Rainforest Fragments Research Articles

Edge effect on the spatial distribution of trees in an Araucaria Rainforest fragment in Brazil

Abstract The objective of this research was to evaluate which species in the Brazilian Araucaria forest have its spatial distribution influenced by edge effects. We performed annual forest inventories inside two one-hectare plots, divided in 10 rectangular subplots, delimited by every 10 meters of edge distance. Each tree with at least 10 cm at DBH was identified to species level, and their allometric measurements and geographical coordinates were recorded considering the categories living, recruitment and mortality. We analyzed the correlation between the abundance of each species in each subplot and its distance by the Spearman's Correlation Coefficient and a Generalized Additive Model (GAM) with a Poisson distribution. We analyzed the distribution of some species and the ecological groups using a Kernel density model. We observed numerous pioneers and early secondary species with relationship with the edge distance, usually concentrated close to the edges. The late secondary/climax species are more evenly distributed in the plots, despite of some species, as Eugenia uniflora, are negatively affected by the edge. From these results, it is observed that some light demanding species can be favored to live close to the edges, even if some shadow tolerant species can inhabit this region as well.

Forest cover and matrix functionality drive the abundance and reproductive success of an endangered primate in two fragmented rainforests

Understanding population responses to landscape structure is critical to improve landscape planning. Yet, large uncertainty remains about how such responses vary among regions with different disturbance intensity. This knowledge is particularly important for forest-specialist species, such as spider monkeys. Assessing the effect of landscape composition and configuration on the abundance and reproductive success of spider monkeys (Ateles geoffroyi) in two fragmented rainforests with different land-use intensity. We calculated the encounter rate (relative abundance) and immature-to-female ratio (reproductive success) of spider monkeys in two Mexican rainforest regions (12 forest patches per region, ~ 1140 h of field observations), and assessed their responses to three landscape predictors (forest cover, matrix functionality, and forest patch density) considering the scale of effect in each region. Spider monkeys showed different responses to landscape structure in each region. Encounter rate increased strongly with matrix functionality in the more disturbed region, and tended to be negatively impacted by patch density in the best-preserved region, but this latter association was weak. Forest cover was positively related to immature-to-female ratio in both regions, but such association was stronger in the best-preserved region. Our findings suggest that forest loss has stronger negative effects on spider monkeys than forest fragmentation, especially in best-preserved rainforests. Matrix composition is relatively more important in more disturbed regions, where monkeys may be pushed to use the matrix more frequently for feeding and/or traveling. Preventing forest loss and improving matrix quality should be a priority for the conservation of this endangered species.

Effects of forest degradation on the moonrat Echinosorex gymnura in Sabah, Malaysian Borneo

Commercial timber extraction and agricultural expansion lead to substantial degradation and loss of tropical rainforests, posing a severe threat to biodiversity in South-east Asia. Although the impacts of these disturbances are well understood for some species, they remain largely unknown for most species, impeding any directed conservation efforts. One of these little known, presumably forest-dwelling species is the moonrat Echinosorex gymnura, an insectivorous mammal ranging from southern Myanmar and southern Thailand to Sumatra and Borneo. While the moonrat is currently listed as Least Concern on The IUCN Red List of Threatened Species, large parts of its range have been severely degraded due to unsustainable logging practices and the conversion of forest to oil palm plantations. We conducted a systematic large-scale camera trap survey in three forest reserves under different forest management strategies in Sabah, Malaysian Borneo. We recorded a total of 67 independent moonrat detections at 22 of 180 camera trap stations over 12,281 camera trap days. We analysed moonrat habitat associations using occupancy modelling and a set of 9 different environmental covariates. Canopy closure and forest quality were positively associated with moonrat occurrence and were the most important determinants of the species’ occurrence in our study area. Proximity to plantations (oil palm and industrial timber) and elevation negatively affected moonrat occurrence. Our results thus indicate that the moonrat strongly depends on high-quality lowland forest and is unlikely to occur close to plantations. Moonrat occupancy was highest in the sustainably managed forest reserve, suggesting that this species responds much better to reduced-impact logging compared to conventional logging practices. Our first ecological survey indicates that the moonrat may be more threatened by the continued conversion, degradation, and fragmentation of tropical lowland rainforests than previously assumed.

