Evaluation of NPP using three models compared with MODIS-NPP data over China

Estimating net primary productivity (NPP) is significant in global climate change research and carbon cycle. However, there are many uncertainties in different NPP modeling results and the process of NPP is challenging to model on the absence of data. In this study, we used meteorological data as input to simulate vegetation NPP through climate-based model, synthetic model and CASA model. Then, the results from three models were compared with MODIS NPP and observed data over China from 2000 to 2015. The statistics evaluation metrics (Relative Bias (RB), Pearson linear Correlation Coefficient (CC), Root Mean Square Error (RMSE), and Nash-Sutcliffe efficiency coefficient (NSE)) between simulated NPP and MODIS NPP were calculated. The results implied that the CASA-model performed better than the other two models in terms of RB, RMSE, NSE and CC whether on the national or the regional scale. It has a higher CC with 0.51 and a smaller RMSE with 111.96 g C·m-2·yr-1 in the whole country. The synthetic model and CASA-model has the same advantages at some regions, and there are lower RMSE in Southern China (86.35 g C·m-2·yr-1), Xinjiang (85.53 g C·m-2·yr-1) and Qinghai-Tibet Plateau (93.22 g C·m-2·yr-1). The climate-based model has widespread overestimation and large systematic errors, along with worse performances (NSEmax = 0.45) and other metric indexes unsatisfactory, especially Qinghai-Tibet Plateau with relatively lower accuracy because of the unavailable observation data. Overall, the CASA-model is much more ideal for estimating NPP all over China in the absence of data. This study provides a comprehensive intercomparison of different NPP-simulated models and can provide powerful help for researchers to select the appropriate NPP evaluation model.

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Quantifying the Variability of Forest Ecosystem Vulnerability in the Largest Water Tower Region Globally

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18147529 ◽

2021 ◽

Vol 18 (14) ◽

pp. 7529

Author(s):

Siqi Sun ◽

Yihe Lü ◽

Da Lü ◽

Cong Wang

Keyword(s):

Forest Ecosystems ◽

Human Impacts ◽

Regional Scale ◽

Principal Component ◽

Tibet Plateau ◽

Slope Aspect ◽

Environmental Disturbances ◽

Restoration Planning ◽

Development Goals ◽

Qinghai Tibet Plateau

Forests are critical ecosystems for environmental regulation and ecological security maintenance, especially at high altitudes that exhibit sensitivity to climate change and human activities. The Qinghai-Tibet Plateau—the world’s largest water tower region—has been breeding many large rivers in Asia where forests play important roles in water regulation and water quality improvement. However, the vulnerability of these forest ecosystems at the regional scale is still largely unknown. Therefore, the aim of this research is to quantitatively assess the temporal–spatial variability of forest vulnerability on the Qinghai-Tibet Plateau to illustrate the capacity of forests to withstand disturbances. Geographic information system (GIS) and the spatial principal component analysis (SPCA) were used to develop a forest vulnerable index (FVI) to assess the vulnerability of forest ecosystems. This research incorporates 15 factors covering the natural context, environmental disturbances, and socioeconomic impact. Results indicate that the measure of vulnerability was unevenly distributed spatially across the study area, and the whole trend has intensified since 2000. The three factors that contribute the most to the vulnerability of natural contexts, environmental disturbances, and human impacts are slope aspect, landslides, and the distance to the farmland, respectively. The vulnerability is higher in forest areas with lower altitudes, steeper slopes, and southerly directions. These evaluation results can be helpful for forest management in high altitude water tower regions in the forms of forest conservation or restoration planning and implementation towards sustainable development goals.

