scholarly journals Does Grazing Exclusion Improve Soil Carbon and Nitrogen Stocks in Alpine Grasslands on the Qinghai-Tibetan Plateau? A Meta-Analysis

2020 ◽  
Vol 12 (3) ◽  
pp. 977 ◽  
Author(s):  
Xiang Liu ◽  
Haiyan Sheng ◽  
Zhaoqi Wang ◽  
Zhiwen Ma ◽  
Xiaotao Huang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Alpine Meadow ◽  
Meta Analysis ◽  
C:N Ratio ◽  
Mean Annual Precipitation ◽  
Alpine Grasslands ◽  
Grazing Exclusion ◽  
Alpine Steppe ◽  
Soc Stock ◽  
Grassland Types

Grazing exclusion has been widely used to restore the degraded alpine grasslands on the Qinghai-Tibetan Plateau (QTP). However, the dynamics of soil organic carbon (SOC) and soil total nitrogen (STN) pools after grazing exclusion and their controlling factors are currently less understood in this region. Here, a meta-analysis was conducted to quantitatively assess the changes in SOC and STN stocks in topsoil (0–30 cm) following grazing exclusion in three major grassland types (alpine meadow, alpine steppe, and alpine desert steppe) on the QTP and to explore the potential factors controlling the effects of grazing exclusion on SOC and STN stocks. The results showed that overall, grazing exclusion significantly increased SOC stock by 16.5% and STN stock by 11.2%. Significant increases in both SOC and STN stocks were observed after grazing exclusion of alpine meadow. In contrast, grazing exclusion did not improve SOC and STN stocks in the other two grassland types. The difference in mean annual precipitation among grassland types was a likely reason for the different dynamics of SOC and STN stocks after grazing exclusion. The effect sizes of both SOC and STN stocks were positively related to the duration of grazing exclusion, and a positive relationship was detected between the effect size of SOC stock and that of STN stock, demonstrating that the dynamics of SOC and STN were closely coupled during the period of grazing exclusion. However, grazing exclusion had no impact on soil C:N ratio for all grassland types, indicating that soil C:N ratio was generally stable after grazing exclusion. Therefore, it is suggested that the increase in STN can support continuous SOC accumulation following grazing exclusion. In conclusion, the findings suggest that the effects of grazing exclusion on SOC and STN stocks differ among grassland types on the QTP, and grazing exclusion of alpine meadows may provide substantial opportunities for improving SOC and STN stocks in this region.

scholarly journals Meta-analysis of relationships between environmental factors and aboveground biomass in the alpine grassland on the Tibetan Plateau

2013 ◽  
Vol 10 (3) ◽  
pp. 1707-1715 ◽  
Author(s):  
J. Sun ◽  
G. W. Cheng ◽  
W. P. Li
Keyword(s):  
Soil Moisture ◽  
Tibetan Plateau ◽  
Environmental Factors ◽  
Aboveground Biomass ◽  
Alpine Meadow ◽  
Meta Analysis ◽  
Alpine Grassland ◽  
Mean Annual Precipitation ◽  
The Tibetan Plateau ◽  
Alpine Steppe

Abstract. The Tibetan Plateau, known as the "world's third pole" for its extremely harsh and fragile ecological environment, has attracted great attention because of its sensitivity to global changes. Alpine grassland on the Tibetan Plateau has an important function in the global carbon cycle. Many studies have examined the effects of various environmental factors on biomass distribution. In this study, the relationships between the habitat parameters and the aboveground biomass (AGB) abundance on the Tibetan Plateau were examined through a meta-analysis of 110 field sites across the widely distributed alpine steppe and meadow. The obtained data were then analysed using the classification and regression tree model and the generalized additive model. The results showed that the AGB abundance in alpine steppe was positively correlated with six environmental factors, namely, soil organic carbon density of the top soil layer from 0 cm to 30 cm (SOC30 cm), longitude, mean annual precipitation (MAP), latitude, clay, and soil moisture. For the alpine meadow, five main factors were detected, namely, altitude, soil moisture, nitrogen, MAP, and mean annual temperature. The increased AGB abundance in the alpine steppe was associated with the increased SOC30 cm, MAP, and latitude, and the increased longitude resulted in decreased AGB abundance. For the alpine meadow, altitude and soil moisture showed strongly negative effects on AGB abundance, and soil nitrogen content was positively related to the AGB distribution across all examined sites. Our results suggest the combined effects of meteorological, topographic, and soil factors on the spatial patterns of AGB on the Tibetan Plateau.

scholarly journals Patterns of soil respiration and its temperature sensitivity in grassland ecosystems across China

