| The oak-rich deciduous forests of the central Appalachian Mountains of eastern North America have changed significantly since the onset of effective fire suppression early in the 20th century. Recently dormant season fire and alteration of the woody plant assemblage have been used in these ecosystems for forest management and restoration. These manipulations often increase light, soil temperature and moisture, and alter short and longer-term nutrient availability. Therefore, the ability of herbaceous plants to survive, reproduce, and establish in these different environments depends on their exhibiting an integrated ecological response. By examining the morphology, physiology, nutrient and reproduction traits of two long-lived understory herbaceous perennials Desmodium nudiflorum (L.) DC and Panicum boscii Gould & CA Clark in the mixed oak forests in southern Ohio, this study aimed to understand the integrated ecological responses of these forest herbs to prescribed burning alone and the combination of burning and thinning, and to reveal the environmental drivers important in shaping plant ecological traits.; The study sites were part of larger Ohio Hills Site of the National Fire and Fire Surrogate Network Study. The original experiment design has randomly assigned control (C), burn (B), thin (T), and thin+burn (T+B) units of 20-30 ha each in three areas of southern Ohio. The T and T+B units were thinned during late fall 2000 and early spring 2001, and the burn and thin+burn units burned in early April 2001 and again in March 2005. I examined ecological traits of the two herbaceous perennials from three treatment units (control, burn, thin+burn) in two of the study sites during 2004 and 2005.; Among the ecological traits measured, specific leaf area (SLA), plant biomass, maximum photosynthesis rate (Amax), leaf area ratio, number of seeds, and leaf nutrient concentrations showed the largest responses to these silvicultural treatments; while leaf nutrient resorption efficiency showed the least response. Desmodium nudiflorum was more responsive to the altered resource conditions following forest manipulation activities than Panicum boscii. However, in both herbs, the ecological responses to different treatments became less pronounced with time after fire.; During the short-term after fire, understory light availability and soil nutrient availability are the most important environmental drivers in shaping the integrated ecological traits of D. nudiflorum. With time since fire, soil nutrient availability becomes less important, while topographical/soil moisture conditions, soil exposure, and light availability act in concert as the most important environmental drivers for the ecological traits of D. nudiflorum. |