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Analysis and Estimation of Geographical and Topographic Influencing Factors for Precipitation Distribution over Complex Terrains: A Case of the Northeast Slope of the Qinghai–Tibet Plateau

Atmosphere ◽

10.3390/atmos9090349 ◽

2018 ◽

Vol 9 (9) ◽

pp. 349 ◽

Cited By ~ 3

Author(s):

Weicheng Liu ◽

Qiang Zhang ◽

Zhao Fu ◽

Xiaoyan Chen ◽

Hong Li

Keyword(s):

Complex Terrain ◽

Multivariate Regression ◽

Estimation Method ◽

Precipitation Forecast ◽

Tibet Plateau ◽

Mean Annual Precipitation ◽

Observation Data ◽

Precipitation Distribution ◽

Precipitation Estimation ◽

Qinghai Tibet Plateau

Due to the complex terrain, sparse precipitation observation sites, and uneven distribution of precipitation in the northeastern slope of the Qinghai–Tibet Plateau, it is necessary to establish a precipitation estimation method with strong applicability. In this study, the precipitation observation data from meteorological stations in the northeast slope of the Qinghai–Tibet Plateau and 11 geographical and topographic factors related to precipitation distribution were used to analyze the main factors affecting precipitation distribution. Based on the above, a multivariate linear regression precipitation estimation model was established. The results revealed that precipitation is negatively related to latitude and elevation, but positively related to longitude and slope for stations with an elevation below 1700 m. Meanwhile, precipitation shows positive correlations with both latitude and longitude, and negative correlations with elevation for stations with elevations above 1700 m. The established multivariate regression precipitation estimating model performs better at estimating the mean annual precipitation in autumn, summer, and spring, and is less accurate in winter. In contrast, the multivariate regression mode combined with the residual error correction method can effectively improve the precipitation forecast ability. The model is applicable to the unique natural geographical features of the northeast slope of the Qinghai–Tibet Plateau. The research results are of great significance for analyzing the temporal and spatial distribution pattern of precipitation in complex terrain areas.

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Geochemical and Isotope Tracers Reveal the Runoff Components Characteristics and the Ecohydrologic Influences at the Qinghai-Tibet Plateau

10.5194/egusphere-egu2020-4048 ◽

2020 ◽

Author(s):

Hongwei Liu ◽

Jiufu Liu ◽

Jin Lin ◽

Wenzhong Wang ◽

Xing Min ◽

...

Keyword(s):

Ground Water ◽

River Water ◽

Laser Scanning ◽

Base Flow ◽

Tibet Plateau ◽

Vacuum Extraction ◽

Observation Data ◽

Runoff Change ◽

Geochemical Elements ◽

Qinghai Tibet Plateau

The glacier recession and the runoff variation on the Qinghai-Tibet plateau conducted by the global warming is changing the regional hydrological and ecological processes. Although there is great need for the knowledge of the runoff evolution and biogenic substances migration and transformation for developing strategies for adaptive utilization of runoff, progress in study on these hydrological questions lags behind because of lack of observation dataset under harsh plateau cold conditions.In order to understand the critical zone ecohydrological dynamics and evaluate the runoff components in the Qinghai-Tibet Plateau, a series of observation and research were carried out in the Niyang River watershed, a tributary of the Yarlung Zangbo River. Four basins embed in a larger basin (1500 km2) were monitored and sampled at altitudes between 3667 to 6140 m. More than 500 samples from rain, snow, river water, spring water, glacier ice, vegetation stem, and soil were collected, with which the&#948;2H, &#948;18O, K, Ca, Na, Mg, Sr, Si, F, Cl, N, and S in the water are examined. 5 automatic hydrometric stations were established, and the water level data was sent back by Beidou satellite. The 3D laser scanning and RTK technologies were used to obtain detailed geomorphological information near the 5 current measurement section, based on which a hydrodynamic model is able to be calibrated for the discharge estimation.The &#948;2H and &#948;18O of the precipitation proposed a local meteoric water isotope line, which is parallel to the WMWL but higher in the &#948;D~&#948;18O graph. The river water isotopes suggest its source is the precipitation, which are similar to the spring ground water (but the geochemical elements are quite different between the surface and ground water). The vegetation stems water and soil water (by cryogenic vacuum extraction) isotope values suggest the attribute of the river/precipitation sources, but a few observation data appear different implying using water formed by the multiple precipitation events or supplied by the higher place under a significant evaporation influence.The time series of the runoff and the snow cover and glacier variation results show that the base flow is varied obviously relate to the temperature which influence the melting processes of the glacier and frozen earth from March to August, and the rain runoff events control the flood peek. It suggests that the concentration time should be less than 10 days in the interested watershed.The tempo-spatial variation characteristics of the geochemical elements are analyzed and mapped in the interested area, which suggested relative steady water components signals contributing to the runoff. Based on which, a set of overdetermined equations are established to evaluate the quantities of different runoff components.This study could help to evaluate runoff components quantitively in Tibet where lack of data. Monitoring and studing is still going on, which is included in the 2nd comprehensive scientific investigation into Qinghai-Tibet Plateau since 2019.Funded by the NSFC project 91647111 and 91647203 included in the Runoff Change and its Adaptive Management in the Major Rivers in Southwestern China Major Research Plan.

