Grazing increased alpine grassland soil respiration rates on the Tibetan Plateau

Introduction: Grazing activities were intensive in alpine grasslands and may alter the soil respiration rates across the Tibetan Plateau. However, grazed alpine grassland soil respiration rates and their underlying driving mechanisms remain unclear across the Tibetan Plateau.

Methods: In this study, we synthesized data from 38 groups to clarify the response of CO₂ emission rates to different grazing intensities.

Results: The effect size was 0.039 ± 0.051 of grazed activity on the ecosystem respiration rates, indicating that grazing increased respiration rates by 3.99%. Furthermore, effect sizes were −0.146 ± 0.209 and 0.076 ± 0.046 in alpine steppes and alpine meadows, respectively, indicating a 13.58% reduction and a 7.90% increase. The effect sizes were 0.051 ± 0.112, 0.029 ± 0.075, and 0.055 ± 0.089 in light, moderate, and high grazing intensity, respectively. Moderate grazing mitigated grassland CO₂ emission rates compared with light and high grazing. Both air temperature and soil organic carbon significantly increased grassland ecosystem respiration rate, explaining 38.47% and 22.57% of variance heterogeneity.

Discussion: In addition, both future global warming and increasing soil organic carbon would increase alpine grassland CO₂ emission rates on the Tibetan Plateau.

1 Introduction

The Tibetan Plateau covered an area of 2.50 million km² at an average altitude of 4,000 m (1). Alpine grasslands comprise the largest alpine ecosystem in the world and provide critical ecosystem services on the Tibetan Plateau (2). Grazing is the primary land use practice in alpine ecosystems (3). Overgrazing is a major contributor to grassland degradation, and grazing alters grassland soil carbon flux and the cycling of alpine meadow (4). Carbon flux between grassland and atmosphere is an important part of the terrestrial carbon cycle, and soil respiration accounts for approximately 25% of global carbon dioxide exchange (5).

Ecosystem respiration outside the growing season was at least equivalent to 9.4% of the CO₂ fluxes during the growing season (6). The annual ecosystem respiration rate was 341.5 g CO₂ m⁻² in alpine grasslands on the Tibetan Plateau (6). The annual cumulative soil CO₂ emissions of alpine meadow and alpine shrub meadow were 284 and 470.8 g m⁻² on the northeastern Tibetan Plateau, respectively (4). Grazing exclusion increases alpine meadow soils’ CO₂ emissions and reduced soil organic carbon stocks (4). However, a 3-year study revealed that grazing increased soil respiration by an average of 13.7% compared to fenced grasslands (7). Grassland soil respiration rates gradually decreased with grazing intensity increasing (8). Grassland soil respiration rose by 5.23%, 2.94%, and 5.65% under light, moderate, and heavy grazing on the Loess Plateau, respectively (9). Heavy grazing significantly increased saline-alkaline grassland heterotrophic respiration (10). In the grazed grasslands, less carbon was lost by shoot respiration, and more was translocated in belowground biomass (11). Furthermore, it was also reported that grazing exclusion significantly decreased annual soil respiration by 21.4% on the Tibetan Plateau (2). There was no significant difference in soil respiration rates between grazing and fencing across all vegetation types (12).

Grazing increases soil respiration primarily by enhancing soil moisture and temperature, which stimulate plant root and microbial activity, and increased aboveground biomass contributes to higher soil respiration through greater organic matter availability and improved decomposition conditions (13). Furthermore, grazing intensity affects soil respiration differently by altering above- and belowground biomass, soil structure, and microbial activity, with light and moderate grazing generally increasing respiration, while heavy grazing tends to reduce it (7). Daily soil respiration was mainly driven by soil temperature in both alpine meadows and steppes (5, 6). Soil CO₂ flux was positively correlated with soil temperature (4). Stepwise regression showed that soil temperature and soil moisture controlled average grassland soil respiration rates (14). Soil temperature explained 63%–83% of seasonal respiration variations on the Tibetan Plateau (15). Changes in soil respiration were primarily driven by variations in autotrophic respiration (9). Increased soil bulk density reduces soil porosity, which restricts the movement of air and water, subsequently inhibiting the respiration processes of soil microorganisms and plant roots (16). A rapid increase in soil respiration was induced by the influx of precipitation, likely driven by enhanced microbial activity and organic matter decomposition (17, 18). Winter soil respiration was driven mainly by microbial oxidation of soil organic matter on the Tibetan Plateau (18). However, mechanisms by which grazing intensity modulates soil respiration in diverse alpine grasslands remain unclear. This meta-analysis systematically quantifies grazing effects across intensities, highlighting the roles of soil temperature, organic carbon, and grazing practices in soil respiration dynamics on the Tibetan Plateau.

