Small Atlantic Forest Fragments Research Articles

Worrisome isolation: noninvasive genetic analyses shed light on the critical status of a remnant jaguar population

Many carnivore species, particularly felids, are sensitive to land use changes and may disappear from landscapes with reduced natural habitat and increased fragmentation. The jaguar (Panthera onca) is highly affected by these factors and is particularly endangered in the Atlantic Forest (AF) of South America, one of the most threatened biomes in the world. We used noninvasive fecal sampling and microsatellite markers to investigate the genetic diversity of jaguars in one of the last remnant populations of this species in the entire coastal AF. This section of the biome is highly fragmented. We observed low levels of genetic diversity (HO = 0.621, HE = 0.532, AR = 3.195), and estimated a small effective size for the population (Nₑ = 7.9 individuals). We performed comparative analyses incorporating data from previously surveyed populations located farther inland (interior AF), revealing that the coastal population studied shows significant genetic differentiation. Our results support a scenario of anthropogenic, drift-induced differentiation among jaguar populations in small AF fragments, affecting both the interior and coastal components of this biome. Despite its low diversity, we detected putatively unique alleles present in the coastal population, supporting its importance in the context of maintaining the remaining genetic variability of jaguars in the AF. Our results highlight the urgent need to implement coordinated conservation actions for jaguars in this highly impacted biome, including management interventions that foster the restoration of genetic connectivity among isolated remnant populations. Muitas especies de carnivoros, particularmente felinos, sao sensiveis as mudancas no uso do solo e podem desaparecer de paisagens com proporcoes reduzidas de habitat natural e elevada fragmentacao. A onca-pintada (Panthera onca) e muito afetada por esses fatores e esta particularmente ameacada na Mata Atlântica, um dos biomas mais ameacados do mundo. Foram utilizadas amostras fecais nao-invasivas e marcadores microssatelite para investigar a diversidade genetica de oncas-pintadas em uma das ultimas populacoes remanescentes desta especie em toda Mata Atlântica costeira. Esta porcao do bioma esta altamente fragmentada e as poucas populacoes remanescentes de onca-pintada ainda nao foram avaliadas geneticamente. Foram observados baixos niveis de diversidade genetica (HO = 0,621; HE = 0,532; AR = 3,195) e estimado um pequeno tamanho populacional efetivo (Nₑ = 7,9 individuos). Analises comparativas incorporando dados de populacoes anteriormente amostradas e localizadas no interior do bioma (Mata Atlântica de interior) revelaram que a populacao costeira estudada apresenta significativa diferenciacao genetica em relacao aos outros remanescentes. Os resultados obtidos apoiam um cenario de diferenciacao induzida por deriva antropogenica entre populacoes de onca-pintada em pequenos fragmentos da Mata Atlântica, afetando tanto os componentes de interior quanto costeiros deste bioma. Apesar de sua baixa diversidade genetica, foram detectados alelos exclusivos na populacao costeira, indicando a importância deste remanescente para a manutencao do que ainda resta da variabilidade genetica das oncas-pintadas da Mata Atlântica como um todo. Mostra-se necessaria a urgente implementacao de acoes coordenadas de conservacao para as oncas-pintadas neste bioma altamente impactado, incluindo intervencoes de manejo que promovam a restauracao da conectividade genetica entre as populacoes remanescentes e isoladas.

Use of small Atlantic Forest fragments by birds in Southeast Brazil

Small forest fragments may play a major role in fragmented areas, but there is scarce empirical data to test this hypothesis. To understand in which context birds can use small Atlantic Forest fragments, we tested the presence of 11 bird species in 30 small fragments (4–10ha), in a range of matrices (eucalyptus-pasture), and in different landscape configurations. The results showed that landscape composition is a good predictor for presence of birds in small fragments and their use can be further associated with matrix type. Considering the number of species, and the species Chiroxiphia caudata, we found a pattern in which models that consider the matrix composition are the most plausible. Relative importance of the variables indicates that matrix is the most important single variable among the selected species (five among eight). This suggests that small fragments are effective for increasing connectivity, mainly in landscapes with a higher percentage of permeable matrix.

