Fragmented Atlantic Forest Landscape Research Articles

Divergence of Ant Communities Over Time in a Fragmented Atlantic Rain Forest Landscape

Habitat fragmentation changes biological communities and its spatiotemporal dynamics – which may lead to either biotic homogenization or heterogenization along time and space. Both processes can occur by addition, replacement or loss of species within communities, altering compositional similarity across the landscape. We investigated which of these two processes (biotic homogenization or heterogenization) occurs, and its possible underlying mechanism, over 15 years in an Atlantic Forest landscape using ants as model organisms. We sampled ants in 17 forest fragments across three different years, compared their composition similarity, species richness, and species richness of groups classified according to their habitat preferences. We sampled a total of 132 ant species. Ant communities in fragments diverged over time, suggesting they experienced an idiosyncratic structuring process. This biotic heterogenization occurred through an additive process, as ant species richness increased over time, mainly due to an increase of generalist ant species, and a decrease of forest specialist ant species. These changes occurred despite the higher forest cover in the landscape along years. Since different species can perform different functions in ecosystems, this biotic heterogenization may have implications for ecosystem functioning. Investigating how disturbances structure biological communities over time, especially those performing important ecosystem functions, can shed light to our understanding of possible changes in ecosystem functions and consequently for forest regeneration.

Tree species richness and composition in a fragmented landscape of the Brazilian lowland Atlantic Forest

Abstract Tropical forests are one of the most important ecosystems and loss of biological diversity in these is a major concern. We studied seven forest remnants on the coast of Rio de Janeiro, southeastern Brazil, three medium-sized (24-63 ha) and four small (5-11 ha), to assess the influence of size, degree of disturbance and isolation on composition and diversity of the tree layer. A total of 443 species in 60 families and 185 genera were recorded, with Myrtaceae, Lauraceae and Fabaceae being the most species-rich families. The results showed areas of high α-diversity (α= 34.86-75.69) and a slightly greater decline of similarity with distance between the study areas. Remnant size not explained the variation in the species composition and we found correlation between the level of disturbance and the floristic composition. The remnants had low floristic similarity, strongly influenced by the degree of disturbance. Results suggest that disturbance influences composition and diversity and confirm the importance of including both medium-sized and small remnants in the conservation of tropical forest diversity.

Effect of habitat loss and fragmentation on fruit-feeding butterflies in the Brazilian Atlantic Forest

Habitat loss and fragmentation have drastically altered the availability and quality of tropical forest habitats, but information on how such changes influence local biodiversity is still insufficient. Here, we examine the effects of both patch and landscape metrics on fruit-feeding butterfly assemblages in a fragmented landscape of the Brazilian Atlantic Forest. Our study was carried out in three habitat types: eight fragments (ranging from 8 to 126 ha), eight areas of forest edge (50 m from forest border), and eight areas of forest interior (>200 m from forest border) of the largest remnant (3500 ha) of the Atlantic Forest of northeast Brazil. Our results demonstrated that fragment area is negatively correlated with observed and estimated richness and abundance of butterflies, whereas habitat type is correlated with estimated richness and abundance of butterflies. Species composition responded to habitat type, fragment area, and distance between sample units. These findings illustrated (i) fruit-feeding butterfly sensitivity to habitat loss and fragmentation, (ii) that species composition and abundance are adequate parameters to access the responses of fruit-feeding butterflies to habitat loss and fragmentation, and (iii) the relevance of a heterogeneous and connected landscape for conservation of butterflies, where small fragments are important for generalist or open-habitat specialists and large remnants are key for disturbance-sensitive and threatened taxa.

