Grazing system and body weight of Tibetan sheep influence biomass allocation and decomposition in alpine meadows

Grazing affects the allocation of aboveground biomass (AGB), and decomposition of litter and dung, thereby regulating material flow in grassland ecosystems. However, the combined effects of grazing system (GS) and body weight (BW) on biomass allocation remain unclear. This study had conducted a two-year experiment in an alpine meadow of Qinghai-Tibetan Plateau (QTP), in order to examine the effects of two GS (continuous grazing - CG, and rotational grazing - RG) and three BWs of Tibetan sheep (23.3, 35.4, and 41.9 kg) on biomass allocation. At the three BW levels, compared to no grazing, CG reduced AGB by 20.9 %, 29.8 %, and 40.8 %, respectively, while RG reduced it by 30.4 %, 37.3 %, and 46.6 %. CG reduced litter decomposition mass by 20.1 %, 27.5 %, and 43.8 %, respectively, while RG reduced it by 22.1 %, 41.0 %, and 54.4 %, respectively. Compared to CG, RG increased dung decomposition mass by 41.6 %, 53.2 %, and 44.4 %, respectively. BW, GS, and GS × BW contributed 72.1 %, -64.0 %, and -11.2 % to litter daily decomposition rate (LDDR), respectively. The contributions were 95.2 %, -21.7 %, and 4.5 % for dung daily decomposition rate (DDDR), and -69.4 %, 25.8 %, and -6.8 % for total matter turnover. RG's LDDR and DDDR were both higher than CG, with DDDR increasing faster than LDDR. RG demonstrates a greater allocation to intake and dung matter turnover compared to CG, particularly at higher BW levels. The findings suggest the significance of GS and BW in biomass allocation and decomposition, providing valuable insights for sustainable grassland management.