Excessive plant compensatory growth: a potential endogenous driver of meadow degradation on the Qinghai-Tibetan Plateau

Understanding the process and mechanisms of alpine meadow degradation is crucial for restoration and management in the Three-River Headwaters region, Qinghai-Tibetan Plateau, China. However, little is known about this complex and controversial problem because identification and quantification of the underlying causes is difficult. This research aimed to build a spatiotemporal dynamical model for alpine meadow degradation, capturing the natural process of erosion at the interface of barren patches and undamaged meadow. The model clarified the role of barren patches and meadow connectivity in degradation, and identified the ecological mechanisms and processes accounting for the spatial and temporal pattern of degradation. A fragmentation and percolation threshold exists in the process of meadow degradation, independent of spatial scale. An impulsive differential equation was used to investigate the consequence of periodic restoration of degraded meadow. Both the level of meadow degradation and the restoration period play crucial roles in determining whether the meadow can be successfully restored. This research has demonstrated theoretically that the effectiveness of meadow restoration by periodic effort depends on the degree of degradation.

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Alpine meadow degradation enhances the temperature sensitivity of soil carbon decomposition on the Qinghai–Tibetan plateau

Applied Soil Ecology ◽

10.1016/j.apsoil.2021.104290 ◽

2022 ◽

Vol 170 ◽

pp. 104290

Author(s):

Junmin Pei ◽

Dong Yan ◽

Jinquan Li ◽

La Qiong ◽

Yuanwu Yang ◽

...

Keyword(s):

Tibetan Plateau ◽

Soil Carbon ◽

Temperature Sensitivity ◽

Alpine Meadow ◽

Carbon Decomposition ◽

Alpine Meadow Degradation ◽

Meadow Degradation

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Variation of soil hydraulic properties with alpine grassland degradation in the eastern Tibetan Plateau

Hydrology and Earth System Sciences ◽

10.5194/hess-21-2249-2017 ◽

2017 ◽

Vol 21 (4) ◽

pp. 2249-2261 ◽

Cited By ~ 23

Author(s):

Tao Pan ◽

Shuai Hou ◽

Shaohong Wu ◽

Yujie Liu ◽

Yanhua Liu ◽

...

Keyword(s):

Tibetan Plateau ◽

Soil Properties ◽

Hydraulic Properties ◽

Total Variance ◽

Dominant Factor ◽

Eastern Tibetan Plateau ◽

Soil Hydraulic Properties ◽

Capillary Porosity ◽

Soil Hydraulic ◽

Meadow Degradation

Abstract. Ecosystems in alpine mountainous regions are vulnerable and easily disturbed by global environmental change. Alpine swamp meadow, a unique grassland type in the eastern Tibetan Plateau that provides important ecosystem services to the upstream and downstream regions of international rivers of Asia and other parts of the world, is undergoing severe degradation, which can dramatically alter soil hydraulic properties and water cycling processes. However, the effects of alpine swamp meadow degradation on soil hydraulic properties and the corresponding influencing mechanisms are still poorly understood. In this study, soil moisture content (SMC), field capacity (FC) and saturated hydraulic conductivity (Ks) together with several basic soil properties under lightly degraded (LD), moderately degraded (MD) and severely degraded (SD) alpine swamp meadow were investigated; the variations in SMC, FC and Ks with alpine swamp meadow degradation and their dominant influencing factors were analysed. The results showed that SMC and FC decreased consistently from LD to SD, while Ks decreased from LD to MD and then increased from MD to SD, following the order of LD  >  SD  >  MD. Significant differences in soil hydraulic properties between degradation degrees were found in the upper soil layers (0–20 cm), indicating that the influences of degradation were most pronounced in the topsoils. FC was positively correlated with capillary porosity, water-stable aggregates, soil organic carbon, and silt and clay content; Ks was positively correlated with non-capillary porosity (NCP). Relative to other soil properties, soil porosity is the dominant factor influencing FC and Ks. Capillary porosity explained 91.1 % of total variance in FC, and NCP explained 97.3 % of total variance in Ks. The combined effect of disappearing root activities and increasing sand content was responsible for the inconsistent patterns of NCP and Ks. Our findings suggest that alpine swamp meadow degradation would inevitably lead to reduced water holding capacity and rainfall infiltration. This study provides a more comprehensive understanding of the soil hydrological effects of vegetation degradation. Further hydrological modelling studies in the Tibetan Plateau and similar regions are recommended to understand the effects of degraded alpine swamp meadows on soil hydraulic properties.

