Badlands, Seed Banks, and Community Disassembly

Abstract

Soil seed banks are a key component of ecological resilience as they provide a temporal reserve for plant species richness and diversity. Soil seed banks depend on on-site reproduction, seed longevity, and seed immigration for maintenance. When immigration of seeds is lost due to a change in land use or a disturbance, such as fragmentation, seed banks rely on on-site reproduction and longevity for maintenance. Within a fragment without seed immigration, seed banks become vulnerable to extinction debt leading to community disassembly over a long time scale. Therefore, we investigated how long-term fragmentation impacts community disassembly in seed banks. Seed bank samples were taken from grassland fragments (sod tables, n = 28) and from the surrounding area (matrix, n = 28). Seed banks were germinated, and emerging plants were identified. We found that community disassembly was not predictable in regard to species identity, and specialist (P < 0.001) and perennial (P < 0.001) species were lost from fragments. However, seed banks in fragments maintained a similar grass-to-forb ratio compared with the surrounding vegetation. Therefore, the ability of seed banks to provide ecological resilience may be limited after long-term fragmentation and land managers may need to reseed specialist species and perennials into grassland fragments.