A limited seed bank in both natural and degraded tropical peat swamp forest: the implications for restoration

Abstract

Carbon-rich tropical peat swamp forests (PSFs) are being degraded at an alarming rate. In response to national and global agendas, landscape-scale PSF restoration is underway, although supporting knowledge of PSF ecosystem restoration ecology remains limited. Seed banks are usually an important source of natural regeneration and crucial in post-degradation forest recovery, even in the humid tropics where reduced seed dormancy leads to typically smaller seed banks than in temperate regions. It has been assumed that PSF degradation reduces the seed bank, limiting natural regeneration, but this has not previously been investigated explicitly. This study of PSF in Central Kalimantan explored seed bank prevalence and regenerative capacity across five forest zones (FZs): degraded, open canopy disturbed, edge, closed canopy disturbed and natural. Numbers and species of seeds and seedlings were recorded from surface peat samples collected from each FZ over one year. Seed density, averaged across FZs, was 41 seeds m-2; total species number was 11; and seedling density was 16.0–73.6 m-2 depending on FZ. These values were much lower than for other forests in this region. There was little difference in seed bank size between natural and degraded FZs, and only the forest edge showed higher than expected seed bank regenerative capability. Overall, our results suggest that seed banks are not of high importance in tropical PSF regeneration, either before or after degradation. These findings are discussed from the perspective of successional traits in different species and their relevance to ecosystem restoration.

Keywords

• dormancy
• germination
• Indonesia
• natural regeneration
• PSF
• seed dispersal
• succession