Underlying and proximate drivers of biodiversity changes in Mesoamerican biosphere reserves.

Protected areas are of paramount relevance to conserving wildlife and ecosystem contributions to people. Yet, their conservation success is increasingly threatened by human activities including habitat loss, climate change, pollution, and species overexploitation. Thus, understanding the underlying and proximate drivers of anthropogenic threats is urgently needed to improve protected areas' effectiveness, especially in the biodiversity-rich tropics. We addressed this issue by analyzing expert-provided data on long-term biodiversity change (last three decades) over 14 biosphere reserves from the Mesoamerican Biodiversity Hotspot. Using multivariate analyses and structural equation modeling, we tested the influence of major socioeconomic drivers (demographic, economic, and political factors), spatial indicators of human activities (agriculture expansion and road extension), and forest landscape modifications (forest loss and isolation) as drivers of biodiversity change. We uncovered a significant proliferation of disturbance-tolerant guilds and the loss or decline of disturbance-sensitive guilds within reserves causing a "winner and loser" species replacement over time. Guild change was directly related to forest spatial changes promoted by the expansion of agriculture and roads within reserves. High human population density and low nonfarming occupation were identified as the main underlying drivers of biodiversity change. Our findings suggest that to mitigate anthropogenic threats to biodiversity within biosphere reserves, fostering human population well-being via sustainable, nonfarming livelihood opportunities around reserves is imperative.

Landscape-scale forest cover drives the predictability of forest regeneration across the Neotropics.

Abandonment of agricultural lands promotes the global expansion of secondary forests, which are critical for preserving biodiversity and ecosystem functions and services. Such roles largely depend, however, on two essential successional attributes, trajectory and recovery rate, which are expected to depend on landscape-scale forest cover in nonlinear ways. Using a multi-scale approach and a large vegetation dataset (843 plots, 3511 tree species) from 22 secondary forest chronosequences distributed across the Neotropics, we show that successional trajectories of woody plant species richness, stem density and basal area are less predictable in landscapes (4 km radius) with intermediate (40-60%) forest cover than in landscapes with high (greater than 60%) forest cover. This supports theory suggesting that high spatial and environmental heterogeneity in intermediately deforested landscapes can increase the variation of key ecological factors for forest recovery (e.g. seed dispersal and seedling recruitment), increasing the uncertainty of successional trajectories. Regarding the recovery rate, only species richness is positively related to forest cover in relatively small (1 km radius) landscapes. These findings highlight the importance of using a spatially explicit landscape approach in restoration initiatives and suggest that these initiatives can be more effective in more forested landscapes, especially if implemented across spatial extents of 1-4 km radius.

Tropical forest loss impoverishes arboreal mammal assemblages by increasing tree canopy openness.

Landscape-scale deforestation poses a major threat to global biodiversity, not only because it limits habitat availability, but also because it can drive the degradation of the remaining habitat. However, the multiple pathways by which deforestation directly and indirectly affects wildlife remain poorly understood, especially for elusive forest-dependent species such as arboreal mammals. Using structural equation models, we assessed the direct and indirect effects of landscape forest loss on arboreal mammal assemblages in the Lacandona rainforest, Mexico. We placed camera traps in 100 canopy trees, and assessed the direct effect of forest cover and their indirect effects via changes in tree basal area and canopy openness on the abundance and diversity (i.e., species richness and exponential of Shannon entropy) of arboreal mammals. We found that forest loss had negative indirect effects on mammal richness through the increase of tree canopy openness. This could be related to the fact that canopy openness is usually inversely related to resource availability and canopy connectivity for arboreal mammals. Furthermore, independently of forest loss, the abundance and richness of arboreal mammals was positively related to tree basal area, which is typically higher in old-growth forests. Thus, our findings suggest that arboreal mammals generally prefer old-growth vegetation with relatively low canopy openness and high tree basal area. However, unexpectedly, forest loss was directly and positively related to the abundance and richness of mammals, probably due to a crowding effect, a reasonable possibility given the relatively short history (~40 years) of deforestation in the study region. Conversely, the Shannon diversity was not affected by the predictors we evaluated, suggesting that rare mammals (not the common species) are the ones most affected by these changes. All in all, our findings emphasize that conservation measures ought to focus on increasing forest cover in the landscape, and preventing the loss of large trees in the remaining forest patches.

Homogenization of terrestrial mammals in fragmented rainforests: the loss of species turnover and its landscape drivers.

