Habitat structure and proximity to forest edge affect the abundance and distribution of forest-dependent birds in tropical coastal forests of southeastern Madagascar

Despite the fact that Madagascar is classified a biological `hotspot' due to having both high levels of species endemism and high forest loss, there has been no published research on how Madagascan bird species respond to the creation of a forest edge or to degradation of their habitat. In this study, we examined how forest bird communities and different foraging guilds were affected by patch habitat quality and landscape context (forest core, forest edge and matrix habitat) in the threatened littoral forests of coastal southeastern Madagascar. We quantified habitat use and community composition of birds by conducting 20 point counts in each landscape contextual element in October and November 2002. We found that littoral forest core habitats had significantly (p<0.01) more bird species than forest edge and matrix habitats. Thirty-one (68%) forest dependent species were found to be edge-sensitive. Forest edge sites had fewer species, and a higher representation of common species than forest interior sites. Twenty-nine species were found in the matrix habitat, and the majority of matrix-tolerant forest species had their greatest abundance within littoral forest edge habitats. Guild composition also changed with landscape context. Unlike other tropical studies with which we are familiar, we found that frugivorous species were edge-sensitive while sallying insectivores were edge-preferring. The majority of canopy insectivores (n=15, 88%), including all six endemic vanga species, were edge-sensitive. When habitat quality was assessed, the distributions of nine edge-sensitive species were significantly (p<0.01) affected by changes in habitat complexity and vegetation vertical structure in core or edge point counts. Therefore, we believe that changes in vegetation structure at the edge of littoral forest remnants may be a key indicator of mechanisms involved in edge sensitivity of forest dependent species in these forests. Our findings indicate that habitat fragmentation and degradation affect Madagascan bird communities and that these processes threaten many species. With continued deforestation and habitat degradation in Madagascar, we predict the further decline of many bird species.     

Are habitat-tracking metacommunities dispersal limited? Inferences from abundance-occupancy patterns of epiphylls in Amazonian forest fragments

In theory, habitat fragmentation alters plant community dynamics by influencing both local (within patch) and regional (among patch) processes. However, the lengthy generation times of plant taxa relative to the short duration of most experiments has precluded studies from assessing the impact of fragmentation at both local and regional scales. Due to their accelerated life cycles, high rates of local extinction, and naturally patchy substrates, epiphyllous bryophyte assemblages are an appropriate plant guild for empirically testing metacommunity-based predictions associated with habitat fragmentation. By examining the local abundance and regional distribution patterns of 67 epiphyllous (leaf-inhabiting) bryophyte species in an experimentally fragmented landscape in Amazonia, we demonstrate that changes in local abundance wrought by habitat fragmentation are best explained by fragment size rather than proximity to forest edge. Furthermore, evidence of a simultaneous inter-specific decline in epiphyll local abundance and regional distribution in small (1- and 10-ha) forest fragments corroborate with metapopulation-based predictions highlighting the importance of immigration in buffering from patch extinction risk (i.e., the rescue effect). Collectively, these results provide indirect evidence that dispersal limitation, rather than compromised habitat quality attributable to edge effects, likely account for species loss from small tropical forest fragments. Whether dispersal limitation is due to increased insularity from regional sources for epiphyll recolonization or rather to lowered within-fragment dispersal potential is unknown; nonetheless, the long-term persistence of these microscopic plant metacommunities depends on the preservation of rain forest reserves of at least 100-ha in size.     

Dissecting habitat loss and fragmentation effects following logging in boreal forest: Conservation perspectives from landscape simulations

