Question: What are the effects of small-scale litter disturbances (simulating large vertebrate scratching and foraging), on Quercus alba, Q. velutina, Fagus grandifolia, and Acer rubrum seedling recruitment?
Location: Southeastern Ohio, USA.
Methods: Two mixed oak forests containing four experimental management units (burned, thinned, thinned & burned, and un-manipulated control) were utilized in this study. Silvicutural treatments were applied in the spring of 2001. A small scale disturbance experiment was initiated in the spring of 2002 (Trial 1) and was replicated again in the spring of 2003 (Trial 2). Experimental hardware cloth exclosures, each containing a control (ambient litter) and experimentally scratched (litter removed to bare soil) compartment, were erected in each management unit (N = 8 exclosures per unit).
Results: Acer rubrum, a species that occupies a wide germination niche, produced the most numerous seedlings. Nut-producing species established more readily in compartments with ambient leaf litter, while A. rubrum was unresponsive to scratching treatment. Units burned (surface leaf litter removed at a broad scale) had the lowest rate of seedling recruitment in Trial 1.
Conclusions: These data suggest that an adequate cover of leaf litter is needed to promote optimal recruitment. Control units had the greatest rate of seedling recruitment in Trial 2. The development of a dense understory layer (promoting excessive shading) between Trial 1 and Trial 2 may have affected the recruitment rate in the thinned and thinned & burned units.