Understanding the factors and mechanisms shaping differences in species composition across space and time (ß-diversity) in human-modified landscapes has key ecological and applied implications. This topic is, however, challenging because landscape disturbance can promote either decreases (biotic homogenization) or increases (biotic differentiation) in ß-diversity. We assessed temporal differences in intersite ß-diversity of medium-bodied and large-bodied mammals in the fragmented Lacandona rainforest, Mexico. We hypothesized that, given the relatively short history of land-use changes in the region, and the gain and loss of some species caused by landscape spatial changes, ß-diversity would increase through time, especially its nestedness component. We estimated ß-diversity between 24 forest sites (22 forest patches and two continuous forest sites) in 2011 and 2017 to assess whether ß-diversity is decreasing or increasing in the region, and calculated its turnover and nestedness components to understand the mechanisms responsible for changes in ß-diversity, separately assessing mammal groups with different body mass, feeding guild, and habitat specialization. We then related such temporal changes in ß-diversity to temporal changes in five landscape variables (forest cover, matrix openness, number of patches, edge density and interpatch distance) to identify the landscape drivers of ß-diversity. In contrast with our expectations, ß-diversity decreased over time, suggesting an ongoing biotic homogenization process. This pattern was mostly driven by a decrease in species turnover in all mammal groups, especially in landscapes with decreasing forest cover and increasing forested matrices. Although the nestedness component showed a three-fold increase through time, species turnover was 22 and six times higher than nestedness in 2011 and 2017, respectively. The decreased turnover appears to be driven by an increase in dispersal (i.e., spillover) of native species among patches. The prevalence of species turnover over nestedness indicates that different forest sites have a fairly distinct subset of species (i.e., high complementarity in species composition). Therefore, conserving all remaining forest patches and increasing forest cover is of utmost importance to effectively maintain ß-diversity and conserve the total diversity (γ) of mammal assemblages in this Mesoamerican biodiversity hotspot.

Preserving 40% forest cover is a valuable and well-supported conservation guideline: reply to Banks-Leite et al.

Banks-Leite et al. (2021) claim that our suggestion of preserving ≥ 40% forest cover lacks evidence and can be problematic. We find these claims unfounded, and discuss why conservation planning urgently requires valuable, well-supported and feasible general guidelines like the 40% criterion. Using region-specific thresholds worldwide is unfeasible and potentially harmful.

Corrigendum: A Severe Lack of Evidence Limits Effective Conservation of the World's Primates.

[This corrects the article DOI: 10.1093/biosci/biaa082.].

Phylogenetic classification of the world's tropical forests.

Knowledge about the biogeographic affinities of the world's tropical forests helps to better understand regional differences in forest structure, diversity, composition, and dynamics. Such understanding will enable anticipation of region-specific responses to global environmental change. Modern phylogenies, in combination with broad coverage of species inventory data, now allow for global biogeographic analyses that take species evolutionary distance into account. Here we present a classification of the world's tropical forests based on their phylogenetic similarity. We identify five principal floristic regions and their floristic relationships: (i) Indo-Pacific, (ii) Subtropical, (iii) African, (iv) American, and (v) Dry forests. Our results do not support the traditional neo- versus paleotropical forest division but instead separate the combined American and African forests from their Indo-Pacific counterparts. We also find indications for the existence of a global dry forest region, with representatives in America, Africa, Madagascar, and India. Additionally, a northern-hemisphere Subtropical forest region was identified with representatives in Asia and America, providing support for a link between Asian and American northern-hemisphere forests.

Support for the habitat amount hypothesis from a global synthesis of species density studies.

Decades of research suggest that species richness depends on spatial characteristics of habitat patches, especially their size and isolation. In contrast, the habitat amount hypothesis predicts that (1) species richness in plots of fixed size (species density) is more strongly and positively related to the amount of habitat around the plot than to patch size or isolation; (2) habitat amount better predicts species density than patch size and isolation combined, (3) there is no effect of habitat fragmentation per se on species density and (4) patch size and isolation effects do not become stronger with declining habitat amount. Data on eight taxonomic groups from 35 studies around the world support these predictions. Conserving species density requires minimising habitat loss, irrespective of the configuration of the patches in which that habitat is contained.

Designing optimal human-modified landscapes for forest biodiversity conservation.

