Plant Community Responses to Soil Disturbance and Herbicide Treatments over 10 Years on the Texas Ltsp Study

Determining how anthropogenic disturbances affect site productivity through bioassays requires a complete understanding of both overstory and understory vegetation. This study was installed in 1997 to determine how soil compaction and intensive harvesting affected the inherent site productivity of pine stands on the western boundary of loblolly pine’s (Pinus taeda L.) natural range. We measured the plant communities at ages 5 and 10 on plots receiving a factorial combination of three levels of soil compaction and three levels of organic matter removal at harvest. Soil compaction had little impact on plant communities. Intensive harvesting, especially when the forest floor was removed, greatly reduced pine survival and growth and somewhat reduced woody understory growth, while increasing herbaceous understory growth. The reduction in woody understory biomass did not improve pine growth because forest floor removal reduced soil fertility and water content, which affected the pines in addition to the understory vegetation.