Improving hurricane assessments with FIA data

hurricane damage to a mixed pine and hardwood forest
A naturally regenerated, mixed hardwood and pine forest shows many down and standing dead tree trees. This photo was taken in the winter, so some deciduous trees are alive but lacking leaves. USDA Forest Service photo by Jason Cooper.

In October of 2018, Hurricane Michael made landfall and left a trail of damage of over six million acres of forest and ten billion cubic feet of timber across Alabama, Florida, and Georgia.  

Timber is a critical part of the economy in all three states, so measuring damage to forested land was vital for the economy as well as the environment. In a new study, USDA Forest Service researchers did just that, using national forest inventory data to improve assessments of hurricane damage by refining existing numbers that underestimated the damage.  

Initially, the SRS Forest Inventory and Analysis (FIA) program assessed forest resource losses immediately after the hurricane hit in October of 2018. However, for this new study, researchers remeasured the results using data from FIA forest inventory plots, which are used to track forest status. Researchers recorded the cubic feet of timber left alive, dead, and harvested after the hurricane at a range of plots across the three affected states.  

Researchers then identified which of the National Oceanic and Atmospheric Administration’s (NOAA) storm damage severity zones each plot fell into – moderate, severe, or catastrophic. They analyzed patterns between the severity of the damage and the state of the forests after the hurricane.  

The research found that of the ten billion cubic feet of timber that stood in the damage zone, only 68% remained alive following the hurricane. Of the other 32%, about half was dead, while the other half was utilized, which the researchers tracked by comparing cut stumps to trees previously recorded on the plot.  

salvaged pine logs from hurricane damage
Post-hurricane harvesting operations recovered a considerable amount of usable timber, as evidenced by these pine logs ready for loading and transport to a mill. USDA Forest Service photo by Jason Cooper.

These percentages varied across the damage severity zones, however. Researchers found twice as much timber alive in moderate damage zones compared to catastrophic damage zones. On the other hand, twice as much timber was harvested from these catastrophic zones compared to the average rate of utilization across the entire damage zone.  

Researchers also found hurricane impacts varied by major tree species groups. Pines were the most heavily impacted, with only 22.7% left alive in the catastrophic zones. Pines were also the most heavily salvaged after the hurricane.  

Finally, there was four times more down woody materials (meaning uprooted wood or wood that is no longer connected to the tree and is lying on the ground) after the hurricane.  

This paper demonstrates the importance of collecting data about hurricane damage as quickly as possible so scientists can share this information with those affected economically and geographically. FIA data will continue to be a useful resource for improving the accuracy and speed of these damage estimates.  

Read the full text of the SRS Research Paper here 

For more information, email thomas.j.brandeis@usda.gov.

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