Agriculture and development transform forest ecosystems to human-modified landscapes. Decades of research in ecology have generated myriad concepts for the appropriate management of these landscapes. Yet, these concepts are often contradictory and apply at different spatial scales, making the design of biodiversity-friendly landscapes challenging. Here, we combine concepts with empirical support to design optimal landscape scenarios for forest-dwelling species. The supported concepts indicate that appropriately sized landscapes should contain ≥ 40% forest cover, although higher percentages are likely needed in the tropics. Forest cover should be configured with c. 10% in a very large forest patch, and the remaining 30% in many evenly dispersed smaller patches and semi-natural treed elements (e.g. vegetation corridors). Importantly, the patches should be embedded in a high-quality matrix. The proposed landscape scenarios represent an optimal compromise between delivery of goods and services to humans and preserving most forest wildlife, and can therefore guide forest preservation and restoration strategies.

A Severe Lack of Evidence Limits Effective Conservation of the World's Primates.

Threats to biodiversity are well documented. However, to effectively conserve species and their habitats, we need to know which conservation interventions do (or do not) work. Evidence-based conservation evaluates interventions within a scientific framework. The Conservation Evidence project has summarized thousands of studies testing conservation interventions and compiled these as synopses for various habitats and taxa. In the present article, we analyzed the interventions assessed in the primate synopsis and compared these with other taxa. We found that despite intensive efforts to study primates and the extensive threats they face, less than 1% of primate studies evaluated conservation effectiveness. The studies often lacked quantitative data, failed to undertake postimplementation monitoring of populations or individuals, or implemented several interventions at once. Furthermore, the studies were biased toward specific taxa, geographic regions, and interventions. We describe barriers for testing primate conservation interventions and propose actions to improve the conservation evidence base to protect this endangered and globally important taxon.

Regional context and dispersal mode drive the impact of landscape structure on seed dispersal.

Land-use change modifies the spatial structure of tropical landscapes, shaping global biodiversity patterns. Yet, it remains unknown how key ecological processes, such as seed dispersal, can be affected by changes in landscape patterns, and whether such effects differ among regions with different climate and disturbance intensity. We assessed the effect of five landscape metrics (forest cover, matrix openness, forest edge density, forest fragmentation, and interpatch distance) on the seed rain recorded in two Mexican fragmented regions (20 forest sites per region): the more deforested, defaunated, and windy Los Tuxtlas rainforest (LTX), and the better-preserved Lacandona rainforest (LAC). We quantified the proportions of dispersed tree species and their seeds, separately evaluating wind- and animal-dispersed species. Our findings support the hypothesis that forest loss is more important than fragmentation per se, negatively impacting the seed rain in both regions. As expected, landscape patterns were comparatively more important for wind-dispersed seeds in LTX, probably because of stronger wind events in this region. Specifically, proportions of wind-dispersed seeds and species decreased with increasing edge density, suggesting that forest edges prevent dispersal of wind-dispersed species, which may occur if edges create physical barriers that limit wind flow. This pattern can also be caused by source limitation in landscapes with more forest edges, as tree mortality rates usually increase at forest edges. The wind-dispersed seed rain was also positively related to matrix openness, especially in LTX, where wind flow can be favored by the dominance of treeless anthropogenic matrices. Surprisingly, the proportion of animal-dispersed seeds in LTX was positively related to matrix openness and patch isolation, suggesting that seed dispersers in more deforested regions may be forced to concentrate in isolated patches and use the available habitat more intensively. Yet, as expected, patch isolation limited wind-dispersed seeds in LAC. Therefore, dispersal (and potentially regeneration) of wind-dispersed trees is favored in regions exposed to stronger wind events, especially in landscapes dominated by regularly shaped patches surrounded by open areas. Conversely, animal-dispersed seeds are primarily favored by increasing forest cover. Preventing forest loss is therefore critical to promote animal seed dispersal and forest recovery in human-modified rainforests.

Direct and cascading effects of landscape structure on tropical forest and non-forest frugivorous birds.

