Spatial pattern and environmental controls of annual litterfall production in natural forest ecosystems in China

Litterfall is an important structure and function unit of nutrient cycling and energy flowing in forest ecosystems. A large number of litterfall studies have been developed in Chinese forests, however, few synthesis studies at the national scale have been reported so far. In this paper we synthesized 308 litterfall datasets during the period of 1970–2014 in Chinese natural forests. The observation sites of those datasets distributed widely in various climate zones with latitudes 18°15′–51°30′N, longitudes 82°53′–129°06′E and altitudes 0–3828 m. The annual litterfall production increased from boreal, temperate, subtropical to tropical forests, the mean values were 2.45, 3.56, 6.66 and 9.30 t hm - 2, respectively. There was significantly negative correlation between annual litterfall production and latitude (R2=0.434). The annual litterfall production decreased by 0.19–0.27 t hm - 2 with latitude increasing 1°. Annual litterfall production was mainly influenced by heat factors, for example, equivalent latitude (the interaction bewteen latitud and altitude) and mean annual temperature, which could both explain approximately 60% of the variation in Chinese natural forests. We found that the relationships would be further improved by 11% or 15% when the observation periods were more than 2 or 3 years, respectively. The results would provide forest ecosystem management and forest fire prediction with quantitative reference of forest littlefall.