Fragmented Brazilian Atlantic Forest Research Articles

Diurnal roosts and minimum home range defined by sleeping sites of a thin-spined porcupine Chaetomys subspinosus (Rodentia: Erethizontidae)

The thin-spined porcupine Chaetomys subspinosus (Olfers, 1818) is a species endemic to the extremely disturbed and fragmented Brazilian Atlantic forest. Little is known about its natural history. We analyzed the preferences of porcupine diurnal roost and home range, based on one relocated adult male that was radio-monitored during 1999. The individual was captured in the urban zone of Santa Teresa, Brazil, and relocated to a forest reserve 6 km from the capture site. The thin-spined porcupine feeds only on leaves. It prefers intermediate forest stratum (6-15 m of height) for roosting during daytime, generally using inclined branches with a diameter of 2 to 5 cm. Most observations indicated a prehensile tail position. Home range was relatively large (15.81 ha) for an arboreal animal of this size and new areas were still being explored after five months of monitoring.

Blood parasites in Brazilian Atlantic Forest birds: effects of fragment size and habitat dependency

SummaryDeforestation, fragmentation and habitat disturbance may alter the relationship between pathogens and hosts. We tested, apparently for the first time, whether habitat fragmentation and degree of dependence on forests affect the prevalence of avian blood parasites. We estimated the prevalence of Plasmodium, Haemoproteus and Trypanosoma through the inspection of 925 blood smears from 109 species captured in six pairs of small (< 30 ha) and large (> 1,000 ha) Brazilian Atlantic Forest fragments. Prevalence of the three types of parasites did not differ between small and large forest patches. Forest-independent birds were usually more infected with Plasmodium and Haemoproteus than other birds, but forest-dependent birds were more infected with Trypanosoma. Parasite richness on birds was not affected by patch size.

Landscape-Level and Fine-Scale Genetic Structure of the Neotropical TreeProtium spruceanum(Burseraceae)

Knowledge of genetic structure at different scales and correlation with the current landscape is fundamental for evaluating the importance of evolutionary processes and identifying conservation units. Here, we used allozyme loci to examine the spatial genetic structure (SGS) of 230 individuals ofProtium spruceanum, a native canopy-emergent in five fragments of Brazilian Atlantic forest (1 to 11.8 ha), and four ecological corridors (460 to 1 000 m length). Wright's statistic and Mantel tests revealed little evidence of significant genetic structure at the landscape-scale (; , ). At fine-scale SGS, low levels of relatedness within fragments and corridors (, ) were observed. Differences in the levels and distribution of the SGS at both spatial scales are discussed in relation to biological and conservation strategies of corridors and forest fragments.

Abundance of tegu lizards (Tupinambis merianae) in a remnant of the Brazilian Atlantic forest

AbstractWe investigated the abundance of the tegu lizard (Tupinambis merianae) in a 21 787 ha Brazilian Atlantic forest fragment (Reserva Natural Vale, RNV). This remnant has a highly irregular perimeter and an extensive network (126 km) of internal unpaved roads. We hypothesized that the high proportion of these edge habitats might benefit active heliothermic lizards like tegus due to greater incidence of sunlight. We estimated population density using the program DISTANCE, and compared sighting frequency of tegus along twelve 500 m long transects located at three distances (25, 200 and 400 m) from the nearest unpaved road or fragment edge. We found no significant differences in sighting frequency among the three distances (Chi-square; χ2 = 4.308; P = 0.116) and no significant association between edge distance and edge type (internal, external) (G test adjusted; G2 = 0.617; P = 0.734). However, as the test comparing distances had relatively low power we assumed that the experimental evidence was not strong enough to prove lack of an edge effect. The estimated density (0.63±0.13 lizard/ha) is within the range of densities found on Brazilian islands where tegus have proliferated to the point of becoming a threat to ground nesting birds and turtles. We caution, however, that the absence of published data on other non-island sites prevents us from concluding that the species has an abnormally high density in RNV.

