Litter decomposition and nutrient release of typical forest communities in non-growing season in cold temperate zone

  Objective   Studying the decomposition and nutrient release characteristics of forest litter during the non-growing season aims to provide theoretical basis for forest nutrient cycling and productivity evaluation in cold temperate zone.

  Method  Four typical forests (Betula platyphylla forest, Populus davidiana forest, Larix gmelinii forest and Pinus sylvestris var. mongolica forest) in cold-temperate regions were selected to conduct the decomposition experiment using bagging method and analyze the decomposition and nutrient release dynamic of litter during autumn, winter and freezing-thawing in spring, respectively.

  Result  The highest mass loss rate and nutrient release of litter was found in autumn. The litter mass loss rate of the four forest types ranged from 17.50% to 30.60%, in which the fastest and slowest litter decomposition were found in the Betula platyphylla and Larix gmelinii forest, respectively. In particularly, the mass loss rate of litter in winter ranged from 0.52% to 5.12%, while the range from 3.12% to 7.65% was found in freezing-thawing period of spring. In the non-growing season, the fastest decomposition rate 1.37 g/(kg·d) occurred in Betula platyphylla, while the slowest was found in Larix gmelinii forest with 0.87 g/(kg·d). Both C, P, and K in the litter of the four forest types exhibited the released state, in which the range of release rate ranged from 17.45% to 65.90%. The release rates of C and P in Betula platyphylla forest were the highest, 8.14% and 65.90%, respectively, and the release rate of K in Populus davidiana forest was the highest, being 58.19%. In contrary, N showed a cumulative state in all forest communities. The release rates of C, P, and K in the four forest communities litter in winter were greatly reduced, while N showed a cumulative state, with the cumulative rate ranged from 1.44% to 51.54%. During the freezing-thawing period in spring, the nutrient release rate of litter increased, but different forest types fluctuated greatly due to the influence of soil temperature and humidity.

  Conclusion  In the non-growing season, the litter mass loss rate of the four forest types in the cold temperate zone ranges from 21.60% to 42.37%. Except for the overall accumulation of N in Populus davidiana forest, the C, N, P and K elements in the litter of other forest types are released. The litter mass loss rate and the release of C, P and K elements are mainly in autumn, while the N release is mainly in spring.