Depauperation and divergence of plant‐specialist herbivore assemblages in a fragmented tropical landscape

1. Our understanding of the structure and spatial organisation of biological assemblages in human‐modified tropical landscapes has critical importance to improve conservation actions. Investigations on this topic have focused on local (α) diversity patterns, overlooking the changes in species turnover (β diversity) between sites, and its consequences on total (γ) diversity.2. This study assessed the differences in α, β and γ diversities of galling insects and their host plants (saplings) in a fragmented Atlantic forest landscape in northeast Brazil. Both assemblages were recorded in 30 plots (total of 0.1 ha for each forest type) located in the interior and on the edges of a large fragment and small forest fragments (10 plots per forest type).3. α diversity of host plants and galling insect assemblages was significantly higher in interior (reference) plots than in edge and fragment plots. Yet, both assemblages showed higher β diversity in fragment and edge plots than in reference plots – a finding potentially associated with the hyperdynamism of fragmented forests and consistent with the landscape divergence hypothesis.4. However, biotic differentiation of host plant and galling insects was not great enough to compensate the loss of α diversity, and thus γ diversity, because most host plant and galling insect species in forest fragments were also registered in reference plots. Our findings indicate that, despite each small forest fragment being very dissimilar from each other, they have low importance for the conservation of plant assemblages and their specialized herbivores at landscape scale.

Temperature and resource availability drive the seasonal abundance of Artibeus lituratus (Chiroptera: Phyllostomidae) in Atlantic Forest remnants of southeastern Brazil

Abstract The great fruit-eating bat (Artibeus lituratus) is a large-sized bat in the New World family Phyllostomidae. It is widely distributed and sometimes very abundant in different Brazilian biomes, in natural and anthropic environments. Studies in the tropics have found evidence of a decrease in A. lituratus captures during the winter, a dry and cold season with low fruit availability, especially in higher latitudes. However, the causes for the decrease in captures are poorly understood. The objective of this study was to test the influence of temperature and fruit availability on capture rates of A. lituratus in a fragmented Atlantic Forest landscape. Results indicate that temperature is the main variable that explains the changes in the number of captures of A. lituratus throughout the year, and that fruit availability plays only an adjacent role. In addition, we highlight possible negative consequences of climate change on the survival of this species.

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 β-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 β-diversity) between forest fragments and along forest edges, or alternatively, (2) these edge-affected forests show increased taxonomic and functional differentiation (increased β-diversity) when compared to forest interior (reference) stands. Taxonomic and functional β-diversity were examined via novel abundance-based metrics and considering functional traits related to plant dispersion, recruitment, and growth. Overall, taxonomic β-diversity among fragments was significantly higher than among edge and reference plots. Edge plots also showed higher β-diversity than reference plots, but only when considering dominant species. In functional terms, β-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.

Habitat fragmentation and the future structure of tree assemblages in a fragmented Atlantic forest landscape

The biodiversity value of human-modified landscapes has become a central question in the tropical forest conservation biology, yet the degree to which plant populations and communities are restructured in response to environmental change remains unclear. Here, we address tree species density in a fragmented Atlantic forest landscape to test the hypothesis that tree assemblages inhabiting edge-dominated forest habitats approach typical conditions of early successional systems. Seedlings and adults from 141 tree species were sampled across 39 0.1-ha plots: 19 in small fragments ( 55 % of all tree species exhibiting higher densities in small fragments than in mature forest, particularly pioneers (>60 % of all species). Seedlings and adults of these proliferating species differed from species exhibiting population declines in terms of wood density and seed size, respectively. Additionally, pioneers were more abundant than shade-tolerant species, as were hardwood species in the case of seedlings. Tree species showing highest population increases consisted largely of long-lived, light-demanding canopy species bearing soft or hardwood and small-to-medium-sized seeds. Tree assemblage structure also differed in terms of forest habitats with small forest fragments supporting few rare species, whereas the most rapidly proliferating species were much more widespread and abundant in fragments. However, 60 % of all adult pioneer species recorded in small fragments were not recorded as seedlings in this habitat type, although both seedling and adult assemblages were dominated by pioneer species. Edge-dominated tree assemblages are likely to experience long-term shifts toward greater dominance of long-lived, pioneer canopy species.