Rediscovery of Furipterus horrens (Chiroptera: Furipteridae) in Costa Rica

Abstract Furipterus horrens is a small insectivorous bat with distinct clawless tiny thumbs, and with a patchy geographic distribution in the Neotropics. We report the rediscovery of F. horrens in Costa Rica 44 years after it was first recorded. A colony of 100–130 individuals, each one with the distinctive external and morphological characteristics of the species, was found roosting in the lower parts of the floor of bungalows located in the Sarapiquí area. The rediscovery of this species validates the protection of several rainforest fragments through ecotourism, a modern way to balance human development and biodiversity conservation.

Dirt roads and fire breaks produce no edge effects on litter-dwelling arthropods in a tropical dry-forest: a case study

Edge effects threaten organisms and ecological processes in habitat remnants, but they have been poorly studied in non-humid forests such as cerradao, a tropical dry forest sometimes derived from fire-suppressed savanna in Brazil. The diverse ecosystem functions performed by arthropods may be disrupted by edge effects, and there is pressing need for more studies on this subject. We sampled fragments of cerradao facing either a road or fire breaks, assessing edge effects in: beta diversity and community composition of epigaeic (litter-dwelling) arthropod orders, ant species, and ant functional groups; ant species richness and diversity; leaf litter depth; and colony residence time of a predatory ground-dwelling ant, Odontomachus chelifer (Ponerinae). None of the variables measured differed between edge and interior of the sites sampled. Dry forests have high micro-climatic variations caused by discontinuities in the canopy cover and, as such, changes in abiotic variables in cerradao edges might not be as clear as those observed in tropical rainforests. Our study demonstrates that edge effects may not be so prevalent in cerradao facing roads or fire breaks, which possibly increases the chances of survival of a higher fraction of the original arthropod fauna compared to rainforest fragments.

Influence of Fire on the Natural Regeneration of a Semideciduous Seasonal Rainforest Fragment

Influence of Fire on the Natural Regeneration of a Semideciduous Seasonal Rainforest Fragment

Impacts of rainforest fragmentation on the composition of ground-active vertebrate communities and their patterns of seed consumption.

Post-dispersal seed consumption by rainforest vertebrates on the forest floor can substantially influence the community dynamics of rainforest trees. Studies of rainforest vertebrate seed predators at a community level, however, are lacking. Furthermore, there is very limited understanding of the effects of forest fragmentation on seed predators and their feeding behaviour. Here, we test whether communities of vertebrate seed predators, and their patterns of feeding on rainforest tree seeds, are altered when clearing creates forest fragments in an agricultural matrix. Using infra-red trail cameras deployed at stations with and without seeds of 20 local tree species, we identified four mammal and three bird species (from 18 recorded vertebrate taxa at mainly species level) as common post-dispersal seed predators in subtropical rainforest of eastern Australia. Statistical comparisons of species-specific frequencies between six sites in continuous forest and six in small rainforest fragments (4–21 ha) showed that habitat fragmentation substantially altered species composition of seed predator communities. Two species, both small rodents, had lower abundances in fragments than in continuous forest, while higher abundances were observed in fragments for a further four species: two small birds, a medium-sized marsupial and the small non-native rodent Rattus rattus. The abundance of one larger bird species did not change. Predatory interest in seeds was also significantly affected by habitat fragmentation and generally increased in each species’ habitat of greater abundance. Collectively, seed predators showed behaviours associated with potential or actual seed consumption on an average of 43% of camera days with seeds, with about 50% of seeds physically removed or damaged after five days’ exposure. Camera data have revealed community-level changes in seed predator abundance and feeding that are likely to cause altered patterns of plant recruitment following rainforest fragmentation, but these will be complex in nature.

Saturniid moths (Lepidoptera: Bombycoidea) from an Atlantic Rain Forest fragment in southeastern Brazil.

