Relationships between common forest metrics and realized impacts of Hurricane Katrina on forest resources in Mississippi

doi:10.1016/j.foreco.2007.11.029

Forest Ecology and Management

Volume 255, Issues 5–6, 5 April 2008, Pages 1692-1700

https://doi.org/10.1016/j.foreco.2007.11.029 Get rights and content

Abstract

This paper compares and contrasts hurricane-related damage recorded across the Mississippi landscape in the 2 years following Katrina with initial damage assessments based on modeled parameters by the USDA Forest Service. Logistic and multiple regressions are used to evaluate the influence of stand characteristics on tree damage probability. Specifically, this paper addresses four primary questions related to post-hurricane damage: (1) do inventory data substantiate damage zone estimates made using remotely sensed and climate data following Hurricane Katrina; (2) were softwoods or hardwoods more susceptible to hurricane damage and does that susceptibility change as distance from landfall increases; (3) what are the primary stand-level factors influencing vulnerability to damage, based on observed damage and measured stand characteristics, and; (4) is tree-level damage related to tree species, and do damage types (bole, branch, lean, or windthrow) differ by species? We were able to accept the hypothesis that damage differed among the developed zones, and to confirm the acceptability of the figures initially generated. However, we were not able to accept the hypothesis that softwoods experienced more damage than hardwoods. Our data showed a marked increase in damage to hardwood species, except in the first zone of impact. Additionally, the likelihood of hardwood damage increased with increasing distance from the zone of impact. However, species group was confounded with the other predictor variables in many cases, making it difficult to separate the effects of each variable.

Introduction

Hurricane Katrina made landfall in Plaquemines Parish, Louisiana on 29 August 2005. Katrina has been termed one of the most costly natural disasters in United States history, as well as one of the strongest hurricanes to make landfall on the U.S. coast in the last century (Graumann et al., 2005). In addition to hurricane-strength winds, Katrina brought massive amounts of rainfall over a very short timeframe, a storm surge of up to 8.5 m across southern Louisiana and Mississippi; extensive wind, rain, and related tornado damage throughout Mississippi, Western Tennessee and Western Kentucky; and extended hurricane-associated precipitation as far north as New York State (Graumann et al., 2005). Peak wind gusts associated with Katrina exceeded 80 km/h throughout the State of Mississippi (Graumann et al., 2005).

Damage assessment was an immediate priority for federal, State, and local governments. The U.S. Forest Service, Southern Research Station, Forest Inventory and Analysis program (USFS-SRS-FIA), among others, developed maps of damage zones using models developed by Jacobs (2007) to aid in damage assessment tasks (Fig. 1). Forest inventory data from 1994 were used in combination with the mapped damage zones to estimate damage potential and possible economic impacts across the State of Mississippi. Subsequently, zone maps and damage estimates were used by researchers and policy makers to aid in the development of recovery and salvage logging plans. Maps and estimates were used to further model hurricane effects on forest stands from the standpoint of individual-tree effects in order to suggest methods for reducing vulnerability to forests in hurricane impact zones (Stanturf et al., 2007). Therefore, estimates derived from models using available ground data, climate data, and remote sensing are important tools for forest management in a post-natural-disaster environment.

Initial estimates generated by USFS-SRS-FIA utilizing spatial models and 1994 inventory data indicated potential timber losses of up to 84.9 million m³ (3 billion ft³) across 1.4 million ha of damaged forest land in Mississippi (USDA Forest Service, 2005). This equates to about 90% of standing timber in severe damage zones, and an average of 37% of standing timber across all damage zones (USDA Forest Service, 2005). Initial estimates (based on 1994 inventory data) suggested that more softwood volume was damaged than hardwood volume.

