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Overgrazing‐induced grassland degradation has become a serious ecological problem worldwide. The diversity and composition of soil microbial communities are sensitive to grazing disturbances. However, our understanding is limited with respect to the effects of grazing intensity on bacterial and fungal communities, especially in plant rhizosphere. Using a long‐term grazing experiment, we evaluated the diversity and composition of microbial communities in both rhizosphere and non‐rhizosphere soils under three grazing intensities (light, moderate, and heavy grazing) in a desert grassland and examined the relative roles of grazing‐induced changes in some abiotic and biotic factors in affecting the diversity and composition of microbial communities. Our results showed that soil bacteria differed greatly in diversity and composition between rhizosphere and non‐rhizosphere zones, and so did soil fungi. Moderate and heavy grazing significantly reduced the rhizosphere bacterial diversity. Grazing intensity substantially altered the bacterial composition and the fungal composition in both zones but with different mechanisms. While root nitrogen and soil nitrogen played an important role in shaping the rhizosphere bacterial composition, soil‐available phosphorus greatly affected the non‐rhizosphere bacterial composition and the fungal composition in both soils. This study provides direct experimental evidence that the diversity and composition of microbial communities were severely altered by heavy grazing on a desert grassland. Thus, to restore the grazing‐induced, degraded grasslands, we should pay more attention to the conservation of soil microbes in addition to vegetation recovery. Our study found that grazing in fragile ecosystems had a stronger effect on rhizosphere soil microorganisms than in non‐rhizosphere soil. The restoration and protection of rhizosphere microbial community should be emphasized when considering the restoration of degraded grassland.

Background and aims The rhizosphere priming effect is caused by root carbon (C) exudation into the rhizosphere; the role of this effect in nutrient cycling and ecosystem recovery of natural grasslands as affected by different grazing intensities is still unknown. The objective of the present study was to investigate the relationships among root C exudation, rhizospheric microbial activity, and their influences on plant nutrient uptake during grazing and recovery periods. Methods Field experiments were conducted in the Hongyuan Alpine Meadow to measure root exudation rate and nutrient cycling processes of the dominant species Elymus nutans. Three grazing intensities (an ungrazed control, moderate grazing and heavy grazing) were introduced for two months, following which all treatments received a recovery practice (no grazing for 21 days). Results Heavy grazing significantly decreased root exudation rate, soil nitrogen (N) mineralization rate, β-1,4-glucosidase (BG) activity, and foliar C concentration, while moderate grazing had no influence on these parameters compared to the control. After the 21 days of recovery, all these parameters, except N mineralization rate and foliar C concentrations in the heavy grazing treatment, returned to similar levels as in the control, whereas root exudation rate and BG activity rose to even higher levels. Meanwhile, moderate grazing significantly promoted root exudation rate, soil inorganic N concentration, net soil N mineralization rate, and β-N-acetylglucosaminidase (NAG) activity during the recovery stage as compared to the control. Foliar quality was also improved by the recovery practice, indicating that the high availability of N and P is a consequence of the positive root–microbe feedback and will ultimately benefit grazers. Conclusions The flush of labile C released to the rhizosphere by grazed plants stimulated extracellular enzyme activities, enhanced soil N mineralization, and increased plant nutrient uptake. These results imply that reasonable (i.e. moderate) grazing followed by a recovery practice can effectively restore and strengthen grassland vegetation, and contribute to the sustainable use of alpine meadows such as Hongyuan.

CONTEXT: Many studies have examined how intensity of grazing and patterns of precipitation individually and interactively influence the spatial and temporal dynamics of grassland vegetation, such as dominance, succession, coexistence, and spatial heterogeneity. However existing models have rarely considered the diet preferences of grazers and how they interact with variation in precipitation amount and timing. OBJECTIVE AND METHODS: We examined how plant community structure responds to the individual and combined effects of grazing intensity, selective grazing, and patterns of precipitation, based on a six-year grazing experiment with seven levels of field-manipulated grazing intensity in a typical steppe of Inner Mongolia. RESULTS: The palatable species, mainly forbs, were most severely damaged at intermediate levels of grazing intensity; given that these species are the major contributors to plant community diversity, a U-shaped diversity-grazing intensity relationship resulted. In contrast, spatial heterogeneity of aboveground biomass and species composition peaked at intermediate levels of grazing intensity. Cold season precipitation positively correlated with the abundance of the dominant C₃ grasses and correlated negatively with the subdominant forbs and C₄ plants. Thus, when cold season precipitation increased, plant community species diversity decreased. Grazing intensity and precipitation did not interact in their effects on species richness. CONCLUSIONS: These findings contrast with the predictions from current disturbance–diversity models and indicate that diet selection of grazing animals is an important factor shaping the diversity-grazing intensity relationship in semi-arid grasslands. Future grassland biodiversity conservation and management practices should take diet preference of grazing animals into account.

