The relative controls of temperature and soil moisture on the start of carbon flux phenology and net ecosystem production in two alpine meadows on the Qinghai-Tibetan Plateau

2020 ◽  
Vol 13 (2) ◽  
pp. 247-255
Author(s):  
Xi Chai ◽  
Peili Shi ◽  
Minghua Song ◽  
Ning Zong ◽  
Yongtao He ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Carbon Flux ◽  
Tibet Plateau ◽  
Vegetation Phenology ◽  
Alpine Ecosystems ◽  
Alpine Meadows ◽  
Alpine Steppe ◽  
Water Sensitivity ◽  
Alpine Shrub ◽  
Steppe Meadow

Abstract Aims Variations in vegetation spring phenology are widely attributed to temperature in temperate and cold regions. However, temperature effect on phenology remains elusive in cold and arid/semiarid ecosystems because soil water condition also plays an important role in mediating phenology. Methods We used growing degree day (GDD) model and growing season index (GSI) model, coupling minimum temperature (Tmin) with soil moisture (SM) to explore the influence of heat requirement and hydroclimatic interaction on the start of carbon uptake period (SCUP) and net ecosystem productivity (NEP) in two alpine meadows with different precipitation regimes on the Qinghai-Tibet Plateau (QTP). One is the water-limited alpine steppe-meadow, and the other is the temperature-limited alpine shrub-meadow. Important Findings We observed two clear patterns linking GDD and GSI to SCUP: SCUP was similarly sensitive to variations in preseason GDD and GSI in the humid alpine shrub-meadow, while SCUP was more sensitive to the variability in preseason GSI than GDD in the semiarid alpine steppe-meadow. The divergent patterns indicated a balance of the limiting climatic factors between temperature and water availability. In the humid meadow, higher temperature sensitivity of SCUP could maximize thermal benefit without drought stress, as evidenced by the stronger linear correlation coefficient (R2) and Akaike’s information criterion (AIC) between observed SCUPs and those of simulated by GDD model. However, greater water sensitivity of SCUP could maximize the benefit of water in semiarid steppe-meadow, which is indicated by the stronger R2 and AIC between observed SCUPs and those of simulated by GSI model. Additionally, although SCUPs were determined by GDD in the alpine shrub-meadow ecosystem, NEP was both controlled by accumulative GSI in two alpine meadows. Our study highlights the impacts of hydroclimatic interaction on spring carbon flux phenology and vegetation productivity in the humid and semiarid alpine ecosystems. The results also suggest that water, together with temperature should be included in the models of phenology and carbon budget for alpine ecosystems in semiarid regions. These findings have important implications for improving vegetation phenology models, thus advancing our understanding of the interplay between vegetation phenology, productivity and climate change in future.

scholarly journals Response of Soil Microbial Communities to Warming and Clipping in Alpine Meadows in Northern Tibet

2020 ◽  
Vol 12 (14) ◽  
pp. 5617
Author(s):  
Haorui Zhang ◽  
Shaowei Li ◽  
Guangyu Zhang ◽  
Gang Fu
Keyword(s):  
Microbial Communities ◽  
Community Composition ◽  
Soil Microbial Communities ◽  
Alpine Meadows ◽  
Soil Microbial ◽  
Alpine Steppe ◽  
Total Plfa ◽  
Kobresia Meadow ◽  
Low Altitude ◽  
Steppe Meadow

In order to explore responses of soil microbial communities among different alpine meadows under warming and clipping, soil microorganisms of three alpine meadow sites (low altitude: 4313 m, alpine steppe meadow, 30°30′ N, 91°04′ E; mid-altitude: 4513 m, alpine steppe meadow, 30°31′ N, 91°04′ E; and high altitude: 4693, alpine Kobresia meadow, 30°32′ N, 91°03′ E) were measured using the phospholipid fatty acid (PLFA) method. Both warming and clipping significantly reduced PLFA content and changed the community composition of soil microbial taxa, which belong to bacterial and fungal communities in the alpine Kobresia meadow. Warming significantly reduced the soil total PLFA content by 36.1% and the content of soil fungi by 37.0%; the clipping significantly reduced the soil total PLFA content by 57.4%, the content of soil fungi by 49.9%, and the content of soil bacteria by 60.5% in the alpine Kobresia meadow. Only clipping changed the total fungal community composition at a low altitude. Neither clipping nor warming changed the microbial community composition at a moderate altitude. Soil temperature, soil moisture, and pH were the main factors affecting soil microbial communities. Therefore, the effects of warming and clipping on soil microbial communities in alpine meadows were related to grassland types and soil environmental conditions.

