Effects Of Forest Fragmentation Research Articles

Genetic variation at microsatellite loci in the tropical herb Aphelandra aurantiaca (Acanthaceae).

Premise of the study:To assess the effect of forest fragmentation on genetic variation and population structure of Aphelandra aurantiaca (Acanthaceae), a tropical and ornamental herbaceous perennial plant, we developed the first microsatellite primers for the species.Methods and Results:Fourteen microsatellite markers were isolated and characterized from A. aurantiaca genomic libraries enriched for di-, tri-, and tetranucleotide repeat motifs. Polymorphism was evaluated in 107 individuals from four natural populations. Twelve out of 14 genetic markers were polymorphic. The number of alleles per locus ranged from two to 12, and the observed and expected heterozygosities ranged from 0.22 to 0.96 and from 0.20 to 0.87, respectively. Fixation indices ranged from −0.41 to 0.44.Conclusions:These newly developed microsatellite markers for A. aurantiaca will be useful for future population genetic studies, specifically to detect the possible loss of genetic diversity due to habitat fragmentation.

Agricultural matrix affects differently the alpha and beta structural and functional diversity of soil microbial communities in a fragmented Mediterranean holm oak forest

Given the increase in habitat fragmentation in the Mediterranean forests, understanding its impacts over the ecology of soil microbial communities, responsible for many ecosystem functions, and their capacity to metabolize different substrates from soil organic matter, is of upmost importance. We evaluated how the influence of the agricultural matrix, as one of the main consequences of forest fragmentation, may affect both the composition and the functioning of soil microbial communities in Mediterranean holm oak forests. We determined structural and functional alpha and beta-diversity of microbial communities, as well as microbial assemblages and metabolic profiles, by using a commonly used fingerprinting technique (Denaturing Gel Gradient Electrophoresis) and a community level physiological profiles (CLPP) technique (EcoPlate). Key drivers of soil microbial structure and metabolism were evaluated by using structural equation models (SEM) and multivariate ordination (envfit) approaches. Our results pointed out that forest fragmentation affects microbial community structure and functioning through a complex cascade of causal-effect interactions with the plant–soil system, which ultimately affects the nutrient cycling and functioning of forest soils. We also found a strong scale-dependency effect of forest fragmentation over the ecology of microbial communities: fragmentation increases the local (alpha) diversity, but affected negatively microbial diversity at the landscape scale (beta diversity). This homogenization of the microbial communities and their metabolism at landscape scale resulting from habitat fragmentation may have unknown potential consequences on the capacity of these communities, and hence these ecosystems, to respond to the climate change. Finally, we found a consistent relation between the structure and functional diversity of bacterial community, which further showed the important role that the assemblage of microbial communities might have over their functioning.

Woodland habitat quality prevails over fragmentation for shaping butterfly diversity in deciduous forest remnants

The effects of forest fragmentation on biodiversity can be partitioned into habitat loss and increased isolation of habitat fragments. Habitat quality may however prevail over the effects of fragment area and isolation, especially for mobile animals such as butterflies. To test this hypothesis we surveyed butterfly communities in 36 deciduous forest fragments embedded in a conifer plantation matrix, along two orthogonal gradients of fragment area and isolation. We also sampled eight deciduous riparian forests to compare the complete pool of forest butterflies, expected to be found in riparian forests, to the composition of deciduous fragments. We quantified the effects of deciduous woodland area, isolation and quality on total and forest butterfly richness, community composition and several Community-Weighted Mean traits known to mediate butterfly responses to habitat fragmentation. For the 36 fragments, forest butterfly richness and community composition were not affected by fragment area or isolation but by habitat quality, especially host-plant composition. Riparian forests had higher forest butterfly richness and hosted more habitat specialists, with higher sensitivity to temperature extremes, than deciduous forest remnants. We thus provide new evidence that habitat quality can prevail over fragment area and isolation in shaping the composition of butterfly communities in mosaic landscapes.

Markedly Divergent Tree Assemblage Responses to Tropical Forest Loss and Fragmentation across a Strong Seasonality Gradient.

