Soil moisture dominated the temporal dynamics of litter moisture content in subtropical forests: a 7-year observation in south China

Study region: Dinghushan watershed, China. Study focus: The dynamics of litter moisture content play an important role in understanding the forest’s internal environmental changes, forest fire forecast and prediction of general forest health and so on. These characteristics have not been extensively analyzed in lower subtropical China and therefore, three typical subtropical evergreen forest ecosystems, Pinus massoniana coniferous forest (PF), mixed conifer-broadleaf forest (CBF), and monsoon evergreen broadleaved forest (MBF), were chosen to explore the changes of the litter moisture content and its response to environmental factors. New hydrological insights for the region: Over a 7-year observation period, the mean annual litter moisture content was 72.0 ± 7.3%, 87.9 ± 11.3%, and 100.5 ± 15.7% for PF, CBF, and MBF respectively. The litter moisture content increased while the litter standing mass decreased after vegetation restoration. The litter moisture content in the three forests during the wet season was substantially higher than that in the dry season. Compared to the soil layer, the coefficient of variation of the litter moisture content during the dry and wet seasons was higher as compared to the topsoil (0–30 cm) water content, indicating the litter layer was more sensitive to changes in external environmental factors. Further analysis revealed that soil water content was the dominating factor controlling the dynamics of litter moisture content both during the dry and wet seasons. Analyses of the litter moisture can be very useful in forests around the world as a guideline in indicating the change in a forest’s environment.