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Evapotranspiration and Its Partitioning in Alpine Meadow of Three-River Source Region on the Qinghai-Tibetan Plateau

Water ◽

10.3390/w13152061 ◽

2021 ◽

Vol 13 (15) ◽

pp. 2061

Author(s):

Lifeng Zhang ◽

Zhiguang Chen ◽

Xiang Zhang ◽

Liang Zhao ◽

Qi Li ◽

...

Keyword(s):

Tibetan Plateau ◽

Water Conservation ◽

Alpine Meadow ◽

Source Region ◽

Water Source ◽

Net Radiation ◽

Area Index ◽

Plant Transpiration ◽

Study Results ◽

Meadow Degradation

The Qinghai-Tibetan Plateau (QTP) is generally considered to be the water source region for its surrounding lowlands. However, there have only been a few studies that have focused on quantifying alpine meadow evapotranspiration (ET) and its partitioning, which are important components of water balance. This paper used the Shuttleworth–Wallace (S–W) model to quantify soil evaporation (E) and plant transpiration (T) in a degraded alpine meadow (34°24′ N, 100°24′ E, 3963 m a.s.l) located at the QTP from September 2006 to December 2008. The results showed that the annual ET estimated by the S–W model (ETSW) was 511.5 mm (2007) and 499.8 mm (2008), while E estimated by the model (ESW) was 306.0 mm and 281.7 mm for 2007 and 2008, respectively, which was 49% and 29% higher than plant transpiration (TSW). Model analysis showed that ET, E, and T were mainly dominated by net radiation (Rn), while leaf area index (LAI) and soil water content at a 5 cm depth (SWC5cm) were the most important factors influencing ET partitioning. The study results suggest that meadow degradation may increase water loss through increasing E, and reduce the water conservation capability of the alpine meadow ecosystem.

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Soil nutrients dynamics and the evolution of multi-decadal degradation in alpine wetlands of the Qinghai-Tibetan Plateau

10.5194/egusphere-egu2020-5235 ◽

2020 ◽

Author(s):

Hailing Li ◽

Tingting Li ◽

Wenjuan Sun ◽

Wen Zhang ◽

Lijun Yu ◽

...

Keyword(s):

Tibetan Plateau ◽

Soil Nutrients ◽

Large Area ◽

Alpine Wetland ◽

The Past ◽

Remote Sensing Technology ◽

Flat Terrain ◽

Sensing Technology ◽

Exponential Rates ◽

Meadow Degradation

The Qinghai-Tibetan Plateau (QTP) is the highest plateau on earth and has a large area of alpine swampy meadows. In the past few decades, overgrazing and climate change have caused severe desiccation and degradation of the alpine wetlands. The remote sensing technology has been used to assess the wetland shrinkage. However, changes in soil nutrients associated with the duration of alpine wetland degradation are poorly known. We took soil samples in three swampy meadows of the QTP, one terrain was relatively flat and the other two were with hummocks and hollows. Decadal gradients of degradation from nondegraded swampy meadows to degraded meadows were selected. The contents of soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP) were analyzed. The SOC, TN, and TP contents loss in degraded swampy meadows occurred mainly during the first decade. The soil nutrients loss was highly affected by the geomorphic characteristics of the wetland area. After degradation, the SOC, TN, and TP contents decreased at exponential rates on the flat terrain site. The top layer SOC, TN, and TP contents of the degraded about 30 years area were 24.76&#177;0.91, 2.22&#177;0.07 and 0.45&#177;0.01 (mean &#177; SE) g kg-1, respectively; and the SOC, TN, and TP contents decrease were 75%, 72% and 56% that of the nondegraded swampy meadows, respectively. On one hummock-hollow sites the top layer SOC, TN, and TP contents of the degraded for about 30 years area were 61.22&#177;11.94, 4.09&#177;0.73 and 0.44&#177;0.05 (mean &#177; SE) g kg-1, respectively; and the SOC, TN, and TP contents decrease were 45%, 52% and 46% that of the nondegraded swampy meadows, respectively. The soil nutrients decomposition rate of hummock-hollow sites was much lower than the flat terrain site. Large and tough hummocks in swampy meadow degradation sites can resist environment erosion and stabilize soil nutrients content at high levels.

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