No abstract

2017. Overstory-derived surface fuels mediate plant species diversity in frequently burned longleaf pine forests. Ecosphere 8(10):

The use of reference models as templates of historical or natural conditions to assess restoration progress is inherently logical; however, difficulties occur in application because of the need to incorporate temporal variation in ecosystems caused by disturbance and succession, as well as seasonal, interannual, or decadal variability. The landscape-scale restoration of the globally threatened and fire-dependent longleaf pine ecosystem in the southeastern United States is an example in which restoration efforts are even more complicated by the limited availability of extant reference sites. This study uses the dynamic reference conceptual framework to assess the direction and rate of recovery with respect to biodiversity restoration goals using a 15-year vegetation data set from an experimental restoration treatment in fire-excluded, hardwood-encroached longleaf pine sandhills. We compared ground-cover vegetation response to midstory hardwood removal through herbicide application, mechanical removal, and fire only. Nonmetric multidimensional scaling ordinations and proportional similarity analyses suggest that, while vegetation changed in all treatments over time, no differences in species composition or hardwood density in the ground cover were attributable to hardwood reduction treatments after 15 years with frequent prescribed fire. Furthermore, the results of this study indicate that considerable variability is associated with reference sites over time. Sites identified in 1994 as attainable restoration targets had become a moving target themselves, changing in magnitude consistent with alterations in restoration plots attributable to treatment effects and shaped by the modest increase in fire frequency imposed since 1998. In a broad restoration context, this study demonstrates a conceptual framework to better understand and integrate the range of spatial and temporal variation associated with the best available reference sites. It also illustrates a practical tool for statistically defining reference sites and for measuring restoration success in continually changing conditions that should be widely applicable to other ecosystems and restoration goals.

Small remotely piloted aircraft systems (RPAS), also known as unmanned aircraft systems (UAS), are expected to provide important contributions to wildland fire operations and research, but their evaluation and use have been limited. Our objectives were to leverage US Air Force-controlled airspace to (1) deploy RPAS in support of the 2012 Prescribed Fire Combustion and Atmospheric Dynamics Research (RxCADRE) project campaign objectives, including fire progression at multiple scales and (2) assess tactical deployment of multiple RPAS with manned flights in support of incident management. We report here on planning for the missions, including the logistics of integrating RPAS into a complex operations environment, specifications of the aircraft and their measurements, execution of the missions and considerations for future missions. Deployments of RPAS ranged both in time aloft and in size, from the Aeryon Scout quadcopter to the fixed-wing G2R and ScanEagle UAS. Real-time video feeds to incident command staff supported prescribed fire operations and a concept of operations (a planning exercise) was implemented and evaluated for fires in large and small burn blocks. RPAS measurements included visible and long-wave infrared (LWIR) imagery, black carbon, air temperature, relative humidity and three-dimensional wind speed and direction.

Reducing fire‐induced mortality of cavity trees used by red‐cockaded woodpeckers (Picoides borealis) is a challenge and concern in managing this federally endangered species. Prior to the 2001 burning season, 814 active and inactive longleaf pine (Pinus palustris) cavity trees on Eglin Air Force Base (AFB) in northwest Florida, USA, were prepared via 6 protection methods (combinations of mechanical, hand, and backfiring preparation) and monitored for postburn survival after 1 year. We collected data on a suite of variables that may be useful in determining cavity tree predisposition to fire‐induced mortality. Mortality of protected trees (2.62%) was significantly lower than that of unprotected trees (6.18%), and protection methods did not differ in their effectiveness at preventing mortality. Bark char was significantly more prevalent on unprepared control trees than protected trees, but no differences were apparent among protection treatments. Mechanical clearing alone took the least amount of time and resources; therefore, we determined mechanical clearing to be the most efficient preparation method. Stem char, needle scorch, percent sap cover, and whether the cavity burned were the characteristics most closely related to mortality 1 year postfire. We recommend that the percent of the bole covered in sap and cavity height be considered when preparing to reduce stem char, needle scorch, and the incidence of burned‐out cavities. Managers of red‐cockaded woodpecker populations can use these results and recommendations to adjust their burn program, improve the efficiency of their cavity tree protection methods, and better target cavity provisioning for maintaining a viable pool of cavity trees.