Preliminary assessment of ecosystem risk based on IUCN criteria in a hierarchy of spatial domains: A case study in Southwestern China

World ecosystems are suffering great losses from anthropogenic and natural pressures. To meet the demand of ecosystem-level risk assessment for biodiversity conservation, the IUCN has adopted a global standard to assess the risk to ecosystems. The IUCN Red List of Ecosystems (IUCN RLE) is a growing tool to raise the public awareness of ecosystem conservation and provide reasonable strategies to managers. As for managing ecosystems with the RLE, the spatial information of degraded patches is important for the efficient allocation of conservation resources. In this paper, a method for assessment across hierarchy of spatial domains was designed to provide spatial information for the IUCN RLE. 105 natural ecosystems of vegetation in Southwestern China were systematically assessed at the hierarchy of spatial domains. According to the results, the declining distributions of most ecosystems have slowed down recently due to protection policies. All vegetative ecosystems containing nationally protected species are threatened, supporting the robustness of this protocol. Limited distributions and degradation in area are the key risk to threatened ecosystems, as threatened ecosystems account for only 1.55% of the total area and the mean of its degradation in area is almost 45%. With the assessment in the hierarchy of spatial domains, the IUCN RLE was featured with spatial information of degraded patches. The hierarchical assessment markedly improved the practical applications of RLE and led to an efficient allocation of conservation resources. The scale effect of hierarchical assessment was significant and the representativeness of ecosystems in systematic assessments is extremely valuable.