Genetic differentiation of the neotropical tree species Protium spruceanum (Benth.) Engler (Burseraceae) between fragments and vegetation corridors in Brazilian Atlantic forest

We studied patterns of genetic differentiation in a connected landscape with an interesting history of human habitat conversion that began two centuries ago, during the Brazilian colonization period. In the fragments of Brazilian Atlantic seasonal forest and corridors of secondary forest, Protium spruceanum is an abundant native, mass-flowering/insect-pollinated and bird-dispersed tree. Genetic diversity was analyzed from 230 individuals in five fragments (1 to 11.8 ha) and four corridors (460 to 1000 m length) using allozyme loci. We did not find evidence of inbreeding within fragments or corridors, but the proportion of heterozygotes (<IMG SRC="/img/revistas/abb/v23n4/a28simb1.gif" WIDTH=287 HEIGHT=96>) were significantly higher in fragments than in the secondary vegetation corridors, based on Goudet's G-test (P = 0.036). Genetic differentiation was low and no pattern of isolation by distance was detected. All fragments generally present low historical genetic differentiation with corridors that they are connected, indicating possible gene flow via seeds and pollen. Due to the consistently low differentiation observed among them and the absence of a significant reduction in gene diversity in second-growth forests, we conclude that corridors of second-growth forests would be an important alternative in the genetic connection of isolated forest fragments.

Spatial Pattern and Fine-Scale Genetic Structure Indicating Recent Colonization of the Palm Euterpe edulis in a Brazilian Atlantic Forest Fragment

Rainforests worldwide are subject to increasing amounts of external pressure and degradation that dissect continuous species distributions into small and isolated fragments (Whitmore 1997). This spatial isolation and reduction of natural populations negatively affects the reproductive success of many tropical plants (Fuchs et al. 2003; Quesada et al. 2004). A reduction in the number of reproductive individuals in a population represents a decrease in the number of pollen/ovary donors and in the quantity of pollen deposited (Aizen and Feinsinger 1994). This may be accompanied by a decrease in the abundance of pollinators and selection for self-compatibility (Stephenson et al. 2000). Subsequently, such impacts can lead to

Is bird incidence in Atlantic forest fragments influenced by landscape patterns at multiple scales?

The degree to which habitat fragmentation affects bird incidence is species specific and may depend on varying spatial scales. Selecting the correct scale of measurement is essential to appropriately assess the effects of habitat fragmentation on bird occurrence. Our objective was to determine which spatial scale of landscape measurement best describes the incidence of three bird species (Pyriglena leucoptera, Xiphorhynchus fuscus and Chiroxiphia caudata) in the fragmented Brazilian Atlantic forest and test if multi-scalar models perform better than single-scalar ones. Bird incidence was assessed in 80 forest fragments. The surrounding landscape structure was described with four indices measured at four spatial scales (400-, 600-, 800- and 1,000-m buffers around the sample points). The explanatory power of each scale in predicting bird incidence was assessed using logistic regression, bootstrapped with 1,000 repetitions. The best results varied between species (1,000-m radius for P. leucoptera; 800-m for X. fuscus and 600-m for C. caudata), probably due to their distinct feeding habits and foraging strategies. Multi-scale models always resulted in better predictions than single-scale models, suggesting that different aspects of the landscape structure are related to different ecological processes influencing bird incidence. In particular, our results suggest that local extinction and (re)colonisation processes might simultaneously act at different scales. Thus, single-scale models may not be good enough to properly describe complex pattern–process relationships. Selecting variables at multiple ecologically relevant scales is a reasonable procedure to optimise the accuracy of species incidence models.

Extirpation of large-seeded seedlings from the edge of a large Brazilian Atlantic forest fragment

In this study we assessed the seedling assemblages of a large fragment of the Atlantic forest to test 2 hypotheses: (1) seedling abundance and richness are lower in the forest edge (0–200 m) than in the forest interior (> 250 m); and (2) large-seeded seedlings (seeds < 1.5 cm) are the main group affected by edge creation. The study was carried out at the Coimbra forest, an old, 3 500-ha fragment surrounded by sugar cane plantations in northeast Brazil. The seedling survey was based on 200-m-long transects along which 420 plots of 1-m2 were set up per habitat and per season (dry and rainy). Within the plots, all shrub, tree, palm, and liana species seedlings ≤ 50 cm tall were counted and classified to morphospecies level. A total of 13 208 seedlings were recorded in the whole survey. At plot level, forest edge and interior showed similar scores for both average seedling density (4.7–11.2 seedlings·m−2) and richness (2.8–5.1 species·m−2) irrespective of season. At community level, however, scores for total species richness were 4.8–17.9% lower in forest edge plots than in those of the forest interior, depending on the estimator used. Moreover, large-seeded species accounted for 2.3–2.7% of all species recorded in forest edge plots, yet this group reached 13.1–14.9% in forest interior plots. As a consequence, the forest edge housed between 166 and 262 large-seeded seedlings·ha−1, whereas the forest interior housed 5 952–6 047 large-seeded seedlings·ha−1. Our results suggest that old forest edges hold biased and impoverished assemblages of seedlings, particularly in terms of large-seeded trees.

