scholarly journals Quantifying the Responses of Evapotranspiration and Its Components to Vegetation Restoration and Climate Change on the Loess Plateau of China

2021 ◽  
Vol 13 (12) ◽  
pp. 2358
Author(s):  
Linjing Qiu ◽  
Yiping Wu ◽  
Zhaoyang Shi ◽  
Yuting Chen ◽  
Fubo Zhao
Keyword(s):  
Climate Change ◽  
Loess Plateau ◽  
Dominant Role ◽  
Vegetation Restoration ◽  
Vegetation Coverage ◽  
Ecological Planning ◽  
The Loess Plateau ◽  
Canopy Interception ◽  
Community Land Model ◽  
Spatiotemporal Trends

Quantitatively identifying the influences of vegetation restoration (VR) on water resources is crucial to ecological planning. Although vegetation coverage has improved on the Loess Plateau (LP) of China since the implementation of VR policy, the way vegetation dynamics influences regional evapotranspiration (ET) remains controversial. In this study, we first investigate long-term spatiotemporal trends of total ET (TET) components, including ground evaporation (GE) and canopy ET (CET, sum of canopy interception and canopy transpiration) based on the GLEAM-ET dataset. The ET changes are attributed to VR on the LP from 2000 to 2015 and these results are quantitatively evaluated here using the Community Land Model (CLM). Finally, the relative contributions of VR and climate change to ET are identified by combining climate scenarios and VR scenarios. The results show that the positive effect of VR on CET is offset by the negative effect of VR on GE, which results in a weak variation in TET at an annual scale and an increased TET is only shown in summer. Regardless of the representative concentration pathway (RCP4.5 or RCP8.5), differences resulted from the responses of TET to different vegetation conditions ranging from −3.7 to −1.2 mm, while climate change from RCP4.5 to RCP8.5 caused an increase in TET ranging from 0.1 to 65.3 mm. These findings imply that climate change might play a dominant role in ET variability on the LP, and this work emphasizes the importance of comprehensively considering the interactions among climate factors to assess the relative contributions of VR and climate change to ET.

scholarly journals Climate change: vegetation and phenological phase dynamics

2020 ◽  
Vol 12 (4) ◽  
pp. 495-509
Author(s):  
Yang Li ◽  
Yaochen Qin ◽  
Liqun Ma ◽  
Ziwu Pan
Keyword(s):  
Climate Change ◽  
Loess Plateau ◽  
Growing Season ◽  
Vegetation Coverage ◽  
The Loess Plateau ◽  
Content Type ◽  
Phase Dynamics ◽  
Filtering Algorithm ◽  
The Past ◽  
Environmental Treatment

Purpose The ecological environment of the Loess Plateau, China, is extremely fragile under the context of global warming. Over the past two decades, the vegetation of the Loess Plateau has undergone great changes. This paper aims to clarify the response mechanisms of vegetation to climate change, to provide support for the restoration and environmental treatment of vegetation on the Loess Plateau. Design/methodology/approach The Savitsky–Golay (S-G) filtering algorithm was used to reconstruct time series of moderate resolution imaging spectroradiometer (MODIS) 13A2 data. Combined with trend analysis and partial correlation analysis, the influence of climate change on the phenology and enhanced vegetation index (EVI) during the growing season was described. Findings The S-G filtering algorithm is suitable for EVI reconstruction of the Loess Plateau. The date of start of growing season was found to gradually later along the Southeast–Northwest direction, whereas the date of the end of the growing season showed the opposite pattern and the length of the growing season gradually shortened. Vegetation EVI values decreased gradually from Southeast to Northwest. Vegetation changed significantly and showed clear differentiation according to different topographic factors. Vegetation correlated positively with precipitation from April to July and with temperature from August to November. Originality/value This study provides technical support for ecological environmental assessment, restoration of regional vegetation coverage and environmental governance of the Loess Plateau over the past two decades. It also provides theoretical support for the prediction model of vegetation phenology changes based on remote sensing data.

