Vascular plant species richness and composition in two types of post-cultivation tropical secondary forest

Question How are plant communities in forests regenerating on post-cultivation land structured along environmental gradients, landscape context, and past land use? Location We investigated this for two types of post-agricultural fates: plantations abandoned with trees intact (abandoned-land forest) versus land that was cleared and left to regenerate into a forest (waste-woodland). The study sites were located in the tropical city-state of Singapore in Southeast Asia. Methods Five 20×20 m plots were surveyed for vascular plants in each of 11 patches of abandoned-land forest and nine patches of waste-woodland. For each plot, we estimated soil nutrient levels (nitrogen, potassium, phosphorous), canopy cover, leaf litter depth, distance to old-growth forest, and the size of the forest patch. Results For both forest types, increasing leaf litter and distance to old-growth forest is associated with lower species richness. Increasing soil nitrogen in abandoned-land forest and increasing soil potassium in waste-woodland is associated with lower total and native species richness, but not exotic species richness. Overall community composition is correlated with leaf litter, canopy cover, soil phosphorous and potassium, and distance to old-growth forest. Conclusions Different ways of land abandonment resulted in different successional trajectories that led to separate sets of environmental drivers of community patterns. Restoring such degraded forms of vegetation to native-rich communities may require management of soil nutrient levels and enrichment planting. This article is protected by copyright. All rights reserved.