Forest dynamics where typhoon winds blow

Area of Science:

• Ecology
• Forestry
• Meteorology

Background:

• Tropical cyclones (TCs) cause significant forest damage, but their impact on mountainous terrain remains poorly understood due to modeling complexities.
• Typhoon Mangkhut (2018) provided a unique opportunity to study TC effects with extensive data from Hong Kong.

Purpose of the Study:

• To investigate the effects of extreme wind events from TCs on forest structure and dynamics in mountainous regions.
• To compare the impact of TCs on natural rainforests versus plantations.

Main Methods:

• Utilized a dense anemometer network and repeated LiDAR surveys to capture forest changes.
• Employed Computational Fluid Dynamics (CFD) models to map wind speeds and analyze canopy height alterations across a large area (>400,000 pixels, 1108 km²).

Main Results:

• Forest height was more constrained by wind exposure than topography, indicating a balance between growth and TC-induced damage.
• Wind-sheltered forests experienced significant damage, resulting in more rugged canopies compared to exposed forests.
• Plantations showed greater susceptibility to TC damage than natural rainforests, with greater canopy height reduction.

Conclusions:

• TCs are a critical, often underestimated, factor shaping forest structure and dynamics, particularly in exposed and mountainous environments.
• Forest management strategies should consider the differential vulnerability of natural forests and plantations to extreme wind events.