Global biodiversity is increasingly threatened by land-use change, but the direct and indirect drivers of species diversity in human-modified tropical landscapes are poorly known. Forest-dependent species are expected to be particularly sensitive to changes in landscape composition (e.g., forest loss) and configuration (e.g., increase of forest edges), both directly and indirectly through cascading landscape effects on local patterns of forest structure and resource availability. In contrast, non-forest-dependent species are probably more strongly related to landscape changes than to local forest patterns, as these species are able to use resources not only from the forest, but also from other landscape elements over larger spatial scales. We tested these hypotheses using structural equation modeling. In particular, we sampled 20 landscapes (115 ha each) from the Brazilian Atlantic rainforest to assess the effect of landscape-scale forest cover and amount of forest edges on the diversity of frugivorous birds, both directly and indirectly through the effect that these landscape variables may have on vegetation complexity and fruit biomass. We separately assessed the response of forest-dependent and non-forest-dependent frugivores to infer potential mechanisms underlying bird assemblages in fragmented landscapes. The diversity of forest-dependent birds mainly decreased with the simplification of vegetation complexity in more deforested landscapes, but increased with increasing fruit biomass in more forested landscapes (indirect effects). Both patterns were significant, thus supporting a strong bottom-up control, i.e., local habitat simplification and resource scarcity in highly deforested landscapes limits the maintenance of forest-dependent birds. Conversely, but as expected, non-forest-dependent birds were more strongly and directly related to landscape-scale patterns. In particular, landscapes with higher forest edge amount showed higher bird species diversity, probably because the increasing length of ecotones and interspersion/juxtaposition of different habitat types in landscapes with more forest edges can increase resource availability and foraging efficiency of non-forest-dependent birds. As the seed dispersal services offered by forest-dependent species cannot be ecologically compensated for by the proliferation of non-forest-dependent species, preventing forest loss is imperative to maintain forest-dependent birds and forest regeneration in this vanishing biodiversity hotspot.

Fragmentation and matrix contrast favor understory plants through negative cascading effects on a strong competitor palm.

Understanding the patterns and processes driving biodiversity maintenance in fragmented tropical forests is urgently needed for conservation planning, especially in species-rich forest reserves. Of particular concern are the effects that habitat modifications at the landscape scale may have on forest regeneration and ecosystem functioning: a topic that has received limited attention. Here, we assessed the effects of landscape structure (i.e., forest cover, open area matrices, forest fragmentation, and mean inter-patch isolation distance) on understory plant assemblages in the Los Tuxtlas Biosphere Reserve, Mexico. Previous studies suggest that the demographic burst of the strong competitor palm Astrocaryum mexicanum in the core area of this reserve limits plant recruitment and imperils biodiversity conservation within this protected area. Yet, the local and landscape predictors of this palm, and its impact on tree recruitment at a regional scale are unknown. Thus, we used structural equation modeling to assess the direct and cascading effects of landscape structure on stem and species density in the understory of 20 forest sites distributed across this biodiversity hotspot. Indirect paths included the effect of landscape structure on tree basal area (a proxy of local disturbance), and the effects of these variables on A. mexicanum. Density of A. mexicanum mainly increased with decreasing both fragmentation and open areas in the matrix (matrix contrast, hereafter), and such an increase in palm density negatively affected stem and species density in the understory. The negative direct effect of matrix contrast on stem density was overridden by the indirect positive effects (i.e., through negative cascading effects on A. mexicanum), resulting in a weak effect of matrix contrast on stem density. These findings suggest that dispersal limitation and negative edge effects in more fragmented landscapes dominated by open areas prevent the proliferation of this palm species, enhancing the diversity and abundance of understory trees. This "positive" news adds to an increasing line of evidence suggesting that fragmentation may have some positive effects on biodiversity, in this case by preventing the proliferation of species that can jeopardize biodiversity conservation within tropical reserves.

Averting biodiversity collapse in tropical forest protected areas.

The rapid disruption of tropical forests probably imperils global biodiversity more than any other contemporary phenomenon. With deforestation advancing quickly, protected areas are increasingly becoming final refuges for threatened species and natural ecosystem processes. However, many protected areas in the tropics are themselves vulnerable to human encroachment and other environmental stresses. As pressures mount, it is vital to know whether existing reserves can sustain their biodiversity. A critical constraint in addressing this question has been that data describing a broad array of biodiversity groups have been unavailable for a sufficiently large and representative sample of reserves. Here we present a uniquely comprehensive data set on changes over the past 20 to 30 years in 31 functional groups of species and 21 potential drivers of environmental change, for 60 protected areas stratified across the world's major tropical regions. Our analysis reveals great variation in reserve 'health': about half of all reserves have been effective or performed passably, but the rest are experiencing an erosion of biodiversity that is often alarmingly widespread taxonomically and functionally. Habitat disruption, hunting and forest-product exploitation were the strongest predictors of declining reserve health. Crucially, environmental changes immediately outside reserves seemed nearly as important as those inside in determining their ecological fate, with changes inside reserves strongly mirroring those occurring around them. These findings suggest that tropical protected areas are often intimately linked ecologically to their surrounding habitats, and that a failure to stem broad-scale loss and degradation of such habitats could sharply increase the likelihood of serious biodiversity declines.

