Spatial and temporal distribution of species diversity in semideciduous seasonal forests with occurrence of fire

Abstract

Abstract:The spatial and temporal distributions of vegetation can be influenced by edaphic and environmental factors as well as disturbances. The present study was undertaken to characterize the distribution and spatial dependence of species diversity in a fragment of semideciduous seasonal forest after a disturbance event by fire and to identify changes during natural regeneration. The fire, occurred in 1999, and surveys were undertaken in 2000, 2005 and 2014 in 26 geo-referenced plots (400 m²) distributed along two transects. The Fire Damage Index (FDI) in each plot was based on a scale from 0 to 5, and all of the arboreal individuals with diameters at breast height (DBH) ≥ 5 cm were identified in each plot. Species diversity was calculated using the Shannon index (H'), and species richness (S) was estimated using species accumulation curves; variations between the surveys compared based on the means and standard errors. The S, H' and FDI data were submitted to non-spatial exploratory and geostatistical analyses. After adjusting the semivariograms, the levels of spatial dependence were classified, and interpolation of the variables values were performed using ordinary kriging to characterize their spatial distributions in the form of maps. Spatial analysis was used to identify and characterize differences between the post-fire surveys in terms of the configurations of the arboreal community. The fire event influenced the spatial and temporal structures of the variables S and H'. These variables showed spatial dependence and aggregated distributions, with reduction in the distance under spatial influences and a uniformity of individuals distribution in the forest fragment at the different surveys. This research characterized the distribution and spatial dependence of the variables S and H' in a forest fragment after a fire event and the alterations in the arboreal community structure during natural regeneration. Rev. Biol. Trop. 65 (2): 525-534. Epub 2017 June 01.Key words: Atlantic Forest, Brazil, forest fragmentation, anthropogenic disturbance, long-duration study, spatial dependence, geostatistics.example, habitat degradation results in reductions of both forest cover and species diversity (Ribeiro, Martensen, Metzer, Tabarelli, Scarano, & Fortin, 2011) with serious implications for forest ecosystem functioning and organization (Silva-Matos, Fonseca, & Silva-Lima, 2005;Lima & Moura, 2008;Pereira, Filho, Eisenlohr, Miranda, & Filho, 2015). The spatial distribution of forest species is an interactive Forest fragmentation is one of the principal factors promoting forest degradation. In addition to generating forest mosaics at different regeneration stages, fragmentation favors the propagation of subsequent fires and other environmental disturbances that promote spatial discontinuity of forest composition (Amaral, Ferreira, Watzlawick, Longhi, & Sebem, 2013b). In the Atlantic Forest biome, for phenomenon involving competition, tree architecture, and the occurrence and availability of forest openings (Sanquetta,...

Geotechnology in the analysis of forest fragments in northern Mato Grosso, Brazil

“…Their size and shape are intrinsically bounded to the edge, that is, the smaller the fragment or more elongated, the more intense the edge effect will be, that is, reducing the inner-margin ratio 42 . It is worth noting that the more it moves away from the standard shape (the perfect circle) the more cut the shape of the spot becomes, and the more it is susceptible to the edge effect 43 .…”

“…It is worth noting that the more it moves away from the standard shape (the perfect circle) the more cut the shape of the spot becomes, and the more it is susceptible to the edge effect 43 . The shape of the spot is more trimmed as its pattern differs from the perfect circle being more susceptible to the edge effect 42,43 .…”