P) pools has been proposed as a key mechanism maintaining plant diversity, but experimental support is lacking. Here, we provided different chemical forms of P to 15 tree species with contrasting root symbiotic relationships to investigate plant P acquisition in both tropical and subtropical forests. Both ectomycorrhizal (ECM) and arbuscular mycorrhizal (AM) trees responded positively to addition of inorganic P, but strikingly, ECM trees acquired more P from a complex organic form (phytic acid). Most ECM tree species and all AM tree species also showed some capacity to take up simple organic P (monophosphate). Mycorrhizal colonisation was negatively correlated with soil extractable P concentration, suggesting that mycorrhizal fungi may regulate organic P acquisition among tree species. Our results support the hypothesis that ECM and AM plants partition soil P sources, which may play an ecologically important role in promoting species coexistence in tropical and subtropical forests.

Plant functional traits regulate ecosystem functions but little is known about how co‐occurring gradients of land use and edaphic conditions influence their expression. We test how gradients of logging disturbance and soil properties relate to community‐weighted mean traits in logged and old‐growth tropical forests in Borneo.We studied 32 physical, chemical and physiological traits from 284 tree species in eight 1 ha plots and measured long‐term soil nutrient supplies and plant‐available nutrients.Logged plots had greater values for traits that drive carbon capture and growth, whilst old‐growth forests had greater values for structural and persistence traits. Although disturbance was the primary driver of trait expression, soil nutrients explained a statistically independent axis of variation linked to leaf size and nutrient concentration. Soil characteristics influenced trait expression via nutrient availability, nutrient pools, and pH.Our finding, that traits have dissimilar responses to land use and soil resource availability, provides robust evidence for the need to consider the abiotic context of logging when predicting plant functional diversity across human‐modified tropical forests. The detection of two independent axes was facilitated by the measurement of many more functional traits than have been examined in previous studies.

Documenting the scale and intensity of fine-scale spatial genetic structure (FSGS), and the processes that shape it, is relevant to the sustainable management of genetic resources in timber tree species, particularly where logging or fragmentation might disrupt gene flow. In this study we assessed patterns of FSGS in three species of Dipterocarpaceae (Parashorea tomentella, Shorea leprosula and Shorea parvifolia) across four different tropical rain forests in Malaysia using nuclear microsatellite markers. Topographic heterogeneity varied across the sites. We hypothesised that forests with high topographic heterogeneity would display increased FSGS among the adult populations driven by habitat associations. This hypothesis was not supported for S. leprosula and S. parvifolia which displayed little variation in the intensity and scale of FSGS between sites despite substantial variation in topographic heterogeneity. Conversely, the intensity of FSGS for P. tomentella was greater at a more topographically heterogeneous than a homogeneous site, and a significant difference in the overall pattern of FSGS was detected between sites for this species. These results suggest that local patterns of FSGS may in some species be shaped by habitat heterogeneity in addition to limited gene flow by pollen and seed dispersal. Site factors can therefore contribute to the development of FSGS. Confirming consistency in species’ FSGS amongst sites is an important step in managing timber tree genetic diversity as it provides confidence that species specific management recommendations based on species reproductive traits can be applied across a species’ range. Forest managers should take into account the interaction between reproductive traits and site characteristics, its consequences for maintaining forest genetic resources and how this might influence natural regeneration across species if management is to be sustainable. ISSN:1932-6203

Aims We use dendroecological methods to test the hypothesis that variation in topographic position is related to radial growth and phenology for individuals of the endangered tropical tree Dalbergia nigra under uniform conditions of climate and irradiance, and to examine effects of seasonality on plant phenology and growth periodicity.

