Geodiversity underpins biodiversity but the relations can be complex: Implications from two biodiversity proxies

Geodiversity incorporates many of the environmental patterns and processes that are considered determinants of biodiversity. However, research on the spatial relations between geodiversity and biodiversity at large regional scales is challenging because estimating biodiversity from field data is usually time consuming and costly. Satellite image textural measures and landscape metrics have been reported as powerful tools and proxies to characterize regional biodiversity. The goal of this study is to explore the spatiotemporal variations in two different biodiversity proxies and their spatial relations with geodiversity in Loess Plateau, China. Geographically-weighted spatial correlation was used to characterize the non-stationary spatial relations between geodiversity and the two proxy measures. The results showed that textural measures and landscape metrics exhibit different features of the spatiotemporal variations, highlighting their complementarity and consequent relevance in conjoint application. Trend analysis of the textural measures during 2000-2015 indicated that habitat heterogeneity increased in most of the region (39.87-62.41%), particularly in the central and southwestern areas. Nonetheless, the landscape metrics decreased in the central and southwestern region (38.14-71.94%), particularly in the Ziwuling and Huanglong forest area and part of Gansu province. The magnitude and direction of the relations between geodiversity and the two biodiversity proxies were context-dependent and varied spatially. Despite the contrasting direction in the relations between geodiversity and textural measures/landscape metrics in the southeastern region, stronger relations indicated by greater absolute value of the correlation coefficient were found in human-dominated areas than those in other areas. Informed by these results, we recommend focusing primarily on the humandominated landscapes and the areas with high geodiversity to promote conservation planning with geodiversity and biodiversity as equal, interrelated concepts.