The spatial and temporal characteristics of precipitation and the key contributing factors in the Loess Plateau since the implementation of Green for Grain Project

2020 ◽  
Author(s):  
Xuerui Gao ◽  
Jichao Wang ◽  
Yubao Wang ◽  
Xining Zhao ◽  
Yong Zhao ◽  
...  
Keyword(s):  
Climate Change ◽  
Loess Plateau ◽  
Temporal Distribution ◽  
Summer Precipitation ◽  
Winter Precipitation ◽  
Vegetation Restoration ◽  
Spatial And Temporal Distribution ◽  
The Loess Plateau ◽  
Contributing Factors ◽  
Increase Rate

<p>      Since the implementation of Green for Grain Project (GFGP) in the 1990s, the precipitation in the Loess Plateau has increased significantly. The warming and wetting trend in this area is becoming statistically significant. However, the correlation between precipitation increase and regional vegetation restoration is still controversial. To explore the main factors influencing the regional precipitation change, this study selected 6 main contributing factors of the precipitation in the Loess Plateau based on the cloud-precipitation physics and used the statistical methods to analyze the long-term change trend and the spatial and temporal distribution of precipitation in the Loess plateau before and after GFGP and to quantify the contribution rate of different factors to precipitation change in this area. The results show that: 1) the precipitation increased significantly (95% confidence level) after Green for Grain Project since 1999, with an increase rate of 4.96 mm/a; 2) From the perspective of spatial and temporal distribution, the precipitation in the southern part of the Loess plateau was significantly increasing with an increase rate of 20-50mm in the period of 2000-2015 compared with the average annual value in the base period (1985-1999). Among them, the summer precipitation increased significantly, while the winter precipitation changed non-significantly; 3) The contribution analysis shows that the summer precipitation in the Loess Plateau is mainly affected by regional actual evapotranspiration (AET) and vegetation coverage (NDVI) after GFGP, with the contribution rates of 27.1% and 40.0%, which respectively indicates that the summer precipitation in the Loess Plateau increased mainly due to the regional vegetation restoration and the associated ET increase. The winter precipitation in the Loess Plateau is mainly affected by the precipitable water (PW) in the air and water vapor flux (VF), with the contribution rates of 33.5% and 31.7%, which indicates that the winter precipitation is mainly affected by atmospheric circulation and transport of external water vapor. Based on this study, we speculate that the warming and wetting trend of Loess Plateau in recent years is not only closely related to global climate change, but also significantly affected by local climate change brought by vegetation restoration. The above conclusions are important for future ecological restoration and water resources management in the water-scarce Loess Plateau.</p>

scholarly journals Vegetation Restoration and Its Environmental Effects on the Loess Plateau

2018 ◽  
Vol 10 (12) ◽  
pp. 4676 ◽  
Author(s):  
Hongfei Zhao ◽  
Hongming He ◽  
Jingjing Wang ◽  
Chunyu Bai ◽  
Chuangjuan Zhang
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Sustainable Development ◽  
Loess Plateau ◽  
Environmental Effects ◽  
Central Area ◽  
Vegetation Restoration ◽  
Ecological Environment ◽  
The Loess Plateau ◽  
Positive Effects

An analysis of land use/cover change (LUCC) on the Loess Plateau over the past 30 years and its environmental effects was performed to provide scientific guidance for a sustainable development policy for the regional ecological environment and social economy. Geostatistical and trend analyses are used to study the LUCC characteristics, driving forces and environmental effects, and the relationship between LUCC and regional sustainable development is explored. The following results were obtained: (1) Overall, the land use structure has not changed, with grassland, farmland, and forest land remaining dominant; however, the vegetation coverage has significantly increased, especially in the central area. (2) LUCC is affected by climate change and human activities, with greater climate change impacts in the northwest than the southeast and greater among which human-induced impacts on the hilly/gully region in the central part. (3) LUCC will produce long-term ecological and environmental processes, such as surface runoff, soil erosion, soil moisture and carbon cycling. Vegetation restoration has both negative and positive effects on the regional ecological environment. Vegetation productivity on the Loess Plateau has approached the water resource carrying capacity threshold. Therefore, improving artificial vegetation stability and promoting the water resources balance have become the main strategies for promoting sustainable development on the Loess Plateau.

scholarly journals Contributions of Vegetation Greening and Climate Change to Evapotranspiration Trend after Large-Scale Vegetation Restoration on the Loess Plateau, China

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1755
Author(s):  
Shuo Wang ◽  
Chenfeng Cui ◽  
Qin Dai
Keyword(s):  
Climate Change ◽  
Loess Plateau ◽  
Large Scale ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Potential Evapotranspiration ◽  
Development Trend ◽  
Future Trend ◽  
Natural Ecosystem ◽  
The Loess Plateau

