Quantitative Assessment of the Impact of Physical and Anthropogenic Factors on Vegetation Spatial-Temporal Variation in Northern Tibet

The alpine grassland on the Qinghai-Tibet Plateau covers an area of about 1/3 of China’s total grassland area and plays a crucial role in regulating grassland ecological functions. Both environmental changes and irrational use of the grassland can result in severe grassland degradation in some areas of the Qinghai-Tibet Plateau. However, the magnitude and patterns of the physical and anthropogenic factors in driving grassland variation over northern Tibet remain debatable, and the interactive influences among those factors are still unclear. In this study, we employed a geographical detector model to quantify the primary and interactive impacts of both the physical factors (precipitation, temperature, sunshine duration, soil type, elevation, slope, and aspect) and the anthropogenic factors (population density, road density, residential density, grazing density, per capita GDP, and land use type) on vegetation variation from 2000 to 2015 in northern Tibet. Our results show that the vegetation index in northern Tibet significantly decreased from 2000 to 2015. Overall, the stability of vegetation types was sorted as follows: the alpine scrub > the alpine steppe > the alpine meadow. The physical factors, rather than the anthropogenic factors, have been the primary driving factors for vegetation dynamics in northern Tibet. Specifically, meteorological factors best explained the alpine meadow and alpine steppe variation. Precipitation was the key factor that influenced the alpine meadow variation, whereas temperature was the key factor that contributed to the alpine steppe variation. The anthropogenic factors, such as population density, grazing density and per capita GDP, influenced the alpine scrub variation most. The influence of population density is highly similar to that of grazing density, which may provide convenient access to simplify the study of the anthropogenic activities in the Tibet plateau. The interactions between the driving factors had larger effects on vegetation than any single factor. In the alpine meadow, the interaction between precipitation and temperature can explain 44.6% of the vegetation variation. In the alpine scrub, the interaction between temperature and GDP was the highest, accounting for 27.5% of vegetation variation. For the alpine steppe, the interaction between soil type and population density can explain 29.4% of the vegetation variation. The highest value of vegetation degradation occurred in the range of 448–469 mm rainfall in the alpine meadow, 0.61–1.23 people/km2 in the alpine scrub and –0.83–0.15 °C in the alpine steppe, respectively. These findings could contribute to a better understanding of degradation prevention and sustainable development of the alpine grassland ecosystem in northern Tibet.

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Spatial and Temporal Differences in Alpine Meadow, Alpine Steppe and All Vegetation of the Qinghai-Tibetan Plateau and Their Responses to Climate Change

Remote Sensing ◽

10.3390/rs13040669 ◽

2021 ◽

Vol 13 (4) ◽

pp. 669

Author(s):

Hanchen Duan ◽

Xian Xue ◽

Tao Wang ◽

Wenping Kang ◽

Jie Liao ◽

...

Keyword(s):

Climate Change ◽

Alpine Meadow ◽

Global Climate ◽

Growing Season ◽

Tibet Plateau ◽

Vegetation Types ◽

Analysis Method ◽

Alpine Steppe ◽

Qinghai Tibet Plateau ◽

Variation Trends

Alpine meadow and alpine steppe are the two most widely distributed nonzonal vegetation types in the Qinghai-Tibet Plateau. In the context of global climate change, the differences in spatial-temporal variation trends and their responses to climate change are discussed. It is of great significance to reveal the response of the Qinghai-Tibet Plateau to global climate change and the construction of ecological security barriers. This study takes alpine meadow, alpine steppe and the overall vegetation of the Qinghai-Tibet Plateau as the research objects. The normalized difference vegetation index (NDVI) data and meteorological data were used as the data sources between 2000 and 2018. By using the mean value method, threshold method, trend analysis method and correlation analysis method, the spatial and temporal variation trends in the alpine meadow, alpine steppe and the overall vegetation of the Qinghai-Tibet Plateau were compared and analyzed, and their differences in the responses to climate change were discussed. The results showed the following: (1) The growing season length of alpine meadow was 145~289 d, while that of alpine steppe and the overall vegetation of the Qinghai-Tibet Plateau was 161~273 d, and their growing season lengths were significantly shorter than that of alpine meadow. (2) The annual variation trends of the growing season NDVI for the alpine meadow, alpine steppe and the overall vegetation of the Qinghai-Tibet Plateau increased obviously, but their fluctuation range and change rate were significantly different. (3) The overall vegetation improvement in the Qinghai-Tibet Plateau was primarily dominated by alpine steppe and alpine meadow, while the degradation was primarily dominated by alpine meadow. (4) The responses between the growing season NDVI and climatic factors in the alpine meadow, alpine steppe and the overall vegetation of the Qinghai-Tibet Plateau had great spatial heterogeneity in the Qinghai-Tibet Plateau. These findings provide evidence towards understanding the characteristics of the different vegetation types in the Qinghai-Tibet Plateau and their spatial differences in response to climate change.