The light-attracted silk moths (Lepidoptera: Saturniidae) of the Boraceia Biological Station in the municipality of Salesópolis, state of São Paulo, southeastern Brazil have been sampled over more than seven decades (1942-2013). A total of 6,288 individuals (including a gynandromorph) belonging to five subfamilies, 46 genera and 133 species were identified. Hemileucinae was the most abundant and speciesrich subfamily, followed by Ceratocampinae, Arsenurinae, Saturniinae, and Oxyteninae. Hylesia Hübner, Automeris Hübner, and Dirphiopsis Bouvier (Hemileucinae) were the dominant genera in abundance and species richness. Only Automeris illustris (Walker), Gamelia remissoides Lemaire, and Hidripa paranensis (Bouvier) (Hemileucinae) were recorded in all months of sampling. Hylesia metapyrrha (Walker) was the most abundant saturniid species recorded at the station, with 375 specimens, followed by Hylesia oratex Dyar with 265 specimens, Dirphia muscosa Schaus with 261 specimens (all Hemileucinae); Copaxa canella Walker (Saturniinae) with 232 specimens, and Lonomia cf. obliqua Walker (Hemileucinae) with 106 specimens. Fifteen additional species were each represented by more than 100 specimens. The importance of the Boraceia Biological Station to the maintenance of the saturniid moth diversity in the Atlantic Forest is discussed.

Influence of the size and degree of conservation of remnants of the Atlantic rain forest on chiropteran assemblages

Reduction in the size and loss of the quality of habitats are considered the greatest threats to bat species. Aiming to complement information, the objective of this study was to evaluate, from compiled data, the influence of the size of forest fragments and their degree of conservation on the richness and composition of chiropteran fauna in the Atlantic rain forest. A total of 33 publications on Chiroptera in the Atlantic rain forest was reviewed and a list of 86 species was extracted from them. The size of forest fragments exhibited positive and significant relationship with the total number of Relatively Common Species, Rare Species, Not Generalist species and with richness. Positive and significant relationship was observed between degree of conservation of the forest fragments and the total number of Rare Species, of Not Generalist species and with richness. The results here presented indicate that large and well-conserved fragments of Atlantic rain forest should be the priority when the intention is to maintain a high richness of Chiroptera and of Rare Species and Not Generalist Species.

Influence of the size and degree of conservation of remnants of the Atlantic rain forest on chiropteran assemblages

Reduction in the size and loss of the quality of habitats are considered the greatest threats to bat species. Aiming to complement information, the objective of this study was to evaluate, from compiled data, the influence of the size of forest fragments and their degree of conservation on the richness and composition of chiropteran fauna in the Atlantic rain forest. A total of 33 publications on Chiroptera in the Atlanticrain forest was reviewed and a list of 86 species was extracted from them. The size of forest fragments exhibited positive and significant relationship with the total number of Relatively Common Species, Rare Species, Not Generalist species and with richness. Positive and significant relationship was observed between degree of conservation of the forest fragments and the total number of Rare Species, of Not Generalist species and with richness. The results here presented indicate that largeand well-conserved fragments of Atlantic rain forest should be the priority when the intention is to maintain a high richness of Chiroptera and of Rare Species and Not Generalist Species.

Edaphic beetle (Insecta: Coleoptera) diversity over a forest-matrix gradient in a tropical rainforest

Species from natural communities show different capacities for moving across contrasting habitats, and they may gradually respond along the transition between forests and anthropogenic areas. Because beetles are effective bioindicators, we analyzed the Coleoptera assemblage structure in the transition between sugarcane matrices and forest fragment. The study was conducted in an Atlantic rainforest fragment and sugarcane matrices after 2 and 6 months of replantation. Beetles were sampled in linear transects that were 50, 100, and 200 m from the forest edge and toward both forest core and matrices. We analyzed beetle abundance, species richness and composition, and diversity numbers. The abundance and species richness were higher in the forest, and species richness was higher at the sampling site 100 m inside the forest than at the gradients within the sugarcane matrices. The species composition differed between the forest and matrices, but not between the matrices with different replantation ages. Alpha diversity based on the number of species was higher in the forest, and alpha diversity based on the Shannon index was higher in the forest and matrix after 6 months of replantation. Our results suggest that the sugarcane matrices, chiefly the matrix after 2 months of replantation, sustain an impoverished beetle assemblage when compared with the forest fragment. Despite the strong habitat distinction, the beetle fauna in the sugarcane matrices was not affected by the horizontal distance from the forest. Here, we have highlighted the importance of forest fragments embedded in harsh matrices for the maintenance of biodiversity.