Since the early 2000s, the vegetation cover of the Loess Plateau (LP) has increased significantly, which has been fully recorded. However, the effects on relevant eco-hydrological processes are still unclear. Here, we made an investigation on the changes of actual evapotranspiration (ETa) during 2000–2018 and connected them with vegetation greening and climate change in the LP, based on the remote sensing data with correlation and attribution analysis. Results identified that the average annual ETa on the LP exhibited an obvious increasing trend with the value of 9.11 mm yr−1, and the annual ETa trend was dominated by the changes of ETa in the third quarter (July, August, and September). The future trend of ETa was predicted by the Hurst exponent. Partial correlation analysis indicated that annual ETa variations in 87.8% regions of the LP were controlled by vegetation greening. Multiple regression analysis suggested that the relative contributions of potential evapotranspiration (ETp), precipitation, and normalized difference vegetation index (NDVI), to the trend of ETa were 5.7%, −26.3%, and 61.4%, separately. Vegetation greening has a close relationship with the Grain for Green (GFG) project and acts as an essential driver for the long-term development trend of water consumption on the LP. In this research, the potential conflicts of water demanding between the natural ecosystem and social-economic system in the LP were highlighted, which were caused by the fast vegetation expansion.

Long-term vegetation restoration promotes the stability of the soil micro-food web in the Loess Plateau in North-west China

CATENA ◽  
2021 ◽  
Vol 202 ◽  
pp. 105293
Author(s):  
Yang Wu ◽  
WenJing Chen ◽  
Wulan Entemake ◽  
Jie Wang ◽  
HongFei Liu ◽  
...  
Keyword(s):  
Food Web ◽  
Loess Plateau ◽  
Vegetation Restoration ◽  
The Loess Plateau ◽  
West China ◽  
North West ◽  
The Stability

scholarly journals Spatiotemporal Changes in Vegetation Cover and Its Influencing Factors in the Loess Plateau of China Based on the Geographically Weighted Regression Model

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 673
Author(s):  
Chen Yang ◽  
Meichen Fu ◽  
Dingrao Feng ◽  
Yiyu Sun ◽  
Guohui Zhai
Keyword(s):  
Regression Model ◽  
Influencing Factors ◽  
Loess Plateau ◽  
Geographically Weighted Regression ◽  
Vegetation Cover ◽  
Weighted Regression ◽  
Vegetation Coverage ◽  
The Loess Plateau ◽  
Geographically Weighted Regression Model ◽  
Spatiotemporal Changes

Vegetation plays a key role in ecosystem regulation and influences our capacity for sustainable development. Global vegetation cover has changed dramatically over the past decades in response to both natural and anthropogenic factors; therefore, it is necessary to analyze the spatiotemporal changes in vegetation cover and its influencing factors. Moreover, ecological engineering projects, such as the “Grain for Green” project implemented in 1999, have been introduced to improve the ecological environment by enhancing forest coverage. In our study, we analyzed the changes in vegetation cover across the Loess Plateau of China and the impacts of influencing factors. First, we analyzed the latitudinal and longitudinal changes in vegetation coverage. Second, we displayed the spatiotemporal changes in vegetation cover based on Theil-Sen slope analysis and the Mann-Kendall test. Third, the Hurst exponent was used to predict future changes in vegetation coverage. Fourth, we assessed the relationship between vegetation cover and the influence of individual factors. Finally, ordinary least squares regression and the geographically weighted regression model were used to investigate the influence of various factors on vegetation cover. We found that the Loess Plateau showed large-scale greening from 2000 to 2015, though some regions showed decreasing vegetation cover. Latitudinal and longitudinal changes in vegetation coverage presented a net increase. Moreover, some areas of the Loess Plateau are at risk of degradation in the future, but most areas showed a sustainable increase in vegetation cover. Temperature, precipitation, gross domestic product (GDP), slope, cropland percentage, forest percentage, and built-up land percentage displayed different relationships with vegetation cover. Geographically weighted regression model revealed that GDP, temperature, precipitation, forest percentage, cropland percentage, built-up land percentage, and slope significantly influenced (p < 0.05) vegetation cover in 2000. In comparison, precipitation, forest percentage, cropland percentage, and built-up land percentage significantly affected (p < 0.05) vegetation cover in 2015. Our results enhance our understanding of the ecological and environmental changes in the Loess Plateau.

scholarly journals Effects of Vegetation Restoration on Soil Erosion on the Loess Plateau: A Case Study in the Ansai Watershed

