Title: Grazing increases litter decomposition rate but decreases nitrogen release rate in an alpine meadow

Authors: Yi Sun,Xiong Z. He, Fujiang Hou *, ZhaofengWang, and Shenghua Chang

Journal: Biogeosciences (环境科学与生态学，二区，IF₂₀₁₆=3.851)

Doi: https://doi.org/10.5194/bg-15-4233-2018

Abstract: Litter decomposition and N release are the key processes that strongly determine the nutrient cycling at the soil?plant interface; however, how these processes are affected by grazing or grazing exclusion in the alpine grassland ecosystems on the Qinghai-Tibetan Plateau (QTP) is poorly understood. So far few studies have simultaneously investigated the in?uence of both litter quality and incubation site on litter decomposition and N release. Moreover, previous studies on the QTP investigating how grazing exclusion in?uences plant abundance and biodiversity usually lasted for many years, and the short-term effects have rarely been reported. This work studied the short-term (6 months) effects of grazing and grazing exclusion on plant community composition (i.e., plant species presented) and litter quality and long-term (27?33 months) effects on soil chemical characteristics and mixed litter decomposition and N release on the QTP. Our results demonstrate that (1) shorter-term grazing exclusion had no effect on plant community composition but increased plant palatability and total litter biomass; (2) grazing resulted in higher N and C content in litter; and (3) grazing accelerated litter decomposition, while grazing exclusion promoted N release from litter and increased soil organic carbon. In addition, incubation site had signi?cantly more impact than litter quality on litter decomposition and N release, while litter quality affected decomposition in the early stages. This study provides insights into the mechanisms behind the nutrient cycling in alpine ecosystems. We suggest that periodic grazing and grazing exclusion is bene?cial in grassland management on the QTP.

链接：https://www.biogeosciences.net/15/4233/2018/