Habitat loss and fragmentation are recognized as major threats to biodiversity. Their respective effects, however, are sometimes not well distinguished, even though habitat loss is recognized as the most important source of variation affecting species abundance and richness at the landscape scale. As ‘habitat’ is a species-specific concept (based on species perception of its environment), habitat loss and fragmentation studies should be conducted on a species-specific basis. We here assessed the influence of habitat loss and fragmentation in the context of a boreal forest considering forest clearcutting as an anthropogenic disturbance inducing mature forest loss and fragmentation that has a potential impact on wildlife. Using 16 simulated patterns of mature forest loss and fragmentation and three natural landscapes as replicates, we assessed the respective influence of forest loss and fragmentation on the abundance of 10 bird species common in the boreal forest of eastern Canada. Species–habitat relationships were modeled through habitat use models that were utilized to predict abundance of the 10 species within each combination of loss and fragmentation patterns (3 landscapes × 16 patterns). We used three-way ANOVAs to assess the effects of mature forest loss, fragmentation and replicates (random effect) on species abundance. Our results indicated that: (1) variation in species abundance mostly depended on mature forest loss, followed by static landscape attributes other than cutovers (e.g. streams, lakes, roads) and finally by fragmentation and (2) responses to mature forest loss and fragmentation differed among species, not necessary in relation to the successional status but in relation to their perception of their environment. Decreasing detrimental effects of mature forest loss through conservation of large continuous patches of forest may be suitable to maintain abundances of mature forest bird species. Our results highlight that studies aiming to quantify effects of habitat loss and fragmentation on wildlife should be conducted on a species-specific basis and use several landscape replicates to avoid potentially biased results.     

Landscape supplementation in adjacent savannas and its implications for the design of corridors for forest birds in the central Cerrado, Brazil

We examined landscape supplementation (sensu [Oikos 65 (1992) 169]) by forest birds along forest/savanna boundaries in central Brazil to: (1) verify the role of savanna vegetation in providing resources to forest bird communities; (2) suggest minimum amounts of savannas to be conserved within corridors, to provide adequate foraging habitat for forest birds outside reserves. Transect counts parallel (n=64) and perpendicular (n=64) to forests were conducted in eight savannas (cerrado sensu stricto) between February 2000 and January 2001. Patterns of species richness and abundance of birds in relation to distances from forests were examined using Generalised Linear Mixed Models. Omnivores were the most abundant birds foraging in savannas, followed by insectivores and frugivores. Landscape supplementation in savannas was proportional to the density of savanna vegetation. Also, it was higher in the breeding season than in the non-breeding period. These two patterns suggest that surrounding savannas play a major role in providing additional foraging areas for forest bird species. We suggest that the environmental policy currently protecting 20 m of gallery forests along each side of rivers be modified to include at least 60 m of savanna along these forests through central Brazil. The study suggests that appropriate conservation efforts should also encompass the surrounding matrix to which the home ranges of target species are expanded, and not only their major habitat.     

Effects of land management on the abundance and richness of spiders (Araneae): A meta-analysis

Human land use, through forest management and conversion of natural habitats into agroecosystems, has often resulted in loss of biodiversity. Spiders are important predators in terrestrial ecosystems, biological control agents against pests in agroecosystems and forests, and useful indicators due to their sensibility to changes in habitat structure and microclimate. Effects of land use on spiders have been reviewed several times but existing reviews are narrative and usually focused on one single kind of management. We summarize the impacts of land use on spider abundance and species richness using meta-analysis. The main ecosystems where the effect of management on spiders has been studied were forests, agroecosystems and rangelands (including meadows and grasslands). Although our survey retrieved studies from all parts of the world and climatic zones, a dominance of studies from temperate habitats in Europe and North America was evident. The meta-analysis showed negative effects on spider species richness and abundance for agroecosystems and rangelands, but were less evident for forests. From 10 kinds of land management identified, all but forest plantation showed effects on spider richness or abundance. These land management scenarios affected either species richness (forest fragmentation and logging, farmland abandonment, and miscellaneous management including plowing, cutting and fire), or spider abundance (forest fragmentation, forest fire, conventional farming, insecticides, grazing, and farmland abandonment), but not both. Edge effects had contrasting effects depending on the ecosystem, affecting spider species richness in agroecosystems and abundance in rangelands and forests. Direct destruction of spiders or negative effects on habitat heterogeneity or prey populations were the most likely causes of the negative effects detected.     

