Abstract:Litter plays an important role as a metabolic product in nutrient cycling and energy transfer in forest ecosystems. Different forest types (e.g., broad-leaved vs. needle-leaved forests, and natural secondary forests vs. plantations) are characterized by different litterfall compositions and dynamics, which are associated with different plant community structure, climate zone, and microclimate. The Yimeng mountainous area is located in a warm-temperate zone and contains the earliest plantations in China. In addition to natural secondary forests, the main forest types in this area are plantations of the introduced needle-leaved species Pinus thunbergii Parl. and the native broad-leaved species Quercus variabilis Bl. In this study, we analyzed the composition and dynamics of litterfall in these three forest types. Seventeen plots were selected, including six plots in P. thunbergii plantation, six in natural secondary forest, and five in Q. variabilis plantation. In each plot, a 1 m×1 m sieve was placed 30 cm above the ground for monthly litter collection from May 2015 through April 2017. The collected litter was transferred to the laboratory and sorted into needle leaf, broad leaf, fruit, and other litter, and then dried to a constant weight at 80℃. The results showed that natural secondary forests had a higher annual litterfall (3368 kg/hm2) than that of Q. variabilis plantation (3256 kg/hm2) and P. thunbergii plantations (3212 kg/hm2). However, there was no significant difference in annual litterfall among the three forest types. The monthly dynamics of overall litterfall in the three forest types all had a two-peak curve, with the higher peak occurring during October through November and the lower peak appearing during April through May. However, minimum litterfall occurred at different times in the different forests, namely, October through November in P. thunbergii plantations, and during July in the other two forest types. The curves of needle leaf, broad leaf, and branch litterfall were similar to that of overall litterfall. The branch litterfall changed smoothly, whereas fruit litterfall mainly appeared in August through September. Leaf litter was the largest component of litterfall, accounting for more than 65.9% of the total in all three forest types. The quantity and ratio of needle leaf litterfall, and quantity of other litter in P. thunbergii plantations were higher than those in Q. variabilis plantations, which in turn were higher than those in natural secondary forests. In contrast, the quantity and ratio of broad leaf litterfall showed the opposite trend. There was no significant difference in the quantity of branch litterfall among the forest types. Litterfall components were influenced by different environmental factors. Multiple linear regression analyses showed that monthly litterfall production was significantly negatively correlated with minimum air temperature and significantly positively correlated with maximum air temperature. Needle leaf litter production was significantly influenced by both minimum and maximum air temperature and maximum precipitation; broad leaf litter production was significantly influenced by minimum air temperature; branch litter production was significantly influenced by precipitation, maximum precipitation, and wind speed; and fruit litter production was significantly influenced by air temperature, wind speed, and precipitation. Natural secondary forests had the largest litterfall, which is beneficial in terms of nutrient cycling and soil fertility. Therefore, protecting natural secondary forests from disturbance in the Yimeng mountainous area is important for the enhancement of carbon sequestration and nutrient cycling, and the maintenance of soil fertility.