Identifying Climatic Refugia by Integrating Continuous Heterogeneity and Discrete Classifications of Variables

Abstract

Climate diversity is essential for safeguarding biological diversity against climate change. Two planning approaches based on continuous heterogeneity or discrete classification have previously been implemented to identify climatic refugia. However, little is known about the performance of the integration of the 2 measurements for identifying climatic refugia. Using the case of Yunnan in southwest China, we examined the relationship between 2 measurements of climatic heterogeneity: the continuous climatic heterogeneity index (CCHI) and the variety of climatic units (VCU). We then identified climatic-heterogeneity refugia focusing only on CCHIs and the comprehensive climate-diversity refugia integrating CCHIs with the rarity and endemism of climatic units. Last, we assessed the coverages of these 2 sets of refugia for current high conservation-value areas, indicated by 5 existing biodiversity priority conservation area (PCA) schemes. The composite-CCHI and VCU demonstrated substantial different distributions, and the climatic heterogeneity level assessed by VCU was higher than that of composite-CCHI. The composite-CCHI levels were significantly positively correlated with the coverage percentages of the 5 PCAs. The Jaccard similarity index between climatic-heterogeneity refugia and climate-diversity refugia at a 30% conservation target was 0.26. The climate-diversity refugia coverages for the 5 biodiversity PCAs were consistently higher than those of climatic-heterogeneity refugia. Existing nature reserves covered 18.6% of the 5% climate-diversity refugia. Our analyses suggest that CCHI is more effective than VCU in revealing climatic heterogeneity and indicating current high conservation-value areas. Integrating continuous climatic heterogeneity with the rarity and endemism of climatic units serves as an optimal approach for identifying climate-diversity refugia.