We examine the effects of forest fragmentation on the structure and composition of tree assemblages within three seasonal and aseasonal forest types of southern Brazil, including evergreen, Araucaria, and deciduous forests. We sampled three southernmost Atlantic Forest landscapes, including the largest continuous forest protected areas within each forest type. Tree assemblages in each forest type were sampled within 10 plots of 0.1 ha in both continuous forests and 10 adjacent forest fragments. All trees within each plot were assigned to trait categories describing their regeneration strategy, vertical stratification, seed-dispersal mode, seed size, and wood density. We detected differences among both forest types and landscape contexts in terms of overall tree species richness, and the density and species richness of different functional groups in terms of regeneration strategy, seed dispersal mode and woody density. Overall, evergreen forest fragments exhibited the largest deviations from continuous forest plots in assemblage structure. Evergreen, Araucaria and deciduous forests diverge in the functional composition of tree floras, particularly in relation to regeneration strategy and stress tolerance. By supporting a more diversified light-demanding and stress-tolerant flora with reduced richness and abundance of shade-tolerant, old-growth species, both deciduous and Araucaria forest tree assemblages are more intrinsically resilient to contemporary human-disturbances, including fragmentation-induced edge effects, in terms of species erosion and functional shifts. We suggest that these intrinsic differences in the direction and magnitude of responses to changes in landscape structure between forest types should guide a wide range of conservation strategies in restoring fragmented tropical forest landscapes worldwide.

Terrestrial mammal diversity in forests close to pineapple crops, Cutris San Carlos, Costa Rica.

Pineapple crops reduce the size of forest fragments and generate pressure on biodiversity in the remnants. To determine potential negative effects of forest fragmentation we assessed diversity and composition of terrestrial mammals in forest patches on three farms under pineapple crops. We placedSherman and Tomahawk traps, footprints traps near water bodies, and made daily tracks to obtain traces and direct observation of mammals. We identified seven species of wild mammals, mostly omnivorous and under a least concern conservation status. The effect of cover type generated by the pineapple crops is consistent with mammal composition. Pineapple crops could enhance the most common wildlife problems, such as predator-prey relationships. Therefore, pineapple plantations, by causing fragmentation and lack of connectivity among forest patches, threaten extinction of mammals in some of their original range.

Tropical Forest Fragmentation Affects Floral Visitors but Not the Structure of Individual-Based Palm-Pollinator Networks

Despite increasing knowledge about the effects of habitat loss on pollinators in natural landscapes, information is very limited regarding the underlying mechanisms of forest fragmentation affecting plant-pollinator interactions in such landscapes. Here, we used a network approach to describe the effects of forest fragmentation on the patterns of interactions involving the understory dominant palm Astrocaryum mexicanum (Arecaceae) and its floral visitors (including both effective and non-effective pollinators) at the individual level in a Mexican tropical rainforest landscape. Specifically, we asked: (i) Does fragment size affect the structure of individual-based plant-pollinator networks? (ii) Does the core of highly interacting visitor species change along the fragmentation size gradient? (iii) Does forest fragment size influence the abundance of effective pollinators of A. mexicanum? We found that fragment size did not affect the topological structure of the individual-based palm-pollinator network. Furthermore, while the composition of peripheral non-effective pollinators changed depending on fragment size, effective core generalist species of pollinators remained stable. We also observed that both abundance and variance of effective pollinators of male and female flowers of A. mexicanum increased with forest fragment size. These findings indicate that the presence of effective pollinators in the core of all forest fragments could keep the network structure stable along the gradient of forest fragmentation. In addition, pollination of A. mexicanum could be more effective in larger fragments, since the greater abundance of pollinators in these fragments may increase the amount of pollen and diversity of pollen donors between flowers of individual plants. Given the prevalence of fragmentation in tropical ecosystems, our results indicate that the current patterns of land use will have consequences on the underlying mechanisms of pollination in remnant forests.

