Structure, diversity, and spatial patterns in a permanent plot of a high Restinga forest in Southeastern Brazil (original) (raw)
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Rodriguésia
Tropical forests are one of the most important ecosystems and loss of biological diversity in these is a major concern. We studied seven forest remnants on the coast of Rio de Janeiro, southeastern Brazil, three medium-sized (24-63 ha) and four small (5-11 ha), to assess the influence of size, degree of disturbance and isolation on composition and diversity of the tree layer. A total of 443 species in 60 families and 185 genera were recorded, with Myrtaceae, Lauraceae and Fabaceae being the most species-rich families. The results showed areas of high α-diversity (α= 34.86-75.69) and a slightly greater decline of similarity with distance between the study areas. Remnant size not explained the variation in the species composition and we found correlation between the level of disturbance and the floristic composition. The remnants had low floristic similarity, strongly influenced by the degree of disturbance. Results suggest that disturbance influences composition and diversity and con...
TREE COMMUNITY STRUCTURE IN A SEASONALLY DRY TROPICAL FOREST REMNANT, BRAZIL
ABSTRACT: Most studies on Seasonally Dry Tropical Forests (SDTFs) investigate phytogeographic patterns and floristic connections of this disjunct biome. However, little is known about the structural characteristics of SDTFs. We aimed to describe the structure of a SDTF in an ecotonal area between the Cerrado and Caatinga domains. In total, 79 tree species were recorded, and high values of Shannon diversity index (3.6 nats/individual) and equability (0.83) were observed. The diameter distribution for the species with higher cover values and for the entire community did not exhibit a reverse-J shaped distribution, which indicates the occurrence of different growth strategies and ecological adaptations to water stress. The results did not indicate the formation of floristic groups, as the high soil fertility in the study area results in a homogeneous environment. The structural characteristics of the study area associated with the soil composition highlight its importance for conservation and emphasize the need for community structure studies in SDTFs.
Bosque (Valdivia), 2017
Seasonally Dry Tropical Forests (SDTF) are gaining recognition as a habitat of global conservation significance. However, these forests often occur on rich soils, and are therefore prone to disturbance by agricultural activities. Across their range, many SDTFs are in various stages of regeneration, although little is known about their regeneration dynamics and temporal change in general. To fill this knowledge gap, we studied the changes in species diversity and community structure of an SDTF tree community with a history of past selective logging located in northern Minas Gerais, Brazil. We hypothesized an increase in species diversity and biomass-related parameters, along with a reduction in stem density for the community after five years of regeneration. In 2005, we measured all trees (diameter ≥ 3.18 cm at 1.3 m) within twenty 20 x 20 m (400 m²) plots in the patch, and we remeasured the trees in 2010. Between the two censuses, we found no significant changes in species richness and diversity, suggesting that species accumulation had leveled out. However, we found significant gains in tree basal area and recruitment, suggesting continual regeneration. Diameter class distributions of the five most abundant tree species showed similar patterns. We conclude that past disturbances can have ongoing effects on SDTF vegetation, although inter-annual variations may also play a regulatory role on community dynamics.
Floristic, Diversity and Spatial Distribution of Tree Species in a Dry Forest in Southern Brazil
Applied Ecology and Environmental Research, 2017
This study was conducted in a fragment of deciduous seasonal forest (DSF), located between the municipalities of Piratuba and Ipira, Santa Catarina. The objective was to evaluate the floristic composition and the successional stage through the ecological groups, the Shannon diversity index (H') and the dispersal syndromes of species, also using the H' and the McGinnies index (IGA) to determine the pattern of spatial distribution of species. 14 transects were installed, each with 1,000 m 2 , considering all trees with Diameter at Breast Hight (DBH) ≤ 4.0 cm. In total, 2,125 individuals were sampled, belonging to 113 species and 34 families. Myrtaceae and Fabaceae were the families with the highest species richness, with 14.2% and 11.5%, respectively. Euphorbiaceae and Lauraceae added approximately 25% of the individuals. The most abundant species were Actiniostemon concolor (Spreng.) Müll. Arg (6.9%) and Luehea divaricata Mart. (6.7%). The ecological group of the pioneers totaled 40% of the individuals and 36.3% of the species. The zoochoric syndrome accounted for just over 60% of individuals and species. The H' was 3.92 nats. ind-1 and the Pielou evenness (J) was 0.82. The IGA revealed that only over 40% of the species and 60% of the individuals showed a clumped dispersion pattern. The community is on successional transition phase, from the initial to the intermediate stage. In this scenario, management measures adopted for the microscale could be implemented in order to preserve this important repository for diversity. The application of McGinnies index can be of great use in conservation and forest management, as its interpretation may contribute to the development of restoration methods of degraded areas, enrichment of forest remnants, germplasm conservation and other activities.
