Precipitation rather than wind drives the response of East Asian forests to tropical cyclones

Abstract. Forests disturbance by tropical cyclones is documented by field studies of exceptionally strong cyclones and satellite-based approaches attributing decreases in leaf area. The biases that come with such approaches may limit our understanding of the impact of cyclones in general. This study overcomes such biases by starting the analysis from the observed storm tracks rather than the observed damage. Changes in forest leaf area in East Asia were assessed by jointly analyzing the cyclone tracks, climate reanalysis, and changes in satellite-based leaf area following the passage of 145 ± 42 cyclones. Sixty days following their passage, 14 ± 6 % of the cyclones resulted in a decrease and 55 ± 21 % showed no change in leaf area compared to nearby forest outside the storm track. For a surprising 31 ± 6 % of the cyclones, an increase in leaf area was observed. Further analysis revealed that cyclones bringing abundant precipitation to dry forest soils in summer could relieve water stress within the storm track increasing its leaf area compared to vegetation outside the storm track. This observation calls for refining the present-day view of cyclones as agents of destruction toward a more nuanced vision that recognizes that cyclones could have minor or even positive effects on leaf area and as such on forest growth.