Do leaf‐cutting ants benefit from forest fragmentation? Insights from community and species‐specific responses in a fragmented dry forest

Abstract The expansion of agriculture has led to forest loss and fragmentation, resulting in dramatic biodiversity impoverishment. Surprisingly, few studies have assessed forest fragmentation effects on leaf‐cutting ant assemblages, and none has dealt with effects on their community richness and composition, despite their known role as key herbivores and ecosystem engineers. We analysed forest area and edge effects on leaf‐cutting ant abundance, richness and assemblage composition, by recording and identifying colonies along edge and interior transects in 12 Chaco Serrano forest remnants of different sizes, in Central Argentina. We also explored leaf‐cutting ant presence in the adjacent soybean matrix. We recorded five leaf‐cutting ant species, in the genus Acromyrmex. In the soybean matrix, colonies of three species were observed, which were also found at the forest edge. Within the forest, edges sustained more species and colonies than interior habitats, whereas forest area was linked positively to colony abundance. Taxonomic composition of leaf‐cutting ant assemblages reflected both area and edge effects. Our results revealed overall positive edge and area effects on leaf‐cutting ant communities, highlighting differential species‐specific responses and a possible role for Acromyrmex crassispinus as a forest status indicator. According to our findings, an increase in edge habitats may favour most leaf‐cutting ant species, providing a suitable interface for access to the cultivated matrix, but hindering species associated with undisturbed forest conditions. As leaf‐cutting ants are acknowledged as cornerstones of ecosystem functioning, the consequences of these trends may be far reaching.

Effects of forest fragmentation on the oak–rodent mutualism

Land‐use changes are expected to affect plant–disperser conditional mutualisms through changes in animal behavior. We analyzed the oak–rodent conditional mutualism in Mediterranean fragmented forests at two climatically different locations. We quantified fragmentation effects on seed dispersal effectiveness and assessed if such effects were due to changes in habitat structure and intraspecific competition for acorns in fragmented areas. Fragmentation decreased cover from predators within mouse territories as well as intraspecific competition for acorns. This resulted in lower dispersal effectiveness in small forest fragments. Globally, habitat structure was the main driver in mouse foraging decisions. In small fragments, low shelter availability precluded mouse movements, leading to short mobilization distances and low caching rates. However, as the proportion of cover from predators increased, mice were able to modulate their foraging decisions depending on intraspecific competition for acorns, resulting in higher dispersal quality. In addition to fragmentation effects, delayed breeding in the southern locality caused lower number of rodents during the dispersal season, which reduced acorn mobilization rates. Our study shows that seed dispersal patterns in managed systems can be analyzed as the result of management effects on key environmental factors in dispersers’ foraging decisions.

Edge‐mediated compositional and functional decay of tree assemblages in Amazonian forest islands after 26 years of isolation

Summary Islands formed upstream of mega hydroelectric dams are excellent experimental landscapes to assess the impacts of habitat fragmentation on biodiversity. We examined the effects of plot‐, patch‐ and landscape‐scale variables on the patterns of floristic diversity across 34 forest islands that had experienced 26 years of isolation since the creation of the 4437 km2 Balbina Hydroelectric Reservoir of central Brazilian Amazonia. In addition, three undisturbed continuous forest sites in neighbouring mainland areas were also sampled across a comparable elevational gradient. We identified all live trees ≥10 cm DBH at species level within a total of 87 quarter‐hectare forest plots and conducted a comprehensive compilation of functional attributes of each tree species. We then examined species‐area relationships (SARs) and the additional effects of patch and landscape‐scale metrics on patterns of tree assemblage heterogeneity, both in terms of taxonomic and functional diversity. Despite a clearly positive SAR, edge‐mediated forest disturbance was the single most important driver of species composition and abundance within islands. Our results suggest that non‐random floristic transitions within island plots followed a predictable pattern, with different life‐history traits either penalizing or rewarding local persistence of different functional groups. Distance to edges mediated the probability of tree mortality induced by windfalls and episodic surface fires, clearly resulting in faster species turnover and unidirectional changes in guild structure within small islands where light‐wooded fast‐growing pioneers largely replaced heavy‐wooded species of the old‐growth flora. Synthesis. Following a simultaneous 26‐year post‐isolation history, we disentangle the effects of habitat loss and insularization on tree assemblages within a large set of Amazonian ‘true’ forest islands, of variable sizes, sharing a uniform open‐water matrix. Area effects are expressed via a response to edge effects, with trees in smaller islands being more vulnerable to edge‐related surface fires and wind‐throws. Additionally, forest edge effects can be a powerful driver of non‐random floristic transitions across islands within the Balbina archipelago via a process of rapid pioneer proliferation, drastically affecting both the taxonomic and functional composition of insular tree communities. Finally, our results indicate that detrimental effects of forest fragmentation induced by hydroelectric dams are considerably stronger than those of forest patches embedded within a terrestrial vegetation matrix.