Grazing is an important modulator of both plant productivity and biodiversity in grassland community, yet how to determine a suitable grazing intensity in alpine grassland is still controversy. Here, we explore the effects of different grazing intensities on plant biomass and species composition, both at community level and functional group level, and examines the productivity–species richness relationship under four grazing patterns: no grazing (CK), light grazing (LG), moderate grazing, (MG) and heavy grazing (HG), attempt to determine a suitable grazing intensity in alpine grassland. The results were as follows. The total aboveground biomass (AGB) reduced with increasing grazing intensity, and the response of plant functional groups was different. AGB of both sedges and legumes increased from MG to HG, while the AGB of forbs reduced sharply and the grass AGB remained steady. There was a significant positive relationship between productivity and species richness both at community level and functional group level. In contrast, the belowground biomass (BGB) showed a unimodal relationship from CK to HG, peaking in MG (8,297.72 ± 621.29 g/m2). Interestingly, the grassland community tends to allocate more root biomass to the upper soil layer under increasing grazing intensities. Our results suggesting that moderate levels of disturbance may be the optimal grassland management strategy for alpine meadow in terms of root production. Aboveground biomass was reduced by increasing grazing intensity, but that individual plant functional groups showed varied responses to the different intensities of livestock grazing. Moderate levels of disturbance may be the optimal grassland management strategy for alpine meadow in terms of root production. The grassland community tends to allocate more root biomass to the upper soil layer under increasing grazing intensities.

Remote sensing data have been widely used in the study of large-scale vegetation activities, which have important significance in estimating grassland yields, determining grassland carrying capacity, and strengthening the scientific management of grasslands. Remote sensing data are also used for estimating grazing intensity. Unfortunately, the spatial distribution of grazing-induced degradation remains undocumented by field observation, and most previous studies on grazing intensity have been qualitative. In our study, we tried to quantify grazing intensity using remote sensing techniques. To achieve this goal, we conducted field experiments at Gansu Province, China, which included a meadow steppe and a semi-arid region. The correlation between a vegetation index and grazing intensity was simulated, and the results demonstrated that there was a significant negative correlation between NDVI and relative grazing intensity (p < 0.05). The relative grazing intensity increased with a decrease in NDVI, and when the relative grazing intensity reached a certain level, the response of NDVI to relative grazing intensity was no longer sensitive. This study shows that the NDVI model can illustrate the feasibility of using a vegetation index to monitor the grazing intensity of livestock in free-grazing mode. Notably, it is feasible to use the remote sensing vegetation index to obtain the thresholds of livestock grazing intensity.

Intensive grazing by herbivores lead to major ecological changes in natural grasslands, including severe degeneration. However, the understanding of how grazing affects the incidence of pathogenic and saprotrophic fungi on leaves and seeds of dominant plant species in grasslands is limited. In this study, the presence of two fungal pathogens that cause lesions on leaves of a dominant grass species of the Hulunber meadow steppe in northeast China, Leymus chinensis, as well as saprotrophic fungi associated with lesions, was investigated in plots with different grazing intensities treatments (0, 0.42, 0.63, 0.83, 1.25, and 1.67 cattle ha−1). In addition, seeds of L. chinensis were harvested from plants of the different grazing intensities and the presence of seed-borne fungi, including pathogenic and saprotrophic fungi, were examined by fungal isolation. The results indicated that with the increase of grazing intensity, the incidence of two fungal diseases on leaves of L. chinensis, leaf blotch diseases caused by Leptosphaeria avenaria and Parastagonospora nodorum, decreased. On seeds, the two most frequently isolated fungi were Le. avenaria and P. nodorum, from 57.2% and 40.6% of seeds respectively. At the highest grazing plots, the frequency of isolation of these two fungi to 23.1 and 15.6% respectively. By contrast, the frequency of isolation of Epicoccum nigrum in the highest grazing plots was 88.9%, approximately 10-fold of that in control plots. In dual-culture studies, E. nigrum isolates had inhibitory effects on the growth of isolates of the two leaf pathogens.

It is well known that biodiversity and ecosystem multifunctionality (EMF) guarantee the well-being of human society. Most studies have focused on the relationship between biodiversity and ecosystem function, and less is known about the individual and combined effects of above- and below-ground biodiversity on ecosystem multifunctionality under grazing disturbance. The aim of our study was to investigate the relationship between plant and soil microbial (bacterial and fungal) diversity and ecosystem multifunctionality under grazing disturbance by using multiple methods to assess ecosystem multifunctionality. We conducted experiments in desert grasslands on the northern slopes of the Tian Shan Mountains and compared the relationship between ecosystem multifunctionality and biodiversity assessed by different methods under light grazing and heavy grazing. Our results showed that at the heavy grazing level, ecosystem multifunctionality calculated by the mean method and plant diversity, soil fungal diversity, soil bacterial diversity and soil fertility calculated by the single function method showed a significant decrease (p < 0.05), but grass productivity was significantly increased (p < 0.05). Among them, ecosystem multifunctionality, soil carbon storage function and soil fertility all showed significant positive correlations with plant diversity and soil microbial diversity (p < 0.05). We calculated that ecosystem multifunctionality also essentially showed positive correlation with plant diversity and soil microbial diversity using the multi-threshold method, and the effect curve was approximately a single-peaked curve, first increasing and then decreasing. Finally, we used plant diversity, soil fungal diversity and soil bacterial diversity under grazing disturbance as biotic factors and soil pH as an abiotic factor to construct structural equation models, and we found that grazing can have direct effects on ecosystem multifunctionality and indirect effects on ecosystem multifunctionality through above- and below-ground biodiversity. Our study emphasizes the importance of the combination of above- and below-ground biodiversity in maintaining the multifunctionality of desert grassland ecosystems on the northern slopes of the Tian Shan Mountains. A moderate reduction in grazing intensity can better conserve biodiversity and improve ecosystem multifunctionality, and it is a feasible strategy to maintain sustainable management of desert grasslands.

