Effects of grazing by large herbivores on plant diversity and productivity of semi-arid alpine steppe on the Qinghai-Tibetan Plateau

2015 ◽  
Vol 37 (4) ◽  
pp. 389 ◽  
Author(s):  
Hasbagan Ganjurjav ◽  
Min-jie Duan ◽  
Yun-fan Wan ◽  
Wei-na Zhang ◽  
Qing-zhu Gao ◽  
...  
Keyword(s):  
Species Diversity ◽  
Tibetan Plateau ◽  
Plant Community ◽  
Plant Diversity ◽  
Net Primary Productivity ◽  
Strong Impact ◽  
Aboveground Net Primary Productivity ◽  
Large Herbivores ◽  
Alpine Steppe ◽  
Semi Arid

Grazing by large herbivores may have a strong impact on plant diversity and productivity, but the effects are expected to vary with grazing pressure. The changes in productivity and species diversity of Stipa purpurea-dominated semi-arid alpine steppe grassland were measured under four different stocking rates of Tibetan sheep [no grazing, light (2.4 sheep units ha–1), moderate (3.6 sheep units ha–1), and heavy (6.0 sheep units ha–1) grazing] in a 5-year (2006–2010) grazing experiment on the Qinghai-Tibetan Plateau, China. Herbage mass and aboveground net primary productivity of alpine steppe declined significantly with increasing stocking rate (P < 0.05). Over the 5 years of the experiment, the proportion of forbs and sedges increased significantly under light and moderate grazing; the proportion of grasses decreased significantly, whereas the proportion of S. purpurea did not change compared with the no grazing treatment. Species diversity was highest under moderate grazing and was significantly higher than the no grazing treatment in 2 years (2008 and 2010). Moderate grazing enhanced the species diversity of the plant community due to an increase in the proportion of forbs. There were significant positive linear correlations between herbage mass and species diversity under no and light grazing. Species diversity was not related to productivity under moderate and heavy grazing. In conclusion, grazing by sheep reduced plant productivity; plant diversity increased under low and moderate grazing, and was as a result of changes in the composition of the plant community of a semi-arid alpine steppe.

Effects of grazing and climate warming on plant diversity, productivity and living state in the alpine rangelands and cultivated grasslands of the Qinghai-Tibetan Plateau

2015 ◽  
Vol 37 (1) ◽  
pp. 57 ◽  
Author(s):  
Yong Zhang ◽  
Qingzhu Gao ◽  
Shikui Dong ◽  
Shiliang Liu ◽  
Xuexia Wang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Plant Diversity ◽  
Climate Warming ◽  
Alpine Meadow ◽  
Vegetation Type ◽  
Vegetation Height ◽  
Rangeland Degradation ◽  
Alpine Steppe ◽  
Forage Species ◽  
Living State

Overgrazing and climate warming may be important drivers of alpine rangeland degradation in the Qinghai-Tibetan Plateau (QTP). In this study, the effects of grazing and experimental warming on the vegetation of cultivated grasslands, alpine steppe and alpine meadows on the QTP were investigated. The three treatments were a control, a warming treatment and a grazing treatment and were replicated three times on each vegetation type. The warming treatment was applied using fibreglass open-top chambers and the grazing treatment was continuous grazing by yaks at a moderately high stocking rate. Both grazing and warming negatively affected vegetation cover. Grazing reduced vegetation height while warming increased vegetation height. Grazing increased but warming reduced plant diversity. Grazing decreased and warming increased the aboveground plant biomass. Grazing increased the preferred forage species in native rangelands (alpine steppe and alpine meadow), while warming increased the preferred forage species in the cultivated grassland. Grazing reduced the vegetation living state (VLS) of all three alpine grasslands by nearly 70%, while warming reduced the VLS of the cultivated grassland and the alpine steppe by 32% and 56%, respectively, and promoted the VLS of the alpine meadow by 20.5%. It was concluded that overgrazing was the main driver of change to the alpine grassland vegetation on the QTP. The findings suggest that grazing regimes should be adapted in order for them to be sustainable in a warmer future.