Fruit-feeding butterflies in edge-dominated habitats: community structure, species persistence and cascade effect

As old-growth forests are converted into edge-affected habitats, a substantial proportion of tropical biodiversity is potentially threatened. Here, we examine a comprehensive set of community-level attributes of fruit-feeding butterfly assemblages inhabiting edge-affected habitats in a fragmented Atlantic forest landscape devoted to sugar cane production. We also explored whether the consequences of habitat loss and fragmentation can interact and cause cascading ecosystem changes, with the pervasive simplification of tree assemblages inhabiting edge-dominated habitats, altering fruit-feeding butterfly persistence. Butterflies were sampled in three forest habitats: small fragments, forest edges and patches of forest interior of a primary forest fragment. Assemblage attributes, including taxonomic composition, correlated to some patch (patch size) and landscape (such as forest cover) metrics as well as habitat structure (tree density and richness). Fruit-feeding butterfly assemblages in the forest interior differed from those in small fragments due to an increased abundance of edge-specialist species. On the other hand, several forest-dependent species were missing in both small fragments and forest edges. Our results suggest that edge-affected habitats dominated by pioneer tree species support taxonomically distinct assemblages, including the presence of disturbance-adapted species, and butterfly community structure is highly sensitive to fragmentation- and plant-related variables, such as forest cover and pioneer tree species. In this way, while the establishment of human-modified landscapes probably results in the local extirpation of forest-dependent species, it allows the persistence of disturbance-adapted species. Thus, forest-dependent species conservation and the plant–animal interaction webs they support could be improved by retaining a significant amount of core forest habitat.

The importance of restoration areas to conserve bird species in a highly fragmented Atlantic forest landscape

In this study, we tested the potential of restored areas to maintain biodiversity in the scope of a recently proposed category of protected area called “Restoration Reserves”. To accomplish this, we compared bird richness and functional group structure of two small forest fragments (<250ha) with adjacent recently reforested areas (9 and 7 years of reforestation). Reforested areas had equal or higher bird richness and similar functional group structure. These results indicate that reforested areas are capable of maintaining current levels of biodiversity and reducing species extinction debt in small forest fragments, which is the main purpose of “Restoration Reserves”. However, when we compared a large forest fragment with an old adjacent reforested area (20 years of reforestation), we found that it was of limited value for certain functional groups. Therefore, “Restoration Reserves” could provide essential additional habitat in highly fragmented landscapes that consists mainly of small forest fragments.

Plant trait distribution and the spatial reorganization of tree assemblages in a fragmented tropical forest landscape

Tropical forests have been rapidly converted into human-modified landscapes but the effects of such conversion on community spatial organization have been rarely addressed. In this paper, we examine to what extent the spatial reconfiguration of tropical landscapes alters plant trait distributions and the spatial organization of tree assemblages. A set of 117 tree species and 1422 individuals (≥10 cm DBH) inhabiting a fragmented Atlantic forest landscape in Brazil were assigned into categories of both vegetative and reproductive life-history traits, and matrices of trait frequencies were correlated to four spatial patch metrics via the concepts of trait-convergent, trait-divergent assembly pattern, and measures of functional richness, evenness, and diversity. Life form and seed dispersal syndrome exhibited the highest and significant degrees of trait-convergence related to connectivity and patch size gradients, respectively. Trait divergence based on seed dispersal syndrome and regeneration strategy emerged as well, particularly in response to patch area and connectivity. Finally, some functional diversity (multiple-traits) measures correlated with either a particular patch metric or species richness. Our results suggest that the spatial distribution of life-history traits and strategies exhibited by tree species correlate with spatial patch metrics, supporting the notion that human disturbances result in new environmental gradients able to spatially reorganize and restructure tree assemblages at broad spatial scales into human-modified landscapes.