This meta-analysis offers a comprehensive quantitative synthesis of grazing impacts, providing insights into ecosystem responses across diverse grassland conditions. We compiled data on soil respiration rates under varying grazing intensities across the Tibetan Plateau to test the hypothesis that grazing activity significantly elevates alpine grassland respiration rates by enhancing soil microbial activity.

2 Materials and methods

2.1 Data compilation and selection criteria

We collected published papers using the keywords “carbon dioxide or CO₂”, “grazing”, “respiration rate”, and “Tibet*” in Web of Science from 1990 to December 2022. After applying inclusion criteria, such as studies that used field-based soil respiration measurements and reported grazing intensity levels, a total of 98 relevant articles were selected. These studies were further categorized based on grazing intensity (light, moderate, and heavy) and grassland type (alpine steppe or meadow) for more detailed analysis. During the data collection process, we extracted soil respiration rate measurements for light, moderate, and heavy grazing directly from the original studies, ensuring consistency and comparability with their respective control treatments. Data were extracted from paper figures by the WebPlotDigitizer software. In this study, we selected 25 published studies, including 38 field experiment results (Figure 1), soil physical characteristics, and plant communities.

Figure 1

Figure 1. Main vegetation types’ distribution and 38 research sites on the Tibetan Plateau.

The log response ratios were used as a measure of effect size. We performed a random-effect model meta-analysis.

$$\text{ln R=Ln}\frac{{\text{x}}_{\text{e}}}{{\text{x}}_{\text{c}}}\text{=ln}({\text{x}}_{\text{e}}){\text{ - ln}(\text{x}}_{\text{c}})$$

where x_c and x_e are the mean values of each individual trait in control and the treatment groups, respectively.

Grazing on CO₂ rates and confidence interval were calculated using the random-effect model.

The weight of an individual effect of grazing on CO₂ emission rates was determined:

$$w_i^{*}=1/(v_i+{\tau }^2)$$

where v_i and ${\tau }^2$ represent the intra-study variance and inter-study variance, respectively.

The average effect size was analyzed:

$$\overline{y}=\frac{{\displaystyle {\sum }_{i=1}^k{w}_i^{*}{y}_i}}{{\displaystyle {\sum }_{i=1}^k{w}_i^{*}}}$$

The heterogeneity test of effect size was measured:

$$Qt={{\displaystyle \sum _{i=1}^{k}w{i}^{*}(yi-\overline{y})}}^2$$

The influence of explanatory variables on effect size was determined:

$$Qm={{\displaystyle \sum _{j=1}^p{\displaystyle \sum _{i=1}^{ni}w{i}^{*}}(yij-\overline{y})}}^2$$

Here, n_i and p meant sample sizes of heterogeneity test value of the control and moderator variable, where i and j meant effect sizes of control and single treatment.

2.2 Statistical analysis

In this study, a random-effects model was employed for the meta-analysis, utilizing the metafor 1.9-8 package within the R software environment (version 3.6.2). This approach allowed for the incorporation of variability across studies, providing more robust and generalized results. Meanwhile, residual heterogeneity was tested with categorical and continuous variables using mixed-effect models (mods).

3 Results

3.1 Grazing activity increased alpine grassland respiration rates on the Tibetan Plateau

The effect size was 0.039 ± 0.051 (−0.061–0.139, 95% confidence interval) of grazing activity on ecosystem respiration rates of alpine grasslands (Figure 2). This indicated that grazing increased respiration rates by 3.99% across the Tibetan Plateau, and this was not significant with control. Furthermore, effect sizes were −0.146 ± 0.209 and 0.076 ± 0.046 in alpine steppes and alpine meadows, respectively (p < 0.05). These decreased and increased ranges were −13.58% and 7.9% (Table 1).