Carbon flux phenology and net ecosystem productivity simulated by a bioclimatic index in an alpine steppe-meadow on the Tibetan Plateau

2019 ◽  
Vol 394 ◽  
pp. 66-75 ◽  
Author(s):  
Xi Chai ◽  
Peili Shi ◽  
Minghua Song ◽  
Ning Zong ◽  
Yongtao He ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Carbon Flux ◽  
The Tibetan Plateau ◽  
Net Ecosystem Productivity ◽  
Ecosystem Productivity ◽  
Alpine Steppe ◽  
Bioclimatic Index ◽  
Steppe Meadow

scholarly journals Thermal impacts of engineering activities on permafrost in different alpine ecosystems in Qinghai-Tibet Plateau, China

2016 ◽  
Author(s):  
Qingbai Wu ◽  
Zhongqiong Zhang ◽  
Siru Gao ◽  
Wei Ma
Keyword(s):  
Soil Temperature ◽  
Climate Warming ◽  
Tibet Plateau ◽  
Alpine Ecosystems ◽  
Railway Ballast ◽  
Alpine Meadows ◽  
Engineering Construction ◽  
Cooling Effects ◽  
Qinghai Tibet Plateau ◽  
Vegetation Layer

Abstract. Climate warming and engineering activities have various impacts on the thermal regime of permafrost in alpine ecosystems of the Qinghai–Tibet Plateau. Using recent observations of permafrost thermal regimes along the Qinghai–Tibet Highway and Railway, the change of such regimes beneath embankments constructed in alpine meadows and steppes are studied. The results show that alpine meadows on the Qinghai–Tibet Plateau can have a controlling role within engineering construction effects on permafrost beneath embankments. The artificial permafrost table (APT) beneath embankments is predominantly controlled by alpine ecosystems, but the change rate of APT is not closely related with those ecosystems; it is mainly related with cooling effects of railway ballast and heat absorption effects of asphalt pavement. Variation of soil temperature beneath embankments is independent of alpine ecosystems, but variation of mean annual soil temperature with depth is closely related to those ecosystems. The vegetation layer in alpine meadows can have an insulation role within engineering activity effects on permafrost beneath embankments. This insulation role is an advantage for alleviating permafrost temperature rise in the short term, but a disadvantage in the long term because of climate warming, suggesting that vegetation layer in alpine meadow should be removed upon initiating engineering construction.

scholarly journals Soil moisture and temperature dynamics in typical alpine ecosystems: a continuous multi-depth measurements-based analysis from the Qinghai-Tibet Plateau, China

2017 ◽  
Vol 49 (1) ◽  
pp. 194-209 ◽  
Author(s):  
Si-Yi Zhang ◽  
Xiao-Yan Li
Keyword(s):  
Soil Moisture ◽  
Soil Temperature ◽  
Climate Changes ◽  
Tibet Plateau ◽  
Qinghai Lake ◽  
Moisture Regime ◽  
Alpine Ecosystems ◽  
Alpine Regions ◽  
Qinghai Tibet Plateau ◽  
Soil Temperature And Moisture

Abstract Soil temperature and moisture are the key variables that control the overall effect of climate and topography on soil and vegetation in alpine regions. However, there has been little investigation of the potential soil temperature and moisture feedbacks on climate changes in different alpine ecosystems and their impact on vegetation change. Soil temperature and moisture at five depths were measured continuously at 10-min intervals in three typical ecosystems (Kobresia meadow (KMd), Achnatherum splendens steppe (ASSt), and Potentilla fruticosa shrub (PFSh)) of the Qinghai Lake watershed on the northeast Qinghai-Tibet Plateau, China. The findings of this study revealed that the KMd and PFSh sites had relatively low soil temperature and high soil moisture, whereas the ASSt site had relatively warm soil temperature and low soil moisture. The soil and vegetation characteristics had important effects on the infiltration process and soil moisture regime; about 47%, 87%, and 34% of the rainfall (minus interception) permeated to the soil in the KMd, PFSh, and ASSt sites, respectively. In the context of the warming climate, changes to soil moisture and temperature are likely to be the key reasons of the alpine meadow deterioration and the alpine shrub expansion in the alpine regions.

