Search Results (8)

Evapotranspiration (ET) and water availability (WA) are critical components of the global water cycle. Although the effects of ecological restoration on ET and WA have been widely investigated, quantifying the impacts of multiple environmental factors on plant water consumption and regional water balance in dryland areas remains challenging. In this study, we investigated the spatial and temporal trends of ET and WA and isolated the contributions of vegetation restoration and climate change to variations in ET and WA in the Beijing–Tianjin Sand Source Region (BTSSR) in Northern China from 2001 to 2021, using the remote sensing-based Priestley–Taylor-Jet Propulsion Laboratory (PT-JPL) model and scenario simulation experiments. The results indicate that the estimated ET was consistent with field observations and state-of-the-art ET products. The annual ET in the BTSSR increased significantly by 1.28 mm yr⁻¹ from 2001 to 2021, primarily driven by vegetation restoration (0.78 mm yr⁻¹) and increased radiation (0.73 mm yr⁻¹). In contrast, the drier climate led to a decrease of 0.56 mm yr⁻¹ in ET. In semiarid areas, vegetation and radiation were the dominant factors driving the variability of ET, while in arid areas, relative humidity played a more critical role. Furthermore, reduced precipitation and increased plant water consumption resulted in a decline in WA by −0.91 mm yr⁻¹ during 2001–2021. Climate factors, rather than vegetation greening, determined the WA variations in the BTSSR, accounting for 77.6% of the total area. These findings can provide valuable insights for achieving sustainable ecological restoration and ensuring the sustainability of regional water resources in dryland China under climate change. This study also highlights the importance of simultaneously considering climate change and vegetation restoration in assessing their negative impacts on regional water availability. Full article

Vegetation primarily draws water from soil moisture (SM), with restoration in drylands often reducing SM storage (SMS). However, anomalies have been detected in the Beijing–Tianjin Sand Source Region (BTSSR) of China via the Global Land Data Assimilation System (GLDAS) and Gravity Recovery and Climate Experiment (GRACE). This study quantified the sources of increased SMS in drylands to elucidate the effects of vegetation restoration on SMS. The results indicated the following: (1) In vegetated drylands, 46.2% experienced a significant increase in SMS while 53.8% remained stable; both were positively correlated with the normalised difference vegetation index (NDVI). (2) The increase in SMS was accompanied by a decrease in groundwater storage (GWS), as indicated by the significant correlation coefficients of −0.710 and −0.569 for SMS and GWS, respectively. Furthermore, GWS served as the primary source of water for vegetation. (3) The results of the redundancy analysis (RDA) indicated that the initial vegetation, the driver of the observed trend of increased SMS and decreased GWS, accounted for 50.3% of the variability in water storage. Therefore, to sustain dryland ecosystems, we recommend that future vegetation restoration projects give due consideration to the water balance while concurrently strengthening the dynamic monitoring of SMS and GWS. Full article

Understanding the interactions between ecosystem services is the foundation for optimizing ecosystem management and improving human well-being. However, studies on the driving mechanism of ecosystem service relationship formation in arid and semiarid climates are scarce. The Beijing–Tianjin Sand Source Control Project (BTSSCP) has been underway for more than 20 years (2001–2022), and a comprehensive scientific assessment of the effects of its implementation is important for managing ecosystems more efficiently. Taking the BTSSCP region as a study area, four ecosystem services (water conservation (WC), soil conservation (SC), wind erosion control (WEC), and net primary productivity (NPP)) were quantified and mapped in 2000, 2010, and 2020. In this study, a Bayesian belief network (BBN) model was used to analyze ecological processes and determine the relationship between the potential influencing factors and ecosystem services. A sensitivity analysis identified the key factors affecting ecosystem service supply on the basis of a Bayesian belief network simulation. The results showed an increasing trend for four ecosystem services over the past 20 years. Regarding spatial distribution, WC, SC, and NPP exhibited an overall “high in the east and low in the west” pattern, while the spatial distribution of WEC was more dispersed. The intensity of the trade-offs among WC, SC, and NPP has increased, while that of the trade-offs between the rest of the variables has decreased in the BTSSCP over the past 20 years. The results of the Bayesian network modeling indicated that precipitation, NDVI, land use, and temperature were the major variables influencing the strength of ecosystem service trade-offs. The conditional probabilities of the key variables in different states showed that the Sunit Left Banner, Sunit Right Banner, and other areas of control of the desertification of arid grassland had a high probability of trade-offs in WC_SC and SC_NPP. However, the probability of a trade-off between WEC and NPP was higher in the southeastern part of the Yanshan Hills Mountain Water Source Reserve than in the other regions; thus, it should be prioritized as an area for ecological restoration in future planning. This paper provides a scientific reference for the effective protection of ecosystems and the formulation of sustainable policies. Full article

