Litter alteration reduces ecosystem multifunctionality through divergent aboveground-belowground feedbacks in alpine...

Plant litter plays critical roles in altering biogeochemical processes and ecological functions in global grasslands. However, little is known about how plant litter alterations influence the multiple ecological functions in semi-humid alpine grasslands. A controlled experiment in field was carried out in alpine grassland, where different plant litter inputs levels were conducted to explore how plant litter manipulation affects the ecosystem multifunctionality (EMF). The results showed that plant litter removal tended to positively affect plant diversity and productivity but negatively affect soil nutrients. In contrast, plant litter addition had a trend to decrease plant diversity and productivity but increase soil nutrients. Both plant litter addition and removal had negative influences on the EMF index in semi-humid alpine grassland. Ecosystem multifunctionality (EMF) was significantly decreased under the L+100 % treatment (p < 0.01). However, we found that the above- and belowground ecological functions responded differently to plant litter manipulation. Plant litter addition had negative impacts on the aboveground ecosystem functioning but tended to positively affect the belowground ecosystem functioning. Aboveground ecosystem multifunctionality (AEMF) was significantly decreased under the L+50 % treatment (p < 0.05), while a significant decrease in AEMF was observed under the L+100 % treatment (p < 0.001). However, plant litter removal had a trend to increase the aboveground ecosystem functioning but significantly decreased the belowground ecosystem functioning. Belowground ecosystem multifunctionality (BEMF) was significantly decreased under the L-50 % treatment (p < 0.05), while a significant decrease in BEMF was observed under the L-100 % treatment (p < 0.001). In addition, the finding revealed that plant litter manipulation affected the ecosystem multiple functioning directly through regulating plant diversity and productivity as well as soil fertility. These results emphasize the significant role of climate change and grazing induced alterations in plant litter inputs in maintaining the ecological functions in alpine grasslands and indicate that such changes in litter inputs may alter the relative contribution of plant diversity to ecosystem functioning by mediating plant productivity and soil nutrient cycling.