Birds,Cattle, and Bracken Ferns: Bird Community Responses to a Neotropical Landscape Shaped by Cattle Grazing Activities

Large areas of tropical moist forests have been converted to cattle pastures, generating complex landscapes where different habitats are represented by small patches with an uneven spatial distribution. Here, we describe how bird communities respond to the different elements present in a livestock landscape that was originally dominated by tropical moist forest. We surveyed six habitats: open pastures, pastures with shrubs, early‐ and middle‐secondary forests, mature forest, and pastures invaded by bracken ferns (Pteridium aquilinum). Bird diversity was high in secondary and mature forests, and low in fern‐invaded sites and open pastures. Fern‐dominated sites had the lowest bird species richness, and trophic guild diversity of all habitats. Habitat structure affected both bird species richness and densities in similar ways. Tree species richness was the habitat attribute that had a bigger positive effect on bird species richness. Bird community structure varied among sampled habitats, separating habitats in two major groups (forests and pastures). Our data indicate that bracken fern‐invaded pastures were the worst habitat condition for avian communities. To increase bird diversity, we recommend to eliminate or manage bracken fern and to increase shrub and tree cover in open pastures to provide food resources and shelter for birds. Finally, we encourage the maintenance of secondary and mature forest remnants as a strategy to conserve resident birds within a landscape dominated by livestock activities.     

Non flying mammals and landscape changes in the tropical rain forest region of Los Tuxtlas, Mexico

The rapid and extensive conversion of Neotropical rain forests to a landscape consisting of pasture lands and other agricultural habitats has meant the local disappearance fragmentation and isolation of vertebrate populations To avoid further losses in biodiversity in Neotropical rain forests, it is imperative to determine how the different species that constitute the different vertebrate communities have responded to the anthropogenic alterations of their natural habitats To provide data in this direction we sampled non flying mammals in 35 forest fragments, in six disturbed forest sites in 12 regenerating forests, in 20 arboreal agricultural habitats (cacao coffee, mixed, citrus and allspice), in four live fence sites and in four pasture sites at Los Tuxtlas, Veracruz Mexico Sampling indicated that area of forest fragments and isolating distance were important variables influencing species richness Disturbed forest had fewer species and individuals present and supported a lower non flying mammal biomass than undisturbed and regenerating forests Shaded plantations (cacao coffee and mixed) were richer in species and in individuals than unshaded ones (citrus, allspice) Species richness in forests and agricultural habitats were associated to horizontal plant diversity and vertical foliage diversity Pasture habitats were the poorest man-made habitats in non flying mammal species Live fences supported a higher biomass and species of non flying mammals than pastures and were similar to forest and shaded man-made habitats in species assemblages     

Dung beetle (Coleoptera: Scarabaeidae: Scarabaeinae) diversity in continuous forest,forest fragments and cattle pastures in a landscape of Chiapas,Mexico: the effects of anthropogenic changes

We studied the diversity of dung beetles in three different habitats in the Lacandona Forest, Chiapas, Mexico. We found a total of 49 species. Of these, 44 were in well-preserved forests (SC) within the limits of the Montes Azules Biosphere Reserve, 42 in fragmented forests (SF), and 13 in cattle pastures (PZ). These two latter habitats were part of a fragmented landscape. Even though the species richness between the two forest habitats is similar, there is a change in guild composition and structure. About 12% of the species were exclusively found in SC, while 4.1% and 2% were exclusive of SF and PZ respectively. β diversity was the most important element for overall diversity (γ), above that of the local richness (α). Within well-preserved forests, species composition changes substantially, even among neighboring sites. Species diversity within the landscape seems to depend on canopy coverage, soil temperature and geographic distance between sites. Functional groups vary with the habitat. Large-bodied, nocturnal species with specific requirements of soil temperature and compaction are more sensitive to anthropogenic changes. In cattle pastures there is a larger number of heliophilic species, with a higher percentage of small-bodied and roller beetles.     