A comparison of biodiversity–ecosystem function relationships in alpine grasslands across a degradation gradient on the Qinghai–Tibetan Plateau

2015 ◽  
Vol 37 (1) ◽  
pp. 45 ◽  
Author(s):  
Xuexia Wang ◽  
Shikui Dong ◽  
Ruth Sherman ◽  
Quanru Liu ◽  
Shiliang Liu ◽  
...  
Keyword(s):  
Species Diversity ◽  
Tibetan Plateau ◽  
Plant Diversity ◽  
Ecosystem Function ◽  
Aboveground Biomass ◽  
Soil Loss ◽  
Plant Biomass ◽  
Plant Functional Groups ◽  
Alpine Grasslands ◽  
C And N

To examine biodiversity–ecosystem function relationships in alpine grasslands of the Qinghai–Tibetan Plateau, we compared differences in plant species and functional group diversity (sedges, grasses, legumes and non-leguminous forbs) to aboveground biomass, soil carbon (C) and nitrogen (N) pools and soil loss in five sites that ranged from healthy to severely degraded grasslands. Plant diversity decreased from 36 species in the healthy grassland to 15 species in the severely degraded grassland, and the plant functional groups changed from predominantly grasses and sedges to mostly forbs as the level of degradation increased. Plant biomass and soil pools of C and N decreased whereas soil loss and the amount of bare ground increased across the degradation gradient from healthy to severely degraded grasslands. Simple linear regressions showed strong positive relationships between species diversity and aboveground biomass of sedges, grasses and legumes and between soil C and N pools, but negative relationships between species diversity and non-leguminous forbs and soil loss. Our results provide strong evidence that plant diversity in grasslands on the Qinghai–Tibetan Plateau is positively related to primary productivity, C and N storage in soils and soil conservation, and that grassland degradation is impairing ecosystem function resulting in a loss in ecosystem services.

scholarly journals Plant diversity enhances productivity and soil carbon storage

2018 ◽  
Vol 115 (16) ◽  
pp. 4027-4032 ◽  
Author(s):  
Shiping Chen ◽  
Wantong Wang ◽  
Wenting Xu ◽  
Yang Wang ◽  
Hongwei Wan ◽  
...  
Keyword(s):  
Soil Carbon ◽  
Plant Diversity ◽  
Soil Ph ◽  
Indirect Effects ◽  
Net Primary Productivity ◽  
Human Impacts ◽  
Integrative Model ◽  
Aboveground Net Primary Productivity ◽  
Positive Effects ◽  
Negative Effect

Despite evidence from experimental grasslands that plant diversity increases biomass production and soil organic carbon (SOC) storage, it remains unclear whether this is true in natural ecosystems, especially under climatic variations and human disturbances. Based on field observations from 6,098 forest, shrubland, and grassland sites across China and predictions from an integrative model combining multiple theories, we systematically examined the direct effects of climate, soils, and human impacts on SOC storage versus the indirect effects mediated by species richness (SR), aboveground net primary productivity (ANPP), and belowground biomass (BB). We found that favorable climates (high temperature and precipitation) had a consistent negative effect on SOC storage in forests and shrublands, but not in grasslands. Climate favorability, particularly high precipitation, was associated with both higher SR and higher BB, which had consistent positive effects on SOC storage, thus offsetting the direct negative effect of favorable climate on SOC. The indirect effects of climate on SOC storage depended on the relationships of SR with ANPP and BB, which were consistently positive in all biome types. In addition, human disturbance and soil pH had both direct and indirect effects on SOC storage, with the indirect effects mediated by changes in SR, ANPP, and BB. High soil pH had a consistently negative effect on SOC storage. Our findings have important implications for improving global carbon cycling models and ecosystem management: Maintaining high levels of diversity can enhance soil carbon sequestration and help sustain the benefits of plant diversity and productivity.

