The effect of landform and plant size on mortallity and recovery of longleaf pine during a 100-year loog1

Unlike annual floods, large floods affect plant species outside of bottomland ecosystems. We know little about the effects of catastrophic floods on upland plants because of the rarity of this type of disturbance. Here we report on mortality and vegetative recovery of upland longleaf pines (Pinus palustris) after a large flood. The flood top-killed most seedlings and advance regeneration, while most large pines survived. About one-half and one-third of affected seedlings and advance regeneration, respectively, recovered vegetatively through resprouting or reflushing. High rates of initial mortality and vegetative recovery were not population-wide phenomena. Mortality decreased with increasing plant height because tall stems maintain more crown volume above floodwaters. Geomorphology alters patterns of mortality as related to size. Landforms retaining surface water had higher rates of mortality than landforms that shed surface water. Responses of longleaf pine to flooding suggest strong geomorphic control over disturbance regimes and, in turn, over population dynamics. Although infrequent, large floods may be important for regulating age structures of longleaf pine. Understanding the effects of large floods may be important for predicting demography of upland plant populations, and more broadly, for understanding the spatial and temporal boundaries of land-water interactions.