Altered herb assemblages in fragments of the Brazilian Atlantic forest

Understanding the response of tropical plant communities to human disturbance is critical for conserving biodiversity in a changing world. Here we examine the shifts experienced by understory herb assemblages while inhabiting small forest fragments in a fragmented Atlantic forest landscape to infer about community-level shifts imposed by either habitat loss or fragmentation. We established 100 25-m2 plots, placed randomly in 10 forest fragments and 10 forest interior patches, in which all herb species were recorded, litter accumulation, soil temperature and moisture were estimated. We recorded a total of 6027 herbs belonging to 134 species, with a predominance of ferns, grasses, aroids, sedges and calatheas. Forest fragments and forest interior exhibited similar densities of herbs: 64.4±57.8herbs/25m2 vs. 56.1±44.1, respectively. Species richness was reduced by a half in forest fragments at plot and habitat spatial scales. Fragments were particularly impoverished in terms of ferns, aroids and calatheas, but supported a subset of proliferating native herbs and indicator/exclusive species; i.e. a taxonomically and ecologically distinct herb flora. Fragments also supported less humid soils covered by a thicker litter layer and these attributes correlated to species distributions in both forest habitats. Our results suggest that habitat loss and fragmentation, particularly the establishment of illuminated and desiccated forest edges, result in the extirpation of particular ecological groups with a few species/ecological groups experiencing proliferation, such as light-demanding species. Collectively, these processes result in impoverished/altered assemblages at multiple spatial scales, potentially limiting the conservation services provided by human-modified landscapes.

Dung beetle (Coleoptera, Scarabaeidae) assemblage of a highly fragmented landscape of Atlantic forest: from small to the largest fragments of northeastern Brazilian region

Human activities in tropical forests are the main causes of forest fragmentation. According to historical factor in deforestation processes, forest remnants exhibit different sizes and shapes. The aim of the present study was to evaluate the dung beetle assemblage on fragments of different degree of sizes. Sampling was performed during rainy and dry season of 2010 in six fragments of Atlantic forest, using pitfall traps baited with excrement and carrion. Also, we used two larger fragments as control. We used General Linear Models to determine whether the fragments presented distinguished dung beetle abundance and richness. Analysis of Similarities and Non-Metric Multidimensional Scaling were used to determine whether the dung beetle assemblage was grouped according to species composition. A total of 3352 individuals were collected and 19 species were identified in the six fragments sampled. Dung beetle abundance exhibited a shift according to fragment size; however, richness did not change among fragments evaluated. Also, fragments sampled and the two controls exhibited distinct species composition. The distinction on abundance of dung beetles among fragments may be related to different amount of resource available in each one. It is likely that the dung beetle richness did not distinguish among the different fragments due to the even distribution of the mammal communities in these patches, and consequent equal dung diversity. We conclude that larger fragments encompass higher abundance of dung beetle and distinct species. However, for a clearer understanding of effects of fragmentation on dung beetles in Atlantic forest, studies evaluating narrower variations of larger fragments should be conducted.

Dung beetle persistence in human-modified landscapes: Combining indicator species with anthropogenic land use and fragmentation-related effects