Roles of fragmented and logged forests for bird communities in industrial Acacia mangium plantations in Indonesia

Industrial timber plantations severely impact biodiversity in Southeast Asia. Forest fragments survive within plantations, but their conservation value in highly deforested landscapes in Southeast Asia is poorly understood. In this study, we compared bird assemblages in acacia plantations and fragmented forests in South Sumatra to evaluate each habitat’s potential conservation value. To clarify the impact of habitat change, we also analyzed the response of feeding guild composition. Five habitat types were studied: large logged forest (LLF), burnt logged forest (BLF), remnant logged forest (RLF), 4-year-old acacia plantation (AP4), and 1-year-old acacia plantation (AP1). Estimated species richness (Chao 2) was highest in LLF then AP4 and BLF, while AP1 and RLF had lower estimated species richness. Community composition was roughly divided into two groups by non-metric multidimensional scaling ordination: acacia plantation and logged forest. Sallying substrate-gleaning insectivores, such as drongos, broadbills, and some flycatchers, were restricted to LLF, whereas acacia plantation hosted many terrestrial frugivores, such as doves. Although fragmented forests in our study site lacked several common tropical forest species, these fragments provide an important habitat for some sallying and terrestrial insectivores. A network of small riparian remnant forests could be a complementary habitat for some species, while the conservation value of burnt forest might be low. In conclusion, the highly fragmented forests in plantations are suboptimal habitats for birds but are still very important, because large primary forest blocks have been nearly lost in the surrounding landscape.     

Pattern of tree species diversity in riparian forest fragments of different widths (SE Brazil)

Width is an essential element of the spatial configuration of riparian forests and may be fundamental in determining their corridor function. In the present study we tested the effect of forest width on floristic structure (tree species composition and diversity) in 15 fragments of riparian forest in an agricultural fragmented landscape of SE Brazil. All these fragments were chosen in a geomorphological homogeneous river reach under similar soil, topographic and human disturbance conditions in order to minimize the influence of these factors. The forest widths considered ranged from 30 to 650 m. The results showed that total species richness and climax species richness were significantly greater when we consider larger fragments, as has been observed in other studies. Nevertheless, species diversity and evenness were not significantly correlated with forest width. The analysis of species composition showed that the narrowest fragments were characterized by species well adapted to temporary flood conditions, while medium and wide fragments showed a composition typical of drier upland areas. Therefore, the effect of forest width on floristic structure appears to be more strongly linked to the effect of river floods in the case of the fragments studied. The existence in riparian corridors of a drier forest, in general richer and more diversified than the annually flooded forest, seems to favor the maintenance of regional species diversity in fragmented landscapes.     

Bird communities of natural and modified habitats in Panama

Only a small proportion of land can realistically be protected as nature reserves and thus conservation efforts also must focus on the ecological value of agroecosystems and developed areas surrounding nature reserves. In this study, avian communities were surveyed in 11 habitat types in central Panama, across a gradient from extensive forest to intensive agricultural land uses, to examine patterns of species richness and abundance and community composition. Wooded habitats, including extensive and fragmented forests, shade coffee plantations, and residential areas supported the most species and individuals. Nearctic-Neotropical migratory species were most numerous in lowland forest fragments, shade coffee, and residential areas. Introduced Pinus caribbea and sugar cane plantations supported the fewest species compared to all other habitats. Cattle pastures left fallow for less than two years supported more than twice as many total species as actively grazed pastures, such that species richness in fallow pastures was similar to that found in wooded habitats. Community similarities were relatively low among all habitat types (none exceeding the observed 65% similarity between extensive and fragmented lowland forests), but communities in shade coffee and residential areas were 43% and 54′% similar to lowland forest fragments, respectively. Fallow pastures and residential areas shared 60% of their species. Bird communities in shade coffee and residential areas were characterized by higher proportions of frugivorous and nectarivorous species than in native forests. These same guilds also were better represented in fallow than in grazed pastures. Raptors and piscivorous species were most prevalent in cattle pastures and rice fields. These results, though based upon only species richness and abundance, demonstrate that many human-altered habitats have potential ecological value for birds, and conservation efforts in tropical areas should focus greater attention on enhancement of agricultural and developed lands as wildlife habitat. To understand the true conservation value of these modified lands will require examination not only of numbers but also of the types of species supported by these habitats, their reproductive output and survival rates.     