Spatial statistics are widely used in studies of ecological processes in plant communities, especially to provide evidence of neutral or non‐neutral mechanisms that might support species coexistence. The contribution of such statistics has been substantial, but their ability to identify any links between underlying processes and emergent patterns is not certain. We investigate the ability of a number of spatial statistics to distinguish theorized mechanisms of species coexistence (spatial and temporal niche differentiation, neutrality, the Janzen–Connell effect and heteromyopia) in a simulated plant community. We find that individual statistics differ substantially in their sensitivity to these mechanisms, with those based on nearest neighbour species identities being the most sensitive. These differences are largely robust to changes in the strength of the modelled mechanisms when simulated independently and in combination. The spatial signal of niche differentiation is always distinct in simulations that combine mechanisms. Synthesis. We describe full spatial signals of modelled coexistence mechanisms that are observed consistently across statistics and simulated strengths and combinations of mechanisms, and identify a set of spatial statistics that holds particular promise for empirical studies designed to investigate mechanisms of these kinds.

The lowland tropical forests of Southeast Asia are dominated by a single family of canopy and emergent trees, the Dipterocarpaceae. The seeds of dipterocarps are gravity or gyration dispersed. Short distance and limited seed dispersal via these mechanisms result in the aggregation of related individuals and strong fine-scale spatial genetic structure (FSGS). In logged and fragmented forests, where gene flow may be disrupted, tree species with strong FSGS are predicted to exhibit increased inbreeding, which consequently can erode genetic diversity, fitness and might limit the potential for natural regeneration of dipterocarps. Developing a set of indirect operational indicators for FSGS provides a solid basis for informing conservation and management of forest genetic resources in logged forests. Our main objective was to use an information theoretic approach to identify these indicators of FSGS in dipterocarps. We quantify FSGS in 19 dipterocarp species across four forest sites in Malaysian Borneo, India and the Seychelles. We detected FSGS in 15 (79%) of our study species, most of which displayed significant inbreeding. Our results suggest that wood density and flower size offer useful indicators of FSGS. We propose some simple guidelines to allow forest managers to account for FSGS when planning approaches to maintain genetically diverse stands in logged dipterocarp forests. The integration of improved understanding of genetic processes is essential for conserving forest tree genetic resources and ensuring the resilience of logged forests.

Recruitment limitation, measured by the failure of some species to arrive and establish in a site, is potentially an important process contributing to the diversity of plant communities. Limited seed production, seed dispersal, and seedling emergence due to abiotic and/or niche-dependent factors result in opportunities for less abundant species to persist. Whereas limitations affecting early phases of plant establishment are relatively well known, the less-examined limitations upon recruitment into more advanced life history stages may also contribute to the maintenance of diversity. We tested this hypothesis by decomposing recruitment limitation into seed limitation, emergence limitation (to seedlings), establishment limitation (saplings) and persistence limitation (adults) in high- and low-diversity communities. We found evidences of recruitment limitation in all ontogenetic stages, but no differences between the examined communities. Limitations in seed, seedling, saplings and adults were explained mainly by abundance in the previous stage. The negative effect of abundance of a given stage on the abundance of the next stage (negative density-dependent plant establishment) was more evident in the high diversity community. There was a reduction in species’ abundance and an increase in species richness from the seed to the adult stages, resulting in an increase in the evenness along ontogenetic stages in both communities; in all stages, the high-diversity community was richer than the low-diversity community. We found evidence that recruitment limitation operates at multiple stages and is density dependent in these two tropical forests. Our results also suggest that these effects may be stronger in the high-diversity community. Thus, recruitment limitation mediated by density dependence across multiple ontogenetic stages has to be considered in future studies of factors maintaining diversity in tropical forests.