scholarly journals Response of freeze-thaw processes to experimental warming in the permafrost regions of the central Qinghai-Tibet Plateau

2016 ◽  
Author(s):  
Shengyun Chen ◽  
Wenjie Liu ◽  
Qian Zhao ◽  
Lin Zhao ◽  
Qingbai Wu ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Moisture Content ◽  
Tibet Plateau ◽  
Active Layer Thickness ◽  
Experimental Warming ◽  
Freeze Thaw ◽  
Alpine Steppe ◽  
Steppe Ecosystems ◽  
Qinghai Tibet Plateau ◽  
Permafrost Regions

Abstract. Assessing quantitatively effect of climate warming on freeze/thaw index (FI/TI), soil freeze-thaw processes and active layer thickness (ALT) is still lacking in the permafrost regions of the Qinghai-Tibet Plateau (QTP) until now. Experimental warming was manipulated using open top chambers (OTCs) in alpine swamp meadow and alpine steppe ecosystems in the permafrost regions of the central QTP during 2009–2011. Under OTCs treatment, air temperature (Ta) significantly increased in the daytime and decreased in the nighttime, diurnal and annual Ta range significantly enhanced, and mean annual Ta increased by 1.4 °C. Owing to the experimental warming, mean annual soil temperature at the depths from 5 cm to 40 cm was increased by 0.2 ~ 0.7 °C in alpine swamp meadow and 0.3 ~ 1.5 °C in alpine steppe. Mean annual soil moisture content at 10 cm depth decreased by 1.1 % and 0.8 %, and mean annual soil salinity at 10 cm depth significantly increased by 0.3 g L-1 and 0.1 g L-1 in alpine swamp meadow and alpine steppe, respectively. Further, FI was significantly decreased by 410.7 °C d while TI was significantly increased by 460.7 °C d. Likewise, the onset dates of shallow soil thawing at 5–40 cm depths were advanced by 9 days and 8 days while the onset dates of freezing were delayed by 10 days and 4 days in alpine swamp meadow and alpine steppe, respectively. Moreover, soil frozen days were significantly decreased by 28 days and 16 days, but thawed days were increased by 18 days and 6 days, and frozen-thawed days were significantly increased by 10 days and 10 days in alpine swamp meadow and alpine steppe, respectively. Furthermore, ALT would be significantly increased by ~ 6.9 cm and ~ 19.6 cm in alpine swamp meadow and alpine steppe ecosystems, respectively.

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.

scholarly journals Effects of Rainfall Manipulation on Ecosystem Respiration and Soil Respiration in an Alpine Steppe in Northern Tibet Plateau

2021 ◽  
Vol 9 ◽  
Author(s):  
Xueqin Li ◽  
Yan Yan ◽  
Lijiao Fu
Keyword(s):  
Climate Change ◽  
Soil Moisture ◽  
Soil Respiration ◽  
Water Content ◽  
Ecosystem Respiration ◽  
Tibet Plateau ◽  
Climate Change Scenarios ◽  
Regional Patterns ◽  
Northern Tibet ◽  
Alpine Steppe

The response mechanism of ecosystem respiration (Re) and soil respiration (Rs) to different water conditions is of great significance for understanding the carbon cycle under future changes in the precipitation patterns. We used seven precipitation treatments to investigate the effects of precipitation on Re and Rs on a typical alpine steppe in Northern Tibet. Precipitation was captured and relocated to simulate the precipitation rates of −25, −50, −75, 0 (CK), +25, +50, and +75%. The soil moisture was influenced by all the precipitation treatments. There was a positive linear relationship between the soil moisture and Re, Rs in the study area during the experiment (July–October). Soil volumetric water content (VWC), absolute water content (AWC), soil temperature (ST), aboveground biomass (AGB), bulk density, soil total nitrogen (TN), and alkaline hydrolysis nitrogen (AHN) were the predictors of Re and Rs. The multiple linear regression analysis showed that ST and AWC could explain 90.6% of Rs, and ST, AWC, and AHN could explain 89.4% of Re. Ecosystem respiration was more sensitive to the increased precipitation (+29.5%) whereas Rs was more sensitive to the decreased precipitation (−23.8%). An appropriate increase in water (+25 and +50%) could improve the Re and Rs, but a greater increase (+75%) would not have a significant effect; it could have an effect even lower than those of the first two. Our study highlights the importance of increased precipitation and the disadvantage of decreased precipitation on Re and Rs in an arid region. The precipitation changes will lead to significant changes in the soil properties and AGB, and affect Re and Rs, to change the climate of the alpine steppe in Northern Tibet in the future. These findings contribute to our understanding of the regional patterns of environmental C exchange and soil C flux under the climate change scenarios and highlight the importance of water availability to the regulating ecosystem processes in semi-arid steppe ecosystems. In view of these findings, we urge future researchers to focus on manipulating the precipitation over longer time scales, seasonality, and incorporating more environmental factors to improve our ability to predict and model Re and Rs and feedback from climate change.