2018 ◽  
Vol 15 (17) ◽  
pp. 5329-5341 ◽  
Author(s):  
Jiguang Feng ◽  
Jingsheng Wang ◽  
Yanjun Song ◽  
Biao Zhu
Keyword(s):  
Soil Respiration ◽  
Soil Temperature ◽  
Temperature Sensitivity ◽  
Annual Precipitation ◽  
Mean Annual Precipitation ◽  
Mean Annual Temperature ◽  
Organic Carbon Content ◽  
Alpine Grasslands ◽  
Q10 Values ◽  
Grassland Types

Abstract. Soil respiration (Rs), a key process in the terrestrial carbon cycle, is very sensitive to climate change. In this study, we synthesized 54 measurements of annual Rs and 171 estimates of Q10 value (the temperature sensitivity of soil respiration) in grasslands across China. We quantitatively analyzed their spatial patterns and controlling factors in five grassland types, including temperate typical steppe, temperate meadow steppe, temperate desert steppe, alpine grassland, and warm, tropical grassland. Results showed that the mean (±SE) annual Rs was 582.0±57.9 g C m−2 yr−1 across Chinese grasslands. Annual Rs significantly differed among grassland types, and was positively correlated with mean annual temperature, mean annual precipitation, soil temperature, soil moisture, soil organic carbon content, and aboveground biomass, but negatively correlated with soil pH (p<0.05). Among these factors, mean annual precipitation was the primary factor controlling the variation of annual Rs among grassland types. Based on the overall data across Chinese grasslands, the Q10 values ranged from 1.03 to 8.13, with a mean (±SE) of 2.60±0.08. Moreover, the Q10 values varied largely within and among grassland types and soil temperature measurement depths. Among grassland types, the highest Q10 derived by soil temperature at a depth of 5 cm occurred in alpine grasslands. In addition, the seasonal variation of soil respiration in Chinese grasslands generally cannot be explained well by soil temperature using the van't Hoff equation. Overall, our findings suggest that the combined factors of soil temperature and moisture would better predict soil respiration in arid and semi-arid regions, highlight the importance of precipitation in controlling soil respiration in grasslands, and imply that alpine grasslands in China might release more carbon dioxide to the atmosphere under climate warming.

scholarly journals Differential response of alpine steppe and alpine meadow to climate warming in the central Qinghai–Tibetan Plateau

2016 ◽  
Vol 223 ◽  
pp. 233-240 ◽  
Author(s):  
Hasbagan Ganjurjav ◽  
Qingzhu Gao ◽  
Elise S. Gornish ◽  
Mark W. Schwartz ◽  
Yan Liang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Climate Warming ◽  
Alpine Meadow ◽  
Differential Response ◽  
Alpine Steppe

scholarly journals Precipitation and aridity index regulating spatial patterns of vegetation production and species diversity based on alpine grassland transect, Tibetan Plateau

2016 ◽  
Author(s):  
Jian Sun
Keyword(s):  
Tibetan Plateau ◽  
Primary Production ◽  
Alpine Meadow ◽  
Net Primary Production ◽  
Aridity Index ◽  
Alpine Grassland ◽  
The Tibetan Plateau ◽  
Aboveground Net Primary Production ◽  
Alpine Steppe ◽  
Unimodal Pattern

Although the relationship between the aboveground net primary production (ANPP) and speciesdiversity (SR) have been widely reported, there is considerable disagreement about the fitting patterns of SR–ANPP, which has been variously described as ‘positive’, ‘negative’, ‘unimodal’, ‘U-shaped’ and so on. Not surprisingly, the effect-factors including precipitation, aridity index and geographic conditions (e.g.,altitude, longitude and latitude) on ANPP and SR continue to interest researchers, especially the effects at high altitude regions. We investigated ANPP and SR from 113 sampled sites (399 plots) across alpine meadow and steppe in the Tibetan Plateau, which included Tibet, Qinghai and Sichuan province. The effects of various environmental factors (precipitation, temperature, aridity index, altitude, longitude,latitude and vegetation type on SR and ANPP) were explored. The results indicate that a unimodal pattern was confirmed between ANPP and SR in alpine steppe (R 2 =0.45, P <0.0001), alpine meadow ( R 2 =0.4, P <0.0001), and all samples across alpine grassland ( R 2 =0.52, P <0.0001). For the aboveground net primary production, the appropriate precipitation and aridity is 600mm and 42, respectively. Under thesame moisture conditions, the maximum value of diversity is 0.75. Longitude ( R 2 =0.69, P <0.0001) and altitude ( R 2 =0.48, P <0.0001) have positive and negative effects on aboveground net primary production, and a similar relationship exists with diversity ( R 2 =0.44, P <0.0001 and R 2 =0.3, P <0.0001).The same patterns of diversity and production responding to precipitation and the aridity index were evident in alpine steppe and meadow, and a unimodal pattern was confirmed between ANPP and SR in both locations.

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