The effect of habitat fragmentation on the bee visitor assemblages of three Australian tropical rainforest tree species.

Tropical forest loss and fragmentation can change bee community dynamics and potentially interrupt plant–pollinator relationships. While bee community responses to forest fragmentation have been investigated in a number of tropical regions, no studies have focused on this topic in Australia. In this study, we examine taxonomic and functional diversity of bees visiting flowers of three tree species across small and large rainforest fragments in Australian tropical landscapes. We found lower taxonomic diversity of bees visiting flowers of trees in small rainforest fragments compared with large forest fragments and show that bee species in small fragments were subsets of species in larger fragments. Bees visiting trees in small fragments also had higher mean body sizes than those in larger fragments, suggesting that small‐sized bees may be less likely to persist in small fragments. Lastly, we found reductions in the abundance of eusocial stingless bees visiting flowers in small fragments compared to large fragments. These results suggest that pollinator visits to native trees living in small tropical forest remnants may be reduced, which may in turn impact on a range of processes, potentially including forest regeneration and diversity maintenance in small forest remnants in Australian tropical countryside landscapes.

Breeding Biology of Great HornbillBuceros bicornisin Tropical Rainforest and Human-Modified Plantation Landscape in Western Ghats, India

Loss of mature tropical forests to agricultural expansion often creates landscapes with forest fragments embedded within a matrix of human-modified habitats and land uses. Such habitat fragmentation may be detrimental to species with specialized habitat and foraging requirements and their ability to persist in such landscapes may depend on their adaptability to habitat modification. Great Hornbills Buceros bicornis, among the largest birds in Asian tropical rainforests, depend on large trees for nesting and a diverse array of patchily distributed fruiting trees. In the human-modified landscape of the Anamalai Hills, India, we compared the breeding biology and nesting behaviour of Great Hornbills in contiguous rainforest (N=3 nests) and in modified habitat consisting of coffee plantations and rainforest fragments (N=5 nests). The nesting cycle of seven of the eight nests monitored varied between 114 and 130 days. Nest provisioning behaviour was similar in contiguous forest and modified habitat in terms of visitation and food delivery rates, but visitation tended to be higher and food delivery rate lower during the nestling phase than during incubation. As expected, tree density and native food plant diversity were lower in modified habitat than in continuous forest. The diversity of food provisioned was lower in modified habitat with a 57.5% dietary overlap with contiguous forest. Hornbills in the modified habitat of coffee plantations used non-native tree species for nesting and foraging, indicating their adaptability to modified landscapes.

Matrix and area effects on the nutritional condition of understory birds in Amazonian rainforest fragments

Forest fragmentation, a result of deforestation, not only decreases the amount of habitat available for wildlife, but also increases the isolation of the remaining fragments and the area of edges surrounding them. Also, deforestation often leads to the creation of a dynamic regenerating matrix where cleared land is subsequently abandoned. Here we examine the effects of fragmentation and landscape change on the nutritional condition of Amazonian rainforest birds at the Biological Dynamics of Forest Fragments Project, near Manaus, Brazil. We analyzed ptilochronology-based measurements of feather growth rate in 12 species living in fragments within a dynamic landscape over 21 years. Ptilochronology serves as an index of nutritional condition by revealing energy available for maintenance over 1–2 weeks while the feather is grown, allowing intraspecific comparison across treatments. Feather growth rate decreased in fragments surrounded by young second-growth borders but increased as fragment size and age of adjacent second-growth vegetation increased. Results from this simple, yet informative, measure of nutritional condition reveal physiological impacts of land cover change, including the response of birds to changes occurring at both local and landscape levels. Our results highlight the importance of looking beyond presence/absence data to describe fragmentation effects, and support the value of landscape-scale approaches for the conservation of tropical forest biodiversity.

Ants on Clerodendrum infortunatum: Disentangling Effects of Larceny and Herbivory.

