Litter Removal Increases Plant Carbon Inputs to Soil in Pinus Massoniana Plantation

Aims: Plants are the main source of soil organic carbon (C) in forest ecosystems; they input photosynthetically assimilated C into the soil through litter, root litter, and root exudates. Variations in plant net primary production caused by global environmental changes are likely to drive shifts in leaf litterfall inputs to soils. However, the effects of these changes on plant aboveground and underground C input remain largely unknown. Methods: We conducted a two-year litter manipulation (litter removal, addition, and control) experiment in a Pinus massoniana plantation and studied its impacts on plant C input via litter, fine root, and root exudates. Results: The results showed that litter removal significantly increased litterfall in summer and autumn and reduced root C exudation rates in spring, but had no influence on the C input of fine root. Whereas litter addition did not significantly affect the C input of litter, fine root, or root exudates. The annual C input of litter, fine root, and root exudates in control plots were 348.28 g C m -2 ,42.39 g C m -2 , and 17.44 g C m -2 , accounting for 85.34%, 10.39%, and 4.27% of the total C input, respectively. Litter removal increased plant annual total C input by 24.55% owing to reducing root exudate C input by 30.50% and increasing litter C input by 31.12%. Conclusions: Increasing the aboveground C input and decreasing underground C input under litter removal is a strategy to maximize forest growth in short term. The increased plant C input under litter removal mitigated the influences of litter alteration caused by global change. This was of great significance for understanding plant growth strategy and forecasting plant growth dynamic under global change.