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Grassland is the largest terrestrial ecosystem in the Yellow River Basin and an important ecological barrier in the basin. Scientific and accurate estimation of the service value of grassland ecosystems in the Yellow River Basin is of great significance for maintaining the ecological security of the Yellow River Basin. This study was based on Constanza, a method based on the correction of natural grassland ecosystem service value in the Yellow River Basin. This method considers grassland biomass, estimates the ecological service value of each type of grassland item by item, and analyzes their spatial distribution and topographic gradient differentiation characteristics. The results showed that the unit price of soil conservation services provided by the grassland ecosystem in the Yellow River Basin has an advantage (6.2 times) which is the lowest unit price of raw materials. The total value of grassland ecosystem services in the Yellow River Basin is 100.82 × 1010 Yuan. Among the various services, the adjustment service has the largest value, accounting for 50.56% of the total value, while the sum of the supply service, support service and cultural service amounted to 49.44%. The high-value areas of grassland ecosystem services are mainly distributed in the upper and lower reaches of the basin, as the low-value areas are located in the Ningxia and Hetao Plains and most parts of the Loess Plateau. The ESV per unit area of grassland in the Yellow River Basin showed a decreasing to increasing trend with the increase in elevation and topographic relief, as the ESV continued to increase with slope increase. [ABSTRACT FROM AUTHOR]

This research was designed to explore the variation characteristics of soil C:N:P stoichiometry and enzyme activity in the Qilian Mountains different grassland types. Thus, 7 grassland types (Upland meadow: UM, Alpine meadow: AM, Temperate steppe: ST, Alpine steppe: AS, Temperate Desert Steppe: TDS, Temperate Desert: TD, Alpine desert: AD) of Qilian Natural Reserve were selected to analyze the variation characteristics of soil enzyme activities and stoichiometry of different grassland types and its relationship with environmental factors. The study indicated that the C/N, C/P, and N/P of different grasslands ranged from 5.08 to 17.35, 2.50 to 72.29, and 0.53 to 4.02.The ranking of different types grassland for the C/N was TS ≥ AM ≥ UM ≥ AS ≥ TDS > AD > TD, and the changing pattern of C/P and N/P is similar to that of C/N. The ranking of different types grassland for the urease enzyme activity was UM ≈AS > AD ≈TDS ≈TS ≈AM > TD, and TS ≈AM ≈UM ≈AS ≈AD > TDS > TD for alkaline phosphatase enzyme activity, and AS ≈AM ≈TS ≈TDS≥UM ≥TD ≈AD for catalase enzyme activity. Based on N/P ratio and RDA analysis, nitrogen was the main factor limiting the grassland productivity, and pH, TN, SOC, Richness index and Simpson diversity index were the main environmental factors affecting the soil C:N:P stoichiometry and enzyme activities. Cluster analysis showed that 7 grassland types were clustered into three categories. In conclusion, the stoichiometric characteristics and soil enzyme activities of different grasslands vary with grassland types. Nitrogen was the main factor limiting the grasslands productivity, and pH, TN, SOC, Richness index and Simpson diversity index were the main environmental factors affecting the soil C:N:P stoichiometry and enzyme activities, and the grassland Qilian Mountain can be managed in the ecological district according to the clustering results. The results of this study can provide data support and theoretical guidance for the scientific management and ecological protection of grassland in Qilian Mountains Reserve. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) stocks and nutrient availability are key indicators of soil quality, and both can be influenced by land‐use change. However, it is still unclear whether the impact of land‐use change on SOC and nutrient stocks differs between ecoregions. Grasslands near the northeast border of the Qinghai‐Tibetan Plateau (QTP) occur across several ecoregions that have recently been subjected to substantial land‐use change. Based on long‐term land‐use history, we conducted a field investigation comparing soil C and nutrient stocks between natural grassland (NGL) and three types of converted grassland (agricultural grassland, AGL; farmland, FL; and abandoned farmland, AFL) in three ecoregions along a climate gradient: alpine meadow, temperate steppe and temperate desert. Compared with NGL, soil C stocks in converted grasslands were 22%–30% lower in the alpine meadow, but 60–82% higher in the temperate steppe and 6%–76% higher in the temperate desert. Converted grasslands also contained higher stocks of available nitrogen and phosphorus than NGL in the temperate steppe and desert. Soils (0–40 cm) in NGL contained 14.8 ± 0.1 kg C m−2 in alpine meadow, 6.7 ± 0.6 kg C m−2 in temperate steppe and 1.7 ± 0.3 kg C m−2 in temperate desert. Together, our results indicate that the responses of soil C and nutrients to grassland conversion differed between ecoregions. Thus, to optimize soil C sequestration rates and overall soil quality, we suggest that land‐use policies in this area should take into account local environmental conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • What and how land-use change affects soil respiration in Qinghai-Tibetan Plateau. • Field monitoring with five land-uses in an alpine agro-pastoral ecotone. • Enclosed grassland had the highest soil respiration while the lowest in abandonment. • Quantified causal pathways from land-use change to variations in soil respiration. • Grasslands benefits for both low soil respiration and high soil C storage. Land-use change alters soil carbon (C) storage in terrestrial ecosystem through affecting soil respirations (Rs). However, the long-term effects of land-use change on Rs are poorly understood. We undertook a field experiment to examine the effects of long-term land-use change on Rs. The land-use types included grazed grassland (GGL), enclosed grassland (EGL), continuous cropland (CCL), rotation cropland (RCL) and abandoned cropland (ACL) in an alpine agro-pastoral ecotone in Qinghai-Tibetan Plateau in China. Our results showed that the accumulative Rs was shown a decreasing order of EGL > CCL > RCL > GGL > ACL, with the highest value of 12.2 t CO 2 ha−1 and the lowest value of 5.3 t CO 2 ha−1. Soil bulk density, moisture, pH and C/N ratio were the key factors regulating Rs with land-use change in Tianzhu alpine agro-pastoral ecotone. Soil pH and C/N ratio regulated Rs indirectly by affecting bacterial diversity, while soil moisture had indirect impacts on Rs mainly by regulating microbial biomass. The net effects of soil bulk density on Rs was mainly through the direct pathway. Considering the soil C stocks showed an increasing order of ACL < RCL < CCL < GGL < EGL, even though ACL had the lowest Rs , grasslands probably the favorable land-use type in alpine agro-pastoral ecotone. Our findings highlight the importance of the land-use change on Rs , which may need to be incorporated into regional and global models for better predicting C-climate feedbacks. [ABSTRACT FROM AUTHOR]