scholarly journals Plant diversity is closely related to the density of zokor mounds in three alpine rangelands on the Tibetan Plateau

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6921 ◽  
Author(s):  
Yujie Niu ◽  
Jianwei Zhou ◽  
Siwei Yang ◽  
Bin Chu ◽  
Huimin Zhu ◽  
...  
Keyword(s):  
Species Richness ◽  
Soil Moisture ◽  
Tibetan Plateau ◽  
Plant Diversity ◽  
Alpine Meadow ◽  
Living Environment ◽  
The Tibetan Plateau ◽  
Alpine Steppe ◽  
Alpine Shrub ◽  
Plateau Zokor

Background Plateau zokor (Myospalax baileyi) is a subterranean rodent endemic to the Tibetan Plateau. This species has been generally viewed as a pest in China due to the competition for food with livestock and also causing soil erosion. As a result, plateau zokor has been the target of widespread poisoning or trapping campaigns designed to control or eliminate it since 1970s. But there is little research on the effect of plateau zokor on plant diversity in alpine rangelands. Therefore, objectively evaluating the positive effects of the plateau zokors disturbance on their living environment and plant communities is of great significance to understand the function of plateau zokor in alpine ecosystem. Methods Here, we selected three rangelands (alpine meadow, alpine steppe and alpine shrub meadow) in which plateau zokors are typically distributed on the Tibetan Plateau, and five zokor mound density gradients were selected in each rangeland type to study the effects of the mounds on soil moisture and temperature related to plant species diversity. Results The results showed that, with the mound density increasing, the soil temperature decreased significantly in all three rangeland types, and the soil moisture significantly increased in all three rangeland types. In the alpine meadow, both the plant diversity and cumulative species richness increased significantly with increasing mound density. The increase in broad-leaved forbs is the main reason for the increase of plant diversity in the alpine meadow disturbed by zokor mounds. In the alpine steppe, the plant diversity decreased significantly with increasing mound density, while the cumulative species richness initially decreased and then increased. In the alpine shrub meadow, the plant diversity first increased and then decreased with increasing mound density as did the cumulative species richness. In conclusion, plateau zokor mounds dominated the distribution of soil moisture and temperature and significantly affected plant diversity in these three rangelands on Tibetan Plateau; the results further deepen our understanding toward a co-evolved process.

Impacts of burrows and mounds formed by plateau rodents on plant species diversity on the Qinghai-Tibetan Plateau

2015 ◽  
Vol 37 (1) ◽  
pp. 117 ◽  
Author(s):  
Ruixin Wu ◽  
Qi Chai ◽  
Jianquan Zhang ◽  
Mengying Zhong ◽  
Yuehua Liu ◽  
...  
Keyword(s):  
Species Diversity ◽  
Tibetan Plateau ◽  
Plant Diversity ◽  
Management Practices ◽  
Source Region ◽  
Diversity Indices ◽  
Rangeland Management ◽  
Community Diversity ◽  
Grassland Productivity ◽  
Total P

The relationships among environmental factors, rodent activity disturbance and plant-community diversity were studied across four sites in a prefecture of the ‘Three-River-Source’ region of the Qinghai-Tibetan Plateau. It was found that burrow number and mound area had little impact on plant diversity indices, which were mainly affected by altitude, soil total P and pH. Altitude and mound area, especially mound area, can strongly affect the aboveground biomass and the vegetation cover of plants was mainly influenced by mound area. There was some evidence that moderate levels of disturbance by rodents could lead to the highest levels of plant diversity. These findings indicated that moderate levels of disturbance by rodents may be beneficial to grassland productivity and plant diversity. Understanding these impacts is vital for better rangeland management practices so that rodents should be controlled within a suitable range rather than being exterminated.

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