Figure 2

Figure 2. Forest plots of 38 effect size estimates for responses of alpine grassland respiration rates to grazing activities. RR, response ratios (effect sizes), and black dots with 95% confidence intervals (CI). The red line and the red dashed line meant RR = 0, and average effect size.

Table 1

Table 1. Effect sizes of graze treatment on soil respiration rates in alpine steppe and meadow on the Tibetan Plateau.

3.2 Effects of different grazing intensity on grasslands CO₂ rates through meta-analysis across the Tibetan Plateau

With the grazing intensity increasing, the effect size decreased firstly, then it increased significantly. The effect sizes were 0.051 ± 0.112, 0.029 ± 0.075, and 0.055 ± 0.089 (Table 2), corresponding to an increase of 5.23%, 2.94%, and 5.65%, respectively. This also indicated that different grazing intensities did not significantly affect ecosystem respiration rates on the Tibetan Plateau. Moderate grazing mitigated grassland CO₂ emission rates. Meanwhile, a significant residual heterogeneity existed (p < 0.001), and we would explain this with categorical variables next.

Table 2

Table 2. Effect sizes of different grazing intensities on soil respiration rates in alpine grasslands on the Tibetan Plateau.

3.3 Effects of climate and soil physical factors on alpine grassland ecosystem respiration rates

Both air temperature and soil organic carbon significantly influenced grassland ecosystem respiration rate through the moderator test analysis (p < 0.001). These factors could explain 38.47% and 22.57% of variance heterogeneity in the CO₂ emission rates between the control and grazed meadow (Table 3). In addition, soil total nitrogen and longitude explained 7.89% and 1.71% of the variation, and this did not reach significance. However, latitude, precipitation, biomass, and altitude had little influence on the effect size. Furthermore, both global warming and increasing soil organic carbon would increase alpine grassland CO₂ emission rates.

Table 3

Table 3. Analysis of air temperature and altitude and other factors on effect sizes.

3.4 Publication bias analysis of effect sizes on alpine grassland ecosystem respiration rates

In this study, Egger’s regression test for funnel plot asymmetry indicated that the result was not significantly affected by a publication bias using the meta-analytic models (z = 0.3799, p = 0.7040, Figure 3).

Figure 3

Figure 3. Funnel plot of effect sizes of grazing on grassland soil respiration. Egger’s regression test for funnel plot asymmetry (z = 0.3799, p = 0.7040).

4 Discussion

4.1 Effects of grazing activity and intensities on alpine grassland CO₂ emission rates on the Tibetan Plateau

Alpine grasslands on the Tibetan Plateau sequester carbon at a rate of 32 Tg C per year (35). China’s terrestrial ecosystems had a soil respiration rate of 777.90 g C m^-2 year^-1, and in recent years, the soil respiration rate in grasslands has gradually increased (35). A strongly increased herd density has promoted alpine grassland ecosystem respiration rates (19). Livestock grazing enclosures could be an effective strategy for reducing CO₂ emissions in alpine meadows (20). The response of these carbon stocks and processes to recent land use changes remains unknown.

In this study, we revealed that grazing slightly increased soil respiration rates of alpine grasslands approximately 3.99% across the Tibetan Plateau. This increase likely results from moderate grazing stimulating certain microbes and enzyme activity, thus supporting respiration (21). Grazing also enhances soil moisture and vegetation regeneration, which sustain microbial activity by improving soil structure and carbon access. Similar studies were detected with grazed and fenced meadow soil respiration rates of 295.67 and 284.67 g m⁻² with an increased range of 3.72% on the northern Tibetan Plateau (22). Meanwhile, Hu reported that grazing activity increased grassland CO₂ emission rates from 610.4 to 625.3 g m⁻², approximately 2.38% on the northeast Tibetan Plateau (14). Grazing significantly increased soil respiration by 13.1% (23). Furthermore, some studies indicated that the increased range of alpine grassland soil reparation rates were 43.48% and 29.57% on the north and central Tibetan Plateau (24, 25). However, other studies demonstrated that grazing decreased grassland CO₂ emission rates approximately 56.96%, 23.37%, and 3.34% on the northern, southeastern, and southwestern Tibetan Plateau, respectively. Grazing exclusion increased respiration rates in alpine steppe and alpine meadow (24).