scholarly journals Thermal impacts of engineering activities and vegetation layer on permafrost in different alpine ecosystems of the Qinghai–Tibet Plateau, China

2016 ◽  
Vol 10 (4) ◽  
pp. 1695-1706 ◽  
Author(s):  
Qingbai Wu ◽  
Zhongqiong Zhang ◽  
Siru Gao ◽  
Wei Ma
Keyword(s):  
Climate Change ◽  
Soil Temperature ◽  
Tibet Plateau ◽  
Alpine Ecosystems ◽  
Railway Ballast ◽  
Alpine Meadows ◽  
Engineering Construction ◽  
Cooling Effects ◽  
Qinghai Tibet Plateau ◽  
Vegetation Layer

Abstract. Climate warming and engineering activities have various impacts on the thermal regime of permafrost in alpine ecosystems of the Qinghai–Tibet Plateau. Using recent observations of permafrost thermal regimes along the Qinghai–Tibet highway and railway, the changes of such regimes beneath embankments constructed in alpine meadows and steppes are studied. The results show that alpine meadows on the Qinghai–Tibet Plateau can have a controlling role among engineering construction effects on permafrost beneath embankments. As before railway construction, the artificial permafrost table (APT) beneath embankments is not only affected by climate change and engineering activities but is also controlled by alpine ecosystems. However, the change rate of APT is not dependent on ecosystem type, which is predominantly affected by climate change and engineering activities. Instead, the rate is mainly related to cooling effects of railway ballast and heat absorption effects of asphalt pavement. No large difference between alpine and steppe can be identified regarding the variation of soil temperature beneath embankments, but this difference is readily identified in the variation of mean annual soil temperature with depth. The vegetation layer in alpine meadows has an insulation role among engineering activity effects on permafrost beneath embankments, but this insulation gradually disappears because the layer decays and compresses over time. On the whole, this layer is advantageous for alleviating permafrost temperature rise in the short term, but its effect gradually weakens in the long term.

scholarly journals Responses of Ecosystem CO2Fluxes to Short-Term Experimental Warming and Nitrogen Enrichment in an Alpine Meadow, Northern Tibet Plateau

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Ning Zong ◽  
Peili Shi ◽  
Jing Jiang ◽  
Minghua Song ◽  
Dingpeng Xiong ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Global Change ◽  
Alpine Meadow ◽  
N Deposition ◽  
Plant Production ◽  
Tibet Plateau ◽  
N Availability ◽  
Soil N ◽  
N Addition ◽  
Alpine Ecosystems

Over the past decades, the Tibetan Plateau has experienced pronounced warming, yet the extent to which warming will affect alpine ecosystems depends on how warming interacts with other influential global change factors, such as nitrogen (N) deposition. A long-term warming and N manipulation experiment was established to investigate the interactive effects of warming and N deposition on alpine meadow. Open-top chambers were used to simulate warming. N addition, warming, N addition × warming, and a control were set up. In OTCs, daytime air and soil temperature were warmed by 2.0°C and 1.6°C above ambient conditions, but soil moisture was decreased by 4.95 m3 m−3. N addition enhanced ecosystem respiration (Reco); nevertheless, warming significantly decreased Reco. The decline of Reco resulting from warming was cancelled out by N addition in late growing season. Our results suggested that N addition enhanced Reco by increasing soil N availability and plant production, whereas warming decreased Reco through lowering soil moisture, soil N supply potential, and suppression of plant activity. Furthermore, season-specific responses of Reco indicated that warming and N deposition caused by future global change may have complicated influence on carbon cycles in alpine ecosystems.

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