Non-native plantation forests as alternative habitat for native forest beetles in a heavily modified landscape

The once extensive native forests of New Zealand’s central North Island are heavily fragmented, and the scattered remnants are now surrounded by a matrix of exotic pastoral grasslands and Pinus radiata plantation forests. The importance of these exotic habitats for native biodiversity is poorly understood. This study examines the utilisation of exotic plantation forests by native beetles in a heavily modified landscape. The diversity of selected beetle taxa was compared at multiple distances across edge gradients between each of the six possible combinations of adjacent pastoral, plantation, clearfell and native forest land-use types. Estimated species richness (Michaelis–Menten) was greater in production habitats than native forest; however this was largely due to the absence of exotic species in native forest. Beetle relative abundance was highest in clearfell-harvested areas, mainly due to colonisation by open-habitat, disturbance-adapted species. More importantly, though, of all the non-native habitats sampled, beetle species composition in mature P. radiata was most similar to native forest. Understanding the influence of key environmental factors and stand level management is important for enhancing biodiversity values within the landscape. Native habitat proximity was the most significant environmental correlate of beetle community composition, highlighting the importance of retaining native remnants within plantation landscapes. The proportion of exotic beetles was consistently low in mature plantation stands, however it increased in pasture sites at increasing distances from native forest. These results suggest that exotic plantation forests may provide important alternative habitat for native forest beetles in landscapes with a low proportion of native forest cover.     

The importance of littoral forest remnants for indigenous bird conservation in southeastern Madagascar

The littoral forests of Madagascar are relatively unexplored ecosystems that are considered seriously threatened by deforestation and habitat fragmentation. We set out to describe the bird communities inhabiting the littoral forest remnants in three different sub-regions of southeastern Madagascar to determine the national importance of these forests for bird conservation. In total, 77 bird species were found inhabiting 14 littoral forest remnants. Of these species, 40 are endemic to Madagascar and a further 21 are endemic to the Indian Ocean sub-region, consisting of Madagascar, the Comoros and the Mascarenes. The matrix habitats (Melaleuca forests, marécage swamp forest, Eucalyptus plantations and Erica grassland) that immediately surround the littoral forests were depauperate of bird species and contained few species that were found within the littoral forests. The geographic location of littoral forest remnants had an important role in determining what bird species occurred within them, with the northern remnants having similar bird communities to nearby humid forest whilst the most southern remnant had a bird community that resembled those of nearby spiny forest habitats. Eleven bird species that have been previously described as being habitat-restricted endemics to either spiny forests or humid forests, were found in littoral forest remnants. These results suggest that these littoral forests may play an important transitional role between the two other major natural habitats (spiny forest and humid forest) of southeastern Madagascar. On this basis we advocate that the littoral forest remnants of southeastern Madagascar should be afforded continuing conservation priority.     