Robust spatial heterogeneity was observed across the Tibetan Plateau, driven by variations in climate, soil properties, and vegetation. Grazing enhances soil respiration by increasing soil moisture and temperature, and stimulating root exudation and microbial activity. These findings highlight the complexity of grazing impacts on carbon cycling, underscoring the need to consider site-specific factors when assessing its broader effects on soil respiration and CO₂ fluxes.

Previous studies suggested that different grazing intensities should be considered when evaluating future carbon cycles in grazed ecosystems on the Tibetan Plateau (23). Annual soil respiration rate is almost twice as high in a lightly grazed meadow (574.2 g m⁻²) as in a fenced meadow (268.8 g m⁻²) on the Tibetan Plateau (26). Increased range of respiration rates were 26.38%, 42.63%, and 43.49% in light, moderate, and high grazed meadows (25). Alpine meadows emitted 196 and 216 g CO₂ m⁻² in light and high grazed intensity with a range of 30.61% and 34.70% on the northern Tibetan Plateau, respectively (27). The present study indicated that increased range was 5.23%, 2.94%, and 5.65% in light, moderate, ang high grazed meadows across the Tibetan Plateau. This study found that moderate grazing led to the smallest increase in soil respiration compared to light and heavy grazing. The plant–microbe interaction hypothesis suggests that moderate grazing strikes an optimal balance between vegetation cover and microbial activity by preserving root growth and soil structure. Light grazing may not sufficiently activate microbial processes, limiting carbon cycling, while heavy grazing can degrade soil integrity, accelerating decomposition and CO₂ emissions. In contrast, moderate grazing enhances organic matter input and stabilizes microbial communities, effectively reducing carbon loss from excessive decomposition. In conclusion, moderate grazing mitigated alpine grassland soil respiration rates.

4.2 Driven factors on the effect size of grazing on alpine grassland respiration rates across the Tibetan Plateau

Grazing activity altered soil carbon storage in alpine grassland ecosystems by affecting soil respirations (16). Soil temperature and moisture well explained the seasonal variations of ecosystem respiration rates in alpine steppe and alpine meadow (24). Soil moisture and belowground biomass explained approximately 83.1% of the respiration variation of alpine meadows (28). Livestock enclosure decreased the temperature sensitivity value of CO₂ emission (26). Positive correlations between soil temperature and respirations were observed during the 3-year study (15).

In conclusion, we determined that both air temperature and soil organic carbon significantly influenced the effect size of grazing on soil respiration across the Tibetan Plateau. Higher air temperatures likely accelerate the metabolic activity of microbes and plant roots, enhancing their respiration, while the increase in soil organic carbon provides more substrate for microbial decomposition, further promoting CO₂ emissions. The increase in soil temperature caused by grazing helps to alleviate the temperature limitations on soil respiration, making it more effective (23). Meanwhile, the temperature sensitivity of soil respiration was also increased by grazing activity (29, 30). The second possible explanation was a larger stimulation of root biomass by increased soil organic carbon, and then increased CO₂ emissions (31). Furthermore, soil organic carbon was the fundamental substrate for soil microbial respiration (32–34). Consequently, global warming and increasing soil organic carbon through degraded grassland restoration would increase alpine grassland CO₂ emission.

5 Conclusions

Grazing activity lightly increased alpine grassland soil respiration rate across the Tibetan Plateau. Meanwhile, grazing decreased soil respiration rate in alpine steppes. Effect sizes of light and high grazing significantly exceeded moderate grazing. Moderate grazing mitigated grassland soil respiration rates. Both air temperature and soil organic carbon significantly influenced the effect size of grazing on the grassland ecosystem respiration rate. Future warming scenarios and increasing soil organic carbon could promote alpine grassland CO₂ emission on the Tibetan Plateau.

Data availability statement

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

Author contributions

YM: Data curation, Investigation, Writing – original draft. YD: Methodology, Writing – review & editing. KC: Funding acquisition, Supervision, Writing – review & editing.

