Emergy-based sustainability assessment of forest ecosystem with the aid of mountain eco-hydrological model in Huanjiang County, China

Comprehensive recognition and evaluation of ecosystem development are fundamental for sustainable decision-making and nature conservation. Using Huanjiang Maonan Autonomous (also named Huanjiang) County-a typical karst mountainous region as example, by coupling the emergy analysis and the mountain eco-hydrological model (MECH), the most suitable vegetation coverages for forest ecosystem sustainable development are obtained in different economic development levels. The results showed that the emergy of renewable resources (R), non-renewable resources (N) and economic feedback input (EFI) accounted for about 69.8%, 12.7%, and 17.5% of the total emergy (U) respectively from 2000 to 2015. Even though the forest ecosystem of Huanjiang maintained sustainable developing tendency; the decrease of the ratio of renewable resources emergy (R) to total emergy (U) resulted in the decrease of emergy self-support ratio (ESR), emergy yield ratio (EYR) and emergy sustainability index (ESI), which may threaten the system sustainability. The increase of vegetation coverage reduced soil loss and total runoff, increased economic feedback input. As the results, the renewability (R/U) and emergy investment ratio (EIR) presented an increase trend, while the emergy self-support ratio (ESR), emergy yield ratio (EYR) and environment loading ratio (ELR) showed a tendency of decrease. The system sustainability will reach the optimal state when the vegetation coverage increased by 30%, 20%, and 10% if the GDP value of the county in the future as those in the 10th, 11th, and 12th Five-year Plan in China. Coupling the emergy analysis and mountain eco-hydrological model provides a new approach to understand the harmonious development between forest ecosystem and human beings. (C) 2019 Elsevier Ltd. All rights reserved.