Identifying and making use of ecological indicators becomes an essential task in the conservation of tropical systems, mainly in fragmented landscapes where land use intensification and habitat loss are confounding factors in the detection of species’ responses to human-caused disturbance. We aimed to analyze the importance of anthropogenic land use and fragmentation-related effects on dung beetle (Coleoptera: Scarabaeinae) persistence according to the interior–exterior non-linear gradient (forest+matrix) in a fragmented Atlantic Forest landscape used to sugar cane production and cattle ranching/farming. We offer scores for a comprehensive set of community-level attributes, from beetle abundance to taxonomic and ecological composition (i.e. species body size), including a list of indicator species of different forest habitats and adjacent matrix. Dung beetles were surveyed by traps across forest interiors (i.e. core forest areas) and edges of a primary forest, small fragments, sugar cane fields and pastures in a total of 60 sites. Indicator analyses were conducted across the landscape, using two well-established methods (IndVal and SIMPER). Our results suggest that (1) cross-habitat taxonomic distinctness is associated with the presence of indicator species, (2) some species benefit or are dependent of open habitats created by human-disturbances, such as forest edges (e.g. Canthon nigripennis) and matrices (e.g. Canthon aff. piluliformis, Dichotomius nisus and Trichilum externepunctatum), (3) although landscape habitats exhibit reduced beta diversity, dung beetle assemblages are spatially organized in response to the presence of both forest habitats and matrix and fragment area, (4) forest interior supports beetle assemblages biased toward large-bodied species, (5) accordingly forest interior, forest edges and matrix support taxonomically distinct assemblages, both contributing to the bulk of species richness at landscape level, (6) the response of dung beetles to the interior–exterior non-linear gradient (i.e. forest edge+matrix) reveals a similar pattern regardless of the nature of the matrix, and (7) there is no within-habitat variation in beetle abundance and species richness associated with distance from forest edge. Given that there is a high number of forest-dependent or forest-interior specialist species (e.g. Aphengium aff. sordidum, Ateuchus aff. alipioi, Dichotomius mormon, Ontherus aff. erosus and Onthophagus aff. clypeatus) dung beetle persistence in human-modified landscape is highly dependent on the presence of core areas, although edge-affected and matrix habitats may be complementary. This information is essential to permit a better prospect for dung beetle persistence in human-modified landscapes as they continue to move toward edge-dominated landscapes with intensively managed matrices.

Secondary succession in a fragmented Atlantic Forest landscape: evidence of structural and diversity convergence along a chronosequence

Changes in physiognomy, species composition and structure, and dispersal mechanisms of canopy and subcanopy plant assemblages were investigated along a chronosequence of three ages: 12, 20, and 50+ years old (=old-growth), three replications in each, in an Atlantic Forest landscape in Northeastern Brazil. Our objective was to investigate whether there is floristic and structural convergence along secondary succession. There were significant differences between secondary and old-growth forests in density and basal area only for the subcanopy. Differences in density between forest ages were noted when the assemblage was analyzed per diameter and height classes. Richness of canopy species of both secondary ages differed from those of old-growth forests. Some dominant species in the canopy of secondary forests showed a significant decrease in density with increasing age, which indicates an ongoing process of floristic changes. The low level of shared species between secondary and old-growth forests supports the idea that species composition is one of the last components to recover during successional process. Zoochory was the most important dispersal guild in species percentage and number, irrespective of stand age. Although regenerating areas can take alternative pathways, our results indicate that secondary Atlantic Forest sites have a high potential for natural regeneration. This recovery is recorded as a physiognomic convergence of the canopy layer in as little as 12 years, and progressive introductions of later successional species into the plant assemblage that lead to convergence in terms of the diversity and richness of the subcanopy and of dispersal guilds just 20 years after abandonment.

Diversity and Distribution of Lizards in Fragmented Atlantic Forest Landscape in Southeastern Brazil

Abstract In this study, we evaluated how different lizard species were distributed in a fragmented Atlantic Forest landscape and the influence of landscape metrics on lizard species richness in sampled fragments. We sampled (between July 2007 and March 2010) three continuous forest sites of the Reserva Ecologica de Guapiacu (REGUA), 12 forest fragments of different sizes and five pasture matrix areas. We recorded 8 lizard species, the most abundant being Ecpleopus gaudichaudii and Enyalius brasiliensis. Species richness in the continuous forest sites (N = 4) was lower than in the set of fragments (N = 8); fragments harbored both typical forest species and more generalist species. The forest areas differed in the composition of lizard species, with continuous forest sites having a composition similar to each other and to larger fragments, whereas the smaller fragments differed from the larger fragments but showed similarity to each other. These data indicated that fragment size (area) can be an important f...

