Distinguishing the roles of dispersal in diversity maintenance and in diversity limitation

Considerable recent research effort has gone into studying how dispersal might affect the diversity of local communities. While this general topic has received attention from theoretical and empirical ecologists alike, the research focus has differed between the two groups; theoretical ecologists have explored the role of dispersal in the maintenance of diversity within local communities, whereas empirical ecologists have sought to quantify the role of dispersal in limiting local diversity. We argue that there is no necessary relationship between these two components of diversity and we therefore need to develop empirical approaches to quantify the dispersal-maintained component of diversity, as well as the dispersal-limited component. We develop one such approach in this paper, based on a quantitative partitioning of the natural regeneration within intact communities onto different sources of recruits (local communityvs. dispersal across different spatial or temporal scales).