Edge type determines the intensity of forest edge effect on epiphytic communities

Edge effect involves microclimatic variations (light, temperature and humidity) in the forest edge that become unsuitable for organisms adapted to forest interior conditions. We speculate that under similar edge types (shrubland matrix), the pattern in the response to forest edge might be different and more hostile for epiphytes in south-oriented edges. Because different matrix types have different effects on microclimate, we hypothesized that the magnitude of the edge effects will depend on the contrast between the physiognomy of the matrix and the forest fragment. The study was carried out in central Spain and consisted of a beech fragment surrounded by different types of vegetation matrices: pine plantation (south orientation), semi-deciduous oak forest (south orientation) and shrubland (north and south orientations). For each type of edge, we established ten transects perpendicular to the edge, running 100 m into the forest patch. Data were collected from three plots placed at 5, 50 and 100 m from the beginning of each transect. The results revealed that variations in the epiphytic composition mainly showed a replacement of forest interior species with generalist light-demanding species at forest edge. Shrubs-bordered edges showed the strongest influence on epiphytic composition, with high species dissimilarity between edge and forest interior, whereas the edge effects were mitigated when the patch was surrounded by other forests. Besides, in the case of shrub-bordered edge, the dissimilarity of species composition between edge interior was higher in the south than in the north-facing edge. We conclude that the magnitude of the edge effect on epiphytic communities is modulated by the physiognomy of the surrounding matrix and the orientation of the forest edge. In the case of a hard contrast matrix, at least 100 m of an edge buffer are required for the conservation of the species with high humidity requirements. Therefore, one of the main problems affecting the loss and even disappearance of shaded species is the decreasing of the amount of core conditions under the increasing forest fragmentation scenarios. This potentially exacerbates forest fragmentation effects linked to livestock use, due to the physiognomically different surrounding matrix compared to forest patches.

Effects of Forest Fragmentation on Genetic Diversity of the Critically Endangered Primate, the Pied Tamarin (Saguinus bicolor): Implications for Conservation.

We analyzed DNA at 9 microsatellite loci from hair samples of 73 pied tamarins (Saguinus bicolor) located in 3 urban forest fragments and a biological reserve in the city of Manaus, Amazonas, Brazil. The forest fragments had become isolated from the continuous forest 6-15 years prior to the time of sampling. Tests for reduction in population size showed that all groups from the urban forest fragments had undergone genetic bottlenecks. Pied tamarins in this region historically formed one biological population, and the fragments were connected by high levels of gene flow. These results indicate the need to implement a conservation plan that allows for connectivity between the urban fragments, as well as protection from further constriction. Such connectivity could be achieved via the creation and protection of corridors. In addition to the current population trends explained by anthropogenic actions, the species also shows a trend of long-term demographic decline that has resulted in approximately an order of magnitude decrease and began 13 thousand years ago.

Effects of forest fragmentation on the mating system of a cool-temperate heterodichogamous tree Acer mono