• Degradation and grazing exclusion had no significant effect on soil bacterial α-diversity. • Degradation and grazing exclusion had significant effect on soil bacterial community composition. • Soil organic carbon and soil total nitrogen were dominant factors affecting soil bacterial α-diversity. • Soil nitrate nitrogen and soil total nitrogen were the main driving factors for soil bacterial community composition. Grazing exclusion by fencing is a common and effective grassland management strategy for degraded grassland restoration. Soil bacteria, the most important decomposers of soil organic matter, is the linkage between plant and soil. However, soil bacterial α-diversity and community composition in the recover process of degraded shrubland – grassland ecotone on the Qinghai-Tibet Plateau has not been well understood. Thus, in this research, lightly and heavily degraded shrubland – grassland ecotone and its adjacent communities (alpine shrubland and alpine meadow) during recover process on the Qinghai-Tibet Plateau were selected to study α-diversity and community composition of soil bacteria, as well as the relationships among soil bacterial community, plant community and soil properties. Our results demonstrated that: 1) Dominant taxa at the phylum and genera level in all samples were similar. Proteobacteria, Acidobacteria and Bacteroidetes were dominant phyla, RB41, H16 and Ferruginibacter were dominant genera. 2) Grazing exclusion had no effect on soil bacterial α-diversity. However, grazing exclusion significantly decreased relative abundance of the Chloroflexi phylum, but grazing exclusion significantly increased the Elusimicrobia phylum relative abundance in the alpine meadow plot. 3) There were no significant differences on soil bacterial α-diversity between the heavily and lightly degraded grassland. However, relative abundance of the Planctomycetes phylum, Deltaproteobacteria class and RB41 genus in the alpine meadow plot of heavily degraded grassland were significantly lower than those in the lightly degraded grassland. 4) The higher plant community α-diversity and soil nutrition of shrubland – grassland ecotone did not result in a higher soil bacterial α-diversity. However, relative abundances of Chloroflexi phylum, Deltaproteobacteria class and Nitrospira class in the shrubland – grassland ecotone were significantly higher than those in the alpine meadow and alpine shrubland plots inside fence of the lightly degraded grassland. 5) Structural equation model (SEM) showed that soil organic carbon and soil total nitrogen were dominant factors affecting soil bacterial α-diversity. 6) Redundancy analysis (RDA) indicated that soil nitrate nitrogen and soil total nitrogen were the main driving factors for soil bacterial community composition. Our research found that the changes of soil bacterial α-diversity is incongruous with plant community α-diversity, while soil bacterial community composition is paralleled with plant community α-diversity and soil characteristics, especially the soil chemical property. These findings can provide management support for the restoration of degraded alpine shrubland. [ABSTRACT FROM AUTHOR]

• Rs, Ra and Rh showed hump-shaped response patterns with the length of fencing. • The Q 10 for Ra and Rh showed hump-shaped patterns with the length of fencing. • Grazing exclusion significantly decreased the growing season average Ra/Rs ratio. Grazing exclusion has been widely used to restore degraded grasslands worldwide. Total soil respiration (Rs) (consisting of heterotrophic respiration (Rh, microbes and soil fauna respiration) and autotrophic respiration (Ra, plant root and their symbionts respiration)) play a critical role in the global carbon (C) balance. Quantifying Rs, Rh and Ra in relation to different grazing exclusion durations is vital to better understanding the impact of grassland management on global C cycling. However, how Rs and its components respond to different grazing exclusion durations remain unclear. Therefore, in this study, a trenching method was used to separate the Ra and Rh in an alpine meadow with different grazing exclusion durations (0, 4, 7, 10 and 12 years) on the north-eastern Qinghai-Tibet Plateau. Our results demonstrated that the growing season Rs, Rh and Ra showed nonlinear (hump-shaped) response patterns with the length of grazing exclusion, with a peak point at the 7-year grazing exclusion. Meanwhile, grazing exclusion treatments significantly increased the Rs, Rh and Ra compared to the grazed site. Grazing exclusion substantially increased the soil respiration temperature sensitivity (Q 10) values of Rs, Rh and Ra. Moreover, the Q 10 values of Ra and Rh showed hump-shaped response patterns with the length of grazing exclusion, with a threshold of 7 years grazing exclusion. The annual Ra/Rs ratio ranged from 53% to 69% during the growing season, indicating that changes in soil respiration were mainly determined by changes in autotrophic respiration. In addition, soil temperature could better explain Rh (R2 = 0.89–0.94) than Ra (R2 = 0.84–0.9). Our research highlights the nonlinear response of Rs, Rh and Ra to the length of grazing exclusion, and suggests that different grazing exclusion durations should be considered for better evaluating the impact of grassland management on global C cycling on the north-eastern Qinghai-Tibet Plateau. [ABSTRACT FROM AUTHOR]