Factors maintaining species diversity in satoyama, a traditional agricultural landscape of Japan

Satoyama is a traditional agricultural landscape in Japan. It contains many kinds of organisms, including endangered species. Satoyama is composed of several habitat types, including paddy fields, secondary forests, secondary grasslands, ponds, and streams. High species richness has been sustained in most habitats by anthropogenic disturbances of intermediate impact, mainly activities related to agriculture. The variety of habitats and connectivity among them have contributed to the high species diversity within satoyama. These factors allow organisms to move among habitats and use different habitat types to obtain different resources. The connectivity among habitats is often more vulnerable than the specific habitats themselves under anthropogenic influences. In satoyama, species that require connectivity among habitats (e.g., grey-faced buzzard [Butastur indicus] and Genji firefly [Luciola cruciata]) have tended to decrease. The grey-faced buzzard is categorized as a “vulnerable” species in the Japanese Red List. It usually nests in forest trees and forages in habitats such as paddy fields, grasslands, and forests. Its foraging locations shift seasonally depending on food availability. It is thought that the degradation of either paddy fields or forests in a landscape may result in the disappearance of this species. The Genji firefly spends its larval period in stream water, pupates underground along streams, and flies near streams after emergence. This species requires not only the integrity of streams and nearby areas, but also connectivity between these areas. The ecology of these species suggests that the variety of habitats and connectivity among them are critical factors for their survival.     

Land use and habitat gradients determine bird community diversity and abundance in suburban, rural and reserve landscapes of Minnesota, USA

Bird species’ community responses to land use in the suburbanizing Twin Cities, Minnesota, USA, were contrasted among reserves, rural lands, and suburbs. For each land use type, bird composition, diversity, and abundance were recorded for 2 years in ≈99 plots in three sampling units (each ≈4500 ha). A habitat gradient defined by canopy structure (grasslands to savannas to forests) was influenced by land use, so ≈300 plots were used to characterize simultaneous variation in bird communities along land use and habitat gradients. At broad scales (aggregate of 33 plots covering ≈4500 ha) suburbs supported the lowest bird richness and diversity and rural landscapes the most, with reserves slightly below rural. Although reserves were like rural lands in diversity of bird communities, they supported more species of conservation concern, particularly of grasslands and savannas. Differences among land use types varied with habitat structure. Suburbs, rural lands, and reserves had similar forest bird communities, but differed in grassland and savanna bird communities. The extensive rural forests are important for the region’s forest birds. Suburban grasslands and savannas had low shrub abundance, low native bird richness and high non-native bird richness and abundance. However, total bird richness and diversity were as high in suburban as in rural and reserve plots because high native richness in suburban forests and high non-native species richness in suburban grasslands and savannas compensated for lower native richness in suburban grasslands and savannas. Bird conservation here and in the Midwest USA should protect rural forests, expand grasslands and savannas in reserves, and improve habitat quality overall.     

Species occurrences at stand level cannot be understood without considering the landscape context: Cyanolichens on aspen in boreal Sweden

A major challenge in conservation biology is to understand species’ responses to habitat loss. In Fennoscandia, the ongoing decline in aspen in forests is of particular concern, since aspen is the boreal forest tree species that supports the most host-specific species of cryptogams and invertebrates. In order to predict the potential effects of aspen decline we compared the occurrence of three epiphytic cyanolichens in old-growth stands of the same habitat quality, in four aspen-rich and four aspen-poor landscapes. Collemacurtisporum and Collemafurfuraceum were, on average, five and six times more frequent, respectively, in the aspen-rich than in the aspen-poor landscapes. Leptogiumsaturninum was not affected by the abundance of aspen stands at the landscape level. Our data suggests that lichen species with poor dispersal abilities may be more sensitive to habitat loss than more easily dispersed species and that species with broader habitat amplitude may be less sensitive to habitat loss than more specialized species, even if they have inferior dispersal ability. We conclude that (i) predictions of species occurrences at the stand level have to take account of the amount of suitable habitat at the landscape level, and (ii) predicting the responses of individual species based on life-history traits can be crucial, but cannot be based on single traits. Thus our study shows that biological value cannot be assessed on the basis of habitat quality alone and that a landscape perspective is needed for the sustainable management of specialist species.     