Nectar larcenists extract nectar from flowers without pollinating them. A reasonable expectation is that any form of nectar larceny should have a detrimental effect on the plant's reproductive success. However, studies reveal an entire range of effects, from highly negative to highly positive. This variation in effect may be partly explained by additional, unmeasured, effects of nectar larcenists on plants. In a study system where two ant species Tapinoma melanocephalum (Fabr.) (Hymenoptera: Formicidae) and Trichomyrmex destructor (Jerd.) (Hymenoptera: Formicidae) act as nectar larcenists, we examined the effect of larceny on the female reproductive success of Clerodendrum infortunatum Gaertn. (Lamiales: Lamiaceae) in rain forest fragments of the Western Ghats, India. This was done through a combination of field observations and a series of field experiments looking at the effects of excluding ants from inflorescences. We found that T. destructor reduces fruit set considerably. Rather than this being a consequence of nectar larceny, however, our experiments show that the negative effect arises instead from the herbivorous behavior of the ant. At a population level, both ant species prefer edges over interiors of forest patches, spatially concentrating the interaction zone to forest edges. Simultaneously considering multiple ecological interactions and disentangling their relative contributions might explain the large variation across species in the observed effect of larceny. The overall population effect of nectar larceny and herbivory is likely to depend on the spatial structuring of plants and ants.

Effect of distance to edge and edge interaction on seedling regeneration and biotic damage in tropical rainforest fragments: A long‐term experiment

AbstractIn forest fragments, edge effects can influence forest regeneration, but little is known about how edge effects influence seedling performance and the interaction between seedlings and their natural enemies over time.In central Amazonia, we recorded survival and growth (in height and leaf number) and damage by insect herbivores and leaf‐fungal pathogens ofChrysophyllum pomiferum(Sapotaceae) seedlings that were exposed to different numbers of edges and to different distances from the forest edge. Grown seedlings were transplanted into one‐square‐metre plots within 1‐ha blocks located in the centre (no edge), the edge (one edge), and the corner (two edges), and at different distances from the edge towards the interior (i.e., 20, 40, 60, 80, and 100 m) of two rectangular fragments (10‐ and 100‐ha in size). Plots were visited once every 2 months for 1 year (1992–1993) and thereafter every 2 years for almost 8 years (1993–2001).Overall, results showed that seedling survival, height, leaf number, and biotic damage varied over time with the presence of nearby edges and with the distance from the edge. Survival was lower in fragment edges and corners than in centres. Increase in height was similar for all positions within the 100‐ha fragment, whereas in the 10‐ha fragment seedling height had a greater increase at the edge and corner than in the centre. Furthermore, survival increased with distance from the edge as did leaf number, whereas height showed a lower increase closer to the edge than farther away.Regarding biotic damage, for both fragments herbivory was greater at the centres and decreased with edge proximity over time, whereas leaf‐fungal damage was greater at the corners than in the edges and increased significantly over time. Biotic damage was correlated with seedling size. Small seedlings were more susceptible to fungal attack, whereas larger seedlings were so to herbivores.Synthesis. This study demonstrated that despite stochastic environmental factors seedling survival, growth, and biotic damage by herbivores and fungal pathogens varied with the level of edge exposure and proximity, which may threaten forest regeneration in the long term.

Agricultural matrices affect ground ant assemblage composition inside forest fragments.

The establishment of agricultural matrices generally involves deforestation, which leads to fragmentation of the remaining forest. This fragmentation can affect forest dynamics both positively and negatively. Since most animal species are affected, certain groups can be used to measure the impact of such fragmentation. This study aimed to measure the impacts of agricultural crops (matrices) on ant communities of adjacent lower montane Atlantic rainforest fragments. We sampled nine forest fragments at locations surrounded by different agricultural matrices, namely: coffee (3 replicates); sugarcane (3); and pasture (3). At each site we installed pitfall traps along a 500 m transect from the interior of the matrix to the interior of the fragment (20 pitfall traps ~25 m apart). Each transect was partitioned into four categories: interior of the matrix; edge of the matrix; edge of the fragment; and interior of the fragment. For each sample site, we measured ant species richness and ant community composition within each transect category. Ant richness and composition differed between fragments and matrices. Each sample location had a specific composition of ants, probably because of the influence of the nature and management of the agricultural matrices. Species composition in the coffee matrix had the highest similarity to its corresponding fragment. The variability in species composition within forest fragments surrounded by pasture was greatest when compared with forest fragments surrounded by sugarcane or, to a lesser extent, coffee. Functional guild composition differed between locations, but the most representative guild was ‘generalist’ both in the agricultural matrices and forest fragments. Our results are important for understanding how agricultural matrices act on ant communities, and also, how these isolated forest fragments could act as an island of biodiversity in an ‘ocean of crops’.

