Long-term effects of catastrophic wind on southern US coastal forests: Lessons from a major hurricane.

Threats posed by windstorms are an increasing concern to forest managers in the southern United States (US). Studies suggest that the southern US will experience an increase in the occurrence as well as the intensity of windstorms, such as hurricanes, in the future. However, forest managers may have difficulty preparing for this future because there is limited understanding of how windstorms affect the structure and composition of forests over the long term. In this study, we evaluated the impacts of Hurricane Ivan, which made landfall in September 2004 near Gulf Shore, Alabama, impacting forests in the western Florida Panhandle and southwestern Alabama. We acquired the United States Department of Agriculture Forest Inventory and Analysis (FIA) plot data available for the period from 2002 to 2018 for the Ivan-affected area and classified the plots into 4 categories: (1). ND (No Disturbance), (2). NDBH (No Disturbance but Harvested), (3). ID (Disturbance caused by Hurricane Ivan), and (4). IDAH (Disturbance caused by Hurricane Ivan and Harvested). The plots that were damaged by Hurricane Ivan (ID and IDAH plots) had significantly (α = 0.05) (1) higher basal area, (2) higher quadratic mean diameter and height, (3) more diverse tree species composition (species richness and Shannon diversity index), (4) denser stocking of seedling and saplings, (5) lower proportion of dead trees or saplings, and (6) higher live aboveground biomass than the plots that were not damaged by the hurricane (ND and NDBH plots). Diverse stands were not necessarily more windstorm resistant. Species diversity in the overstory may not improve forest resistance to hurricane damage but may improve its resilience following the hurricane. The study suggests that managing stand structure through density management and stand improvement could be critical to windstorm resilience and resistance in the southern US forests.

Soil nitrate leaching in silvopastures compared with open pasture and pine plantation.

Wide acceptance of silvopasture as an alternative sustainable agricultural system in the southeastern United States will depend on an improved understanding of the tree-forage interactions and recognition of its environmental benefits. The objective of this study was to evaluate differences in soil nitrate leaching in different land-use systems, in north Florida. An 18-yr-old loblolly pine (Pinus taeda L.) plantation was thinned in the summer of 2002 to create a fifth-row thinned, nontraditional intensive pine plantation (FO), silvopastures (HE = fourth-row conventionally thinned with random tree distribution and DO = double-row sets of trees with 15-m wide alleys), and an open pasture (PA). 'Argentine' bahiagrass (Paspalum notatum Flügge.) was established as understory vegetation in HE, DO, and PA. From 2004 to 2005 soil nitrate leaching was sampled and compared in the DO, HE, PA, and FO systems at 0.3 and 1.2 m depths after fertilizer application. Significant nitrate peaks were observed at 0.3 m depth after N fertilizer application in all systems. At the 1.2 m depth, the maximum nitrate concentrations were 67, 18, and 8 mg L(-1), in the forest plantation, open pasture, and both silvopastures, respectively. In general, reduced nitrate leaching at 1.2 m depth was observed in silvopastures compared with other land-used systems. These results are not intended to have a direct bearing on traditional pine plantation management, but rather support the potential role of silvopasture systems in reducing nitrate losses from the soil.