Funding

The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. This study was supported by the National Natural Science Foundation of China (U21A20186) and Key Development Projects of Qinghai (2022-NK-135).

Conflict of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher’s note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

References

1. Anslan S, Azizi M, Buckel J, Echeverria G, Kai J, Kang WG, et al. Reviews and syntheses: How do abiotic and biotic processes respond to climatic variations in the Nam Co catchment (Tibetan Plateau). Biogeosciences. (2023) 17:1261–79. doi: 10.5194/bg-17-1261-2020

Crossref Full Text | Google Scholar

2. Chen J, Zhou X, Wang J, Hruska T, Shi WY, Cao JY, et al. Grazing exclusion reduced soil respiration but increased its temperature sensitivity in a meadow grassland on the Tibetan Plateau. Ecol Evol. (2023) 6:675–87. doi: 10.1002/ece3.1867

PubMed Abstract | Crossref Full Text | Google Scholar

3. Zhang T, Xu MJ, Zhang YJ, Zhao TH, An TT, Li YG, et al. Grazing-induced increases in soil moisture maintain higher productivity during droughts in alpine meadows on the Tibetan Plateau. Agric For Meteorol. (2019) 156:269–70. doi: 10.1016/j.agrformet.2019.02.022

Crossref Full Text | Google Scholar

4. Guo N, Wang A, Allen DA, Deng B, Shang ZH, Ding LM, et al. Grazing exclusion increases soil CO₂ emission during the growing season in alpine meadows on the Tibetan Plateau. Atmos Environ. (2018) 174:92–8. doi: 10.1016/j.atmosenv.2017.11.053

Crossref Full Text | Google Scholar

5. Cui S, Zhu X, Wang S, Zhang Z, Xu B, Luo C, et al. Effects of seasonal grazing on soil respiration in alpine meadow on the Tibetan plateau. Soil Use Manage. (2014) 30:435–8. doi: 10.1111/sum.2014.30.issue-3

Crossref Full Text | Google Scholar

6. Gong YM, Mohammat A, Liu XJ, Li KX, Christie P, Fang F, et al. Response of carbon dioxide emissions to sheep grazing and N application in an alpine grassland &ndash. Biogeosciences. (2014) 11:1751. doi: 10.5194/bg-11-1751-2014

Crossref Full Text | Google Scholar

7. Qu Y, Wang DP, Jin SL, Zheng ZR, Diao ZY, et al. Flooding length mediates fencing and grazing effects on soil respiration in meadow steppe. Plants. (2019) 13(5):666. doi: 10.3390/plants13050666

PubMed Abstract | Crossref Full Text | Google Scholar

8. Li YT, Yi SH, Hou FJ, Chang SH, Wang ZF, Qin Y, et al. Response of CO₂ exchanges to short-term grazing by Euler’s sheep in an alpine meadow in the peak of the growing season. Acta Pratacult Sin. (2017) 26:24–32. doi: 10.11686/cyxb2016168

Crossref Full Text | Google Scholar

9. Wang Z, Wan X, Tian M, Wang XY, Chen JB, Chen XJ, et al. Grazing season alters soil respiration in a semiarid grassland on the Loess Plateau, China. Nutrient Cycling Agroecosys. (2020) 119:307–20. doi: 10.1007/s10705-020-10092-889

Crossref Full Text | Google Scholar

10. Diao H, Hao J, Yang Q, Gao YY, Ma TF, Han F, et al. Soil environment and annual rainfall co-regulate the response of soil respiration to different grazing intensities in saline-alkaline grassland. Catena. (2024) 236:107709. doi: 10.1016/j.catena.2023.107709

Crossref Full Text | Google Scholar

11. Hafner S, Unteregelsbacher S, Seeber E, Lena B, Xu X, Li X, et al. Effect of grazing on carbon stocks and assimilate partitioning in a Tibetan montane pasture revealed by ¹³CO₂ pulse labeling. Global Change Biol. (2012) 18:528–38. doi: 10.1111/j.1365-2486.2011.02557.x

