Aristida stricta var. beyrichiana (wiregrass) is a foundation bunchgrass species in many southeastern U.S. native pine communities, but it has been dramatically reduced in extent. The potential for reintroduced A. stricta to reproduce and spread is not well known because of its slow growth and limited conditions for successful reproduction, including growing season fire. We present a case study where transplanted tussocks of A. stricta were recensused twice in 37 years to study their population dynamics, including sexual reproduction, clonal fragmentation, and diameter-density relationships suggesting intraspecific competition. In 1981, 160 tussocks were transplanted from three native pine savanna sites within the region to a single post-agricultural site where they were planted in paired rows (0.75 or 1.5 m spacing) with five or more meters in between pairs. The population was mapped and its tussocks measured for diameter in 1999, and the measurements were repeated in 2018. Prescribed fires were applied at 1-3 year intervals from February-July.
Results/Conclusions
The initial population of 160 tussocks increased to 1199 by the end of the study, attributable to seed dispersal and clonal fragmentation, and the total basal area approximately tripled. Tussocks increasingly developed a hollow center and fragmented over time. Size class distributions suggested periodically successful episodes of sexual reproduction. Tussock diameter-density relationships and their changes over time suggest density-dependent regulation, possibly from intraspecific competition and competitive exclusion. As the longest study of A. stricta to date, this study suggests that a low-density population planted or transplanted into native soil types has a slow but robust tendency to reproduce by seed, fill in areas where it was not previously, and expand if provided frequent fire with at least occasional growing season fires. A. stricta is also known to depend on high light levels and protection from soil disturbance. Under these conditions, A. stricta in native pine communities appears to be a highly competitive, K-selected species tending to dominate what could be described as stable climax community, and its potential for restoration in previously disturbed sites is promising.