Effects of grassland degradation on ecological stoichiometry of soil ecosystems on the Qinghai-Tibet Plateau

Wang, Ying; Ren, Ze; Ma, Panpan; Wang, Zhaomin; Niu, Decao; Fu, Hua; Elser, James J.

doi:10.1016/j.scitotenv.2020.137910

Cited by 97 publications

(78 citation statements)

References 74 publications

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“…We also found that the soil bacterial Shannon diversity decreased greatly in the highly degraded plots. The decreased vegetation biomass due to grassland degradation is likely responsible for decreased C and N concentrations in the soil 27 , which, in turn, decreased the soil bacterial Shannon diversity under the highly degraded plots caused by overgrazing. This was in agreement with previous results obtained by Zhang et al 28 .…”

Section: Discussionmentioning

confidence: 99%

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Soil degradation influences soil bacterial and fungal community diversity in overgrazed alpine meadows of the Qinghai-Tibet Plateau

Dong

Sun

et al. 2021

Sci Rep

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Over half of the alpine meadows in the Qinghai-Tibet Plateau (QTP) are degraded due to human activities. Soil degradation from overgrazing is the most direct cause of grassland degradation. It is thus important to synthesize the effects of multiple soil degradation indicators on the belowground biomass of plants and soil microorganisms in the degraded QTP. We studied the diversities and structures of soil bacterial and fungal communities using soil bacterial 16S rRNA and the fungal ITS gene under four degradation gradients, D1: lightly degraded, D2: moderately degraded, D3: highly degraded, and a non-degraded control site (CK). The bacterial Shannon diversity in D3 was significantly lower than that in D1 (p < 0.001), and the bacterial richness index in D3 was significantly lower than that in D1 (p < 0.001). There was no difference in soil fungal diversity among the different degradation levels; however, soil fungal richness decreased significantly from CK to D3. The phyla Actinobacteria, Acidobacteria and the genus Mortierella were differed significantly under the four degradation gradients. Plant litter mass and root C/N ratio were important factors associated with bacterial and fungal diversity and richness. These results indicated that alpine meadow degradation can lead to variations in both microbial diversity and the potential functioning of micro-organisms in the QTP.

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Section: Discussionmentioning

confidence: 99%

“…In addition, soil pH increased significantly in degraded alpine meadows. Thus, the development of microbial communities could be limited by the high pH caused by grassland degradation 27 . As previously reported 42 , 43 , Bacteroidetes was significantly positively correlated with pH, and this was confirmed in the present study.…”

Section: Discussionmentioning

confidence: 99%

Soil degradation influences soil bacterial and fungal community diversity in overgrazed alpine meadows of the Qinghai-Tibet Plateau

Dong

Sun

et al. 2021

Sci Rep

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“…In grassland watersheds, large proportions of organic carbon and nutrient stocks are concentrated in the top soil layers (Gill et al, 1999;Du et al, 2019). External disturbances likely cause dramatic soil nutrient depletion and soil texture changes (Steffens et al, 2008;Dlamini et al, 2014;Wang et al, 2020). In degraded grassland ecosystems, increased soil erosion, loss of vegetation cover, and soil texture changes aggravate scour from surface flow, causing large losses of soil organic matter and nutrients to adjacent aquatic ecosystems (Dong et al, 2012;Su et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

“…As one of the largest terrestrial biomes in the world (Suttie et al, 2005), grasslands are facing widespread degradation (Gang et al, 2014), largely driven by anthropogenic activities (e.g., overgrazing and climate change) (Daily, 1995;Gang et al, 2014). Defined as a retrogressive ecosystem succession, grassland degradation has been demonstrated to disrupt aboveground vegetation (Deng et al, 2014;Wang et al, 2019) as well as soil physical, chemical, and biological properties (Viragh et al, 2011;Dlamini et al, 2014;Wang et al, 2020). These influences are likely transferred to adjacent aquatic ecosystems .…”

Section: Introductionmentioning

confidence: 99%

Bacterial Communities in Stream Biofilms in a Degrading Grassland Watershed on the Qinghai–Tibet Plateau

Ren

Niu

et al. 2020

Front. Microbiol.

