Factors influencing distribution and first-year survivorship of a cohort of beech (Fagus grandifolia Ehrh.) [Texas]

Seedling density of a 1980 beech cohort was lowest in depressions and highest on well-drained microsites in a mature Southern Mixed Hardwood forest in southeast Texas. In addition, density declined with distance from mature beech trees. Litter depth, percent moisture, and light intensity had no effect on initial seedling density. Survivorship was positively related to distance from a beech tree, but was not significantly related to any other environmental variables, or to initial density. However, there appeared to be a trend towards lower survivorship on the drier microsites. In addition, the summer drought in 1980 resulted in lower survivorship than was experienced by a 1976 cohort. Final density was similar to initial density in its relationship to topography and distance from parent tree. The fact that both microtopography and distance affect initial seedling density suggests that germination rate and seed distribution are the primary determinants of both the size and distribution of the seedling population. Favorable climate in the year of germination also contributes greatly to the success of a particular cohort.