Pollination is a key process for reproduction and gene flow in flowering plants. Anthropogenic habitat fragmentation, however, can disrupt plant–pollinator interactions, and may have a negative impact on the reproductive success and population viability of entomophilous plants. Heterodichogamous plants containing protandrous and protogynous individuals within a population may be susceptible to habitat fragmentation due to a lack of available mating partners. In this study, we investigated the effects of forest fragmentation on the mating system in the heterodichogamous plant Acer mono, a major constituent of cool-temperate deciduous forests in Japan. Microsatellite analysis was applied to 212 adult trees and 17 seed families from continuous and fragmented forests. Dispersal kernel modeling using the neighborhood model indicated that pollen dispersal of A. mono was highly fat-tailed. The estimated parameters of the model suggested that the siring success of a pollen donor increased approximately fivefold, with a 100 cm increase in its diameter at breast height (DBH), and that disassortative mating was five times more frequent than assortative mating. The mating system parameters of each mother tree, outcrossing rate (tm), biparental inbreeding (tm−ts), and paternity correlation (rpm) varied among sites and conditions, depending on the local density of potential pollen donors. Whereas A. mono was effectively outcrossed (tm=0.901, tm−ts=0.052, and the number of effective sires was 1/rpm=14.93) in the continuous forest, clumped trees within the fragmented forest showed increased biparental inbreeding and reduced pollen pool genetic diversity (tm=0.959, tm−ts=0.245,1/rpm=1.742) as a result of localized mating combined with spatial genetic structures. In contrast, the isolated trees had a higher selfing rate, but the pollen pool diversity was maintained (tm=0.801, tm−ts=0.022, and 1/rpm=15.63) due to frequent long-distance pollination. These results suggest that although pollen limitation following habitat fragmentation could result in negative genetic consequences, enhanced long-distance pollination across a fragmented landscape could partly compensate for this limitation depending on the degree of forest fragmentation.

Forest fragmentation in an African biodiversity hotspot impacts mixed-species bird flocks

The effect of forest fragmentation on mixed-species foraging bird flocks has been poorly evaluated, particularly in African forests. We examined the consequences of forest fragmentation on such flocks in the East Usambara Mountains, Tanzania, by addressing ecological as well as behavioral components. We counted these flocks in five small (<31ha), isolated fragments and six widely spaced continuous forest sites. Given that flock cohesion and stability might be facilitated via positive interactions of leader or nuclear species, we focused on one putative nuclear species, the square-tailed drongo (Dicrurus ludwigii), and using playback of its vocalisations, we evaluated (i) if its vocalisations attracted flocking birds as expected by a nuclear species, and (ii) if loss of this species in fragments contributed to flock declines. We found that flocks in forest fragments had smaller sizes, reduced species richness, a reduced proportion of understorey specialists, a higher proportion of forest generalists and non-forest species, and were more variable in size and composition compared to flocks observed in continuous forest. Furthermore, flocks in fragments were composed of a higher proportion of omnivores than insectivores. Despite lower absolute abundance in fragments, D. ludwigii was observed in 86% of natural occurring flocks in both fragments and continuous forest, and flocks with D. ludwigii were significantly larger than those without it––especially in the continuous forest. Playback vocalisations of D. ludwigii attracted flocks of similar abundance and species richness in fragments and continuous forest, but a vastly different composition, confirming (i) its nuclear role and (ii) that, in fragments, flock assemblages had a distinct composition, with a high proportion of forest generalists and non-forest species. Loss or diminished abundance of nuclear species due to fragmentation may be an important factor that affects the presence and composition of mixed-species flocks. Given that 67% of flocking species forage in the understorey, and that insectivores were more negatively affected in fragments than omnivores, the implications of our findings are relevant for conservation in tropical forests.

Not all in the same boat: trends and mechanisms in herbivory responses to forest fragmentation differ among insect guilds

Habitat fragmentation can alter fundamental ecological interactions such as insect herbivory. Few studies of habitat fragmentation effects on herbivory have examined the mechanisms involved, and differences among insect guilds have been largely ignored. Here, we studied area and edge effects on herbivory by three guilds of phytophagous insects in a fragmented Chaco Serrano forest. We estimated herbivory levels on native Croton lachnostachyus plants and assessed plant availability (distance to nearest conspecific) and quality indicators (leaf water, carbon and nitrogen content), as well as richness and abundance of the associated insect community, in order to explore mechanisms underlying herbivory changes. Herbivory by chewing and sap-sucking insects decreased, and herbivory by leaf miners increased in plants growing at the forest edge, compared with those at the interior. Forest area effects were detected only in interaction with edge effects on chewing, leaf mining and total herbivory. Lower herbivory at the edge appeared to be mediated by changes in leaf water and nitrogen content for sap-sucking herbivory, and linked to strong direct effects for chewing damage and total herbivory. Instead, higher damage levels by leaf miners at the forest edge seemed to be driven by increased plant availability and lower water content. Further studies are needed to unravel the factors involved in the strong direct effects detected here for all herbivory types. These results emphasize the necessity to consider differential responses from diverse phytophagous insect guilds, and factors operating at multiple levels, in order to disentangle, and ultimately understand, forest fragmentation effects on herbivory.