Borneo contains some of the world’s most biodiverse and carbon dense tropical forest, but this 750 000-km2 island has lost 62 % of its old-growth forests within the last 40 years. Efforts to protect and restore the remaining forests of Borneo hinge on recognising the ecosystem services they provide, including their ability to store and sequester carbon. Airborne Laser Scanning (ALS) is a remote sensing technology that allows forest structural properties to be captured in great detail across vast geographic areas. In recent years ALS has been integrated into state-wide assessment of forest carbon in Neotropical and African regions, but not yet in Asia. For this to happen, new regional models, need to be developed for estimating carbon stocks from ALS in tropical Asia, as the forests of this region are structurally and compositionally distinct from those found elsewhere in the tropics. By combining ALS imagery with data from 173 permanent forest plots spanning the lowland rain forests of Sabah, on the island of Borneo, we develop a simple-yet-general model for estimating forest carbon stocks using ALS-derived canopy height and canopy cover as input metrics. An advanced feature of this new model is the propagation of uncertainty in both ALS- and ground-based data, allowing uncertainty in hectare-scale estimates of carbon stocks to be quantified robustly. We show that the model effectively captures variation in aboveground carbons stocks across extreme disturbance gradients spanning tall dipterocarp forests and heavily logged regions, and clearly outperforms existing ALS-based models calibrated for the tropics, as well as currently available satellite-derived products. Our model provides a simple, generalised and effective approach for mapping forest carbon stocks in Borneo, and underpins ongoing efforts to safeguard and facilitate the restoration of its unique tropical forests.

Climate is widely recognised as an important determinant of the latitudinal diversity gradient. However, most existing studies make no distinction between direct and indirect effects of climate, which substantially hinders our understanding of how climate constrains biodiversity globally. Using data from 35 large forest plots, we test hypothesised relationships amongst climate, topography, forest structural attributes (stem abundance, tree size variation and stand basal area) and tree species richness to better understand drivers of latitudinal tree diversity patterns. Climate influences tree richness both directly, with more species in warm, moist, aseasonal climates and indirectly, with more species at higher stem abundance. These results imply direct limitation of species diversity by climatic stress and more rapid (co-)evolution and narrower niche partitioning in warm climates. They also support the idea that increased numbers of individuals associated with high primary productivity are partitioned to support a greater number of species.

The frequency of extreme precipitation events is predicted to increase in some tropical regions in response to global climate change, but the impacts of this form of disturbance on the structure and dynamics of tropical tree communities across heterogeneous landscapes remain understudied. We determined the effects of an extreme precipitation event (EPE) in July 2006 on mortality of dipterocarps on a 68 ha permanent inventory plot in Sepilok Forest Reserve, Sabah. For stems ≥30 cm dbh, 12 of the 15 species of Dipterocarpaceae on this plot have significant positive and/or negative associations to habitats defined by topography and soil type. Short-term mortality induced by the EPE was much greater for individuals growing on the alluvial floodplain (13.7%) than in the mudstone (1.4%) or sandstone (0.0%) habitats, but mortality of dipterocarps did not differ among these habitats in the subsequent 5-yr interval. The likelihood of mortality in response to the EPE was highest for a small group of fast growing dipterocarps that possess low wood density and a strong association to the alluvial forest habitat. This group of species represents a high percentage of dipterocarp individuals but a low proportion of dipterocarp diversity in this habitat. We conclude that disturbance induced by high rainfall events contributes to the episodic nature of tropical forest dynamics, and that increases in the frequency of these events would disproportionately impact low-lying alluvial forest environments and some of the species growing in them.