Demographic structure of a threatened palm (Euterpe edulis Mart.) in a fragmented landscape of Atlantic Forest in northeastern Brazil

ABSTRACT At the northern limits of the range of the palm species Euterpe edulis there is an endemic ecotype, known as the “Bahia” ecotype, which is distinguished by its reddish crownshaft and low seed production. Unfortunately, little is known about its demographic characteristics. Therefore, we contrasted the density of E. edulis populations in the Una region, in the southern part of the Bahia state, Brazil, with that of other populations of the species in southern and southeastern Brazil. In addition, within the Una region, we compared a long-protected forest fragment (F1) with three recently protected fragments (F2, F3, and F4), in terms of demographic parameters and plant size, in order to determine what influence, if any, time since protection has on E. edulis populations. Population densities within the Una region were higher than in regions where E. edulis populations are stressed by harvesting or intense seed predation but much lower than in regions with well protected populations. Among the Una fragments, density was highest in F1 and lowest in F2. The proportion of individuals at the various developmental stages differed among the fragments (χ²=25.219, df=12,

Community-Level Patterns of Insect Herbivory in a Fragmented Atlantic Forest Landscape

Insect herbivores largely affect plant population structure, community organization, and ecosystem functioning, but little is known on how insect herbivory is altered in human-modified landscapes. Here we assessed 3,566 woody seedlings inhabiting 20 Atlantic forest fragments (3-91 ha) in northeast Brazil to examine the extent to which standing levels of herbivory on woody seedlings correlated with forest fragment metrics (fragment area and distance to forest edge) and resource availability (pioneer plants). Overall, 78% of all seedlings and 36% of the 23,003 recorded leaves experienced injuries caused by folivorous insects, the bulk of them promoted by chewing insects (85.9% of damaged leaves). This insect guild removed 9.2 ± 1.9 cm(2) of foliar tissue per leaf, which represented 10.2 ± 1.8% of the standing leaf area. Contrary to our expectations, frequency and magnitude of foliar damage by insects were statistically uncorrelated to either basic forest fragment metrics (fragment area, edge proximity) or resource abundance (percentage of pioneer seedlings). Our findings indicate that insect herbivory is a pervasive ecological process in fragmented landscapes. However, rather than being a function of simple fragment metrics or resource availability, its variation seems to be caused by a range of drivers, such as dispersal ability of folivorous insects and vulnerability of their parasitoids and predators to human disturbance.

The confounded effects of habitat disturbance at the local, patch and landscape scale on understorey birds of the Atlantic Forest: Implications for the development of landscape-based indicators

The search for surrogates of changes in species richness and community structure in fragmented landscapes involves not only the selection of predictors, such as landscape metrics or environmental variables, but also the identification of the spatial scale that is most relevant to the taxa in question. However the heavily intercorrelated nature of many structural features in fragmented landscapes complicates analyses, and the wide variation in species responses prevents the identification of a general trend. In this study, we used a two-tiered hierarchical variation partitioning to identify the unique and shared effects of: 1 – changes in vegetation structure at the plot scale, patch structure (size and shape), and forest cover at the landscape scale; and 2 – variables within these scales; as predictors of species richness and species’ abundances of birds in a fragmented landscape of Atlantic Forest; with the goal of aiding to the development of biodiversity indicators. Birds were sampled with mist-nets with a constant effort of 680 net-h at each of 23 sites, which resulted in almost 2600 captures. At the community level, regression models showed that changes in plot, patch and landscape scale variables explained a large proportion of the variation in species richness, but results from variation partitioning showed that the intercorrelation among predictors was so high that the unique contribution of each was non-significant. Our results point to a relatively large unique effect of local and landscape scale variables at the community level, but we also show that results vary greatly depending on the trophic guild being analysed. At the species level, multiple scale models also presented high explanatory power, however, species responses were so varied that we could not detect a general trend. We conclude that there is no single ‘best’ scale that could function as a proxy for changes in bird communities because each species and functional guild is uniquely affected by the environment, and suggest that efforts should be focused on finding indicators that encompasses all scales and the needs of different taxa.