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Grassland is among the largest terrestrial biomes and is experiencing serious degradation, especially on the Qinghai-Tibet Plateau (QTP). However, the influences of grassland degradation on microbial communities in stream biofilms are largely unknown. Using 16S rRNA gene sequencing, we investigated the bacterial communities in stream biofilms in sub-basins with different grassland status in the Qinghai Lake watershed. Grassland status in the sub-basins was quantified using the normalized difference vegetation index (NDVI). Proteobacteria, Bacteroidetes, Cyanobacteria, and Verrucomicrobia were the dominant bacterial phyla. OTUs, 7,050, were detected in total, within which 19 were abundant taxa, and 6,922 were rare taxa. Chao 1, the number of observed OTUs, and phylogenetic diversity had positive correlations with carbon (C), nitrogen (N), and/or phosphorus (P) in biofilms per se. The variation of bacterial communities in stream biofilms was closely associated with the rate of change in NDVI, pH, conductivity, as well as C, N, P, contents and C:N ratio of the biofilms. Abundant subcommunities were more influenced by environmental variables relative to the whole community and to rare subcommunities. These results suggest that the history of grassland degradation (indicated as the rate of change in NDVI) influences bacterial communities in stream biofilms. Moreover, the bacterial community network showed high modularity with five major modules (>50 nodes) that responded differently to environmental variables. According to the module structure, only one module connector and 12 module hubs were identified, suggesting high fragmentation of the network and considerable independence of the modules. Most of the keystone taxa were rare taxa, consistent with fragmentation of the network and with adverse consequences for bacterial community integrity and function in the biofilms. By documenting the properties of bacterial communities in stream biofilms in a degrading grassland watershed, our study adds to our knowledge of the potential influences of grassland degradation on aquatic ecosystems.

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“…Simultaneously, the rich species composition promoted the number of plant remains, which was the main source of soil C in forest ecosystem [18,31]. Therefore, soil C:P ratio was also rich.…”

Section: Altitudinal Patterns In Soil C N and P Contents At Sunny And Shady Slope Aspectsmentioning

confidence: 98%

Effects of slope aspect on altitudinal pattern of soil C:N:P stoichiometry in alpine forest of Tibet

Guo

He-ping

et al. 2021

E3S Web Conf.

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Knowledge of altitudinal patterns in soil C, N and P distribution is important for understanding biogeochemical processes in mountainous forests, yet the influence of slope aspects on soil stoichiometry has been largely neglected in previous studies. In this paper, a total number of 150 topsoil samples at four altitudes (3700, 3900, 4100, 4380 m a.s.l.) on sunny and shady slopes of Sygera mountains in the Southeastern Tibet were collected. Soil C, N and P contents, and pH, were measured. Soil temperature, moisture and richness of plant species were investigated at each sampling site. The results showed that: 1) in sunny slope, soil C, N and P concentrations increased with the increase in altitude, whereas soil C:N, C:P, and N:P decreased along the altitudinal gradient on s. Soil moisture was the main regulator of soil nutrition and stoichiometric ratios. 2) In shady slope, soil C and N contents had no significant difference along the altitudinal gradient except the higher values at low altitude, whereas soil P increased first and then decreased. Soil C:N increased with the increase in altitude, whereas C:P and N:P decreased first and then increased. Soil temperature and species richness were the main factors influencing soil nutrition and stoichiometric ratios. 3) Decoupling of soil C:N:P stoichiometry was observed in shady slope owing to changes in soil pH and temperature. 4) The rich contents of soil C and P were observed at two slopes along the altitudinal gradient, and high capacity of N supply existed at the topsoil in shady slope. These results suggested that slope aspect plays an important role in shaping the altitudinal pattern of soil C:N:P stoichiometry in mountainous forests.

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Effects of grassland degradation on ecological stoichiometry of soil ecosystems on the Qinghai-Tibet Plateau

Cited by 97 publications

References 74 publications

Soil degradation influences soil bacterial and fungal community diversity in overgrazed alpine meadows of the Qinghai-Tibet Plateau

Soil degradation influences soil bacterial and fungal community diversity in overgrazed alpine meadows of the Qinghai-Tibet Plateau

Bacterial Communities in Stream Biofilms in a Degrading Grassland Watershed on the Qinghai–Tibet Plateau

Effects of slope aspect on altitudinal pattern of soil C:N:P stoichiometry in alpine forest of Tibet

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