Bird species abundance–occupancy patterns and sensitivity to forest fragmentation: Implications for conservation in the Brazilian Atlantic forest

Developing a predictive theory for species responses to habitat fragmentation is a large, complex challenge in conservation biology, and meeting this challenge likely requires tailoring predictions to specific habitats and taxa. We evaluate the effects of fragmentation on forest birds living in three distinct forest ecosystems found in Brazilian Atlantic forest: seasonal semi-deciduous forest (SF), mixed rain forest (MF), and dense rain forest (DF). We test the hypotheses that (1) bird species most prevalent in SF (relative to other habitat types) will be least vulnerable to population declines in fragmented SF, and (2) species with stronger affiliations with DF or MF will be relatively more sensitive to fragmentation in SF. Using an exploratory statistical technique called “Rank Occupancy–Abundance Profiles (ROAPs),” we compared distribution and abundance of birds among large “continuous” areas of each forest type, then compared abundances in continuous SF forests with patterns of abundance in small fragments of SF, where edge effects could play a marked role in population dynamics. Overall, 39 species showed substantially lower local abundance, occupancy, or both in SF fragments versus continuous SF. As predicted, a higher proportion of bird species associated with DF appeared sensitive to fragmentation in SF; by contrast, species most abundant in SF and MF were similarly abundant in fragmented SF. Our study demonstrates how quantifying distribution and abundance in diverse habitats may enhance managers’ ability to incorporate species-specific responses to human disturbances in their conservation plans, and points out ways that even small reserves may have significant conservation value.     

‘Ecological forestry’ and eucalypt forests managed for wood production in south-western Australia

The model of ‘ecological forestry’ has evolved as a part of the development of the concept of ecosystem management. ‘Ecological forestry’ emphasises that manipulation of a forest ecosystem should consider, and as far as practicable work within the limits of, natural disturbance patterns prior to extensive human alteration of the landscape. This paper evaluates the extent to which forest management practices in jarrah (Eucalyptus marginata) and karri (Eucalyptus diversicolor) forests of south-western Australia align with this view of the characteristics and appropriate silviculture of ‘ecological forestry’. Characteristics and appropriate silviculture of ‘ecological forestry’ are evaluated in relation to (i) the stand level decisions of stand structure and harvest timing and (ii) the landscape level decisions of harvest levels and age structures, and spatial patterns of harvest. Forest management in south-western Australia is found to align with appropriate silviculture under this model of ‘ecological forestry’. Additionally, the landscape triad of areas managed to ‘ecological forestry’ principles, conservation reserves and areas managed to production forestry is in place in the south-western forests of Australia. Strengths and weaknesses in the model of ‘ecological forestry’ and the ability to interpret consistency of practices in the forests of south-western Australia with the characteristics of ‘ecological forestry’ are identified.     

Landscape patterns influencing bird assemblages in a fragmented neotropical cloud forest

The cloud forest is one of the rarest and most threatened ecosystems in Mexico, although it contributes highly to the country's biological diversity and provides important ecological services. It is a naturally fragmented ecosystem, but anthropogenic deforestation and fragmentation has been severe. Consequently, it is essential to identify landscape patterns critical for the conservation of cloud forest. In order to understand how landscape patterns affect diversity in this ecosystem, this study explores the consequences of cloud forest fragmentation on bird diversity in eastern Mexico. I analysed the response of bird species richness and abundance as a function of forest fragment size, shape, topographical complexity, altitudinal range, connectivity, and proportion of landscape forested area in a system of 13 cloud forest fragments. Fragment shape was the main characteristic positively related to species richness in the bird community, but a differential response to landscape patterns was also detected. Fragment size was the main characteristic influencing the segment of the bird community depending mostly on forest, that is to say, forest interior and generalist species. In contrast, the extent of forest edge, expressed as fragment shape, produced a positive response of forest border species. Both, forest dependent and border dependent species positively responded to the extent of their suitable habitat. The immediate and most effective ecologically oriented conservation strategy for the region is the conservation of the largest cloud forest fragments.     

