Dynamics in foliar litter decomposition for Pinus koraiensis and Quercus mongolica in a snow-depth manipulation experiment北大核心CSCD

Aims Changes in snowpack induced by climate change may alter water and heat regimes at the ground surface, thus influencing activities of decomposers and litter decomposition in snow-covered regions. However, effects of snow-depth changes on litter decomposition are unclear. Our objective was to characterize the decomposition dynamics of two contrasting tree species—Korean pine (Pinus koraiensis) and Mongolian oak (Quercus mongolica) in a snow-depth manipulation experiment. Methods The snow-depth manipulation experiment that included three treatments (i.e., snow-addition, snow-removal, and control) was conducted in a temperate Korean pine plantation in the Maoershan Forest Ecosystem Research Station, Northeast China. Air-dried foliar litter of the pine or oak (10 g litter per bag) was sealed in a nylon litterbag (15 cm × 20 cm). A total of 648 litterbags (3 plots × 3 treatments × 2 tree species × 3 replicates × 12 sampling dates) were placed evenly on the forest floor in October 2014. Three replicate litterbags per species were buried in each treatment plot and sampled 12 times (i.e., freezing onset stage, deep freezing stage, thawing stage, early, middle and late snow-free seasons) during the two-year period (2014–2016) to determine the temporal variation of the decomposition rate. Associated factors (i.e., mean temperature at litter layer, freeze-thaw cycle, available nitrogen and phosphorus at the organic layer) were measured simultaneously. Important findings Tree species, snow-depth treatment, decomposition stage, and the measured associated factors all influenced the decomposition rates of the foliar litter. The litter mass loss was 52.1%–54.5% for the pine, and 53.9%–59.1% for the oak during the two-year period. The decomposition coefficients for the litter of the two species were the highest in the snow-addition plot, and the lowest in the snow-removal plot. Moreover, the snow-depth manipulation dramatically changed the relative contribution of the mass loss (R ratio) during the snow-covered or snow-free seasons to the yearly total loss. Compared with the control, the snow-addition treatment increased the R ratio during the snow-covered season by 9.1% for the pine and 10.4% for the oak, while the snow-removal treatment increased the R ratio during the snow-free season by 10.4% and 12.7%, respectively. In conclusion, changes in snowpack induced by climate change may significantly affect the foliar decomposition in temperate forests, and also alter the relative contribution of the litter decomposition in the snow-covered and snow-free seasons to the yearly decomposition. © 2018 Editorial Office of Chinese Journal of Plant Ecology. All rights reserved.