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Regional-scale vegetation-climate interactions on the Qinghai-Tibet Plateau

Ecological Informatics ◽

10.1016/j.ecoinf.2021.101413 ◽

2021 ◽

pp. 101413

Author(s):

Chan Diao ◽

Yu Liu ◽

Liang Zhao ◽

Ga Zhuo ◽

Yongqing Zhang

Keyword(s):

Regional Scale ◽

Tibet Plateau ◽

Climate Interactions ◽

Qinghai Tibet Plateau

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Evaluation of SMAP, SMOS-IC, FY3B, JAXA, and LPRM Soil Moisture Products over the Qinghai-Tibet Plateau and Its Surrounding Areas

Remote Sensing ◽

10.3390/rs11070792 ◽

2019 ◽

Vol 11 (7) ◽

pp. 792 ◽

Cited By ~ 6

Author(s):

Jin Liu ◽

Linna Chai ◽

Zheng Lu ◽

Shaomin Liu ◽

Yuquan Qu ◽

...

Keyword(s):

Soil Moisture ◽

Land Surface ◽

Regional Scale ◽

Temporal Variations ◽

Comparison Method ◽

Tibet Plateau ◽

Quantitative Evidence ◽

Retrieval Algorithms ◽

Qinghai Tibet Plateau

High-quality and long time-series soil moisture (SM) data are increasingly required for the Qinghai-Tibet Plateau (QTP) to more accurately and effectively assess climate change. In this study, to evaluate the accuracy and effectiveness of SM data, five passive microwave remotely sensed SM products are collected over the QTP, including those from the soil moisture active passive (SMAP), soil moisture and ocean salinity INRA-CESBIO (SMOS-IC), Fengyun-3B microwave radiation image (FY3B), and two SM products derived from the advanced microwave scanning radiometer 2 (AMSR2). The two AMSR2 products are generated by the land parameter retrieval model (LPRM) and the Japan Aerospace Exploration Agency (JAXA) algorithm, respectively. The SM products are evaluated through a two-stage data comparison method. The first stage is direct validation at the grid scale. Five SM products are compared with corresponding in situ measurements at five in situ networks, including Heihe, Naqu, Pali, Maqu, and Ngari. Another stage is indirect validation at the regional scale, where the uncertainties of the data are quantified by using a three-cornered hat (TCH) method. The results at the regional scale indicate that soil moisture is underestimated by JAXA and overestimated by LPRM, some noise is contained in temporal variations in SMOS-IC, and FY3B has relatively low absolute accuracy. The uncertainty of SMAP is the lowest among the five products over the entire QTP. In the SM map composed by five SM products with the lowest pixel-level uncertainty, 66.64% of the area is covered by SMAP (JAXA: 19.39%, FY3B: 10.83%, LPRM: 2.11%, and SMOS-IC: 1.03%). This study reveals some of the reasons for the different performances of these five SM products, mainly from the perspective of the parameterization schemes of their corresponding retrieval algorithms. Specifically, the parameterization configurations and corresponding input datasets, including the land-surface temperature, the vegetation optical depth, and the soil dielectric mixing model are analyzed and discussed. This study provides quantitative evidence to better understand the uncertainties of SM products and explain errors that originate from the retrieval algorithms.