The importance of forest area and configuration relative to local habitat factors for conserving forest mammals: A case study of koalas in Queensland, Australia

The loss and fragmentation of forest habitats by human land use are recognised as important factors influencing the decline of forest-dependent fauna. Mammal species that are dependent upon forest habitats are particularly sensitive to habitat loss and fragmentation because they have highly specific habitat requirements, and in many cases have limited ability to move through and utilise the land use matrix. We addressed this problem using a case study of the koala (Phascolarctos cinereus) surveyed in a fragmented rural-urban landscape in southeast Queensland, Australia. We applied a logistic modelling and hierarchical partitioning analysis to determine the importance of forest area and its configuration relative to site (local) and patch-level habitat variables. After taking into account spatial autocorrelation and the year of survey, we found koala occurrence increased with the area of all forest habitats, habitat patch size and the proportion of primary Eucalyptus tree species; and decreased with mean nearest neighbour distance between forest patches, the density of forest patches, and the density of sealed roads. The difference between the effect of habitat area and configuration was not as strong as theory predicts, with the configuration of remnant forest becoming increasingly important as the area of forest habitat declines. We conclude that the area of forest, its configuration across the landscape, as well as the land use matrix, are important determinants of koala occurrence, and that habitat configuration should not be overlooked in the conservation of forest-dependent mammals, such as the koala. We highlight the implications of these findings for koala conservation.     

Priority areas for the conservation of Atlantic forest large mammals

Large mammal faunas in tropical forest landscapes are widely affected by habitat fragmentation and hunting, yet the environmental determinants of their patterns of abundance remain poorly understood at large spatial scales. We analysed population abundance and biomass of 31 species of medium to large-bodied mammal species at 38 Atlantic forest sites (including three islands, 26 forest fragments and six continuous forest sites) as related to forest type, level of hunting pressure and forest fragment size using ANCOVAs. We also derived a novel measure of mammal conservation importance for each site based on a “Mammalian Conservation Priority index” (MP_i) which incorporates information on species richness, population abundance, body size distribution, conservation status, and forest patch area. Mammal abundance was affected by hunting pressure, whereas mammalian biomass of which was largely driven by ungulates, was significantly influenced by both forest type and hunting pressure. The MP_i index, when separated into its two main components (i.e. site forest area and species-based conservation index C_i), ordered sites along a gradient of management priorities that balances species-focused and habitat-focused conservation actions. Areas with the highest conservation priority were located in semi-deciduous forest fragments, followed by lowland forests. Many of these fragments, which are often embedded within large private landholdings including biofuel and citrus or coffee crops, cattle ranches and pulpwood plantations, could be used not only to comply with environmental legislation, but also enhance the prospects for biodiversity conservation, and reduce edge effects and hunting.     

Landscape and habitat factors affecting cabot's tragopan Tragopan caboti occurrence in habitat fragments.

Cabot's tragopan Tragopan caboti is an endemic and endangered pheasant of the lower montane forests of southeastern China. The typical habitats of the tragopan have been seriously fragmented because of forest management for timber production and farmland reclamation in recent years. The effects of the fragment size and isolation on the distribution of the cabot's tragopan were studied in Wuyanling Natural Reserve. Thirty one habitat fragments (2.5-48.5 ha) surrounded by non-habitat sapling coniferous forests, in an intensively managed forested landscape, were surveyed over four seasons for the occurrence of cabot's tragopan. Five of the 31 fragments were occupied in all four seasons and nine were not occupied. Both landscape and habitat factors affected the occurrence of cabot's tragopan, with landscape factors having the greatest effect. Large and less isolated habitat fragments containing a larger amount of the tree Daphniphyllum macropodum were occupied significantly more often than small, isolated fragments. The appearance of cabot's tragopan in the habitat fragments was best explained by the size of the fragments, the distance to the nearest suitable habitat and the amount of macropdous daphniphyllum trees. Our results could be used to improve the management of the forests where Cabot's tragopan occurs in southeastern China.     

