Comparative analysis of growth and mortality among saplings in a dry oak-pine forest in southeast Texas

The role of shade tolerance in the dynamics of a sandy upland pine-oak forest in Big Thicket National Preserve, southeast Texas was investigated. Using a forest dynamics modeling framework, radial growth of saplings as a function of light availability and mortality as a function of recent growth history for species with a range of shade tolerance levels was investigated. In low light, shade-tolerant species grew faster than shade-intolerant species. However, in high light, shade-intolerant species did not grow faster than shade-tolerant species possibly because some of them are adapted for drought resistance. They did not survive better, either, perhaps because of recent increases in canopy shading. Mesic, shade-tolerant species had better performance at the dry site than at the mesic site, possibly because of a difference in the competitive environment of the two sites. An implication of invasion and higher growth and survival of the mesic species is that these species may have been limited to a larger extent by fire than by site conditions on this site in the past.