Hurricane Katrina-induced forest damage in relation to ecological factors at landscape scale

Abstract

Forest stand stability to strong winds such as hurricanes has been found to be associated with a number of forest, soil and topography factors. In this study, through applying geographic information system (GIS) and logit regression, we assessed effects of forest characteristics and site conditions on pattern, severity and probability of Hurricane Katrina disturbance to forests in the Lower Pearl River Valley, USA. The factors included forest type, forest coverage, stand density, soil great group, elevation, slope, aspect, and stream buffer zone. Results showed that Hurricane Katrina damaged 60% of the total forested land in the region. The distribution and intensity of the hurricane disturbance varied across the landscape, with the bottomland hardwood forests on river floodplains most severely affected. All these factors had a variety of effects on vulnerability of the forests to the hurricane disturbance and thereby spatial patterns of the disturbance. Soil groups and stand factors including forest types, forest coverage and stand density contributed to 85% of accuracy in modeling the probability of the hurricane disturbance to forests in this region. Besides assessment of Katrina's damage, this study elucidates the great usefulness of remote sensing and GIS techniques combined with statistics modeling in assessment of large-scale risks of hurricane damage to coastal forests.

Large-Scale Forest Modeling: Deducing Stand Density from Inventory Data

“…The self-thinning parameter k determines the absolute value of N max for a given b, however, because in this study only relative density is used and never absolute numbers of N, k have no influence on our results. As shown in [8] mortality due to self-thinning in a closed stand (dB dc /dt, (5)) is proportional to the increment of live biomass (dB c /dt)…”

“…In an unthinned (closed) stand, net increment (dB c /dt) and self-thinning mortality (dB dc /dt) are linked according to (5). In a thinned (open) stand, net increment is a function of gross production (8), selfthinning (9), and density-independent mortality (dB di /dt; (10)).…”

“…These effects depend on many factors of which forest productivity, stand density, and characteristics of management, such as thinning and rotation length, are particularly important [1,2]. In addition, stand density and thinning are important in relation to other forestry topics, such as carbon sequestration in forests [3], biodiversity [4], sensitivity to wind damage [5], sensitivity to insect damage [6], and fire risk [7].…”

Using Regional-scale Pre- and Post Hurricane Katrina Lidar for Monitoring and Modeling

“…The spatial patterns of the hurricane's disturbance are essential for managers and scientists to perform efficient management practices such as rebuilding structures, insurance estimations, forest salvage harvesting, habitat protection, as well as to make assessments on long-term environmental impacts and forest ecosystem recovery. Due to the sheer size of areas affected by Katrina, a full-scale ground-based assessment is technically difficult and not very economical (Wang and Xu, 2009). As a result, remote sensing methods are the best option for quantifying disturbed areas over large regions, such as Katrina affected areas.…”

Potential of MODIS EVI in Identifying Hurricane Disturbance to Coastal Vegetation in the Northern Gulf of Mexico

“…The level of devastation exerted by a hurricane on the vegetation are related to a complex set of biotic and abiotic factors, such as vegetation attributes and site conditions, as well as hurricane wind speed and direction. For example, the severity and spatial patterns of Katrina disturbance to forests in southeastern Louisiana were mainly determined by soil properties, forest types, forest coverage and stand density [4]. In coastal wetlands, the salinity level following hurricane disturbance is a crucial factor in determining the specific effects of a storm on coastal vegetation [3].…”