Crossref Full Text | Google Scholar

12. Li W, Cao WX, Liu HD, Li XL, Xu CL, Shi SL, et al. Analysis of soil respiration under different grazing management patterns in the alpine meadow-steppe of the Qinghai-Tibet Plateau. Acta Pratacult Sin. (2015) 24:22–32. doi: 10.11686/cyxb2015152

Crossref Full Text | Google Scholar

13. Wang JL, Liu YZ, Cao WX, Li W, Wang XJ, Zhang DG, et al. Effects of grazing exclusion on soil respiration components in an alpine meadow on the north-eastern Qinghai-Tibet Plateau. Catena. (2020) 194:104750. doi: 10.1016/j.catena.2020.104750

Crossref Full Text | Google Scholar

14. Hu YG, Zhang ZH, Wang SP, Zhang ZS, Zhao Y, Wang ZR, et al. The weak effects of fencing on ecosystem respiration, CH₄, and N₂O fluxes in a Tibetan alpine meadow during the growing season. Sci Cold Arid Region. (2017) 98:158–62. doi: 10.3724/SP.J.1226.2017.0055

Crossref Full Text | Google Scholar

15. Lin XW, Zhang ZH, Wang SP, Hu YG, Xu GP, Luo CY, et al. Response of ecosystem respiration to warming and grazing during the growing seasons in the alpine meadow on the Tibetan plateau. Agric For Meteorol. (2011) 151:792–802. doi: 10.1016/j.agrformet.2011.01.009

Crossref Full Text | Google Scholar

16. Huang XM, Lu XR, Zhou GY, Shi YF, Zhang DG, Zhang WJ, et al. How land-use change affects soil respiration in an alpine agro-pastoral ecotone. Catena. (2022) 214:106291. doi: 10.1016/j.catena.2022.106291

Crossref Full Text | Google Scholar

17. Sun SB, Che T, Li HY, Wang TJ, Ma CF, Liu B, et al. Water and carbon dioxide exchange of an alpine meadow ecosystem in the northeastern Tibetan Plateau is energy-limited. Agric For Meteorol. (2019) 275:283–95. doi: 10.1016/j.agrformet.2019.06.003

Crossref Full Text | Google Scholar

18. Yuan H, Matthew C, He XZ, Sun Y, Liu Y, Zhang T, et al. Seasonal variation in soil and herbage CO₂ efflux for a sheep-grazed alpine meadow on the north-east Qinghai-Tibetan Plateau and estimated net annual CO₂ exchange. Front Plant Sci. (2022) 13:15997. doi: 10.3389/fpls.2022.860739

PubMed Abstract | Crossref Full Text | Google Scholar

19. Unteregelsbacher S, Hafner S, Guggenberger G, George M, Xu XL, Liu JQ, et al. Response of long-, medium- and short-term processes of the carbon budget to overgrazing-induced crusts in the Tibetan Plateau. Biogeochemistry. (2012) 111:187–201. doi: 10.1007/s10533-011-9632-9

Crossref Full Text | Google Scholar

20. Luo C, Wang S, Zhang L, Wilkes A, Zhao L, Zhao XQ, et al. CO₂, CH₄ and N₂O fluxes in an alpine meadow on the Tibetan Plateau as affected by N-addition and grazing exclusion. Nutrient Cycling Agroecosys. (2020) 117:29–42. doi: 10.1007/s10705-020-10062-0

Crossref Full Text | Google Scholar

21. Li C, Xiao CW, Li MX, Xu L, He NP. The quality and quantity of SOM determines the mineralization of recently added labile C and priming of native SOM in grazed grasslands. Geoderma. (2023) 432:116385. doi: 10.1016/j.geoderma.2023.116385

Crossref Full Text | Google Scholar

22. Xu Z, Cheng S, Zhen L, Pan L, Zhang XZ, Wu JX, et al. Impacts of dung combustion on the carbon cycle of alpine grassland of the north Tibetan plateau. Environ Manage. (2013) 52:441–9. doi: 10.1007/s00267-013-0107-8

PubMed Abstract | Crossref Full Text | Google Scholar

23. Wang H, Liu HY, Wang YH, Xu W, Liu AR, Ma ZY, et al. Warm- and cold- season grazing affect soil respiration differently in alpine grasslands. Agricult Ecosyst Environ. (2017) 248:136–43. doi: 10.1016/j.agee.2017.07.041