Apparent environmental synergism drives the dynamics of Amazonian forest fragments

Many contemporary ecosystems are likely to be affected by multiple environmental drivers, complicating efforts to predict future changes in those ecosystems. We studied long‐term changes (1980–2012) in forest dynamics and liana (woody vine) abundance and biomass in fragmented and intact forests of the central Amazon. We did so by contrasting trends in 33 permanent 1‐ha plots near forest edges (plot center &lt;100 m from the nearest edge) with those in 36 1‐ha plots in intact‐forest interiors (150–3300 m from nearest edge). In fragmented and edge‐affected forests, rates of tree (≥10 cm diameter at breast height) mortality and recruitment were often sharply elevated, especially in the first 10–15 years after fragmentation. Lianas (≥2 cm stem diameter) also increased markedly in abundance (mean ± SD = 1.78 ± 1.23% per yr) and biomass (1.30 ± 1.39% per yr) over time, especially in plots with high edge‐related tree mortality. However, plots in undisturbed forest interiors, which were originally established as experimental controls, also experienced long‐term changes. In these plots, tree mortality and recruitment rose significantly over time, as did liana abundance (1.00 ± 0.88% per yr) and biomass (0.32 ± 1.37% per yr). These changes were smaller in magnitude than those in fragments but were nonetheless concerted in nature and highly statistically significant. The causes of these changes in forest interiors are unknown, but are broadly consistent with those expected from rising atmospheric CO2 or regional climate drivers that influence forest dynamics. Hence, the dynamics of Amazonian forest fragments cannot be understood simply as a consequence of forest fragmentation. Rather, the changes we observed appear to arise from an interaction of fragmentation with one or more global‐ or regional‐scale drivers affecting forest dynamics. Both sets of phenomena are evidently increasing forest dynamics and liana abundances in fragmented forests, changes that could reduce carbon storage and alter many aspects of forest ecology.

Effects of Population Size, Forest Fragmentation, and Urbanization on Seed Production and Gene Flow in an Endangered Maple (Acer miyabei)

Forest fragmentation threatens the reproduction of tree species, for which habitats overlap with urban and rural areas. An endangered maple, Acer miyabei f. miyabei, is such a species in northern Japan. We examined the effects of forest fragmentation on seed production and mate diversity and assessed gene flow within and between fragmented forests. We measured the density, viability, and kinship of seeds dispersed around 82 target trees in 21 fragmented forests in rural and urban areas. The dispersed seed density decreased as the size of the target trees and the number of adult trees in each forest decreased. The viable seed proportion also decreased as the number of adult trees in each forest decreased. We did not find any effects on the kinship co-efficient among seeds dispersed around each target tree. The regression line of the pairwise kinship co-efficient of the seeds against the distance had a higher intercept and a more gently declining slope between the forests than within the forests, indicating forest fragmentation altered gene flow patterns. The results suggest reduced seed production due to pollen limitation and changes in the genetic structure of regenerating populations of A. miyabei in fragmented forests.

Area and edge effects on leaf-litter decomposition in a fragmented subtropical dry forest

South American subtropical dry forests are highly threatened by fragmentation. Despite considerable research efforts aimed at predicting ecosystem alterations due to this driver of global change, we still need to deal with general principles to improve our ability to predict the impact of fragmentation. Our work is one of the few studies that analyse the relationship between forest fragmentation and decomposition. In 12 remnants of Chaco Serrano forest in Central Argentina we tested if decomposition rates of a common leaf-litter substrate varied with fragment size and between the forest edge and interior. Decomposition declined with fragment size, with no significant effects of location (edge/interior) or interaction between the two components of fragmentation. Our results suggest that in situ conditions for decomposition may change as a consequence of forest fragmentation, specifically as a result fragment size. This may lead to impaired nutrient recycling in smaller forest remnants.