Use of Fruiting Trees by Birds in Continuous Forest and Riparian Forest Remnants in Los Tuxtlas,Veracruz, Mexico1

The composition of plant species in fragmented landscapes may be influenced by the pattern of visitation by birds to fruiting trees and by the movement of seeds among and within fragments. We compared bird visitation patterns to two tree species (Dendropanax arboreus, Araliaceae; Bursera simaruba, Burseraceae) in continuous forest and remnants of riparian vegetation in a region dominated by pasture in Los Tuxtlas, Veracruz, Mexico. We quantified frequency of visitation, fruit consumption, consistency of visitation (percentage of total tree observation periods during which a given bird species was recorded), and species composition of birds at individuals of both tree species in continuous forest and riparian remnants. Bird visitation rate, species richness, and fruit consumption rates were similar within both tree species in the two habitats. Species assemblages at D. arboreus were different between continuous forest and remnants. Species assemblages at B. simaruba did not differ by habitat. Our results demonstrate that habitat disturbance may influence avian visitation patterns, which may in turn affect subsequent recruitment patterns in some tree species. Our results, however, were not consistent between the tree species, suggesting that it is difficult to generalize concerning the effects of forest disturbance on avian species assemblages in fruiting trees.     

Do riparian forest strips in modified forest landscapes aid in conserving bat diversity?

Agricultural practices lead to losses of natural resources and biodiversity. Maintaining forests alongside streams (riparian forest strips) has been used as a mechanism to minimize the impact of clearing for agriculture on biodiversity. To test the contribution of riparian forest strips to conserve biodiversity in production landscapes, we selected bats as a biodiversity model system and examined two dimensions of diversity: taxonomic and functional. We compared bat diversity and composition in forest, with and without stream habitat, and in narrow forest riparian strips surrounded by areas cleared for agriculture. We tested the hypothesis that riparian forest strips provide potential conservation value by providing habitat and serving as movement corridors for forest bat species. Riparian forest strips maintained 75% of the bat species registered in forested habitats. We found assemblage in sites with riparian forest strips were dominated by a few species with high abundance and included several species with low abundance. Bat species assemblage was more similar between sites with streams than between those sites to forests without stream habitat. These results highlight the importance of stream habitat in predicting presence of bat species. We registered similar number of guilds between forest sites and riparian forest strips sites. Relative to matrix habitats, stream and edge habitats in riparian forest strips sites were functionally more diverse, supporting our hypothesis about the potential conservation value of riparian forest strips. Results from this study suggest that maintaining riparian forest strips within cleared areas for agricultural areas helps conserve the taxonomic and functional diversity of bats. Also, it provides basic data to evaluate the efficacy of maintaining these landscape features for mitigating impacts of agricultural development on biodiversity. However, we caution that riparian forest strips alone are not sufficient for biodiversity maintenance; their value depends on maintenance of larger forest areas in their vicinity.     

Forest cover and heterogeneous pastures shape the diversity of predatory rove beetles in tropical riparian habitats

In tropical landscapes, forest remnants have been reduced to narrow strips of vegetation along rivers and streams surrounded by agricultural land that affects biodiversity, depending on the habitat and landscape characteristics. To assess the effect of riparian forest loss on the diversity of Staphylininae predatory rove beetles, we considered two habitat conditions (river sites with riparian vegetation and sites with heterogeneous pastures) within two micro-basin types (with >70% and <40% forest cover) in a tropical montane cloud forest landscape, Mexico. Beetles were collected using baited pitfall traps during the rainy season of 2014. No differences were found between micro-basin types and, although species richness (⁰D) was similar between habitat conditions, when the diversity of common (¹D) and dominant (²D) species was considered, sites with heterogeneous pastures were almost twice as diverse as those with riparian vegetation. All diversity measurements were greater in sites with heterogeneous pastures of either micro-basin type. Air temperature and canopy cover were the environmental variables that best explained the variation in beetle species composition. The greatest environmental differences related to species composition were detected between habitat conditions and were more evident in sites with heterogeneous pastures and low forest cover in the surroundings. The results suggest that replacing riparian vegetation with heterogeneous pastures, within micro-basins that lost between 30% and 60% of their forest cover, does not significantly reduce the diversity of predatory rove beetle but rather modifies the beetle composition. Effective formulation of management strategies to mitigate the impact of land use modification therefore requires an understanding of the interaction between vegetation remnants and landscape characteristics.     

