Spatial Variation and Dynamics of Flooding,Canopy Openness,and Structure in a Neotropical Swamp Forest |
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Authors: | Alexandre?F?Souza Email author" target="_blank">Fernando?R?MartinsEmail author |
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Institution: | 1.Programa de Pós-Gradua??o em Biologia: Diversidade e Manejo da Vida Silvestre,Universidade do Vale do Rio dos Sinos,S?o Leopoldo,Brazil;2.Departamento de Botanica, Instituto de Biologia,Universidade Estadual de Campinas,Campinas,Brazil |
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Abstract: | Temporal changes and spatial variation of soil drainage and understory light availability in 2001 and 2002, small stem (5 ≤ dbh
(diameter at breast height) < 10 cm) density, forest successional phase and large stem (dbh ≥ 10 cm) spatial distribution
were investigated in 1 ha of tropical swamp forest in southeastern Brazil. Building patches and treefall gaps comprised, respectively,
69.75 and 7.5% of the area in 2002. Semivariograms indicated spatial segregation of successional phases, with mature areas
predominating in the North and gaps aggregated into the South. Exclusion of outliers showed large unpredictability of background
variation in canopy openness, but patches with high canopy openness values concentrated along the South and East plot borders.
Overall canopy openness increased from 2001 to 2002, and was locally autocorrelated between years. In 2001, well-drained and
flooded sites comprised 46.75 and 38.19% of the study area, respectively, and were not spatially autocorrelated. In the study
period, the number of flooded sites decreased by 40.4%. Canopy openness and small stem density were independent from drainage
and were not correlated. Large trees aggregated at scales larger than 40 m, while arborescent palms were aggregated at all
scales. Our findings suggest that tropical swamp forests have architectural characteristics similar to that of young, secondary
forests and treefall gaps in old-growth forests. Patterns at larger scales pointed to the occurrence of widespread forest
degradation, which seems to be particularly advanced in some forest sectors. |
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Keywords: | Crown densiometry Forest degradation Forest dynamics Ground-surface heterogeneity Ripley’ s K function |
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