Most plant communities are comprised of many different growth forms with one that usually dominates in biomass. Ecological studies tend to focus on the dominant growth form and species, primarily because they process most of the energy that flows through the system. However, when species richness is considered, it is usually species within the subordinate growth forms that contribute most to diversity. With the exception of ruderal species, relatively little is known about the mechanisms by which subordinate species, especially long-lived perennials, maintain themselves in communities. A comprehensive evaluation of the mechanisms of persistence of these less common species is critical to maintaining diversity within natural and restored communities. This study will experimentally examine the mechanisms of persistence of tallgrass prairies forbs (non-woody, perennial herbs) at the Konza Prairie Research Natural Area. This site is characterized primarily by just two growth forms (the dominant grasses and forbs) and this facilitates comparisons of resource use and responses to fire, grazing, light regime, and nitrogen between dominant and subordinate growth forms. The forbs share many life history characteristics and owe their persistence within the tallgrass matrix to the long residence times of established individuals/clones. A combination of descriptive studies and a full factorial experiment involving water, N and light manipulations will be used to elucidate the processes by which long-lived forbs maintain their presence in a "sea of grass" that varies topographically and in fire history.