Anthropogenic landscape changes and avian diversity at Los Tuxtlas, Mexico

Faced with rapid and extensive conversion of tropical rain forests to a landscape consisting of pasture lands, and with the need to preserve the avian diversity of tropical regions, it is imperative to determine how different species have responded to anthropogenic alterations of their natural habitats. We sampled birds in undisturbed and disturbed forest islands in regenerating forests and in four replicates of each of the following man-made habitats: arboreal agricultural habitats (cacao, coffee, mixed, citrus and allspice), non-arboreal agricultural habitats (corn, jalapen~o chili pepper and bananas), live fences and pastures, at Los Tuxtlas, Veracruz, Mexico. We censused 22145 birds representing 226 species. We detected 79% of the species in forest habitats, 80% in agricultural habitats, 43% in live fences and only 5% in pastures. Isolating distance and continued disturbance by humans of forest fragments were important variables influencing species' richness. Arboreal agricultural habitats and live fences were richer in species and in birds than non-arboreal man-made habitats. Economic surveys showed that some of the crops investigated yield higher returns than cattle ranching based on pastures. We discuss the conservation value for birds of agricultural islands and of live fences as landscape elements that help reduce physical and biotic isolation among remaining configurations of forest fragments in Los Tuxtlas.     

Potential Effects of Ateline Extinction and Forest Fragmentation on Plant Diversity and Composition in the Western Orinoco Basin,Colombia

Cattle and agricultural farming in the western Orinoco Basin began in 1555, and since then fragmentation of continuous forest has occurred. We evaluated the effects of the disturbances and the absence of large primates on plant community composition, diversity, and regeneration patterns. Atelines (Lagothrix and Ateles) inhabited the lowlands close to the Andean mountains, but no longer live in fragmented habitats. Their absence may have negative effects on plant populations because atelines play important roles as seed dispersers in neotropical forests, especially for large-seeded plants, which are rarely swallowed by other seed dispersers. We compared 2 1-ha vegetation plots in forest fragments north of the La Macarena Mountains with 7 plots in continuous forest in Tinigua National Park. Both sites share the same climatic conditions and have similar geological origins. There is floristic affinity between forests with similar ecological characteristics; the fragmented forests are also less diverse than the continuous forests. As predicted, the forest fragments have fewer individuals with large seeds. The results suggest that forest fragmentation and local ateline extinctions affect plant communities, reducing diversity and affecting large-seeded plants.     

Vegetation diversity, composition and structure in a cattle agro-landscape of Matiguás, Nicaragua

The diversity, composition and structure of vegetation in a cattle landscape in Matiguás, Nicaragua was characterized, and the floristic and structural differences of six types of habitats (secondary forests, riparian forests, charrales, live fences and pastures with high and low tree cover) were compared. A total of 3 949 trees of 180 species and 52 families were recorded. Forty six percent of the total trees reported for the landscape were represented by Guazuma ulmifolia (18.5%), Bursera simaruha (13.2%), Tabebuia rosea (6.3%), Enterolobium cyclocarpum (4.2%) and Albizia saman (3.4%). Many of the dominant species in the landscape were typical of open and disturbed areas. There were significant differences between the different habitats in the patterns of tree species richness, abundance, diversity, structure and floristic composition. The riparian forests had greater tree richness (p=0.0001) and diversity (p=0.0009) than other habitats. The floristic composition varied across habitats. with pairs of habitats sharing between 18.4 and 51.6% of the same tree species, and with clear differences in composition between the forested (riparian and secondary forests) and agricultural habitats. Of the habitats studied, the riparian forests and secondary forests seem to have greatest value for the conservation of the flora in the agropaisaje because they have the greatest species richness, and maintain small populations of endangered species. On the basis of the study, we recommend including agricultural landscapes in strategies to conserve tree diversity and suggest measures to ensure the maintenance of tree diversity in the Matiguas landscape.     

