Identification and optimization methods for delineating ecological red lines in Sichuan Province of southwest China

Abstract

Ecological red lines (ERLs) are one of innovation regional ecological management systems, and a major strategy of construction of ecological civilization of China. Assessments of ecosystem services and the ecological sensitivity of the environment are the conventional methods for ERL delineation, which cannot quickly identify protection patterns, and also lacks the recognition of geological and geographical processes mechanism and influencing factors of ERLs. However, this omission may lead to inaccurate ERL delineation in mountainous areas. This study constructed an ecological–geological (eco–geo) environment vulnerability assessment index system to quickly identify protection patterns and optimize conventional ERL, taking Sichuan Province of Southwest China as the study region. The results showed that the conventional ERL covered 148,000 km2, accounting for 30.45 % of the total area. The extreme and severe vulnerability areas in the eco–geo environment together covered 189,700 km2, accounting for 39.10 %. The conventional ERL was almost completely included in the extreme vulnerability zone. Two optimization methods were analyzed by overlaying the vulnerability zone (extreme/extreme and severe) on nature reserves and the conventional ERLs. The first scheme covered an area of 188,600 km2 and 238,400 km2 for extreme and extreme and severe vulnerability, respectively; this reflected a more comprehensive vulnerability and protection pattern. The second scheme covered 197,600 km2 and 241,700 km2 for extreme and extreme and severe vulnerability, respectively, and could rapidly identify the vulnerability zones and protected areas. The study found that the geological and geographical processes in mountainous areas were the key factors shaping the ERLs. The assessment and the two schemes on provincial scale were practical, referential for similar mountainous area of China, and also be applied to other scales, serving the comprehensive management of ERL and the regional ecological security.