Continental tropical forests are thought to be resistant to alien plant invasion due to a lack of disturbance, or low propagule pressure from introduced species. We assessed the importance of disturbance and edge effects by surveying areas of submontane and lowland forest of Amani Nature Reserve in the East Usambara mountains, Tanzania. These areas are in the vicinity of Amani Botanic Garden (ABG)—a propagule source for many alien plant species. We surveyed three edges in the vicinity of the ABG plantations, using plots interspersed along multiple 250 m transects. Survey plots were either in secondary or seminatural forest, representing a difference in past disturbance). Alien plant species richness and abundance declined with increasing distance from forest edges, indicating that edge effects were important. In addition, the effect of distance on richness and abundance of alien species as adults was much smaller in seminatural than secondary forest, emphasizing that invasion of seminatural forest is less likely to occur. Abundance and occurrence of individual species showed broadly similar declines with increasing distance from the forest edge, and lower abundance in seminatural compared to secondary forest. Alien species were dominant in 15 percent of plots surveyed. As 28 percent of the Amani nature reserve forest is within 250 m of an edge, the importance of disturbance and edges could make a potentially large proportion of the forest vulnerable to alien species invasion. Muhtasari Misitu ya ukanda wa kitropiki ina uwezo mkubwa wa kustahimili mashambulizi kutoka kwa mimea isiyo na asili ya eneo hilo. Hii inatokana na kutokuwepo kwa usumbufu unaoletwa na mimea hiyo isiyo asili. Tulitathmini mabadiliko yatokanayo na athari za mimea isiyo na asili ya eneo la kitropiki katika misitu yenye asili hiyo kwenye hifadhi ya Amani. Amani ipo mashariki mwa milima ya Usambara nchini Tanzania karibu na bustani ya mimea ambapo majaribio ya mimea mingi isiyo na asili ya kitropiki hufanyika. Tulichunguza athari ya mabadiliko kwa kugawanya mashamba ya bustani ya mimea Amani katika ukubwa wa mita 250. Mashamba ya kuchunguzia yalikua ama katika hali isiyo ya asili ama hali ya nusu asili (kuwakilisha tofauti katika mabadiliko ya awali). Mimea isiyo na asili ya kitropiki ilipungua kwa idadi na ustawi kutegemeana na umbali wake kutoka ilipo misitu ya asili, kuashiria umuhimu wa athari za mabadiliko. Pia athari ya umbali katika idadi na ustawi wa mimea isiyo ya asili ilikua ndogo katika misitu ya hali ya nusu asili ukilinganisha na misitu isiyo ya asili, kudhihirisha kuwa mashambulizi si rahisi kutokea katika misitu ya nusu asili. Mabadiliko katika wingi na ustawi wa mimea na upungufu wake unategemea umbali toka misitu ya asili na aina ya misitu kama ni nusu asili ikilinganishwa na misitu isiyo ya asili. Mimea isiyo ya asili ilistawi kwa asilimia 15 katika mashamba ambayo uchunguzi ulifanyika. Kwa kuwa asilimia 28 ya hifadhi ya msitu wa Amani iko ndani ya mita 250 za eneo la tathmini, athari za mabadiliko zinaweza kupelekea msitu wa Amani kushambuliwa na mimea hiyo isiyo ya asili.

Understanding the ecological mechanisms that constrain forest succession in tropical degraded anthropogenic grasslands is a prerequisite for the design of techniques for restoring biodiversity and ecosystem processes. In this context, succession on post-agricultural lands may be arrested by a variety of site-specific biotic and abiotic factors. Here we synthesise our research on the effects of five biotic factors (seed dispersal, development of a soil seed bank, seedling emergence, herbivory, competition) and five abiotic factors (fire, microclimatic conditions, soil nutrients, water availability, disturbance) as constraints to forest succession on degraded anthropogenic grasslands in a tropical lower montane forest landscape in Sri Lanka. The aim of this research was to deduce ecologically and socially acceptable restoration techniques to accelerate forest recovery. Colonisation of grasslands by trees is constrained by limited seed dispersal from adjacent remnant forest patches and their incorporation into grassland soil seed banks. For the few tree seeds that are dispersed into grasslands, a combination of vertebrate herbivory and annual dry season fires reduces the likelihood that they emerge as seedlings. Removal of the grass canopy by clipping or tilling increases the emergence of woody plant seedlings close to the boundaries of forest patches, but has no effect beyond 20 m into the established grassland. Our research shows that isolation of seedling root systems from those of competing grasses increases the growth and survival of tree seedlings transplanted directly into grassland swards, while above-ground competition and exclusion of vertebrate herbivores has no effects on seedling growth and survival. These experiments identified that the early-successional species Macaranga indica Wight and Symplocos cochinchinensis (Lour.) S. Moore are potential candidates for use in reforestation programmes on abandoned grasslands. We propose a strategy for a model forest restoration programme based on the creation of vegetation islands using early-successional native tree species, the application of a tilling treatment around remnant forest patches, creation of fire breaks around vegetation islands, and the protection of isolated individual trees and tree patches within established grasslands. We highlight the importance of further research on the ecology and biology of seed dispersers and seed predators, and expansion of knowledge on the regeneration traits of native tree species, for future refinements of this restoration strategy.