An estimate of the number of tropical tree species.

The high species richness of tropical forests has long been recognized, yet there remains substantial uncertainty regarding the actual number of tropical tree species. Using a pantropical tree inventory database from closed canopy forests, consisting of 657,630 trees belonging to 11,371 species, we use a fitted value of Fisher's alpha and an approximate pantropical stem total to estimate the minimum number of tropical forest tree species to fall between ∼ 40,000 and ∼ 53,000, i.e., at the high end of previous estimates. Contrary to common assumption, the Indo-Pacific region was found to be as species-rich as the Neotropics, with both regions having a minimum of ∼ 19,000-25,000 tree species. Continental Africa is relatively depauperate with a minimum of ∼ 4,500-6,000 tree species. Very few species are shared among the African, American, and the Indo-Pacific regions. We provide a methodological framework for estimating species richness in trees that may help refine species richness estimates of tree-dependent taxa.

Tropical forest loss and its multitrophic effects on insect herbivory.

Forest loss threatens biodiversity, but its potential effects on multitrophic ecological interactions are poorly understood. Insect herbivory depends on complex bottom-up (e.g., resource availability and plant antiherbivore defenses) and top-down forces (e.g., abundance of predators and herbivorous), but its determinants in human-altered tropical landscapes are largely unknown. Using structural equation models, we assessed the direct and indirect effects of forest loss on insect herbivory in 40 landscapes (115 ha each) from two regions with contrasting land-use change trajectories in the Brazilian Atlantic rainforest. We considered landscape forest cover as an exogenous predictor and (1) forest structure, (2) abundance of predators (birds and arthropods), and (3) abundance of herbivorous arthropods as endogenous predictors of insect leaf damage. From 12 predicted pathways, 11 were significant and showed that (1) leaf damage increases with forest loss (direct effect); (2) leaf damage increases with forest loss through the simplification of vegetation structure and its associated dominance of herbivorous insects (indirect effect); and further demonstrate (3) a lack of top-down control of herbivores by predators (birds and arthropods). We conclude that forest loss favors insect herbivory by undermining the bottom-up control (presumably reduced plant antiherbivore defense mechanisms) in forests dominated by fast-growing pioneer plant species, and by improving the conditions required for herbivores proliferation.

Phylogenetic impoverishment of plant communities following chronic human disturbances in the Brazilian Caatinga.

Chronic disturbances, such as selective logging, firewood extraction and extensive grazing, may lead to the taxonomic and phylogenetic impoverishment of remaining old-growth forest communities worldwide; however, the empirical evidence on this topic is limited. We tested this hypothesis in the Caatinga vegetation--a seasonally dry tropical forest restricted to northeast Brazil. We sampled 11,653 individuals (adults, saplings, and seedlings) from 51 species in 29 plots distributed along a gradient of chronic disturbance. The gradient was assessed using a chronic disturbance index (CDI) based on five recognized indicators of chronic disturbances: proximity to urban center, houses and roads and the density of both people and livestock. We used linear models to test if mean effective number of lineages, mean phylogenetic distance and phylogenetic dispersion decreased with CDI and if such relationships differed among ontogenetic stages. As expected, the mean effective number of lineages and the mean phylogenetic distance were negatively related to CDI, and such diversity losses occurred irrespective of ontogeny. Yet the increase in phylogenetic clustering in more disturbed plots was only evident in seedlings and saplings, mostly because clades with more descendent taxa than expected by chance (e.g., Euphorbiaceae) thrived in more disturbed plots. This novel study indicates that chronic human disturbances are promoting the phylogenetic impoverishment of the irreplaceable woody flora of the Brazilian Caatinga forest. The highest impoverishment was observed in seedlings and saplings, indicating that if current chronic disturbances remain, they will result in increasingly poorer phylogenetically forests. This loss of evolutionary history will potentially limit the capacity of this ecosystem to respond to human disturbances (i.e., lower ecological resilience) and particularly their ability to adapt to rapid climatic changes in the region.

Taxonomic and functional divergence of tree assemblages in a fragmented tropical forest.

