Impacts of Hurricanes on Forest Hydrology and Biogeochemistry

Abstract

Hurricanes, typhoons, tropical cyclones, and other tropical storms affect many areas of the globe. Although the names used vary regionally, here I will refer to hurricanes to describe the impacts of these tropical storms globally. The intensity and frequency of hurricanes vary dramatically in different areas of the globe, but their origins are always in warm tropical waters such as the North Atlantic off the African coast, or the central Pacific Ocean. Hurricanes result from the interaction of heated sea water with global wind circulation patterns to create a contained meteorological system with persistent cyclonic circulation rotating around a low-pressure center (Fig. 32.1). Hurricanes initially arise from tropical storms with incomplete circulation, and as they grow in strength the circulation (counterclockwise in the Northern Hemisphere, clockwise in the Southern) closes with an “eye” in the center. Once the circulation is complete, the system is referred to as a hurricane if wind speeds exceed 119 km h −1 . Each hurricane has both a speed (the rate at which the storm is moving across the face of the earth) and a strength (the velocity of the cyclonic circulation). The strength of the hurricane changes over time, and usually declines after initial landfall. Damage to forests is typically a function of the hurricane strength, which determines the likelihood of both damage to trees and the storm surges that can occur in low-lying coastal areas. Hurricanes are often associated with high rains, with totals of 25 cm or more.