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

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...

本研究针对刀耕火种弃耕后自然更新的次生林，沿撂荒年龄梯度调查了森林多样性与结构相关参数。首先，我们分别测定了更新次生林与原始老龄林的树木多样性及森林结构指数；随后，评估了相较于原始老龄林，树木多样性与森林结构参数的恢复程度；最后，借助线性混合效应模型（Linear Mixed Effect Models, LMM），分析了不同环境变量对森林多样性与结构恢复的影响。

最老龄撂荒样地的物种密度显著更高，而原始老龄林的香农指数（Shannon's Index）、物种均匀度、植株数量、胸高断面积与叶面积指数均更高。高龄撂荒样地的物种组成均一性较强。多变量分析结果显示，斑块面积是刀耕火种后树木多样性与森林结构恢复的重要预测因子。

次生林……