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Driving Forces of the Changes in Vegetation Phenology in the Qinghai–Tibet Plateau

Remote Sensing ◽

10.3390/rs13234952 ◽

2021 ◽

Vol 13 (23) ◽

pp. 4952

Author(s):

Xigang Liu ◽

Yaning Chen ◽

Zhi Li ◽

Yupeng Li ◽

Qifei Zhang ◽

...

Keyword(s):

Air Temperature ◽

Vegetation Index ◽

Normalized Difference Vegetation Index ◽

Driving Forces ◽

Growing Season ◽

Tibet Plateau ◽

Vegetation Phenology ◽

Climate Change Research ◽

Temperature And Precipitation ◽

Qinghai Tibet Plateau

Phenological change is an emerging hot topic in ecology and climate change research. Existing phenological studies in the Qinghai–Tibet Plateau (QTP) have focused on overall changes, while ignoring the different characteristics of changes in different regions. Here, we use the Global Inventory Modeling and Mapping Studies (GIMMS3g) normalized difference vegetation index (NDVI) dataset as a basis to discuss the temporal and spatial changes in vegetation phenology in the Qinghai–Tibet Plateau from 1982 to 2015. We also analyze the response mechanisms of pre-season climate factor and vegetation phenology and reveal the driving forces of the changes in vegetation phenology. The results show that: (1) the start of the growing season (SOS) and the length of the growing season (LOS) in the QTP fluctuate greatly year by year; (2) in the study area, the change in pre-season precipitation significantly affects the SOS in the northeast (p < 0.05), while, the delay in the end of the growing season (EOS) in the northeast is determined by pre-season air temperature and precipitation; (3) pre-season precipitation in April or May is the main driving force of the SOS of different vegetation, while air temperature and precipitation in the pre-season jointly affect the EOS of different vegetation. The differences in and the diversity of vegetation types together lead to complex changes in vegetation phenology across different regions within the QTP. Therefore, addressing the characteristics and impacts of changes in vegetation phenology across different regions plays an important role in ecological protection in this region.

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Evaluation and Hydrological Simulation of CMADS and CFSR Reanalysis Datasets in the Qinghai-Tibet Plateau

Water ◽

10.3390/w10040513 ◽

2018 ◽

Vol 10 (4) ◽

pp. 513 ◽

Cited By ~ 26

Author(s):

Jun Liu ◽

Donghui Shanguan ◽

Shiyin Liu ◽

Yongjian Ding

Keyword(s):

Wind Speed ◽

Relative Humidity ◽

Yellow River ◽

Hydrological Processes ◽

Tibet Plateau ◽

Maximum Temperature ◽

The Yellow River ◽

Observation Data ◽

Yellow River Source ◽

Qinghai Tibet Plateau

Multisource reanalysis datasets provide an effective way to help us understand hydrological processes in inland alpine regions with sparsely distributed weather stations. The accuracy and quality of two widely used datasets, the China Meteorological Assimilation Driving Datasets to force the SWAT model (CMADS), and the Climate Forecast System Reanalysis (CFSR) in the Qinghai-Tibet Plateau (TP), were evaluated in this paper. The accuracy of daily precipitation, max/min temperature, relative humidity and wind speed from CMADS and CFSR are firstly evaluated by comparing them with results obtained from 131 meteorological stations in the TP. Statistical results show that most elements of CMADS are superior to those of CFSR. The average correlation coefficient (R) between the maximum temperature and the minimum temperature of CMADS and CFSR ranged from 0.93 to 0.97. The root mean square error (RMSE) for CMADS and CFSR ranged from 3.16 to 3.18 °C, and ranged from 5.19 °C to 8.14 °C respectively. The average R of precipitation, relative humidity, and wind speed for CMADS are 0.46; 0.88 and 0.64 respectively, while they are 0.43, 0.52, and 0.37 for CFSR. Gridded observation data is obtained using the professional interpolation software, ANUSPLIN. Meteorological elements from three gridded data have a similar overall distribution but have a different partial distribution. The Soil and Water Assessment Tool (SWAT) is used to simulate hydrological processes in the Yellow River Source Basin of the TP. The Nash Sutcliffe coefficients (NSE) of CMADS+SWAT in calibration and validation period are 0.78 and 0.68 for the monthly scale respectively, which are better than those of CFSR+SWAT and OBS+SWAT in the Yellow River Source Basin. The relationship between snowmelt and other variables is measured by GeoDetector. Air temperature, soil moisture, and soil temperature at 1.038 m has a greater influence on snowmelt than others.