Postdispersal Seed Fate of Tropical Montane Trees in an Agricultural Landscape, Southern Costa Rica

Variation in postdispersal seed fate is an important factor driving patterns of forest regeneration. Because most previous studies have not tracked final seed fate and have commonly equated seed removal with predation without considering the possibility of secondary dispersal, little is known about individual seed mortality factors in successional and degraded habitats. This study tracked the postdispersal fate of large-seeded tropical montane trees in abandoned pasture, young secondary forests, and small forest fragments during two consecutive years in an agricultural landscape in southern Costa Rica. The incidence of secondary dispersal by animals, scatterhoarding in particular, and the effects of seed burial on germination were measured. Overall, seeds survived through germination more often in secondary forests with high levels of mortality occurring in abandoned pastures and forest fragments. The majority of seed mortality was caused by rodent predation in forest fragments, insects and fungal pathogens in secondary forests, and a combination of desiccation, insects, and fungal pathogens in pastures. Seeds were frequently secondarily dispersed in larger forest fragments, whereas they were only rarely moved in pastures and secondary forests. Burial tended to improve germination in pastures and was important for an often scatterhoarded species, Otoba novogranatensis, in all habitats. The results of this study suggest that: (1) seed mortality factors differ in response to the type of habitat degradation; (2) large-seeded species have high potential for survival when dispersed to young secondary forests; and (3) seed removal is not a reliable proxy for seed predation, particularly in less degraded forest fragments.     

Simulating the Long-term Response of Tropical Wet Forests to Fragmentation

In the coming decades, a large fraction of the world's tropical forests will be fragmented into remnants surrounded by secondary vegetation, land-use areas, or roads. It is important to develop integrative tools to monitor the evolution of these fragmented ecosystems. We used the individual-oriented and process-based forest growth simulator FORMIND2.0 to investigate the spatial and temporal effects on standing biomass and functional diversity of various intensities and patterns of fragmentation within a forest landscape. The simulator was calibrated for an old-growth wet forest in French Guiana, South America. We found that the standing biomass of forest remnants was reduced significantly compared to a similar area of nonfragmented forest. When fewer but larger remnants were created rather than many small ones, the total loss in biomass and the increase in the abundance of early-successional species were significantly reduced, confirming that edge effects dominate the functioning of forest remnants. We also performed simulations of secondary succession after the landscape had been abandoned. The simulated recovery time in those secondary forests depends on both the size of cleared area and the spatial pattern of the remnant forests. Received 30 January 2002; accepted 16 July 2002.     

Structure and diversity of phyllostomid bat assemblages on riparian corridors in a human‐dominated tropical landscape

Tropical forests around the world have been lost, mainly because of agricultural activities. Linear elements like riparian vegetation in fragmented tropical landscapes help maintain the native flora and fauna. Information about the role of riparian corridors as a reservoir of bat species, however, is scanty. We assessed the value of riparian corridors on the conservation of phyllostomid bat assemblage in an agricultural landscape of southern Mexico. For 2 years (2011–2013), mist‐netting at ground level was carried out twice during the dry season (December to May) and twice during the wet season (June to November) in different habitats: (1) riparian corridors in mature forest, (2) riparian corridors in pasture, (3) continuous forest away from riparian vegetation, and (4) open pastures. Each habitat was replicated three times. To determine the influence of vegetation structure on bat assemblages, all trees (≥10 cm dbh) were sampled in all habitats. Overall, 1752 individuals belonging to 28 species of Phyllostomidae were captured with Sternodermatinae being the most rich and abundant subfamily. Riparian corridors in mature forest and pastures had the greatest species richness and shared 65% of all species. Open pastures had the lowest richness and abundance of bats with no Phyllostominae species recorded. Six of the 18 species recorded could be considered as habitat indicators. There was a positive relationship between bat species composition and tree basal area. Our findings suggest that contrary to our expectations, bats with generalist habits and naturally abundant could be useful detector taxa of habitat modification, rather than bats strongly associated with undisturbed forest. Also in human‐dominated landscapes, the maintenance of habitat elements such as large trees in riparian corridors can serve as reservoirs for bat species, especially for those that are strongly associated with undisturbed forest.     

