Building ecosystem services-based ecological networks in energy and chemical industry areas

The massive utilization of fossil energy by humans has promoted socio-economic development. However, it has also generated severe regional eco-environmental problems, including water shortage, soil erosion, and land desertification. An optimal ecological-network-based regulation of eco-environmentally damaged areas is necessary to balance economic development with rigid eco-environmental constraints in pursuit of sustainable regional development. Using remote-sensing, meteorology, land use, and soil data of energy and chemical industrial areas in the mid-upper reaches of the Yellow River, we quantitatively evaluated the related ecosystem services (ESs) by applying InVEST, CASA, and RWEQ models. Additionally, we constructed ecological conservation networks comprising ecological source areas, resistance surface, corridors, and nodes. The results are as follows. First, from 2000 to 2020, the areas of cultivated and unused land decreased, but those of forest, grassland, water bodies, and construction land increased. Regarding spatial distribution, the proportion of grassland was the highest, followed by unused land, and other types of land accounting for a relatively low proportion. Second, from 2000 to 2020, all ESs and the overall ecosystem improved. However, ESs demonstrated a clear spatial heterogeneity (i.e., better in the southeast than in the northwest). Third, comparing the two ecological networks constructed by minimum cumulative resistance (MCR) and circuit models, the MCR-based ecological network was considered better because of its higher epsilon, theta, and sigma values. Robustness analysis also showed that the MCR-based ecological network was more stable. Finally, ecological source areas of 110,300 km(2) were obtained, accounting for 21.69 % of the study region. Ecological resistance was relatively high in desert areas, which are to the northwest of the study region, and relatively low in the southeast. Fifty-nine ecological corridors (including 31 important ones) and 22 ecological nodes were extracted. The finalized ecological network was diamond-shaped, with the ecological source areas in four directions (i.e., east, south, west, and north) of the study region being closely connected. To promote the spatial optimization of the study region, appropriate measures (e.g., afforestation and soil improvement) must be taken to reduce regional imbalance in ecological condition, improve ecosystem functions and landscape connectivity, reduce various resistance, and ultimately promote conservation outcomes.