Global change is impacting forests worldwide, threatening biodiversity and ecosystem services including climate regulation. Understanding how forests respond is critical to forest conservation and climate protection. This review describes an international network of 59 long-term forest dynamics research sites (CTFS-ForestGEO) useful for characterizing forest responses to global change. Within very large plots (median size 25ha), all stems 1cm diameter are identified to species, mapped, and regularly recensused according to standardized protocols. CTFS-ForestGEO spans 25 degrees S-61 degrees N latitude, is generally representative of the range of bioclimatic, edaphic, and topographic conditions experienced by forests worldwide, and is the only forest monitoring network that applies a standardized protocol to each of the world's major forest biomes. Supplementary standardized measurements at subsets of the sites provide additional information on plants, animals, and ecosystem and environmental variables. CTFS-ForestGEO sites are experiencing multifaceted anthropogenic global change pressures including warming (average 0.61 degrees C), changes in precipitation (up to +/- 30% change), atmospheric deposition of nitrogen and sulfur compounds (up to 3.8g Nm(-2)yr(-1) and 3.1g Sm(-2)yr(-1)), and forest fragmentation in the surrounding landscape (up to 88% reduced tree cover within 5km). The broad suite of measurements made at CTFS-ForestGEO sites makes it possible to investigate the complex ways in which global change is impacting forest dynamics. Ongoing research across the CTFS-ForestGEO network is yielding insights into how and why the forests are changing, and continued monitoring will provide vital contributions to understanding worldwide forest diversity and dynamics in an era of global change.

Question What strategies are most appropriate for restoring tree seedling recruitment whilst avoiding the spread of invasive plant species in high conservation value tropical forests disturbed by planting a shade-demanding crop? Location Knuckles Forest Reserve, Sri Lanka (7°21′–7°24′ N, 80°45′–80°48′ E). Methods An experiment was conducted to test the effects of clipping or removal of established cardamom plants on recruitment of native tree seedlings and spread of non-native plants in a tropical montane forest with abandoned cardamom stands in the understorey. The number and composition of tree seedling emergents, the cover of herbaceous plants and the recovery of cardamom were assessed for 3 yr. Results Tree seedling recruitment was higher in plots from which above-ground cardamom biomass had been removed through slashing (mean ± SE per 5 m2; 28.9 ± 2.70) and those where cardamom plants had been removed completely through uprooting (32.2 ± 3.17), or when dead cardamom leaves and stems were removed with small-scale extraction of pods (22.5 ± 2.16), than in unmanipulated control plots (16.6 ± 1.13) over 15 mo. The species composition of tree seedling emergents did not differ in response to removal of cardamom. However, the cover of herbaceous plants, including the non-native invasive Ageratina riparia, increased in response to removal of cardamom. Recovery of cardamom was higher when the plants had been slashed than when entire plants were uprooted and removed. Conclusion Slashing or uprooting cardamom plants is a potential strategy for restoring tree seedling recruitment in forests with abandoned cardamom stands in the understorey, but these interventions would need to be repeated annually over many years to be successful, and they risk promoting expansion of the cover of herbaceous plants, including non-native species. Hence, this approach would be labour-intensive and costly. An alternative approach to promoting tree seedling emergence and establishment is to clear dead cardamom leaves and stems, and to encourage small-scale extraction of pods from the residual cardamom plants. Harvesting pods reduces the likelihood that the crop will be sustained in situ through natural regeneration, and supplies an income to local communities, which would enhance the social acceptability of the intervention.