Crossref Full Text | Google Scholar

24. Zhao JX, Li X, Li RC, Tian LH, Zhang T. Effect of grazing exclusion on ecosystem respiration among three different alpine grasslands on the central Tibetan Plateau. Ecol Eng. (2016) 94:599–607. doi: 10.1016/j.ecoleng.2016.06.112

Crossref Full Text | Google Scholar

25. Guo XW, Dai LC, Li YK, Zhang FW, Lin L, Li Q, et al. Major greenhouse gas fluxes in different degradation levels of alpine meadow on the Qinghai-Tibetan plateau. Res Soil Water Conserv. (2019) 299:56–68. doi: 10.13869/j.cnki.rswc.2019.05.028

Crossref Full Text | Google Scholar

26. Yu SY, He HL, Cheng P, Hou ZF. Depth heterogeneity of soil organic carbon dynamics in a heavily grazed alpine meadow on the northeastern Tibetan Plateau: A radiocarbon-based approach. J Geophys Res: Biogeosci. (2017) 122:154–63. doi: 10.1002/2016JG003567

Crossref Full Text | Google Scholar

27. Zhang T, Zhang YJ, Xu MJ, Zhu JT, Michael W, Yu GR, et al. Light-intensity grazing improves alpine meadow productivity and adaption to climate change on the Tibetan Plateau. Sci Rep. (2015) 5:15949. doi: 10.1038/srep15949

PubMed Abstract | Crossref Full Text | Google Scholar

28. Luo CY, Zhu XX, Wang SP, Cui SJ, Zhang ZH, Bao XY, et al. Ecosystem carbon exchange under different land use on the Qinghai-Tibetan plateau. Photosynthetica. (2015) 53:189–96. doi: 10.1007/s11099-015-0142-1

Crossref Full Text | Google Scholar

29. Cao GM, Tang YH, Kishimoto M, Mo WH, Wang YS, Li YN, et al. Grazing intensity alters soil respiration in an alpine meadow on the Tibetan plateau. Soil Biol Biochem. (2004) 36:237–43. doi: 10.1016/j.soilbio.2003.09.010

Crossref Full Text | Google Scholar

30. Liu YW, Chen TZ, Geng XD, Wei D, Dai DX, Xu R. Grazing exclusion enhanced net ecosystem carbon uptake but decreased plant nutrient content in an alpine steppe. Catena. (2020) 195:104799. doi: 10.1016/j.catena.2020.104799

Crossref Full Text | Google Scholar

31. Du CJ, Zhou GY, Gao YH. Grazing exclusion alters carbon flux of alpine meadow in the Tibetan Plateau. Agric For Meteorol. (2022) 314:108774. doi: 10.1016/j.agrformet.2021.108774

Crossref Full Text | Google Scholar

32. Chen J, Shi W, Cao JJ. Effects of grazing on ecosystem CO₂ exchange in a meadow grassland on the Tibetan plateau during the growing season. Environ Manage. (2015) 55:347–59. doi: 10.1007/s00267-014-0390-z

PubMed Abstract | Crossref Full Text | Google Scholar

33. Guo ZP, Zhao YP, Zhang PH, Zhang H, Baskin CC, Zhang TW, et al. Rodents mediate the relationship between seed rain, seed bank, and plant community with increased grazing disturbance. Ecol Appl. (2024) 34:2984. doi: 10.1002/eap.v34.5

PubMed Abstract | Crossref Full Text | Google Scholar

34. Wang GX, Qiu J, Cheng GD, Lai YM. Soil organic carbon pool of grassland soils on the Qinghai-Tibetan Plateau and its global implication. Sci Total Environ. (2002) 291:207–17. doi: 10.1016/S0048-9697(01)01100-7

PubMed Abstract | Crossref Full Text | Google Scholar

35. Yang YH, Shi Y, Sun WJ, Chang JF, Zhu JX, Chen LY, et al. Terrestrial carbon sinks in China and around the world and their contribution to carbon neutrality. Science China Life Sciences (2022) 65(5):861–895. doi: 10.1007/s11427-021-2045-5

PubMed Abstract | Crossref Full Text | Google Scholar