Reproductive phenology, seed removal and early regeneration in relation to distance from parental plants of a native palm in small Atlantic forest fragments

The Brazilian Atlantic Forest is a global biodiversity hotspot, but most of what remains are small fragments. Small fragments are often harsh environments for forest plant recruitment due to edge effects and the loss of frugivorous animals that provide seed dispersal. We recorded the one-year reproductive phenology of the keystone palm Syagrus romanzoffiana in small (<2.5ha) Atlantic Forest fragments in southeastern Brazil. We tested the Janzen-Connell hypothesis with seed-removal experiments and followed the five-year survival of recruits in relation to the distance from parental plants. Palms produced many fruits throughout the year (mean 2,600/plant). More seedlings were found away from parental plants than near them, thereby supporting the Janzen-Connell hypothesis. Almost 45% of seedlings alive in 2010 were dead five years later, but recruitment of new seedlings compensated for this mortality. Distance-dependent factors influenced the density of early ontogenetic stages, but had limited effects on juveniles or on seed removal. High seed production, seed dispersal provided by disturbance-tolerant frugivores and the relatively long-term survival of adults, seedlings and juveniles seem to allow the persistence of S. romanzoffiana in the forest fragments, but possibly at the cost of an increased clumped distribution and reduced gene flow at the landscape scale.

Increased female reproduction favours the large-seeded palm Attalea humilis in small Atlantic Forest fragments

Palms are important components of tropical forest plant communities, due both to their abundance (Henderson et al. 2000) and to the network of interactions with their pollinators and dispersers (Henderson 2002, Zona &amp; Henderson 1989). Forest fragmentation alters the biotic and abiotic conditions of habitats (Ewers &amp; Didham 2006, Fahrig 2003) and it has been observed that Attalea palms increase their densities in disturbed sites (Aguiar &amp; Tabarelli 2009, Andreazzi et al. 2012, Lorenzi et al. 2004). Increased light availability (Salm 2005, Souza &amp; Martins 2004), changes in seed dispersal and predation patterns (Andreazzi et al. 2012, Pimentel &amp; Tabarelli 2004, Wright et al. 2000), and ability to recover after disturbance (Souza &amp; Martins 2004) are among the main mechanisms that have been proposed to explain enhanced palm densities. However, how altered conditions following disturbances influence the dynamics of flower and fruit production is still little understood.

Differences in seed rain composition in small and large fragments in the northeast Brazilian Atlantic Forest

Tropical forests are seriously threatened by fragmentation and habitat loss. The impact of fragment size and forest configuration on the composition of seed rain is insufficiently studied. For the present study, seed rain composition of small and large forest fragments (8-388 ha) was assessed in order to identify variations in seed abundance, species richness, seed size and dispersal mode. Seed rain was documented during a 1-year period in three large and four small Atlantic Forest fragments that are isolated by a sugarcane matrix. Total seed rain included 20,518 seeds of 149 species of trees, shrubs, palms, lianas and herbs. Most species and seeds were animal-dispersed. A significant difference in the proportion of seeds and species within different categories of seed size was found between small and large fragments. Small fragments received significantly more very small-sized seeds (<0.3 cm) and less large-seeded species (>1.5 cm) that were generally very rare, with only one species in small and eight in large fragments. We found a negative correlation between the inflow of small-sized seeds and the percentage of forest cover. Species richness was lower in small than in large fragments, but the difference was not very pronounced. Given our results, we propose changing plant species pools through logging, tree mortality and a high inflow of pioneer species and lianas, especially in small forest fragments and areas with low forest cover. Connecting forest fragments through corridors and reforestation with local large-seeded tree species may facilitate the maintenance of species diversity.

Increased Productivity and Reduced Seed Predation Favor a Large‐seeded Palm in Small Atlantic Forest Fragments

ABSTRACTLarge‐seeded plants are especially vulnerable to the loss of seed dispersers in small forest fragments. The palm Attalea humilis goes against this trend by reaching high abundances in small remnants. Productivity, seed dispersal and seed predation of A. humilis were investigated in two large (2400 and 3500 ha) and three small (19, 26 and 57 ha) Atlantic Forest fragments in southeastern Brazil. Palms in the small fragments produced more female inflorescences, resulting in a higher fruit production in these places. Seed dispersal rates were higher in the large fragments, where scatter hoarding was more frequent. Scolytine beetles were the main seed predators and damaged a larger number of seeds in small fragments, but predation by rodents and bruchine beetles was low irrespective of fragment size. As scolytines do not necessarily kill the seeds, low predation by bruchines and rodents, together with its own high productivity, allow A. humilis to be more abundant in small fragments despite the scarcity of its main dispersers. This increased abundance, by its turn, can increase competitive interactions between A. humilis and other plants in small fragments. Thus, abundance patterns of A. humilis are a good example of fragmentation affecting the balance of ecological interactions in a complex way, emphasizing the role of preserving ecological processes for conserving biodiversity in fragmented tropical landscapes.Abstract in Portuguese is available at http://www.blackwell‐synergy.com/loi/btp.

