资源环境科技发展态势分析平台

In 2011, the most destructive wildfire in Texas history (Bastrop County Complex Fire, BCCF) burned 34,000 acres including most of Bastrop State Park. We used dendrochronological analysis of vegetation paired with documentary information to reconstruct the historical fire regime, changes in forest composition, and possible human influences leading up to this seemingly unique event. In addition, demographics of fire-killed and immediate post-fire regenerating trees were determined through stem aging and a regeneration census. Historical fire frequency was lower during the pre-EuroAmerican Settlement period (pre-1830) compared to later time periods before the 1920s. Since the 1920s, fire occurrence has significantly decreased. Historical fire characteristics appeared to change with local and regional cultural and land use changes. Within the BCCF area were extensive areas of very old (up to 359 yrs old) open-grown post oaks (Quercus stellata) that had been overtopped by 60 year old loblolly pines (Pinus taeda). Historically, oak woodlands likely persisted in the study area due to recurring fire and, though less well documented, by grazing and selective logging for loblolly pines. This region is an ecotone between the oak woodlands and Lost Pines and our data show transitions between the two types through time. It is unclear how this vegetation interaction may have affected the destructive BCCF, but its severity and effects were unprecedented during at least the last three centuries. Little to no loblolly pine natural regeneration existed despite being dominant in the pre-fire forest overstory. Based on stump sprout abundance, blackjack oak (Q marilandica) will likely be the dominant tree species in the next few decades. (C) 2017 Elsevier B.V. All rights reserved.