In order to explore responses of soil microbial communities among different alpine meadows under warming and clipping, soil microorganisms of three alpine meadow sites (low altitude: 4313 m, alpine steppe meadow, 30°30′ N, 91°04′ E; mid-altitude: 4513 m, alpine steppe meadow, 30°31′ N, 91°04′ E; and high altitude: 4693, alpine Kobresia meadow, 30°32′ N, 91°03′ E) were measured using the phospholipid fatty acid (PLFA) method. Both warming and clipping significantly reduced PLFA content and changed the community composition of soil microbial taxa, which belong to bacterial and fungal communities in the alpine Kobresia meadow. Warming significantly reduced the soil total PLFA content by 36.1% and the content of soil fungi by 37.0%; the clipping significantly reduced the soil total PLFA content by 57.4%, the content of soil fungi by 49.9%, and the content of soil bacteria by 60.5% in the alpine Kobresia meadow. Only clipping changed the total fungal community composition at a low altitude. Neither clipping nor warming changed the microbial community composition at a moderate altitude. Soil temperature, soil moisture, and pH were the main factors affecting soil microbial communities. Therefore, the effects of warming and clipping on soil microbial communities in alpine meadows were related to grassland types and soil environmental conditions.

How climate change and fencing will affect forage nutrition quality of alpine grasslands is still unknown in the Northern Tibet. Here, we reported the effects of climate change and fencing on forage nutrition quality (i.e., CP: crude protein, ADF: acid detergent fiber, NDF: neutral detergent fiber, Ash: crude ash, EE: ether extract and DTS: dissolvable total sugar) in alpine grasslands across the Northern Tibet based on a transect survey dataset from 2018. Over the whole survey transect, fencing reduced the NDF content by 5.15% and the EE content by 15.79%, but did not affect forage nutrition quality (R² = 0.04, p = 0.389). Air temperature and precipitation explained 24% and 8% of variation in the CP content under the fencing conditions, respectively. Precipitation explained 22% of variation in the NDF content under the fencing conditions. The CP content decreased and increased exponentially with increasing air temperature under the fencing and grazing conditions, respectively. The NDF content showed logarithmic and negative relationships with precipitation under the fencing and grazing conditions (−8.45 vs. −6.68lnNDF). The response of the CP content to fencing showed negative relationships with temperature and the response of AGB to fencing, but showed a positive relationship with precipitation. The CP and DTS contents showed negative relationships with AGB under the fencing and grazing conditions. In contrast, the ADF content showed a positive relationship with AGB. The response of AGB, SR and community composition to fencing explained 11%, 56% and 35% of variation in the response of forage nutrition quality to fencing, respectively. Therefore, climate change may not always have adverse effects on forage nutrition quality, whereas fencing may not always have favorable effects on forage nutrition quality. Fencing and climate change can have an interactive effect on forage nutrition quality. Fencing can alter the temperature and precipitation sensitivities of forage nutrition quality. In colder and wetter regions, the forage nutrition quality may be more responsive to fencing. There may be a trade-off between forage nutrition quality and quantity. Compared to the change in AGB caused by fencing, the changes in species α-diversity and community composition caused by fencing can have greater effects on the response of forage nutrition quality to fencing. Local climate conditions and the trade-offs between forage nutrition quality and biomass should be considered when evaluating the effects of fencing on the restoration of degraded grassland plants.

The uncertainty response of soil fungi community to climate warming in alpine agroecosystems will limit our ability to fully exploit and utilize soil fungi resources, especially in alpine regions. In this study, a warming experiment was conducted in one perennial leguminous agroecosystem [i.e., alfalfa (Medicago sativa)], perennial gramineous agroecosystem (i.e., Elymus nutans) and annual gramineous agroecosystem [i.e., highland barley (Hordeum vulgare L)] in Tibet since 2016 to investigate the response of soil fungi community to climate warming. Soils at two layers (i.e., 0–10 cm and 10–20 cm) were collected in August 2017 to estimate soil fungi community based on the ITS method. The α-diversity, community composition and functional group abundance of soil fungi in the leguminous agroecosystem were more sensitive to climate warming. The α-diversity of soil fungi in the perennial gramineous agroecosystem were more sensitive to climate warming, but topology parameters of soil fungi species cooccurrence network in the annual gramineous agroecosystem were more sensitive to climate warming. Compared with 0–10 cm, soil fungal α-diversity, community composition and functional group abundance at 10–20 cm were more sensitive to climate warming. The topological parameters of soil fungi species cooccurrence network at 0–10 cm in the gramineous agroecosystem were more sensitive to climate warming, but those at 10–20 cm in the leguminous agroecosystem were more sensitive to climate warming. Warming increased the differences of soil fungi α-diversity and functional composition. For the Medicago sativa agroecosystem, warming increased the abundance of soil pathogenic fungi but decreased the abundance of soil symbiotic and saprophytic fungi at 10–20 cm. Therefore, responses of the soil fungi community to climate warming varied with agroecosystem types and soil depth. Climate warming can alter the differences of the soil fungi community among agroecosystems. Changes in soil fungi community caused by climate warming may be detrimental to the growth of alpine crops, at least for perennial Medicago sativa in Tibet.