Anthropogenic determinants of primate and carnivore local extinctions in a fragmented forest landscape of southern Amazonia

Habitat fragmentation has been shown to influence the abundance, movements and persistence of many species. Here, we examine the effects of forest patch and landscape metrics, and levels of forest disturbance on the patterns of local extinction of five primate and 14 carnivore species within 129 forest patches in a highly fragmented forest landscape of southern Brazilian Amazonia. Classic habitat area effects were the strongest predictors of species persistence, explaining between 42% and 55% of the overall variation in primate and carnivore species richness. Logistic regression models showed that anthropogenic disturbance, including surface wildfires, timber extraction and hunting pressure, had detrimental effects on the persistence of some species over and above those of fragment size. Different species ranged in their responses from highly sensitive to highly tolerant to forest fragmentation. Patterns of local extinction documented here were by no means chance events, and the nestedness of the overall species-by-site matrix was highly nonrandom in terms of the sets of species extirpated from the most to the least species-rich forest patches.     

Does time or habitat make old-growth forests species rich? Bryophyte richness in boreal Picea mariana forests

The relative importance of time since disturbance and habitat variables in creating diversity in old-growth forests will influence conservation strategies. However, the independent roles of these factors are not well understood, as they are rarely examined independently. This study examines the respective roles of habitat variables and time (stand age) in determining bryophyte diversity in Picea mariana (Mill. (BSP)) forests. Bryophytes are frequently used as indicators of old-growth forest, but their true dependence on forest continuity is unknown. Bryophytes were classified into taxonomic-habitat guilds: true mosses (forest), forest liverworts, bog liverworts and sphagna (bog). Diversity increased with age and peaked at approximately 275 years since fire, driven by liverworts. Multiplicative habitat modeling indicated that time and habitat played different roles for the different taxonomic-habitat guilds. True mosses and forest liverworts were primarily influenced by habitat variables, while sphagna and bog liverworts were influenced by time and habitat variables. The models for sphagna were particularly strong, indicating that many important factors were included, while forest liverwort models were particularly weak. This unexplained variability may represent site specific random factors, such as secondary disturbances that create habitat in a fully occupied space. Overall, high richness was created by small species dependent on habitat variables and chance factors for establishment. Therefore, time since disturbance was not the primary factor limiting richness in these forests. These results suggest that in boreal North America, where forest fragmentation is limited and recent, conservation strategies that emphasize habitat variables rather than forest continuity may be effective for some bryophytes.     

Use of landscape metrics to predict avian nest survival in a fragmented midwestern forest landscape

Habitat fragmentation fundamentally affects trophic interactions and ecosystem function. Understanding how the landscape matrix modulates such interactions can improve our understanding of fragmentation ecology. Studies of breeding birds provide clear examples of the consequences of habitat fragmentation, but the landscape context of these effects are unclear. We sampled avian nesting success in 12 moderately-large forest patches (>250 ha) embedded in different types of landscapes in southern Illinois, USA. We then evaluated eight models that predicted the probability of nest success and brood parasitism by Brown-headed Cowbirds. These models incorporated landscape composition (% grassland, % agriculture, fragmentation), year and seasonal effects, conspecific density, predator density, and combinations of these variables. Temporal factors (stage of nesting cycle, seasonal effects, annual variation) had the most effect on nesting success; landscape factors had little influence on nesting success. The rate and intensity of brood parasitism were significantly influenced by the amount of grassland for the Wood Thrush, but not for the Acadian Flycatcher. Fine-scale management of the matrix surrounding the patches may dictate the local abundance and movements of nest predators and parasites. Other major nest predators may prefer the forest interior and at least partially compensate for the lower abundance of nest predators that depend upon the matrix. Overall, landscape metrics were weak predictors of avian nesting success in complex landscapes that have diverse predator communities.     

Sex matters: Modeling male and female habitat differences for jaguar conservation

Competition for mates, cub rearing, and other behaviors differ between males and females in large carnivores. Although these differences can be reflected in patterns of habitat use, gender has rarely been incorporated into habitat models. We evaluated differences in habitat use between male and female jaguars in the Mayan Forest of the Yucatan Peninsula by modeling occupancy as a function of land cover type, distance to roads, and sex. Nested models were fitted to high-spatiotemporal resolution satellite (GPS) telemetry, controlled for temporal autocorrelation, and eliminated selection bias of pseudo-absences using a semi-non-parametric bootstrap. Although both male and female jaguars prefer tall forest, short forest was also preferred by females but avoided by males. Whereas females significantly avoided roads, males didn’t and ventured into low-intensity cattle ranching and agriculture. Females’ preference for intact forests and against roads led to their habitat being fragmented to a greater degree than that of males. Models that ignored sexual differences failed to capture the effect of roads and agriculture on jaguar habitat use, blurred the distinction of use between short and tall forest, and underestimated fragmentation of female jaguar habitat; but incorporating these differences increased precision of habitat maps and allowed the identification of potential jaguar-human conflict areas associated with male’s use of cattle and agricultural lands. Specifying sex differences increases the power of habitat models to understand landscape occupancy by large carnivores, and so greater attention should be paid to these differences in their modeling and conservation.     