Efficiency of playback for assessing the occurrence of five bird species in Brazilian Atlantic Forest fragments

Playback of bird songs is a useful technique for species detection; however, this method is usually not standardized. We tested playback efficiency for five Atlantic Forest birds (White-browed Warbler Basileuterus leucoblepharus, Giant Antshrike Batara cinerea, Swallow-tailed Manakin Chiroxiphia caudata, Whiteshouldered Fire-eye Pyriglena leucoptera and Surucua Trogon Trogon surrucura) for different time of the day, season of the year and species abundance at the Morro Grande Forest Reserve (South-eastern Brazil) and at thirteen forest fragments in a nearby landscape. Vocalizations were broadcasted monthly at sunrise, noon and sunset, during one year. For B. leucoblepharus, C. caudata and T. surrucura, sunrise and noon were more efficient than sunset. Batara cinerea presented higher efficiency from July to October. Playback expanded the favourable period for avifaunal surveys in tropical forest, usually restricted to early morning in the breeding season. The playback was efficient in detecting the presence of all species when the abundance was not too low. But only B. leucoblepharus and T. surrucura showed abundance values significantly related to this efficiency. The present study provided a precise indication of the best daily and seasonal periods and a confidence interval to maximize the efficiency of playback to detect the occurrence of these forest species.

Patch size and isolation effects on epiphytic and epiphyllous bryophytes in the fragmented Brazilian Atlantic forest

An inventory of the understory forest epiphyte and epiphyllous bryophyte floras was carried out in eight Atlantic rain forest fragments. The fragments were between 7 and 500 ha in size and belonged to two areas (lowland and submontane) of the state of Pernambuco, northeastern Brazil. The aim of this study was to investigate the effect of habitat fragmentation and changes in the natural landscape on community structure (composition, richness, diversity, and abundance). Although the influence of altitude was noted in this study by increasing richness, diversity, and abundance, it was clear that in some fragments the influence of fragment size and isolation can be more important than this positive environmental factor. Fragment size and isolation affect both communities but the last one seems to be a stronger threatening factor for the epiphylls. The least isolated and the largest fragments housed the richest floras – especially in relation to the epiphylls – and had the greatest proportion of shade species. Habitat fragmentation negatively affected epiphytic and epiphyllous bryophytes and increased the representation of species with larger niches (generalists) while decreasing the representation of species with smaller niches (typically found in shady or in sunny areas). The results suggests that the critical fragment size necessary for bryophyte preservation must be correlated with insularity levels; for epiphytes, however, it is likely that low levels of isolation cannot compensate borderline effects as with the epiphyllous bryophytes.

Morphology and anatomy of a leaf mine in Vismia guianensis (Aubl.) Choisy (Clusiaceae) in a fragment of Brazilian Atlantic forest

Mines or hyponomes are channels caused by larva miners consuming internal plant tissues. These miners live on the leaf and feed from these tissues. Leaf mines are usually visible on the exterior of the leaf as serpentine paths, blotches, or other characteristic shapes of discolored tissues. Morphological and structural modifications undergone by mined leaves of Vismia guianensis (Aubl.) Choisy are presented here with the purpose of elucidating their structure and to contribute to studies about insect-plant interactions. Healthy and mined leaves were harvested from thirty plants and taken to the laboratory. For each branch, the total number of young and mature leaves, the number of leaves with mines and the number of mine per leaf were counted. Transverse sections of healthy and mined leaves were obtained to observe the morpho-anatomic aspects. From the 1,438 mature leaves and 379 young leaves analyzed, 214 (14.9%) and 70 (18.5%) were mined, where most of the leaves (67%) presented one mine per leaf. Transverse sections of the mine revealed that the larva consumed only mesophyll parenchyma tissue and the epidermis remains intact. There is not a pattern of leaf mining, but the larvae did not consume the druses observed on mesophyll and the vascular tissues of the mid-vein and lateral vein.

Influence of edge and fire-induced changes on spatial distribution of small mammals in Brazilian Atlantic forest fragments

The spatial distribution of small mammals in relation to distance from forest edges, before and after fire, was studied in Atlantic Forest fragments in Brazil. None of nine species was captured exclusively on either edges or forest interior. Before the fire only the rodents Akodon cursor and Oecomys con-color were captured more often at the edge than randomly expected. After the fire only A. cursor remained associated with edges; it had increased in number and penetrated farther than before into the forest fragments. The marsupial Micoureus demerarae became more restricted to the forest interior than randomly expected. These results suggest that small mammal species tolerant to habitat changes induced by edge effects and fire have better chances to survive in forest fragments.