Pennisetum flaccidum can be used as a pioneer species for the restoration of degraded grasslands and as a high-quality forage for local yak and sheep in alpine regions. The geographical distribution pattern of soil fungal community can modify that of P. flaccidum. A field survey along 32 sampling sites was conducted to explore the geo-distribution patterns of soil fungal community of P. flaccidum in Tibet. Soil fungal species, phylogenetic and function diversity generally had a closer correlation with longitude/elevation than latitude. The geo-distribution patterns of soil fungal species, phylogenetic and function diversity varied with soil depth. Soil fungal species, phylogenetic and function diversity had dissimilar geo-distribution patterns. Precipitation had stronger impacts on total abundance, species α-diversity, phylogenetic α-diversity, and function β-diversity than temperature for both topsoil (0–10 cm depth) and subtopsoil (10–20 cm depth). Furthermore, precipitation had stronger impacts on function α-diversity for topsoil, species β-diversity for topsoil, and phylogenetic β-diversity for subtopsoil than temperature. The combination of species, phylogenetic and function diversity can better reflect geo-distribution patterns of soil fungal community. Compared to global warming, the impact of precipitation change on the variation in soil fungal community of P. flaccidum should be given more attention.

In order to investigate the general tendency of soil microbial community responses to fertilizers, a meta-analysis approach was used to synthesise observations on the effects of inorganic and organic fertilizer addition (N: nitrogen; P: phosphorus; NP: nitrogen and phosphorus; PK: phosphorus and potassium; NPK: nitrogen, phosphorus and potassium; OF: organic fertilizer; OF+NPK: organic fertilizer plus NPK) on soil microbial communities. Among the various studies, PK, NPK, OF and OF+NPK addition increased total phospholipid fatty acid (PLFA) by 52.0%, 19.5%, 334.3% and 58.3%, respectively; while NP, OF and OF+NPK addition increased fungi by 5.6%, 21.0% and 8.2%, respectively. NP, NPK and OF addition increased bacteria by 6.4%, 9.8% and 13.3%, respectively; while NP and NPK addition increased actinomycetes by 7.0% and 14.8%, respectively. Addition of ammonium nitrate rather than urea decreased gram-negative bacteria (G–). N addition increased total PLFA、bacteria and actinomycetes in croplands, but decreased fungi and bacteria in forests, and the F/B ratio in grasslands. NPK addition increased total PLFA in forests but not in croplands. The N addition rate was positively correlated with the effects of N addition on gram-positive bacteria (G+) and G–. Therefore, different fertilizers appear to have different effects on the soil microbial community. Organic fertilizers can have a greater positive effect on the soil microbial community than inorganic fertilizers. The effects of fertilizers on the soil microbial community varied with ecosystem types. The effect of N addition on the soil microbial community was related to both the forms of nitrogen that were added and the nitrogen addition rate.

There are still great uncertainties about effects of climate warming and no-tillage on soil carbon, nitrogen, phosphorus and potassium contents and pH in alpine farmlands. A warming (control; daytime warming, DW; nighttime warming, NW; all-day warming, DW + NW) and no-tillage (no-tillage vs. tillage) experiment was conducted in an alpine farmland of the Lhasa, Xizang since 2015. Soil organic carbon, total nitrogen, total phosphorus, total potassium (TK), available nitrogen, available phosphorus, available potassium, dissolved organic carbon (DOC), active organic carbon, particulate organic carbon (POC), light fraction organic carbon, and heavy fraction organic carbon contents and pH at four depths (0–5, 5–15, 15–25, and 25–35 cm) were measured. Warming effects on concerned soil variables differed with warming time, soil depth, and no-tillage. No-tillage effects on concerned soil variables differed with warming-time (daytime, nighttime, and all-day warming) and soil depths. Therefore, daytime warming and nighttime warming have different effects on soil variables, although the effects of nighttime warming on soil variables are not always greater than those of daytime warming. Effects of daytime warming and nighttime warming on soil variables are not simple addition or subtraction effects. There are interactions between diurnal asymmetrical warming and no-tillage on soil variables.