Effect of Soil Texture and Microtopography on Germination and Seedling Growth in'Boltonia decurrens' (Asteraceae), a Threatened Floodplain Species

摘要

Boltonia decurrens, a perennial species endemic to Illionois River valley, isthreatened with extinction. Field observations indicate the B. decurrens is confined to areas with sandy soils formed from alluvial deposits, but there is little understanding of the factors controlling its distributuion. Plans for reintroduction of the species to suitable habitats within its historical range are hampered by a lack of understanding of the site characteristics necessary for germination and seeding growth. This study examined the effect of soil texture and soil surface features on germination and growth of B. decurrens under greenhouse conditions. We found that both paramenters are greater on sand, compared to clay, and on bare soil with either a smooth or lumpy surface, compared to litter-covered surfaces. These conditions are identical to those in which B. decurrens has persisted along the Illinois River and may be important in determining its distribution pattern.