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Dryad

Forest diversity and structure in regenerating secondary forests after shifting cultivation abandonment in the Philippines uplands

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May 19, 2021 version files 25.27 KB

Abstract

We investigated parameters of forest diversity and structure along a fallow age gradient in secondary forests regenerating after shifting cultivation abandonment. We first measured the tree diversity and forest structure indices in regenerating secondary forests and old-growth forest. We then measured the recovery of tree diversity and forest structure parameters in relation to the old-growth forest. Finally, using linear mixed effect models (LMM), we assessed the effect of different environmental variables on the recovery of forest diversity and structure.

Species density was significantly higher in the oldest fallow sites, while Shannon’s index, species evenness, stem number, basal area and leaf area index were higher in the old-growth forest. A homogeneous species composition was found across the sites of older fallow age. Multivariate analysis revealed patch size as a strong predictor of tree diversity and forest structure recovery after shifting cultivation.

Secondary forests regenerating after shifting cultivation abandonment can recover rapidly after five years. Although recovery of forest structure was not as rapid as the tree diversity, our older fallow sites contained a similar number of species as the old-growth forest. Many of these species are also endemic to the Philippines. Novel and emerging ecosystems like tropical secondary forests are of high conservation importance and can act as a refuge for dwindling tropical forest biodiversity.