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Changes in vegetation composition and plant diversity with rangeland degradation in the alpine region of Qinghai-Tibet Plateau

The Rangeland Journal ◽

10.1071/rj14077 ◽

2015 ◽

Vol 37 (1) ◽

pp. 107 ◽

Cited By ~ 20

Author(s):

Lin Tang ◽

Shikui Dong ◽

Ruth Sherman ◽

Shiliang Liu ◽

Quanru Liu ◽

...

Keyword(s):

Plant Diversity ◽

Large Scale ◽

Alpine Meadow ◽

Vegetation Indices ◽

Desert Ecosystem ◽

Tibet Plateau ◽

Vegetation Composition ◽

Rangeland Degradation ◽

Alpine Steppe ◽

Qinghai Tibet Plateau

The changes in vegetation composition and plant diversity of three different alpine ecosystems: alpine meadow, alpine steppe and alpine desert, impacted by different levels of degradation (healthy, lightly degraded and moderately degraded) were examined across a large-scale transect on the Qinghai-Tibet Plateau. The alpine meadow was dominated by sedges, the alpine steppe was dominated by grasses and the alpine desert was dominated by shrubs. The alpine meadow had the highest species diversity, whereas the alpine steppe had the lowest and tended to be dominated by a few species. Forbs were the dominant and most diverse functional group in the alpine meadow and the alpine steppe, which was different from the alpine desert. The importance values of the dominant species and levels of diversity measured by various vegetation indices were only slightly different in the degraded sites as compared with the non-degraded alpine meadow and steppe, whereas the alpine desert showed large changes in the composition and diversity of the plant community in response to degradation. In conclusion, the plant composition of the alpine meadow and alpine steppe ecosystems was more stable and appeared more resistant to disturbance than that of the alpine desert ecosystem.

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The aridity index governs the variation of vegetation characteristics in alpine grassland, Northern Tibet Plateau

PeerJ ◽

10.7717/peerj.7272 ◽

2019 ◽

Vol 7 ◽

pp. e7272 ◽

Cited By ~ 4

Author(s):

Biying Liu ◽

Jian Sun ◽

Miao Liu ◽

Tao Zeng ◽

Juntao Zhu

Keyword(s):

Structural Equation ◽

Alpine Meadow ◽

Aridity Index ◽

Alpine Grassland ◽

Tibet Plateau ◽

Mean Annual Precipitation ◽

Vegetation Dynamic ◽

Vegetation Biomass ◽

Northern Tibet ◽

Alpine Steppe

The vegetation dynamic (e.g., community productivity) is an important index used to evaluate the ecosystem function of grassland ecosystem. However, the critical factors that affect vegetation biomass are disputed continuously, and most of the debates focus on mean annual precipitation (MAP) or temperature (MAT). This article integrated these two factors, used the aridity index (AI) to describe the dynamics of MAP and MAT, and tested the hypothesis that vegetation traits are influenced primarily by the AI. We sampled 275 plots at 55 sites (five plots at each site, including alpine steppe and meadow) across an alpine grassland of the northern Tibet Plateau, used correlation analysis and redundancy analysis (RDA) to explore which key factors determine the biomass dynamic, and explained the mechanism by which they affect the vegetation biomass in different vegetation types via structural equation modelling (SEM). The results supported our hypothesis, in all of the environmental factors collected, the AI made the greatest contribution to biomass variations in RDA , and the correlation between the AI and biomass was the largest (R = 0.85, p < 0.05). The final SEM also validated our hypothesis that the AI explained 79.3% and 84.4% of the biomass variations in the alpine steppe and the meadow, respectively. Furthermore, we found that the soils with higher carbon to nitrogen ratio and soil total nitrogen had larger biomass, whereas soil organic carbon had a negative effect on biomass in alpine steppe; however, opposite effects of soil factors on biomass were observed in an alpine meadow. The findings demonstrated that the AI was the most critical factor affecting biomass in the alpine grasslands, and different reaction mechanisms of biomass response to the AI existed in the alpine steppe and alpine meadow.