2021 ◽  
Vol 18 (12) ◽  
pp. 6266
Author(s):  
Hui Wei ◽  
Wenwu Zhao ◽  
Han Wang
Keyword(s):  
Land Use ◽  
Soil Erosion ◽  
Loess Plateau ◽  
Water Conservation ◽  
Large Scale ◽  
Land Use Changes ◽  
Vegetation Restoration ◽  
The Loess Plateau ◽  
Local Soil ◽  
Erosion Environment

Large-scale vegetation restoration greatly changed the soil erosion environment in the Loess Plateau since the implementation of the “Grain for Green Project” (GGP) in 1999. Evaluating the effects of vegetation restoration on soil erosion is significant to local soil and water conservation and vegetation construction. Taking the Ansai Watershed as the case area, this study calculated the soil erosion modulus from 2000 to 2015 under the initial and current scenarios of vegetation restoration, using the Chinese Soil Loess Equation (CSLE), based on rainfall and soil data, remote sensing images and socio-economic data. The effect of vegetation restoration on soil erosion was evaluated by comparing the average annual soil erosion modulus under two scenarios among 16 years. The results showed: (1) vegetation restoration significantly changed the local land use, characterized by the conversion of farmland to grassland, arboreal land, and shrub land. From 2000 to 2015, the area of arboreal land, shrub land, and grassland increased from 19.46 km2, 19.43 km2, and 719.49 km2 to 99.26 km2, 75.97 km2, and 1084.24 km2; while the farmland area decreased from 547.90 km2 to 34.35 km2; (2) the average annual soil erosion modulus from 2000 to 2015 under the initial and current scenarios of vegetation restoration was 114.44 t/(hm²·a) and 78.42 t/(hm²·a), respectively, with an average annual reduction of 4.81 × 106 t of soil erosion amount thanks to the vegetation restoration; (3) the dominant soil erosion intensity changed from “severe and light erosion” to “moderate and light erosion”, vegetation restoration greatly improved the soil erosion environment in the study area; (4) areas with increased erosion and decreased erosion were alternately distributed, accounting for 48% and 52% of the total land area, and mainly distributed in the northwest and southeast of the watershed, respectively. Irrational land use changes in local areas (such as the conversion of farmland and grassland into construction land, etc.) and the ineffective implementation of vegetation restoration are the main reasons leading to the existence of areas with increased erosion.

scholarly journals A Weighted-Time-Lag Method to Detect Lag Vegetation Response to Climate Variation: A Case Study in Loess Plateau, China, 1982–2013

2021 ◽  
Vol 13 (5) ◽  
pp. 923
Author(s):  
Qianqian Sun ◽  
Chao Liu ◽  
Tianyang Chen ◽  
Anbing Zhang
Keyword(s):  
Climate Change ◽  
Loess Plateau ◽  
Time Lag ◽  
New Method ◽  
Climate Factors ◽  
The Loess Plateau ◽  
Climate Conditions ◽  
Vegetation Growth ◽  
Lag Effect

Vegetation fluctuation is sensitive to climate change, and this response exhibits a time lag. Traditionally, scholars estimated this lag effect by considering the immediate prior lag (e.g., where vegetation in the current month is impacted by the climate in a certain prior month) or the lag accumulation (e.g., where vegetation in the current month is impacted by the last several months). The essence of these two methods is that vegetation growth is impacted by climate conditions in the prior period or several consecutive previous periods, which fails to consider the different impacts coming from each of those prior periods. Therefore, this study proposed a new approach, the weighted time-lag method, in detecting the lag effect of climate conditions coming from different prior periods. Essentially, the new method is a generalized extension of the lag-accumulation method. However, the new method detects how many prior periods need to be considered and, most importantly, the differentiated climate impact on vegetation growth in each of the determined prior periods. We tested the performance of the new method in the Loess Plateau by comparing various lag detection methods by using the linear model between the climate factors and the normalized difference vegetation index (NDVI). The case study confirmed four main findings: (1) the response of vegetation growth exhibits time lag to both precipitation and temperature; (2) there are apparent differences in the time lag effect detected by various methods, but the weighted time-lag method produced the highest determination coefficient (R2) in the linear model and provided the most specific lag pattern over the determined prior periods; (3) the vegetation growth is most sensitive to climate factors in the current month and the last month in the Loess Plateau but reflects a varied of responses to other prior months; and (4) the impact of temperature on vegetation growth is higher than that of precipitation. The new method provides a much more precise detection of the lag effect of climate change on vegetation growth and makes a smart decision about soil conservation and ecological restoration after severe climate events, such as long-lasting drought or flooding.

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