Species richness and relative abundance of birds in natural and anthropogenic fragments of Brazilian Atlantic forest.

Bird communities were studied in two types of fragmented habitat of Atlantic forest in the State of Paraná, southern Brazil; one consisted of forest fragments that were created as a result of human activities (forest remnants), the other consisted of a set of naturally occurring forest fragments (forest patches). Using quantitative data obtained by the point counts method in 3 forest patches and 3 forest remnants during one year, species richness and relative abundance were compared in those habitats, considering species groups according to their general feeding habits. Insectivores, omnivores, and frugivores presented similar general tendencies in both habitats (decrease of species number with decreasing size and increasing isolation of forest fragment). However, these tendencies were different, when considering the relative abundance data: the trunk insectivores presented the highest value in the smallest patch while the lowest relative abundance was in the smallest remnant. In the naturally fragmented landscape, time permitted that the loss of some species of trunk insectivores be compensated for the increase in abundance of other species. In contrast, the remnants essentially represented newly formed islands that are not yet at equilibrium and where future species losses would make them similar to the patches.

Patch Structure within Brazilian Atlantic Forest Fragments and Implications for Conservation1

ABSTRACTForest structure and tree species composition were studied in four Atlantic seasonal forest fragments ranging from 0.7 to 220 ha, isolated for more than a century in southeastern Brazil. Four physiognomic units were recognized within these fragments: (1) low forest, (2) bamboo forest, (3) high forest, and (4) mature forest. Tree density, basal area, and species diversity (Shannon‐Wiener index) increased from low forest to bamboo forest to high forest to mature forest. Liana cover was highest in low forest. Gap‐opportunistic species were the dominant ecological group in low forest, bamboo forest, and high forest, while shade tolerant canopy species formed the dominant group in mature forest. These structural and compositional features formed a gradient of forest development from the least developed low and bamboo forests to the most developed mature forest. Low forest is hypothesized to be in a stage of arrested succession and high forest a stage of degraded forest. A conceptual model is suggested to explain how these physiognomic units may be related to one another. Although these fragments were covered mainly by high and low forests and thus had a degraded structure, species diversity remained high in all of them. Fragments thus may undergo degradation long after isolation, even when they have been protected from human disturbance for a considerable period. Nonetheless, they also preserve important samples of local and regional floristic diversity for a long time after isolation.

Patch Structure within Brazilian Atlantic Forest Fragments and Implications for Conservation1

Forest structure and tree species composition were studied in four Atlantic seasonal forest fragments ranging from 0.7 to 220 ha, isolated for more than a century in southeastern Brazil. Four physiognomic units were recognized within these fragments: (1) low forest, (2) bamboo forest, (3) high forest, and (4) mature forest. Tree density, basal area, and species diversity (Shannon-Wiener index) increased from low forest to bamboo forest to high forest to mature forest. Liana cover was highest in low forest. Gap-opportunistic species were the dominant ecological group in low forest, bamboo forest, and high forest, while shade tolerant canopy species formed the dominant group in mature forest. These structural and compositional features formed a gradient of forest development from the least developed low and bamboo forests to the most developed mature forest. Low forest is hypothesized to be in a stage of arrested succession and high forest a stage of degraded forest. A conceptual model is suggested to explain how these physiognomic units may be related to one another. Although these fragments were covered mainly by high and low forests and thus had a degraded structure, species diversity remained high in all of them. Fragments thus may undergo degradation long after isolation, even when they have been protected from human disturbance for a considerable period. Nonetheless, they also preserve important samples of local and regional floristic diversity for a long time after isolation.

The influence of edge on small mammals: evidence from Brazilian Atlantic forest fragments

Small mammal diversity was examined in relation to distance from the forest/farmland edge in two fragments of Brazilian Atlantic forest in Sergipe, Brazil. Tolerance to and use of the edge and surrounding matrix of agricultural land by nine species of small mammals, as well as microclimatic conditions and vegetation structure were measured along 12 transects placed both inside the forest and in the surrounding matrix. As distance from edge increased into the forest, both the number of species and species diversity significantly increased, air temperature significantly decreased and relative humidity significantly increased. During the study, no small mammals were captured outside of the forest in the surrounding farmland. Of the 671 total captures, only 43 occurred along the edge, and 39 of the 43 were captures of only two species. This influence that edge may have on some small mammals may be a key to discerning a species' probability of survival in small fragments with hard edges.