Seasonal dynamics and controls of deep soil water infiltration in the seasonally-frozen region of the Qinghai-Tibet plateau

et al. 2020

Sustainability

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The degradation of alpine grasslands directly affects their ability to conserve water, but changes in soil water storage in grassland under different degrees of degradation are poorly understood. Here, we selected four grassland plots along a degradation gradient: no-degradation grassland (NG), lightly degraded grassland (LG), moderately degraded grassland (MG) and severely degraded grassland (SG). We then applied an automatic soil moisture monitoring system to study changes in soil water storage processes. Results revealed significant (p < 0.05) differences in soil water storage among NG, LG, MG and SG. Specifically, LG lost 35.9 mm of soil water storage compared with NG, while soil water storage in LG, MG and SG decreased by 24.5%, 32.1% and 36.7%, respectively. The shallow groundwater table, air temperature and grass litter were the key controlling factors of soil water storage in the grassland. Grazing and future global warming will significantly reduce soil water storage in alpine grasslands.

Section: Grazing Significantly Reduced Soil Water Storagementioning

confidence: 65%

Light Grazing Significantly Reduces Soil Water Storage in Alpine Grasslands on the Qinghai-Tibet Plateau

Guo

et al. 2020

Sustainability

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“…Thus, there is a sense of urgency to determine a suitable stocking rate in the alpine grassland for restoring degraded grassland and improving livestock production both at the local and at the landscape scale (Barcella, Filipponi, & Assini, ; Metera, Sakowski, Słoniewski, & Romanowicz, ). In this study, we found that the maximum value of BGB occurred in moderate levels of grazing disturbance (i.e., 7.5 sheep/ha), suggesting that such stocking rates may be an optimal grassland management strategy for the alpine meadow in terms of root production, especially considering the BGB almost accounts for more than 80% biomass of plants (Dai, Guo, Du, Ke, et al, ; Dai, Guo, Zhang, et al, ; Dai, Ke, et al, ), which could provide new insight for local people and policy‐makers in government. However, it should be noted that the species richness shows the lowest value in MG in spite of the BGB peaked in MG.…”

Section: Discussionmentioning

confidence: 89%

“…The region has a characteristic plateau continental monsoon climate, with a mean annual air temperature of −1.7°C, and maximum and minimum air temperatures in July (9.8°C) and January (−14.80°C), respectively. The average annual precipitation is approximately 618 mm, with almost 80% falling in the growing season (i.e., from early May to late September; Dai, Guo, Du, Ke, et al, ; Dai, Guo, Du, Zhang, et al, ; Dai, Guo, Zhang, et al, ; Dai, Ke, et al, ). The soil is classified as Mat cryo‐sod soil on the basis of the Chinese National Soil Survey and Classification System (Institute of Soil Science, CAS, 2001).…”

Section: Methodsmentioning

confidence: 99%

“…The Qinghai–Tibetan Plateau (QTP) is the main region of alpine meadow and alpine steppe, with an area of approximately 2.5 million km 2 of alpine grassland representing one of the world's largest areas of alpine grassland (Dai, Guo, Du, Ke, et al, ; Dai, Guo, Zhang, et al, ; Dai, Ke, et al, ; Lu et al, ; Wesche et al, ). Most importantly, the QTP is the one of the most important natural pastures in China and has provided the main pastures for Tibetan communities for many years (Klein, Harte, & Zhao, ).…”

Section: Introductionmentioning

confidence: 99%

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Moderate grazing promotes the root biomass in Kobresia meadow on the northern Qinghai–Tibet Plateau

Guo

et al. 2019

Ecology and Evolution

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Grazing is an important modulator of both plant productivity and biodiversity in grassland community, yet how to determine a suitable grazing intensity in alpine grassland is still controversy. Here, we explore the effects of different grazing intensities on plant biomass and species composition, both at community level and functional group level, and examines the productivity–species richness relationship under four grazing patterns: no grazing (CK), light grazing (LG), moderate grazing, (MG) and heavy grazing (HG), attempt to determine a suitable grazing intensity in alpine grassland. The results were as follows. The total aboveground biomass (AGB) reduced with increasing grazing intensity, and the response of plant functional groups was different. AGB of both sedges and legumes increased from MG to HG, while the AGB of forbs reduced sharply and the grass AGB remained steady. There was a significant positive relationship between productivity and species richness both at community level and functional group level. In contrast, the belowground biomass (BGB) showed a unimodal relationship from CK to HG, peaking in MG (8,297.72 ± 621.29 g/m2). Interestingly, the grassland community tends to allocate more root biomass to the upper soil layer under increasing grazing intensities. Our results suggesting that moderate levels of disturbance may be the optimal grassland management strategy for alpine meadow in terms of root production.

“…The study site was protected by fence from 2007, to prevent disturbance from human or grazing activities. The soil is classified as Mat‐cryosod soil, with a texture belonging to a loamy soil, and abundant organic matter in the top soil layer (approximately 12.7% in the top 0–10 cm); consequently, the soil has strong water‐holding capacity (Dai, Guo, Du, et al, ; Dai, Guo, Zhang, et al, ). The dimensions of this study site were 250 m × 230 m, covering typical alpine Kobresia humilis meadow.…”

Section: Methodsmentioning

confidence: 99%

Nitrogen controls the net primary production of an alpine Kobresia meadow in the northern Qinghai‐Tibet Plateau

et al. 2019

Ecology and Evolution

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Net primary production (NPP) is a fundamental property of natural ecosystems. Understanding the temporal variations of NPP could provide new insights into the responses of communities to environmental factors. However, few studies based on long‐term field biomass measurements have directly addressed this subject in the unique environment of the Qinghai‐Tibet plateau (QTP). We examined the interannual variations of NPP during 2008–2015 by monitoring both aboveground net primary productivity (ANPP) and belowground net primary productivity (BNPP), and identified their relationships with environmental factors with the general linear model (GLM) and structural equation model (SEM). In addition, the interannual variation of root turnover and its controls were also investigated. The results show that the ANPP and BNPP increased by rates of 15.01 and 143.09 g/m 2 per year during 2008–2015, respectively. BNPP was mainly affected by growing season air temperature (GST) and growing season precipitation (GSP) rather than mean annual air temperature (MAT) or mean annual precipitation (MAP), while ANPP was only controlled by GST. In addition, available nitrogen (AN) was significantly positively associated with BNPP and ANPP. Root turnover rate averaged 30%/year, increased with soil depth, and was largely controlled by GST. Our results suggest that alpine Kobresia meadow was an N‐limited ecosystem, and the NPP on the QTP might increase further in the future in the context of global warming and nitrogen deposition.