Short-Term Changes in the Soil Respiration of Casuarina equisetifolia L. Plantations After Severe Typhoon Disturbance

Typhoon disturbances significantly influence forest carbon cycling by altering both physical structures and biogeochemical processes. Typhoon-induced fluctuations in soil respiration can substantially affect the carbon balance in forest ecosystems. In this study, we conducted a comparative investigation of soil respiration in plantations of Casuarina equisetifolia L. that were either affected or unaffected by the severe Typhoon Yagi, which ravaged Hainan Island, China, in 2024. The soil respiration and its components in Casuarina equisetifolia L. plantations in the coastal areas of Hainan, China, as well as their responses to environmental factors before and after typhoon disturbance, were investigated based on total soil respiration rate (Rs), heterotrophic respiration rate (Rh), 5 cm soil temperature (T5), and 10 cm soil moisture (W10) to support the carbon emission estimation in coastal sandy land plantations. The mean Rs and Rh in the typhoon-disturbed plots were (1.82 ± 0.16) and (1.19 ± 0.26) μmol·m−2·s−1, respectively, while those in the control plots were (2.62 ± 1.08) and (1.41 ± 0.23) μmol·m−2·s−1, respectively, with statistically significant differences (p < 0.05). In both plots, Rs exhibited a significant positive correlation with T5 (p < 0.01). The T5 correlation and Q10 values for soil respiration were significantly higher in the typhoon-disturbed plots than in the control plots (p < 0.05). W10 of the soil exhibited significant negative correlations with Rs and Rh in typhoon disturbance plots (p < 0.05). Consequently, typhoon disturbance markedly inhibited soil respiration and its components in the Casuarina equisetifolia L. plantations, indicating substantial impacts of typhoons on soil respiration processes and carbon cycling within the forest ecosystem. This study provides key parameters and empirical evidence to improve the accuracy of soil carbon emission estimates in Casuarina equisetifolia L. plantations on coastal sandy soils affected by typhoon events.