Using the USFS-derived damage zone information, combined with additional information from the Texas Forest Service, Stanturf et al. (2007) simulated equivalent hurricane forces to forecast stem breakage in a hypothetical set of nine softwood forest stands spanning an array of stand structure and density combinations. The resulting simulations suggested that stand spacing and tree height were more important in softwoods for determining stem-breakage potential than species, indicating that manipulating stand structure to reflect the least vulnerable conditions could aid landowners in decreasing the damage potential of forests in hurricane-impact zones (Stanturf et al., 2007).

Following Hurricane Katrina, the USFS-SRS-FIA began systematically sampling the forest resource across the entire State, following protocols outlined in the FIA sampling field guide (USDA Forest Service, 2005). One goal of the inventory was to determine the actual damage caused by Hurricane Katrina at the forest landscape and individual tree level. Here, we compare and contrast hurricane-related damage recorded across the Mississippi landscape in the 2 years following Katrina with initial damage assessments based on modeled parameters by USFS. We also use logistic and multiple regression to evaluate the influence of stand characteristics on tree damage probability to see if our data reflect the findings of Stanturf et al. (2007). Specifically, we address four primary questions related to post-hurricane damage:

1.
Do inventory data substantiate damage zone estimates made using remotely sensed and climate data following Hurricane Katrina?
2.
Were softwoods or hardwoods more susceptible to hurricane damage and does that susceptibility change as distance from landfall increases?
3.
What are the primary stand-level factors influencing vulnerability to damage, based on observed damage and measured stand characteristics?
4.
Is tree-level damage related to tree species, and do damage types (bole, branch, lean, or windthrow) differ by species?

Section snippets

FIA field methods

The USDA Forest Service FIA program collects data on systematically arranged plots at the scale of roughly one plot for every 2428 ha of land base. Each field plot consists of four subplots about 0.016 ha in size (for a total of 0.06 ha for each complete plot). Each plot is designated as “sampled” or “not sampled” and each subplot within each plot is similarly designated. Subplots may be divided if they are partially forested, a procedure referred to as “condition mapping” (Bechtold and Patterson,

Measured hurricane damage

A total of 1581 entirely forested single-condition plots had been collected in the state of Mississippi at the time of analysis. Of those plots, a total of 693 (44%) experienced some degree of wind-related damage. Eighty-seven percent of plots in zone 1 (the zone encompassing landfall) experienced hurricane damage, and the percent of plots experiencing damage decreased as distance from landfall increased, with the exception of zone 5 (Fig. 1). The amount of damage sustained on plots differed by

Landscape level damage

Initial estimates of the damage caused by Hurricane Katrina were based on models produced by the USDA Forest Service and others (Jacobs, 2007). These models utilized data from the most recent FIA surveys in the effected States combined with maps of the hurricane storm track. The USFS-FIA initially estimated that 90% of timberland area within the approximately 8-county zone (zone 1) surrounding landfall had been damaged, and 37% of the entire State's timberland had been damaged. Our results

Conclusions

Our study illustrates the effectiveness of spatial models using remotely sensed data and USDA Forest Service FIA data to forecast damage following severe weather events. Models developed using 11-year-old data in the aftermath of Hurricane Katrina were still comparable to results derived from field data collected immediately following the storm. However, this study also illustrates the need to appropriately interpret the results to the general public. For example, stating that damage occurred

Acknowledgments

The authors thank Dennis Jacobs for the use of his shapefile depicting Hurricane Katrina damage zones, as developed in the fall of 2005 and published in 2007. In addition, the authors thank John Coulston and John Stanturf for their candid reviews of the manuscript. Special thanks to FIA field crews in the State of Mississippi for their dedication to quality data collection.

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Published by Elsevier B.V.

Relationships between common forest metrics and realized impacts of Hurricane Katrina on forest resources in Mississippi

Abstract

Introduction

Section snippets

FIA field methods

Measured hurricane damage

Landscape level damage

Conclusions

Acknowledgments

For. Ecol. Manage.

For. Ecol. Manage.

For. Ecol. Manage.

Species and stand response to catastrophic wind in central New England, U.S.A.

J. Ecol.