Soil seed banks in a mature coniferous forest landscape: dominance of native perennials and low spatial variability

Soil seed banks are important to vegetation recruitment, ecosystem functioning and land management. We evaluated composition of 0-5 cm soil seed banks and relationships of seed banks with forest community types (ranging from low-elevation pinyon-juniper to high-elevation bristlecone pine), vegetation cover and environmental variables within a 40,000-ha relatively undisturbed coniferous forest landscape in Nevada, USA. We collected samples from 36 sites and used the emergence method to assay seed banks. Seed density averaged 479 seeds m(-2) across sites and a total of 39 taxa were detected. Most (79%) of these taxa were perennials and 35 of 39 (90%) were native. Moreover, 62% of seed-bank taxa were in the vegetation of mature forests, an uncommon finding in studies of forest soil seed banks. Seed-bank density, species richness and composition did not display strong relationships with forest community types, vegetation cover or environmental variables. Weak relationships likely arose from the relatively uniform seed-bank density among sites, where 50% of sites had seed densities in the range of 106-282 m(-2). Results suggest that while seed banks on this landscape are not large, they provide recruitment potential for some native perennial species of mature, relatively undisturbed communities.