Effect of present and past landscape structures on the species richness and composition of ground beetles (Coleoptera: Carabidae) and spiders (Araneae) in a dynamic landscape

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English. Species diversity may have time-lagged responses to landscape changes, but whether species are more strongly related to present or past landscape could vary with the taxa or functional traits. In this study, the effects of present and past landscape structures on carabid and spider communities were investigated. We hypothesized that present landscape structure was more highly correlated to small, omnivorous or macropterous carabids and small or ground-hunting spiders, while past landscape structure was more highly correlated to large or predatory carabids and large spiders. We analyzed landscape data from 1955, 1977, 1984, 1993 and 2013 and species data from 1995 and 2013 within the suburb of Qianjiang, a city in China. We found that both past and present landscape metrics affected present species richness in 1995 and species composition in 2013 due to the correlation between past and present landscape metrics. The time delay or immediate response of species was species-specific and not dependent on different groups in relation to body size, wing morphology, dietary preference or foraging method. The stable landscape structure from 1984 to 1993 had the greatest impact on species richness in 1995. In addition, the semi-natural land without dramatic changes since 1977 significantly affected the carabid species diversity. In addition, the excessive increase in building lands from 1993 to 2013 also significantly affected species composition in 2013. Our studies suggested that both historical and present landscape structures, the magnitude of land use change and each species' traits should be the focus of biodiversity conservation activities.