scholarly journals Environmental Factors and Soil CO2Emissions in an Alpine Swamp Meadow Ecosystem on the Tibetan Plateau in Response to Experimental Warming

2016 ◽  
Vol 2016 ◽  
pp. 1-7
Author(s):  
Bin Wang ◽  
Ben Niu ◽  
Xiaojie Yang ◽  
Song Gu
Keyword(s):  
Tibetan Plateau ◽  
Environmental Factors ◽  
Soil Temperature ◽  
Environmental Factor ◽  
Seasonal Variations ◽  
Environmental Control ◽  
The Tibetan Plateau ◽  
Control Mechanisms ◽  
Experimental Warming ◽  
Upward Trend

We examined the response of soil CO2emissions to warming and environmental control mechanisms in an alpine swamp meadow ecosystem on the Tibetan Plateau. Experimental warming treatments were performed in an alpine swamp meadow ecosystem using two open-top chambers (OTCs) 40 cm (OA) and 80 cm (OB) tall. The results indicate that temperatures were increased by 2.79°C in OA and 4.96°C in OB, that ecosystem CO2efflux showed remarkable seasonal variations in the control (CK) and the two warming treatments, and that all three systems yielded peak values in August of 123.6, 142.3, and 166.2 g C m−2 month−1. Annual CO2efflux also showed a gradual upward trend with increased warming: OB (684.1 g C m−2 year−1) > OA (580.7 g C m−2 year−1) > CK (473.3 g C m−2 year−1). Path analysis revealed that the 5 cm depth soil temperature was the most important environmental factor affecting soil CO2emissions in the three systems.

Grazing alters environmental control mechanisms of evapotranspiration in an alpine meadow of the Tibetan Plateau

2019 ◽  
Vol 12 (5) ◽  
pp. 834-845
Author(s):  
Tingting An ◽  
Mingjie Xu ◽  
Tao Zhang ◽  
Chengqun Yu ◽  
Yingge Li ◽  
...  
Keyword(s):  
Community Structure ◽  
Tibetan Plateau ◽  
Alpine Meadow ◽  
Environmental Control ◽  
Water Cycle ◽  
Limiting Factor ◽  
Peak Time ◽  
The Tibetan Plateau ◽  
Control Mechanisms ◽  
Water Conditions

Abstract Aims Evapotranspiration (ET) is an important component of the terrestrial water cycle and is easily affected by external disturbances, such as climate change and grazing. Identifying ET responses to grazing is instructive for determining grazing activity and informative for understanding the water cycle. Methods This study utilized 2 years (2014 and 2017) of eddy covariance data to test how grazing regulated ET for an alpine meadow ecosystem on the Tibetan Plateau (TP) by path analysis. Important Findings Radiation dominated ET with a decision coefficient of 64–74%. The soil water content (SWC) worked as the limiting factor in the fenced site. However, in the grazing site, the limiting factor was the vapor pressure deficit (VPD). Grazing had large effects on ET because it greatly affected the water conditions. The SWC and VPD were enhanced by 14.63% and 4.36% in the grazing site, respectively. Therefore, sufficient water was supplied to ET, especially during drought, and strengthened the transpiration pull. As a result, a favorable micrometeorological environment was created for ET. Grazing shifted the limiting factor of ET from the SWC to VPD, which weakened the limiting effect of the water conditions on ET and advanced the ET peak time. In addition, grazing altered the compositions of ET by changing the community structure, which directly resulted in an increased ET. In summary, grazing enhanced ET through altering the community structure and micrometeorological environments. The findings of this study further improve our understanding of the driving mechanisms of grazing on ET and will improve our predictions for the global water cycle.

scholarly journals EXPERIMENTAL WARMING, NOT GRAZING, DECREASES RANGELAND QUALITY ON THE TIBETAN PLATEAU

2007 ◽  
Vol 17 (2) ◽  
pp. 541-557 ◽  
Author(s):  
Julia A. Klein ◽  
John Harte ◽  
Xin-Quan Zhao
Keyword(s):  
Tibetan Plateau ◽  
The Tibetan Plateau ◽  
Experimental Warming

scholarly journals Spatial-Temporal Patterns and Controls of Evapotranspiration across the Tibetan Plateau (2000–2012)

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Hao Zhang ◽  
Jian Sun ◽  
Junnan Xiong
Keyword(s):  
Tibetan Plateau ◽  
Environmental Factors ◽  
Vegetation Type ◽  
Middle Part ◽  
Rate Of Change ◽  
Ecological Indicator ◽  
The Tibetan Plateau ◽  
Grassland Ecosystems ◽  
Key Factor ◽  
Positive Correlations

Evapotranspiration (ET) is a key factor to further our understanding of climate change processes, especially on the Tibetan Plateau, which is sensitive to global change. Herein, the spatial patterns of ET are examined, and the effects of environmental factors on ET at different scales are explored from the years 2000 to 2012. The results indicated that a steady trend in ET was detected over the past decade. Meanwhile, the spatial distribution shows an increase of ET from the northwest to the southeast, and the rate of change in ET is lower in the middle part of the Tibetan Plateau. Besides, the positive effect of radiation on ET existed mainly in the southwest. Based on the environment gradient transects, the ET had positive correlations with temperature (R>0.85, p<0.0001), precipitation (R > 0.89, p < 0.0001), and NDVI (R > 0.75, p < 0.0001), but a negative correlation between ET and radiation (R = 0.76, p < 0.0001) was observed. We also found that the relationships between environmental factors and ET differed in the different grassland ecosystems, which indicated that vegetation type is one factor that can affect ET. Generally, the results indicate that ET can serve as a valuable ecological indicator.