High frequency/ultrasonic communication in a critically endangered nocturnal primate, Claire's mouse lemur (Microcebus mamiratra).

The critically endangered Claire's mouse lemur, only found in the evergreen rain forest of the National Park Lokobe (LNP) and a few lowland evergreen rain forest fragments of northern Madagascar, was described recently. The present study provides the first quantified information on vocal acoustics of calls, sound associated behavioral context, acoustic niche, and vocal activity of this species. We recorded vocal and social behavior of six male-female and six male-male dyads in a standardized social-encounter paradigm in June and July 2016 at the LNP, Nosy Bé island. Over six successive nights per dyad, we audio recorded and observed behaviors for 3 hr at the beginning of the activity period. Based on the visual inspection of spectrograms and standardized multiparametric sound analysis, we identified seven different call types. Call types can be discriminated based on a combination of harmonicity, fundamental frequency variation, call duration, and degree of tonality. Acoustic features of tonal call types showed that for communication, mouse lemurs use the cryptic, high frequency/ultrasonic frequency niche. Two call types, the Tsak and the Grunt call, were emitted most frequently. Significant differences in vocal activity of the Tsak call were found between male-female and male-male dyads, linked primarily to agonistic conflicts. Dominant mouse lemurs vocalized more than subdominant ones, suggesting that signaling may present an honest indicator of fitness. A comparison of our findings of the Claire's mouse lemur with published findings of five bioacoustically studied mouse lemur species points to the notion that a complex interplay between ecology, predation pressure, and phylogenetic relatedness may shape the evolution of acoustic divergence between species in this smallest-bodied primate radiation. Thus, comparative bioacoustic studies, using standardized procedures, are promising to unravel the role of vocalization for primate species diversity and evolution and for identifying candidates for vocalization-based non-invasive monitoring for conservation purposes.

The effectiveness of acoustic indices for forest monitoring in Atlantic rainforest fragments

Forest monitoring is essential to maintain the integrity of protected areas, which has become a more pressing issue due to anthropogenic pressures and global climate change. Birds are widely used for this purpose, and as bird diversity is correlated with acoustic indices, it has been suggested that sounds can be used as an ecological indicator of ecosystem complexity and environmental changes. However, previous studies yield controversial results. Thus, we evaluated the effectiveness of six acoustic indices compared with the results obtained from a traditional point-counts survey for forest monitoring in an Atlantic rainforest fragment in Southern Bahia, Brazil. We also determined differences between acoustic indices calculated in the presence and absence of the researcher in the field to quantify the bias caused by human presence during data collection. There was a moderate correlation between the number of bird species just with the acoustic evenness index, from the six acoustic indices evaluated. We also determined that the presence of the researcher in the field at the point-count survey caused bias in acoustic indices. Therefore, more research must be done with autonomous recording units and the acoustic indices before they can be widely adopted for monitoring purposes in complex and diverse habitats such as the Atlantic tropical rainforest.

Survey of social wasps (Hymenoptera, Vespidae, Polistinae) in Amazon rainforest fragments in Acre, Brazil

ABSTRACT The State of Acre, in the southwestern Brazilian Amazon, harbors high biodiversity and a high degree of endemisms. Nevertheless, there are few studies on the diversity of social wasps occurring in this region. This study presents a list of social wasps (Hymenoptera, Vespidae, Polistinae) collected actively with attractive bait in three rainforest fragments in Acre. A total of 758 wasps belonging to 11 genera and 36 species were collected. Nineteen species were new distribution records for Acre and three others were new records for Brazil. Based on our results, further investigations should lead to a significant increase in Polistinae diversity in this region, producing information for biogeographic studies and management of natural areas.