The Lost Pines region in central Texas has the westernmost stands of loblolly pine (Pinus taeda) in the United States. In September 2011, during a record drought, a wildfire in this region killed or top-killed almost all of the trees and consumed most understory vegetation. We investigated the effects of soil type, burn severity, and canopy cover on post-fire plant assemblages, focusing on herbaceous diversity and on three woody species that were abundant before the fire: loblolly pine, sand post oak (Quercus margaretta), and yaupon (Ilex vomitoria). Fifty-six plots within the Park were surveyed using protocols from the National Park Service Fire Monitoring Handbook (FMH) between 1999 and 2015.
Results/Conclusions
Oaks re-sprouted vigorously, especially in severely-burned plots, creating a strong pre-fire legacy effect. Loblolly pine, which recruits only from seed, initially had poor recruitment post-fire, so that for several years after the fire it appeared that oaks would replace pines in this community. However, in 2015 a large loblolly pine recruitment event occurred following a year of unusually high precipitation, deflecting the recovery trajectory back towards a composition closer to the pre-fire community composition. Yaupon re-sprouted well in all burn severity classes and appeared likely to eventually re-form the dense mid-story that it had created pre-fire, unless management practices to prevent this are adopted. Herbaceous understory species were much more abundant and diverse post-fire than pre-fire; whether this remains true will likely depend on whether future management practices maintain a relatively open canopy or allow a closed canopy to re-form.