Bat frugivory in a remnant of Southeastern Brazilian Atlantic forest

Knowledge of bat diets may be important for the conservation of small Atlantic Forest fragments because these animals play an important role in seed dispersal and natural recovery of tropical forests. The ‘Reserva Particular do Patrimônio Natural Feliciano Miguel Abdala’ (RPPN-FMA) is a 886-hectare Atlantic forest fragment consisting of a mosaic of distinct successional phases resulting from logging and natural causes, in the state of Minas Gerais, Brazil. We collected 216 fecal samples containing blood, arthropods, pollen-nectar, vegetation (leaflets and fruit peel), fruit pulp (fibers and juice) and seeds, from 18 bat species at the RPPN-FMA. Piperaceae, Solanaceae, Cecropiaceae, and Guttiferae were the most important food resources for frugivorous bats at RPPN-FMA. Piper infrutescences were consumed by Artibeus obscurus, A. fimbriatus, Carollia perspicillata, and Sturnira lilium throughout the year, functioning as key species, as already observed for other tropical rainforest sites.

Food habits of sympatric opossums coexisting in small Atlantic Forest fragments in Brazil

The diets of sympatric species of opossums coexisting in small (<10 ha) Atlantic Forest fragments were studied at Poço das Antas Biological Reserve, southeastern Brazil. Food items consumed by Caluromys philander and Didelphis aurita were investigated through the analysis of faecal contents, and compared with the diet of Micoureus demerarae analysed in a previous study. The major diet components for all three species were arthropods and fruits, with a high richness of items of both feeding categories; feathers were also found in the diet of D. aurita. The most frequent insect orders overall were Hymenoptera and Coleoptera, and most seeds were from plants of secondary vegetation such as Cecropia and Piper. The diets showed little variation along time and space for all three species. Diets were also similar among species, except for a larger consumption of Arachnida and Diplopoda and a smaller consumption of Lepidoptera by D. aurita when compared to M. demerarae. Diversity of food items was lower for C. philander when compared with either other species. There was a high feeding niche overlap between species, suggesting that differentiation in diet composition would not be enough to allow coexistence of the three species in small fragments. Coexistence may rather be allowed by vertical segregation and/or by differences in prey size.

Metapopulation viability of the marsupial Micoureus demerarae in small Atlantic forest fragments in south-eastern Brazil

Metapopulation viability of the marsupial Micoureus demerarae in small Atlantic forest fragments in south-eastern Brazil

Metapopulation viability of the marsupial Micoureus demerarae in small Atlantic forest fragments in south‐eastern Brazil

AbstractA population viability analysis (PVA) was carried out for populations of the arboreal didelphid Micoureus demerarae in eight small (1.5–15.0 ha) forest fragments in south‐eastern Brazil. Analysis was based on field data obtained through demographic studies carried out since 1995. Populations are small, but connected by dispersing individuals, thus forming a metapopulation. Frequency of catastrophic fires was estimated from the Reserve's historical records. We used the computer package VORTEX for all analyses. All populations and the metapopulation were found to be endangered within 100 years (extinction probability &gt; 0.98). A sensitivity analysis was run varying six parameters: three demographic (sex ratio, migration and mortality rates), two environmental (K, fire frequency) and one genetic (level of inbreeding depression). Genetics, K, mortality rates and sex ratio seemed to play major roles to population persistence, whereas catastrophes and migration rates had a secondary role. Among demographic factors, extinction rate was least sensitive to migration rate. Micoureus demerarae can be used as a model species, thus improving our knowledge of how extinction‐prone populations of neotropical arboreal marsupials in forest fragments might be, and which management actions could decrease such risks.

Use of space by the marsupial Micoureus demerarae in small Atlantic Forest fragments in south-eastern Brazil

The spatial patterns presented by the marsupial Micoureus demerarae were studied through capture–mark–recapture in two small Atlantic Forest fragments (areas 7.1 and 8.8 ha). The study took place from March 1995 to August 1997. Considering all captures of each individual, males did not have larger home ranges within the fragments than did females. A negative correlation was found between home range sizes and population densities. For males, home ranges overlapped often, and were larger during the breeding season. For females, home ranges did not overlap except for a short period when there were many individuals present, and home range sizes were not significantly larger in the breeding season. Five movements between the two forest fragments were detected, across 300 m of open vegetation. All the movements were performed by males during the reproductive season. M. demerarae in the small fragments therefore displays a metapopulation structure, although possibly an atypical one where only males disperse.