Restoration treatments and regeneration dynamics in East Texas mixed wood forests

Abstract

Extensive harvesting, fire exclusion, and plantation forestry altered composition and structure, and thus function and habitat values of east Texas Pineywoods uplands. Upland restoration efforts are made difficult by the abundance of sprouting mesophytic species and by the complex silvics of the historical mixed wood types. This study evaluated the effects of restoration sequences on regeneration dynamics at the Boggy Slough Conservation Area, in Trinity County, TX, USA. A chronosequence was used to evaluate population-level changes in four species groups: historically dominant oaks and pines and contemporary competitors yaupon holly and sweetgum. Individual seedlings were tracked to evaluate the effects of harvesting, dormant season prescribed burning, foliar herbicide application, and growing season prescribed burning on growth, topkill, and mortality. None of the treatment sequences caused significant mortality of yaupon holly, but its growth rate was reduced by herbicide applied soon after prescribed burning. Mortality was also low among oak species, which remained intermediate in abundance to other species in the study and maintained a growth rate which was relatively unaffected by treatments. Treatment sequences involving herbicide led to high mortality of both sweetgum and pine species. The treatments successfully re-established the desired two-layered woodland structure by topkilling large yaupon holly, however, resprouts were abundant. Overall, results indicated the need for continued management to maintain a two-layered woodland structure and allow the successful recruitment of the desired pine and oak species to the midstory and overstory.