Acta Botanica Brasilica, 2013
Th e aim of this work was to evaluate the fl oristic composition, richness, and diversity of the upper and lower strata of a stretch of mixed rain forest near the city of Itaberá, in southeastern Brazil. We also investigated the diff erences between this conservation area and other stretches of mixed rain forest in southern and southeastern Brazil, as well as other nearby forest formations, in terms of their fl oristic relationships. For our survey of the upper stratum (diameter at breast height [DBH] ≥ 15 cm), we established 50 permanent plots of 10 × 20 m. Within each of those plots, we designated fi ve, randomly located, 1 × 1 m subplots, in order to survey the lower stratum (total height ≥ 30 cm and DBH < 15 cm). In the upper stratum, we sampled 1429 trees and shrubs, belonging to 134 species, 93 genera, and 47 families. In the lower stratum, we sampled 758 trees and shrubs, belonging to 93 species, 66 genera, and 39 families. In our fl oristic and phytosociological surveys, we recorded 177 species, belonging to 106 genera and 52 families. Th e Shannon Diversity Index was 4.12 and 3.5 for the upper and lower strata, respectively. Cluster analysis indicated that nearby forest formations had the strongest fl oristic infl uence on the study area, which was therefore distinct from other mixed rain forests in southern Brazil and in the Serra da Mantiqueira mountain range.
Spatial variability of tree species diversity in a mixed tropical forest in Southern Brazil
Anais da Academia Brasileira de Ciências
Floristic surveys and diversity indices are often applied to measure tree species diversity in mixed tropical forest remnants. However, these analyses are frequently limited to the overall results and do not allow to evaluate the spatial variability distributions of tree diversity, leading to develop additional tools. This study aimed to estimate the spatial variability of tree diversity and map their spatial patterns in a Brazilian mixed tropical forest conservation area. We used indices to measure the tree species diversity (dbh ≥ 10 cm) in 400 sampling units (25 m x 25 m) from a continuous forest inventory. Semivariograms were fitted to estimate spatial dependences and punctual kriging was applied to compose maps. Mean diversity values were constant in the continuous inventories, indicating a forest remnant in an advanced stage of ecological succession. On the other hand, tree diversity presented spatial patterns identified by geostatistics, in which the dynamics were composed of heterogeneous mosaics spatially influenced by tree species with different ecological features and densities, gap dynamics, advancement of forest succession, mortality, and Araucaria angustilofia's cohorts.
A hot-point within a hot-spot: a high diversity site in Brazil’s Atlantic Forest
Biodiversity and Conservation, 2007
The Brazilian Atlantic Forest is considered one of the world’s most important sites for biodiversity conservation, and within this biome there are regions with differing levels of species richness, species composition, and endemism. The present study was undertaken in southern Bahia, Brazil, and employed a standardized sampling method to compare the density of arboreal species in this region with other areas throughout the world known for their high tree species density. A total of 144 tree species with DBH > 4.8 cm were sampled within a 0.1 ha plot of old-growth forest (OGF), and these data were then compared with 22 other world sites that had been sampled using the same methodology and likewise demonstrated high densities of arboreal species. Only one site of ombrophilous forest in Colombia demonstrated a higher tree species density (148 spp. in 0.1 ha) than was encountered in southern Bahia. Other areas of Brazil, including other Atlantic Forest sites, showed significantly inferior tree species densities. These results indicate that this region of southern Bahia has one of the greatest numbers of tree species in Brazil and in the world. These results, associated with the high levels of endemism there, indicate the high biological importance of this region. It is therefore fundamental that efforts aimed at halting the degradation of these forests be linked to programs that will increase our knowledge of the species found there as well as the ecological and evolutionary processes that originated these unique forests.
Brazilian Decidual Tropical Forest enclaves: floristic, structural and environmental variations
Brazilian Journal of Botany, 2017
Several theories have been proposed to explain the raised richness and diversity of species in native tropical forests, with an emphasis on those that invoke the niche characteristics. In the present study, we sample the woody vegetation in four enclaves of Deciduous Forests and investigate whether environmental variables can explain the floristic and structural differences among the sampled fragments. The studied areas are located the ''Cerrado'' biome core zone and in ''Cerrado''-Atlantic Forest and ''Cerrado-Caatinga'' transition zones. The woody vegetation (diameter at breast height-DBH C 5 cm) was sampled in 100 plots of 20 9 20 m, 25 plots in each enclaves. The investigated environmental variables were chemical and textural properties of the soil, rockiness, declivity and altitude. We found significant differences for the floristic variables (richness, diversity), among all the environmental variables, as well as for the density, height and for the DBH first class. We noticed strong influence of the environmental variables, and the nutrients availability, texture, soil acidity and the land relief are the most responsible for the floristic-cultural difference. We propose that the gradient existence of rainfall has influenced the edaphic characteristics, creating variations in the habitats, which may have favored the arrival and establishment of different species in each study area and the distinctive development of the woody vegetation at the enclaves to the Deciduous Forest.