Summary: Tropical forest above-ground wood production (AGWP) varies substantially along environmental gradients. Some evidence suggests that AGWP may vary between regions and specifically that Asian forests have particularly high AGWP. However, comparisons across biogeographic regions using standardized methods are lacking, limiting our assessment of pan-tropical variation in AGWP and potential causes. We sampled AGWP in NW Amazon (17 long-term forest plots) and N Borneo (11 plots), both with abundant year-round precipitation. Within each region, forests growing on a broad range of edaphic conditions were sampled using standardized soil and forest measurement techniques. Plot-level AGWP was 49% greater in Borneo than in Amazonia (9.73 ± 0.56 vs. 6.53 ± 0.34 Mg dry mass ha -1 a -1 , respectively; regional mean ± 1 SE). AGWP was positively associated with soil fertility (PCA axes, sum of bases and total P). After controlling for the edaphic environment, AGWP remained significantly higher in Bornean plots. Differences in AGWP were largely attributable to differing height-diameter allometry in the two regions and the abundance of large trees in Borneo. This may be explained, in part, by the greater solar radiation in Borneo compared with NW Amazonia. Trees belonging to the dominant SE Asian family, Dipterocarpaceae, gained woody biomass faster than otherwise equivalent, neighbouring non-dipterocarps, implying that the exceptional production of Bornean forests may be driven by floristic elements. This dominant SE Asian family may partition biomass differently or be more efficient at harvesting resources and in converting them to woody biomass. Synthesis. N Bornean forests have much greater AGWP rates than those in NW Amazon when soil conditions and rainfall are controlled for. Greater resource availability and the highly productive dipterocarps may, in combination, explain why Asian forests produce wood half as fast again as comparable forests in the Amazon. Our results also suggest that taxonomic groups differ in their fundamental ability to capture carbon and that different tropical regions may therefore have different carbon uptake capacities due to biogeographic history. North Bornean forests have much greater AGWP rates than those in north-western Amazon when soil conditions and rainfall are controlled for. Greater resource availability and the highly productive dipterocarps may, in combination, explain why these Asian forests produce wood half as fast again as comparable forests in the Amazon. Our results also suggest that taxonomic groups differ in their fundamental ability to capture carbon and that different tropical regions may therefore have different carbon uptake capacities due to biogeographic history.

Background: Connections between mature trees and seedlings via ectomycorrhizal (EcM) hyphal networks existing in dipterocarp-dominated tropical rain forests of South-east Asia could have strong implications for seedling growth and survival and the maintenance of high diversity in such forests. Aim: To test whether EcM hyphal network connections are important for the growth and survival of dipterocarp seedlings. Methods: We conducted four independent experiments that prevented contact of experimental seedlings with an EcM network by using a series of fine meshes and/or plastic barriers. We measured the growth and survival (and foliar δ13C in one experiment) of seedlings of six dipterocarp species over intervals ranging from 11 to 29 months. Results: Seedling growth (diameter, height or leaf number) was unaffected by exclusion from the EcM network in three experiments and there were no differences in foliar δ13C values in the fourth. Seedling survival was reduced following exclusion from the EcM network in one experiment. Our results give little support to the hypothesis that dipterocarp seedlings growing in the shaded forest understorey benefit from being connected, through a common EcM network, to surrounding trees. Conclusions: We suggest that our negative results, in contrast to studies conducted in low diversity boreo-temperate or tropical forests, are due to these high diversity forests lacking host species-specific EcM fungi and therefore providing little opportunity for adaptive support of seedlings via hyphal networks.