Interspecific effects of forest fragmentation on bats

Wind-farm development may be an important contributor to forest fragmentation, but how such developments impact bats is poorly understood. We hypothesized that bat activity at a wind farm would be explained, at least in part, by attraction and avoidance behaviours caused by deforestation. We tested predictions of this hypothesis via a landscape-level acoustic, capture, and radiotelemetry survey of little brown bats (Myotis lucifugus (Le Conte, 1831)) and northern long-eared myotis (Myotis septentrionalis (Trouessart, 1897)). Acoustic and capture data indicated no significant difference in magnitude of activity between the fragmented wind farm and the less-fragmented surrounding areas. However, only 2 of 19 radio-tracked bats were ever located inside the wind farm despite being captured adjacent to it. Bat locations were compared against randomly generated locations within the same area in a logistic regression framework to rank landscape variables in order of association with bats. A multicriteria evaluation of forest metrics showed that, over a 3-year period, there was an increase of suitable habitat inside the wind farm for M. lucifugus and a decrease for M. septentrionalis. These results support the contention that, at this level of disturbance, M. lucifugus may use the cleared areas, while M. septentrionalis is negatively impacted by increased deforestation caused by wind-farm development.

Efficiency of small mammal trapping in an Atlantic Forest fragmented landscape: the effects of trap type and position, seasonality and habitat.

Trapping methods can strongly influence the sampling of mammal communities. This study compared the efficiency of the capture of small mammals in Sherman traps in two positions (at ground level and in trees) and pitfall traps in a fragmented landscape. Trapping sessions were carried out between October 2008 and October 2009 at two fragments (8 and 17 ha), an agroforest corridor between them, and the adjacent pasture. A total effort of 4622 trap-nights resulted in 155 captures of 137 individuals from six species. Pitfalls had greater success (4.03%), followed by Shermans on the ground (2.98%) and on trees (2.37%; χ2 = 6.50, p = 0.04). Five species were caught in Sherman ground traps, four in pitfalls and just two on trees. There was no difference among trap types for marsupials (χ2 = 4.75; p = 0.09), while for rodents, pitfalls were more efficient than Shermans on the ground (Fisher's exact test, p = 0.02). As a result, the efficiency of each trap type differed among habitats, due to differences in their species composition. Pitfalls were more efficient in the rainy season (Fisher's exact test, p <0.0001) while Shermans on trees were more efficient in the dry season (Fisher's exact test, p = 0.009). There was no difference between seasons for Shermans on the ground (Fisher's exact test, p = 0.76). Considering the results found, we recommend that future studies of forest mammal communities, particularly those designed to test the effects of forest fragmentation, include combinations of different trap types.

Habitat fragmentation, tree diversity, and plant invasion interact to structure forest caterpillar communities.

Habitat fragmentation and invasive species are two of the most prominent threats to terrestrial ecosystems. Few studies have examined how these factors interact to influence the diversity of natural communities, particularly primary consumers. Here, we examined the effects of forest fragmentation and invasion of exotic honeysuckle (Lonicera maackii, Caprifoliaceae) on the abundance and diversity of the dominant forest herbivores: woody plant-feeding Lepidoptera. We systematically surveyed understory caterpillars along transects in 19 forest fragments over multiple years in southwestern Ohio and evaluated how fragment area, isolation, tree diversity, invasion by honeysuckle and interactions among these factors influence species richness, diversity and abundance. We found strong seasonal variation in caterpillar communities, which responded differently to fragmentation and invasion. Abundance and richness increased with fragment area, but these effects were mitigated by high levels of honeysuckle, tree diversity, landscape forest cover, and large recent changes in area. Honeysuckle infestation was generally associated with decreased caterpillar abundance and diversity, but these effects were strongly dependent on other fragment traits. Effects of honeysuckle on abundance were moderated when fragment area, landscape forest cover and tree diversity were high. In contrast, negative effects of honeysuckle invasion on caterpillar diversity were most pronounced in fragments with high tree diversity and large recent increases in area. Our results illustrate the complex interdependencies of habitat fragmentation, plant diversity and plant invasion in their effects on primary consumers and emphasize the need to consider these processes in concert to understand the consequences of anthropogenic habitat change for biodiversity.