Identifying appropriate indicator species for the impact of deer on forest vegetation is crucial for forest management in deer habitats and is required to be sensitive to temporal and spatial variations in deer density. Dryopteris crassirhizoma was selected as a new indicator to evaluate the response to these variations. We examined the population-level characteristics, morphological characteristics at the individual level, and grazing intensity of D. crassirhizoma at temporally different deer density sites in Hokkaido, Japan. The response of D. crassirhizoma to spatial variation in deer density was also examined within and between two regions in Hokkaido, Japan. Although the population-level characteristics and morphological characteristics did not significantly respond to short-term decreases in deer density, grazing intensity significantly decreased with decreasing deer density. The grazing intensity was also positively related to the spatial variation of deer density within both regions, but the estimated coefficient of the grazing intensity differed between regions. We concluded that D. crassirhizoma can be a useful indicator species of the impact of deer on forest vegetation. The grazing intensity of the indicator species was sensitive to temporal and spatial variations in deer density within the region.

Overgrazing is the key factor that has exacerbated grassland degradation in China’s pastoral regions. Herder’s grazing-based livestock production behavior becomes important to grassland conservation. Several formal environmental institutions and policies exist to improve grassland degradation; however, there remain contradicting conclusions regarding the contribution of these policies. Informal institutions become major instruments that might encourage herder’s behavior on overgrazing. Using village rules and conventions (VRC) as a proxy for informal institutions, the article attempts to scrutinize whether the VRC emerge to respond to herders’ willingness to reduce grazing intensity for grassland conservation and elicit factors affecting their reduction behavior using a Double-Hurdle model. Based on a survey of 193 respondents in Inner Mongolia and Xinjiang Autonomous regions of China, the empirical results provide evidence that VRC is effective in reducing herders’ grazing intensity. In detail, the VRC in written form and an unchanging context within five years could significantly improve herders’ willingness to reduce grazing intensity. Herders who consider the VRC as an important impact to their livestock production observe an increased reduction degree of grazing intensity. Additionally, variables referring to herder’s education and religious belief play a significant role in the reduction degree of grazing intensity. Our findings highlight the importance of VRC in controlling herders’ overgrazing behavior.

Grazing effects on soil properties under different soil and environmental conditions across the globe are often controversial. Therefore, it is essential to evaluate the overall magnitude and direction of the grazing effects on soils. This global meta-analysis was conducted using the mixed model method to address the overall effects of grazing intensities (heavy, moderate, and light) on 15 soil properties based on 287 papers published globally from 2007 to 2019. Our findings showed that heavy grazing significantly increased the soil BD (11.3% relative un-grazing) and PR (52.5%) and reduced SOC (-10.8%), WC (-10.8%), NO.sub.3 .sup.- (-23.5%), and MBC (-27.9%) at 0-10 cm depth, and reduced SOC (-22.5%) and TN (-19.9%) at 10-30 cm depth. Moderate grazing significantly increased the BD (7.5%), PR (46.0%), and P (18.9%) (0-10 cm), and increased pH (4.1%) and decreased SOC (-16.4%), TN (-10.6%), and P (-23.9%) (10-30 cm). Light grazing significantly increased the SOC (10.8%) and NH.sub.4 .sup.+ (28.7%) (0-10 cm). Heavy grazing showed much higher mean probability (0.70) leading to overgrazing than the moderate (0.14) and light (0.10) grazing. These findings indicate that, globally, compared to un-grazing, heavy grazing significantly increased soil compaction and reduced SOC, NO.sub.3 .sup.-, and soil moisture. Moderate grazing significantly increased soil compaction and alkalinity and reduced SOC and TN. Light grazing significantly increased SOC and NH.sub.4 .sup.+ . Cattle grazing impacts on soil compaction, SOC, TN, and available K were higher than sheep grazing, but lower for PR. Climate significantly impacted grazing effects on SOM, TN, available P, NH.sub.4 .sup.+, EC, CEC, and PR. Heavy grazing can be more detrimental to soil quality based on BD, SOC, TN, C: N, WC, and K than moderate and light grazing. However, global grazing intensities did not significantly impact most of the 15 soil properties, and the grazing effects on them had insignificant changes over the years.