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Socio-Environmental Dynamics of Alpine Grasslands, Steppes and Meadows of the Qinghai–Tibetan Plateau, China: A Commentary

Applied Sciences ◽

10.3390/app10186488 ◽

2020 ◽

Vol 10 (18) ◽

pp. 6488 ◽

Cited By ~ 1

Author(s):

Haiying Feng ◽

Victor R. Squires

Keyword(s):

Alpine Meadow ◽

Tibet Plateau ◽

South East Asia ◽

Alpine Grasslands ◽

Growing Seasons ◽

Alpine Steppe ◽

Tibetan Sheep ◽

Low Humidity ◽

Bactrian Camels ◽

Qinghai Tibet Plateau

Alpine grasslands are a common feature on the extensive (2.6 million km2) Qinghai–Tibet plateau in western and southwestern China. These grasslands are characterized by their ability to thrive at high altitudes and in areas with short growing seasons and low humidity. Alpine steppe and alpine meadow are the principal plant Formations supporting a rich species mix of grass and forb species, many of them endemic. Alpine grasslands are the mainstay of pastoralism where yaks and hardy Tibetan sheep and Bactrian camels are the favored livestock in the cold arid region. It is not only their importance to local semi nomadic herders, but their role as headwaters of nine major rivers that provide water to more than one billion people in China and in neighboring countries in south and south-east Asia and beyond. Grasslands in this region were heavily utilized in recent decades and are facing accelerated land degradation. Government and herder responses, although quite different, are being implemented as climate change and the transition to the market economy proceeds apace. Problems and prospects for alpine grasslands and the management regimes being imposed (including sedentarization, resettlement and global warming are briefly discussed.

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Distinguishing Stoichiometric Homeostasis of Soil Microbial Biomass in Alpine Grassland Ecosystems: Evidence From 5,000 km Belt Transect Across Qinghai–Tibet Plateau

Frontiers in Plant Science ◽

10.3389/fpls.2021.781695 ◽

2021 ◽

Vol 12 ◽

Author(s):

Jihui Fan ◽

Tianyuan Liu ◽

Ying Liao ◽

Yiying Li ◽

Yan Yan ◽

...

Keyword(s):

Microbial Biomass ◽

Soil Microbial Biomass ◽

Alpine Meadow ◽

Alpine Grassland ◽

Tibet Plateau ◽

Trade Off ◽

Soil C ◽

Soil Microbial ◽

Alpine Steppe ◽

Qinghai Tibet Plateau

The biogeographic characteristics of soil microbial biomass stoichiometry homeostasis and also its mechanisms are commonly thought to be key factors for the survival strategies and resource utilization of soil microbes under extreme habitat. In this work, we conducted a 5,000-km transect filed survey in alpine grassland across Qinghai–Tibet Plateau in 2015 to measure soil microbial biomass carbon (MBC) and nitrogen (MBN) across alpine steppe and meadow. Based on the differences of climate and soil conditions between alpine steppe and meadow, the variation coefficient was calculated to investigate the homeostatic degree of MBC to MBN. Furthermore, the “trade-off” model was utilized to deeply distinguish the homeostasis degree of MBC/MBN between alpine steppe and meadow, and the regression analysis was used to explore the variability of trade-off in response to environmental factors in the alpine grassland. The results showed that the coefficient of variation (CV) of MBC/MBN in alpine meadow (CV = 0.4) was lower than alpine steppe (CV = 0.7). According to the trade-off model, microbial turnover activity of soil N relative to soil C increased rapidly and then decreased slightly with soil organic carbon (SOC), soil total nitrogen (STN), and soil water content across alpine meadow. Nevertheless, in alpine steppe, SOC/STN had a positive effect on microbial turnover of soil N. These results suggested that water, heat, and soil nutrients availability were the key factors affecting the C:N stoichiometry homeostasis of soil microbial biomass in Qinghai–Tibet Plateau (QTP)’s alpine grassland. Since the difference of survival strategy of the trade-off demands between soil C and N resulting in different patterns and mechanism, the stoichiometry homeostasis of soil microbial biomass was more stable in alpine meadow than in alpine steppe.

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