The importance of landscape structure for seed dispersal in rain forest fragments

AbstractQuestionsWhat are the main features of the seed rain in a fragmented Atlantic forest landscape? Can seed rain species attributes (life form, dispersal mode, successional status) relate to the spatial arrangement (size and number of fragments, edge density and presence of corridor) of forest fragments in the landscape? How does the rain forest landscape structure affect the seed rain?LocationAtlantic rainforest, São Paulo State, Southeastern Brazil.MethodsSeed rain samples were collected monthly throughout 1 yr, counted, identified and classified according to species dispersal mode, successional status and life form. Seed rain composition was compared with woody species near the seed traps. Relationships between seed rain composition and landscape spatial arrangement (fragment area, presence of corridor, number of fragments in the surroundings, proximity of fragments, and edge density) were tested using canonical correspondence analysis (CCA).ResultsWe collected 20 142 seeds belonging to 115 taxa, most of them early successional and anemochorous trees. In general, the seed rain had a species composition distinct from that of the nearby forest tree community. Small isolated fragments contained more seeds, mainly of anemochorous, epiphytic and early‐successional species; large fragments showed higher association with zoochorous and late‐successional species compared to small fragments. The CCA significantly distinguished the species dispersal mode according to fragment size and isolation, anemochorous species being associated to small and isolated fragments, and zoochorous species to larger areas and fragment aggregation. Nevertheless, a gradient driven by proximity (PROX) and edge density (ED) segregated lianas (in the positive extremity), early successional and epiphyte species (in the negative end); large fragments were positively associated to PROX and ED.ConclusionsThe results highlight the importance of the size and spatial arrangement of forest patches to promote habitat connectivity and improve the flux of animal‐dispersed seeds. Landscape structure controls seed fluxes and affects plant dispersal capacity, potentially influencing the composition and structure of forest fragments. The seed rain composition may be used to assess the effects of landscape spatial structure on plant assemblages, and provide relevant information for biodiversity conservation.

Carbon Storage in a Fragmented Landscape of Atlantic Forest: The Role Played by Edge-Affected Habitats and Emergent Trees

Patterns of carbon retention and distribution across human-modified landscapes have been poorly investigated. In this paper carbon distribution across three forest habitats of a fragmented Atlantic forest landscape in northeast Brazil is examined. Data on tree assemblages (DBH ≥10 cm) inhabiting forest interior stands, forest edges and fragments (2.05–365 ha) were obtained via information from 59 0.1-ha plots (a total of 4,845 stems and 198 tree species), and it was further incorporated in four allometric equations for estimation of above-ground biomass and carbon. Stocks of carbon were highly variable within habitats of Serra Grande, but forest interior plots retained almost three times more carbon (202.8 ± 23.7 TonC/ha) than edge and fragment plots, while these edge-affected habitats exhibited similar scores. Moreover, emergent tree species accounted for the majority of the carbon retained (59.13%) in interior plots with understorey species playing a minor role. However, carbon retained by emergent species decreased by a half across forest edges and forest fragment since large stems (&gt; 70 cm DBH) and very tall trees (&gt; 31 m height) were very rare in these habitats. Finally, a forest cover mapping revealed the occurrence of 213.19 km2 of forest interior habitat in the whole Atlantic forest of northeast Brazil. This figure means that only 8% of total remaining forest habitat has a full potential for carbon storage, with the other 92% (edge-affected habitats) storing just a half of that. Our results suggest that habitat fragmentation and the consequent establishment of edge-affected habitats (forest edges and fragments) drastically limit forest capacity for carbon storage across human-modified landscapes since the loss of carbon due to reduced abundance of large trees is not compensated by either canopy or understorey species.