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Evaluation of the Township Proper Carrying Capacity over Qinghai-Tibet plateau by CASA model

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/108/4/042079 ◽

2018 ◽

Vol 108 ◽

pp. 042079

Author(s):

Chengyong Wu ◽

Guangchao Cao ◽

Huaju Xue ◽

Gang Jiang ◽

Qi Wang ◽

...

Keyword(s):

Carrying Capacity ◽

Tibet Plateau ◽

Casa Model ◽

Qinghai Tibet Plateau

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Interactions between landscape changes and host communities can regulate Echinococcus multilocularis transmission

Parasitology ◽

10.1017/s0031182003003512 ◽

2003 ◽

Vol 127 (S1) ◽

pp. S121-S131 ◽

Cited By ~ 87

Author(s):

P. GIRAUDOUX ◽

P. S. CRAIG ◽

P. DELATTRE ◽

G. BAO ◽

B. BARTHOLOMOT ◽

...

Keyword(s):

Echinococcus Multilocularis ◽

Alveolar Echinococcosis ◽

Regional Scale ◽

Central China ◽

Tibet Plateau ◽

Landscape Changes ◽

Rural Landscapes ◽

Increased Risk ◽

Mammal Communities ◽

Qinghai Tibet Plateau

An area close to the Qinghai-Tibet plateau region and subject to intensive deforestation contains a large focus of human alveolar echinococcosis while sporadic human cases occur in the Doubs region of eastern France. The current review analyses and compares epidemiological and ecological results obtained in both regions. Analysis of rodent species assemblages within quantified rural landscapes in central China and eastern France shows a significant association between host species for the pathogenic helminth Echinococcus multilocularis, with prevalences of human alveolar echinococcosis and with land area under shrubland or grassland. This suggests that at the regional scale landscape can affect human disease distribution through interaction with small mammal communities and their population dynamics. Lidicker's ROMPA hypothesis helps to explain this association and provides a novel explanation of how landscape changes may result in increased risk of a rodent-borne zoonotic disease.

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Effects of Ocean Tide Load on Vertical Crustal Deformation in Northeastern Margin of Qinghai Tibet Plateau

E3S Web of Conferences ◽

10.1051/e3sconf/202020601010 ◽

2020 ◽

Vol 206 ◽

pp. 01010

Author(s):

Guolin Yang ◽

Chuanyin Zhang ◽

Xuexian Sun ◽

Tao Liu ◽

Xuwei An

Keyword(s):

Crustal Deformation ◽

Harmonic Coefficient ◽

Tibet Plateau ◽

Ocean Tide ◽

Observation Data ◽

Atmospheric Loading ◽

Actual Observation ◽

The Impact ◽

Qinghai Tibet Plateau ◽

Vertical Crustal Deformation

Periodic crustal movement are mainly caused by ocean tides and changes of atmospheric pressure. In this project, the researcher has used the spherical harmonic coefficient of the ocean tide and actual observation data to study the impact on vertical crustal deformation due to changes of oceanic tide loading from 2012 to 2017 at the northeastern margin of the Qinghai-Tibet Plateau, based on the theory of crustal load deformation. The result shows that changes in oceanic tide loading have little impact on vertical crustal deformation compared with the impact of atmospheric loading at the northeastern margin of the Qinghai. The impact range of oceanic tide loading in this region is within ±3mm. In contrast, impact of atmospheric loading can reach ±12mm.

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