Landscape context of plantation forests in the conservation of tropical mammals

Plantation forests have been expanding in many tropical and subtropical environments. Howerver, even when they replace less wildlife friendly land uses such as pastures and annual crops, the biodiversity levels of pristine natural habitats often have not been recovered. Here we addressed how the landscape context of plantation forests located in South-eastern Brazil affects species richness and community resilience of medium and large size mammals. The area covered by native habitat fragments surrounding plantation forests is positively related to functional richness, including the presence of species more vulnerable to extinction in fragmented landscapes. In addition, the degree of aggregation of plantation forest stands is negatively related to more vulnerable species. No primates were recorded in our seven plantation forest sites (ranging from 272 to 24,921 ha), even when they were seen in native habitat fragments adjacent to commercial tree stands. Two invasive species (Sus scrofa and Lepus capensis) were recorded in four plantation forest sites. The impoverishment of fauna in plantation forests is due to two factors. First, plantation forests generally are structurally simplified habitats when compared to highly diverse tropical forests. Secondly, the isolation from habitat fragments which act as source of individuals in the landscape precludes the establishment of individual in plantation forest. We also highlighted the management practices to improve the complexity of vegetation in commercial tree stands should be taken cautiously, insofar as reduced productivity per area entails a greater demand for land. Thus, an alternative would be intensify the management of the commercial tree stands for wood production together with the restoration of adjacent areas set aside to conservation and native habitat fragments protection.     

Genetic rescue of remnant tropical trees by an alien pollinator.

Habitat fragmentation is thought to lower the viability of tropical trees by disrupting their mutualisms with native pollinators. However, in this study, Dinizia excelsa (Fabaceae), a canopy-emergent tree, was found to thrive in Amazonian pastures and forest fragments even in the absence of native pollinators. Canopy observations indicated that African honeybees (Apis mellifera scutellata) were the predominant floral visitors in fragmented habitats and replaced native insects in isolated pasture trees. Trees in habitat fragments produced, on average, over three times as many seeds as trees in continuous forest, and microsatellite assays of seed arrays showed that genetic diversity was maintained across habitats. A paternity analysis further revealed gene flow over as much as 3.2 km of pasture, the most distant pollination precisely recorded for any plant species. Usually considered only as dangerous exotics, African honeybees have become important pollinators in degraded tropical forests, and may alter the genetic structure of remnant populations through frequent long-distance gene flow.     

High butterfly beta diversity between Brazilian cerrado and cerrado–caatinga transition zones

Tropical dry forests are among the most diverse and threatened habitats in the world, yet they are rarely protected and remain poorly studied. In Brazil, dry forests are naturally fragmented and embedded within various biomes, thus making it important to assess biotic homogeneity among geographically separated forest fragments. We sampled 7732 individuals belonging to 48 species to quantify the diversity of fruit-feeding butterfly communities at four Brazilian dry forest sites, and found differences in community structure between northern and central sites. Species richness per plot was the same in both areas, but abundance per plot was higher in northern sites. Species composition differed between sites mostly due to species of Satyrinae. Additive partitioning showed that beta diversity corresponded to 70.1% of all diversity. Rather than species loss, beta diversity primarily represented species turnover that was potentially driven by differences in the surrounding habitats. Butterfly community composition and abundance were influenced by vegetation where abundance increased with tree density and basal area, and decreased with the average tree height. Butterfly species richness and abundance were higher in the wet season than in the dry season, and all species sampled in the dry season were present in the wet season. Differences in community structure across relatively short geographic distances in the same type of habitat highlight the importance of conserving tropical dry forest fragments to ensure the maintenance of butterfly diversity and, presumably, other insects.