Grazing exclosures solely are not the best methods for sustaining alpine grasslands

Abstract

Background Grazing is widely regarded as a critical factor affecting the vegetation structure, productivity and nutritional value of natural grasslands. To protect and restore degraded grasslands, non-grazed exclosures are considered as a valuable tool. However, it is not clear whether long term non-grazed exclosures of grazers can improve the condition and nutritional value of vegetation and soil properties. Methods We have compared the impact of long-term non-grazed and continuous grazed management strategy on vegetation structure, nutritional values and soil properties of alpine meadow of the Qinghai-Tibet Plateau by field investigation (11–13 years) and indoor analysis during 2015–2017. Results Our results showed that long-term non-grazed exclosures clearly increased the aboveground biomass and coverage of plant functional types. Long-term non-grazed exclosures improved the development of all vegetation types, except NG (GG, grass species type; SG, sedge species type; LG, leguminous species type; FG, forbs species type and NG, noxious species type). Long-term non-grazed exclosures significantly improved all six measured soil properties (TN, total nitrogen; TP, total phosphorus; TK, total potassium; AN, available nitrogen; AP, available phosphorus and AK, available potassium) in 0–10 cm soil layer, considerable effect on the improvement of all measured soil properties, except TK in 10–20 cm soil layer and all measured soil properties, except TN and TK in 20–30 cm soil layer were observed. However, long-term non-grazed exclosures significantly decreased biodiversity indicators i.e., species richness, Shannon diversity index and Evenness index of vegetation. A substantial decrease in the density, biodiversity and nutritional values (CP (crude protein), IVTD (in vitro ture digestibility) and NDF (neutral detergent fiber)) of all vegetation types, except NG were recorded. While a downward trend in aboveground biomass and all measured soil properties except TP and TK were observed during 2015–2017 in alpine meadows due to long-term grazed treatment. The density, diversity and nutritional value (CP and IVTD) of long-term non-grazed alpine meadows showed a downward trend over time (2015–2017). By considering the biodiversity conservation and grassland livestock production, long-term non-grazed exclosures are not beneficial for the improvement of density, biodiversity and nutritional values of plant functional types. Thus, our study suggests that rotational non-grazed and grazed treatment would be a good management strategy to restore and improve the biodiversity and nutritional values of plant functional types in natural grassland ecosystems.

Rotational grazing promotes grassland aboveground plant biomass and its temporal stability under changing weather conditions on the Qinghai‐Tibetan plateau

“…Grazing exclosure is beneficial for soil C sequestration in degraded alpine grassland (Yu, Chen, Sun, & Huang, 2019), it also increased the aboveground biomass and coverage of plant, soil properties. However, long‐term grazing exclosure decreased biodiversity (Yao, Wu, Gong, Lang, & Wang, 2019), rotational grazing therefore would be a better grassland management strategy. Researches confirmed that rotational grazing improved ground cover and animal production (McDonald, Lawrence, Kendal, & Rader, 2019), biomass (Boavista, Trindade, Overbeck, & Müller, 2019), functional diversity (Li et al, 2019), and alleviate soil erosion (Sanjari, Yu, Ghadiri, Ciesiolka, & Rose, 2009).…”

Soil fungal networks are more sensitive to grazing exclusion than bacterial networks

“…Therefore, grazing exclusion has been widely used in Inner Mongolia for curbing grassland degradation and restoring damaged ecosystems (Bai et al, 2004;Hao et al, 2014). However, the effects of grazing exclusion are controversial depends on its vegetation types, environmental conditions, and duration (Jing et al, 2014;Yan & Lu, 2015;Yao et al, 2019).…”

Drivers, Process, and Consequences of Native Grassland Degradation: Insights from a Literature Review and a Survey in Río de la Plata Grasslands

“…Climate change appears to be a significant driver on arid grasslands [20,50,51,137] while it is not mentioned in humidity grasslands analysis. On the other hand, light grazing intensity or grazing exclusion, have different effects depending on the bioclimatic region, with a positive effect on arid environments [57,58], and a negative one on humidity regions [59,60]. Regarding consequences, desertification is exclusively reported on arid and semiarid areas [9].…”

“…On the other hand, extreme under-grazing (or grazing abandonment) could also be a source of degradation affecting productivity and species composition. Although long term livestock exclosures increased standing biomass and vegetation cover, and they may be a useful management tool to restore the vegetation in degraded grassland of arid regions [57,58], they sometimes decreased grassland biodiversity [59,60] and ANPP [59].…”