Soil environmental factors drive seed density across vegetation types on the Tibetan Plateau

2017 ◽  
Vol 419 (1-2) ◽  
pp. 349-361 ◽  
Author(s):  
Miaojun Ma ◽  
James W. Dalling ◽  
Zhen Ma ◽  
Xianhui Zhou
Keyword(s):  
Tibetan Plateau ◽  
Environmental Factors ◽  
The Tibetan Plateau ◽  
Seed Density ◽  
Vegetation Types ◽  
Soil Environmental Factors

scholarly journals Seasonal variations in aerosol optical properties over China

2008 ◽  
Vol 8 (3) ◽  
pp. 8431-8453 ◽  
Author(s):  
Y. Wang ◽  
J. Xin ◽  
Z. Li ◽  
S. Wang ◽  
P. Wang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Seasonal Variations ◽  
Rural Areas ◽  
Meteorological Data ◽  
Agricultural Practices ◽  
Hainan Island ◽  
Northern China ◽  
The Tibetan Plateau ◽  
Northern Forest ◽  
Aerosol Emissions

Abstract. The seasonal variations in background aerosol optical depth (AOD) and aerosol type are investigated over various ecosystems in China based upon three years' worth of meteorological data and data collected by the Chinese Sun Hazemeter Network. In most parts of China, AODs are at a maximum in spring or summer and at a minimum in autumn or winter. Minimum values (0.10~0.20) of annual mean AOD at 500 nm are found in the Qinghai-Tibetan Plateau, which is located in the remote northeast corner of China, the northern forest ecosystems and Hainan Island. Annual mean AOD ranges from 0.25 to 0.30 over desert and oasis areas as well as the desertification grasslands in northern China; the annual mean AOD over the Loess Plateau is moderately high at 0.36. Regions where the highest density of agricultural and industrial activities are located and where anthropogenic sulphate aerosol and soil aerosol emissions are consistently high throughout the whole year (e.g. the central-eastern, southern and eastern coastal regions of China) experience annual mean AODs ranging from 0.50~0.80. Remarkable seasonal changes in the main types of aerosol over northern China (characterized by the Angstrom exponent, α) are seen. Due to biomass and fossil fuel burning from extensive agricultural practices in northern rural areas, concentrations of smoke and soot aerosols rise dramatically during autumn and winter (high α), while the main types of aerosol during spring and summer are dust and soil aerosols (low α). Over southeast Asia, biomass burning during the spring leads to increases in smoke and soot emissions. Over the Tibetan Plateau and Hainan Island where the atmosphere is pristine, the main types of aerosol are dust and sea salt, respectively.

scholarly journals Effects of Soil Temperature and Moisture on Soil Respiration on the Tibetan Plateau

PLoS ONE ◽  
2016 ◽  
Vol 11 (10) ◽  
pp. e0165212 ◽  
Author(s):  
Xiaoying Bao ◽  
Xiaoxue Zhu ◽  
Xiaofeng Chang ◽  
Shiping Wang ◽  
Burenbayin Xu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Soil Respiration ◽  
Soil Temperature ◽  
The Tibetan Plateau ◽  
Soil Temperature And Moisture

scholarly journals Diagnostic and model dependent uncertainty of simulated Tibetan permafrost area

2016 ◽  
Vol 10 (1) ◽  
pp. 287-306 ◽  
Author(s):  
W. Wang ◽  
A. Rinke ◽  
J. C. Moore ◽  
X. Cui ◽  
D. Ji ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Soil Temperature ◽  
Air Temperature ◽  
Land Surface ◽  
Ground Temperature ◽  
Diagnostic Methods ◽  
The Tibetan Plateau ◽  
Temperature Profiles ◽  
Land Surface Models ◽  
Surface Models

Abstract. We perform a land-surface model intercomparison to investigate how the simulation of permafrost area on the Tibetan Plateau (TP) varies among six modern stand-alone land-surface models (CLM4.5, CoLM, ISBA, JULES, LPJ-GUESS, UVic). We also examine the variability in simulated permafrost area and distribution introduced by five different methods of diagnosing permafrost (from modeled monthly ground temperature, mean annual ground and air temperatures, air and surface frost indexes). There is good agreement (99 to 135  ×  104 km2) between the two diagnostic methods based on air temperature which are also consistent with the observation-based estimate of actual permafrost area (101  × 104 km2). However the uncertainty (1 to 128  ×  104 km2) using the three methods that require simulation of ground temperature is much greater. Moreover simulated permafrost distribution on the TP is generally only fair to poor for these three methods (diagnosis of permafrost from monthly, and mean annual ground temperature, and surface frost index), while permafrost distribution using air-temperature-based methods is generally good. Model evaluation at field sites highlights specific problems in process simulations likely related to soil texture specification, vegetation types and snow cover. Models are particularly poor at simulating permafrost distribution using the definition that soil temperature remains at or below 0 °C for 24 consecutive months, which requires reliable simulation of both mean annual ground temperatures and seasonal cycle, and hence is relatively demanding. Although models can produce better permafrost maps using mean annual ground temperature and surface frost index, analysis of simulated soil temperature profiles reveals substantial biases. The current generation of land-surface models need to reduce biases in simulated soil temperature profiles before reliable contemporary permafrost maps and predictions of changes in future permafrost distribution can be made for the Tibetan Plateau.

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