Tropical forests are being exposed to increasing levels of habitat loss and fragmentation, threatening the maintenance of global biodiversity. However, the effect that land-use change may have on the spatial dissimilarities in taxonomic and functional composition of remaining assemblages (i.e., taxonomic/functional ß-diversity) remains poorly understood. We examined a large vegetation database from an old and severely fragmented Atlantic forest landscape to test two alternative hypotheses: (1) tree assemblages experience a taxonomic and functional homogenization (reduced ß-diversity) between forest fragments and along forest edges, or alternatively, (2) these edge-affected forests show increased taxonomic and functional differentiation (increased ß-diversity) when compared to forest interior (reference) stands. Taxonomic and functional ß-diversity were examined via novel abundance-based metrics and considering functional traits related to plant dispersion, recruitment, and growth. Overall, taxonomic ß-diversity among fragments was significantly higher than among edge and reference plots. Edge plots also showed higher ß-diversity than reference plots, but only when considering dominant species. In functional terms, ß-diversity among reference plots was also lower than among forest fragments and among edge plots. These patterns support the landscape-divergence hypothesis, which postulates that variable human disturbances among forest fragments and along forest edges can lead to contrasting trajectories of vegetation changes, thus increasing the compositional and functional differentiation of tree communities in these emerging environments. Our results also show that such differentiation can preserve landscape-wide biodiversity, thus overriding negative effects of habitat fragmentation on local (α) diversity. Therefore, our findings demonstrate that forest fragments and forest edges can be more valuable for maintaining species diversity and ecosystem function in fragmented tropical landscapes than previously thought.

Patterns and predictors of ß-diversity in the fragmented Brazilian Atlantic forest: a multiscale analysis of forest specialist and generalist birds.

Biodiversity maintenance in human-altered landscapes (HALs) depends on the species turnover among localities, but the patterns and determinants of ß-diversity in HALs are poorly known. In fact, declines, increases and neutral shifts in ß-diversity have all been documented, depending on the landscape, ecological group and spatial scale of analysis. We shed some light on this controversy by assessing the patterns and predictors of bird ß-diversity across multiple spatial scales considering forest specialist and habitat generalist bird assemblages. We surveyed birds from 144 point counts in 36 different forest sites across two landscapes with different amount of forest cover in the Brazilian Atlantic forest. We analysed ß-diversity among points, among sites and between landscapes with multiplicative diversity partitioning of Hill numbers. We tested whether ß-diversity among points was related to within-site variations in vegetation structure, and whether ß-diversity among sites was related to site location and/or to differences among sites in vegetation structure and landscape composition (i.e. per cent forest and pasture cover surrounding each site). ß-diversity between landscapes was lower than among sites and among points in both bird assemblages. In forest specialist birds, the landscape with less forest cover showed the highest ß-diversity among sites (bird differentiation among sites), but generalist birds showed the opposite pattern. At the local scale, however, the less forested landscape showed the lowest ß-diversity among points (bird homogenization within sites), independently of the bird assemblage. ß-diversity among points was weakly related to vegetation structure, but higher ß-diversity values were recorded among sites that were more isolated from each other, and among sites with higher differences in landscape composition, particularly in the less forested landscape. Our findings indicate that patterns of bird ß-diversity vary across scales and are strongly related to landscape composition. Bird assemblages are shaped by both environmental filtering and dispersal limitation, particularly in less forested landscapes. Conservation and management strategies should therefore prevent deforestation in this biodiversity hotspot.

Which is the appropriate scale to assess the impact of landscape spatial configuration on the diet and behavior of spider monkeys?

Understanding the response of species to changes in landscape configuration is required to design adequate management and conservation strategies. Yet, the most appropriate spatial scale (i.e., landscape size) to assess the response of species to changes in landscape configuration (so-called "scale of effect") is largely unknown. In this paper, we assess the impact of landscape forest cover, forest fragmentation, edge density, and inter-patch isolation distance on the diet and behavior of six communities of spider monkeys (Ateles geoffroyi) in the fragmented Lacandona rainforest, Mexico. We evaluated the strength of the relationship between each landscape predictor and each response variable within ten different-sized landscapes (range = 50-665 ha) to identify the landscape size that best predicted changes in diet and behavior. The strength of most associations varied across spatial scales, with the 126-ha landscape showing the strongest relationships between landscape predictors and response variables in many cases. Yet forest cover represented the main driver of the diet and behavior of spider monkeys, being positively associated with time traveling and time feeding on wood, but negatively related to time resting and time feeding on leaves. Although weaker, the impact of edge density was opposite to forest cover for most response variables. Forest fragmentation and isolation distance showed the weakest associations with the diet and behavior of this species. Our findings thus indicate that different landscape attributes operate on different response variables at different spatial scales. Therefore, the scale of effects cannot be generalized to all response variables and to all predictors, and a multi-scale analysis will be required to accurately assess the impact of landscape configuration on species' responses.