From the perspective of economic benefit, this paper uses the DEA method to measure the input–output efficiency of the Beijing–Tianjin sandstorm source control project in Beijing, Hebei, Shanxi, and Inner Mongolia. The results show that from 2003 to 2019, the efficiency of the four regions revealed a U-shaped trend, first decreasing and then increasing, which reflects the lagging characteristics of forestry engineering. The TFP of the sand source control project in these four places was calculated; the average efficiency growth rate was 1.4%, and it was found to be affected greatly by the rate of technological progress. The Tobit model was used to explore the influencing factors, and the results show that educational input and economic development level have a great effect on efficiency, fiscal pressure has a small effect on efficiency, and financial development level has a restraining effect on efficiency. Full article

Grasslands in northern China form an important ecological barrier that prevents and controls desertification. The Beijing–Tianjin Sand Source Control (BTSSC) Project has been implemented to restore grassland in order to control sand sourced pollution. This study aimed to understand the impacts of four applied restoration practices on the productivity, composition, and species diversity of vegetation communities in the BTSSC Project. The results indicated the following: (1) All the restoration practices tended to increase the height and cover of communities, and the effect was most obvious where grazing was excluded; (2) total biomass (87%), above-ground biomass (164%) and below-ground biomass (58%) only increased consistently when grazing was excluded from the steppe; (3) fenced and grazing exclusion practice significantly increased the abundance of species in communities, but all the practices tended to decrease the evenness of species; and, (4) the correlation analysis revealed that the Shannon–Wiener diversity index, and Pielou evenness index, showed significant negative correlations with the above-ground biomass of grassland communities after restoration, while no significant relationships were shown in reference plots. Our comparison of applied practices in the BTSSC project revealed that grazing exclusion might be a high priority for more successful restoration in this region. Full article

Based on the daily precipitation data from 53 meteorological stations, 11 extreme precipitation indices were selected, categorized and calculated; the temporal and spatial patterns in these indices and their teleconnections with the large-scale circulations were analyzed by the non-parametric Mann-Kendall test; and Sen’s slope estimator and linear regression for the period of 1960–2014 were calculated. The results indicated that all extreme precipitation indices had spatial patterns decreasing from the southeastern to the northwestern parts of the Beijing-Tianjin Sand Source Region (BTSSR), except for the consecutive dry days (CDD), which exhibited a reverse spatial pattern. At the whole-region scale, most extreme precipitation indices showed an insignificant decreasing trend, with exceptions in the intensity indices (RX1day and RX5day) with a statistical significance at the 90% confidence level. The total annual precipitation showed a general shift towards a drier climate in the study area. Spatially, all indices for extreme precipitation showed decreasing trends at most stations, except for simple daily intensity index (SDII) and heavy precipitation days (R10). The change in extreme precipitation may be affected by the El Niño-Southern Oscillation (ENSO), East Asian Summer Monsoon (EASM) and Pacific Decadal Oscillation (PDO). Better understanding of extreme precipitation for the BTSSR may be useful in the regional planning for ecological restoration and water management. Full article

Several grassland conservation programs aiming to relieve grazing pressure have been implemented in Inner Mongolia since 2000 to reverse grassland degradation and protect local and regional environments. Previous studies on the effects of these programs usually used small-scale data generated from field experiments and household surveys, inhibiting the discovery of large-scale effects due to spatial heterogeneity. For a typical study region in Xilingol League, we used fixed-effects models and a panel dataset at the county level from 1998 to 2013 to examine the effects of two programs, namely, the Beijing–Tianjin Wind/Sand Source Control Program and the Ecological Subsidy and Award System and other drivers on vegetation rehabilitation. The modeling results suggested that the programs had a positive but delayed impact on grassland vegetation rehabilitation. Enrollment in the two programs in a specific year was predicted to increase the vegetation index value by amounts equivalent to 186 mm and 98 mm more annual precipitation after two years, respectively (p < 0.01). Fixed effects (including site factors and land use history) had a greater effect, hence the design and implementation of government conservation policies should be context-based. Full article

Soil degradation is one of the most serious ecological problems in the world. In arid and semi-arid northern China, soil degradation predominantly arises from wind erosion. Trends in soil degradation caused by wind erosion in northern China frequently change with human activities and climatic change. To decrease soil loss by wind erosion and enhance local ecosystems, the Chinese government has been encouraging residents to reduce wind-induced soil degradation through a series of national policies and several ecological projects, such as the Natural Forest Protection Program, the National Action Program to Combat Desertification, the “Three Norths” Shelter Forest System, the Beijing-Tianjin Sand Source Control Engineering Project, and the Grain for Green Project. All these were implemented a number of decades ago, and have thus created many land management practices and control techniques across different landscapes. These measures include conservation tillage, windbreak networks, checkerboard barriers, the Non-Watering and Tube-Protecting Planting Technique, afforestation, grassland enclosures, etc. As a result, the aeolian degradation of land has been controlled in many regions of arid and semiarid northern China. However, the challenge of mitigating and further reversing soil degradation caused by wind erosion still remains. Full article