Seed rain into a degraded tropical peatland in Central Kalimantan, Indonesia

Forested tropical peatlands in Southeast Asia are important as global carbon stores and for biodiversity conservation yet are being rapidly converted to agriculture or degraded into fire-prone non-forest vegetation. Although large areas have been abandoned, there is little evidence for the subsequent recovery of forest. As part of a study of forest degradation and recovery, we assessed seed rain into an area of non-forest regrowth in degraded tropical peatland in the former Mega Rice Project: an abandoned attempt to convert 1 million hectares of tropical peatland for rice production in Central Kalimantan, Indonesia. Fifty seed traps were placed in the open and fifty under trees. Seeds were collected every 15 ± 3 days for 1 year. Seed rain and foreign seed rain (species different from the tree over the trap) was higher for traps under trees (1127.8 seeds and 465.0 seeds m−2 y−1 respectively) than for traps in the open (95.2 seeds m−2 y−1). Foreign seed rain consisted largely of species that also grow in mature forest, but was dominated by a few abundant wind-dispersed species (particularly from the woody liana, Uncaria elliptica, and the tree, Combretocarpus rotundatus) and the majority of animal-dispersed foreign seeds were found under trees. While seed rain both in the open and under trees appears sufficient for the development of woody plant cover, diversity will be limited in the early stages of succession. We recommend enrichment planting with species that would have been present before forest destruction but are not represented in the current seed rain.