Global dung beetle response to tropical forest modification and fragmentation: A quantitative literature review and meta-analysis

Although insects are crucial for maintaining ecosystem function, our understanding of their overall response to human activity remains limited. This is no less true of dung-burying beetles (Coleoptera: Scarabaeidae: Scarabaeinae), which provide a suite of critical ecosystem functions and services, yet but face multiple conservation threats, particularly from landscape conversion. Here we use a review and meta-analysis to synthesize the current knowledge concerning response to tropical forest modification and fragmentation of dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae). For every modified habitat type and individual forest fragment across 33 studies, we calculated six dung beetle community parameters, standardized relative to intact tropical forest. We organized modified habitats along an approximate disturbance gradient ranging from selectively logged, late and early secondary forest, through agroforestry, tree plantations, to annual crops, cattle pastures and clear-cuts. Secondary forests, selectively logged forest and agroforests supported rich communities with many intact forest species, while cattle pastures and clear-cuts contained fewer species overall with few forest-dwelling species. Abundance generally declined with increasing modification, but was quite variable. Communities in open habitats were often characterized by hyper-abundance of a small number of small-bodied species, leading to low evenness. Across fragmentation studies, dung beetle species richness, abundance and evenness declined in smaller forest fragments. Richness and abundance sometimes declined in more isolated fragments, although this response appeared to depend on matrix quality. Across both habitat modification and fragmentation studies, geographic location and landscape context appeared to modify dung beetle response by influencing the available pool of colonists. We discuss potential underlying mechanisms and conclude with recommendations for management and conservation and for future research.     

Prospects for biodiversity conservation in the Atlantic Forest: Lessons from aging human-modified landscapes

Recent global assessments have shown the limited coverage of protected areas across tropical biotas, fuelling a growing interest in the potential conservation services provided by anthropogenic landscapes. Here we examine the geographic distribution of biological diversity in the Atlantic Forest of South America, synthesize the most conspicuous forest biodiversity responses to human disturbances, propose further conservation initiatives for this biota, and offer a range of general insights into the prospects of forest species persistence in human-modified tropical forest landscapes worldwide. At the biome scale, the most extensive pre-Columbian habitats across the Atlantic Forest ranged across elevations below 800 masl, which still concentrate most areas within the major centers of species endemism. Unfortunately, up to 88% of the original forest habitat has been lost, mainly across these low to intermediate elevations, whereas protected areas are clearly skewed towards high elevations above 1200 masl. At the landscape scale, most remaining Atlantic Forest cover is embedded within dynamic agro-mosaics including elements such as small forest fragments, early-to-late secondary forest patches and exotic tree monocultures. In this sort of aging or long-term modified landscapes, habitat fragmentation appears to effectively drive edge-dominated portions of forest fragments towards an early-successional system, greatly limiting the long-term persistence of forest-obligate and forest-dependent species. However, the extent to which forest habitats approach early-successional systems, thereby threatening the bulk of the Atlantic Forest biodiversity, depends on both past and present landscape configuration. Many elements of human-modified landscapes (e.g. patches of early-secondary forests and tree monocultures) may offer excellent conservation opportunities, but they cannot replace the conservation value of protected areas and hitherto unprotected large patches of old-growth forests. Finally, the biodiversity conservation services provided by anthropogenic landscapes across Atlantic Forest and other tropical forest regions can be significantly augmented by coupling biodiversity corridor initiatives with biota-scale attempts to plug existing gaps in the representativeness of protected areas.