The first author was supported by the European Union under a IEF Marie-Curie Action. Accurate estimation of tree biomass is necessary to provide realistic values of the carbon stored in the terrestrial biosphere. A recognized source of errors in tree above-ground biomass (AGB) estimation is introduced when individual tree height values (H) are not directly measured but estimated from diameter at breast height (DBH) using allometric equations. In this paper we evaluate the performance of 12 alternative DBH : H equations and compare their effects on AGB estimation for three tropical forests that occur in contrasting climatic and altitudinal zones. We found that fitting a 3-parameter Weibull function using data collected locally generated the lowest errors and bias in H estimation, and that equations fitted to these data were more accurate than equations with parameters derived from the literature. For computing AGB, the introduced error values differed notably among DBH : H allometric equations, and in most cases showed a clear bias that resulted in either over- or under-estimation of AGB. Fitting the three-parameter Weibull function minimized errors in AGB estimates in our study and we recommend its widespread adoption for carbon stock estimation. We conclude that many previous studies are likely to present biased estimates of AGB due to the method of H estimation. Publisher PDF

This study was supported by the FP7-PEOPLE-2013-IEF Marie-Curie Action – SPATFOREST. Tree data from BCI were provided by the Center for Tropical Forest Science of the Smithsonian Tropical Research Institute and the primary granting agencies that have supported the BCI plot tree census. Data for the liana censuses were supported by the US National Science Foundation grants: DEB-0613666, DEB-0845071, and DEB-1019436 (to SAS). Soil data was funded by the National Science Foundation grants DEB021104, DEB021115, DEB0212284 and DEB0212818 supporting soils mapping in the BCI plot. 1. Prediction of carbon dynamics in response to global climate change requires an understanding of the processes that govern the distribution of carbon stocks. Above ground biomass (AGB) in tropical forests is regulated by variation in soil fertility, climate, species composition and topography at regional scales, but the drivers of fine-scale variation in tropical forest AGB are poorly understood. The factors that control the growth and mortality of individual trees may be obscured by the low resolution of studies at regional scales. 2. In this paper, we evaluate the effects of soil nutrients, topography and liana abundance on the fine-scale spatial distribution of AGB and density of trees for a lowland tropical moist forest in Panama using additive regression models. 3. Areas with larger values of AGB were negatively associated with the presence of lianas, which may reflect competition with lianas and/or the association of lianas with disturbed or open canopy patches within forests. AGB was positively associated with soils possessing higher pH and K concentrations, reflecting the importance of below-ground resource availability on AGB independently of stem density. 4. Synthesis: Our results shed new light the factors that influence fine-scale tree AGB and carbon stocks in tropical forests: liana abundance is the strongest predictor, having a negative impact on tree AGB. The availability of soil nutrients was also revealed as an important driver of fine-scale spatial variation in tree AGB. Postprint

Questions Species-habitat associations may contribute to the maintenance of species richness in tropical forests, but previous research has been conducted almost exclusively in lowland forests and has emphasized the importance of topography and edaphic conditions. Is the distribution of woody plant species in a Peruvian cloud forest determined by microhabitat conditions? What is the role of environmental characteristics and forest structure in habitat partitioning in a tropical cloud forest? Location Cloud Forest, north Peruvian Andes. Methods We examined species-habitat associations in three 1-ha plots using the torus-translation method. We used three different criteria to define habitats for habitat partitioning analyses, based on microtopography, forest structure and both sets of factors. The number of species associated either positively or negatively with each habitat was assessed. Results Habitats defined on the basis of environmental conditions and forest structure discriminated a greater number of positive and negative associations at the scale of our analyses in a tropical cloud forest. Conclusions Both topographic conditions and forest structure contribute to small-scale microhabitat partitioning of woody plant species in a Peruvian tropical cloud forest. Nevertheless, canopy species were most correlated with the distribution of environmental variables, while understorey species displayed associations with forest structure. © 2012 International Association for Vegetation Science.