The Impact Of Spatial And Temporal Structure Of Agriculture Landscape On Plant And Arthropod Diversity

Farmland biodiversity provides the genetic and species resources, as well as biological control and pollination for agricultural production, but intensive agriculture is the main reason for the current global decline of biodiversity. Therefore, current agriculture is facing the most important challenge that how to protect biodiversity under the growing food needs with population growth. Landscape ecology has done much research to coordinate their relationship, but there are still some controversies and shortcomings. Firstly, the presence and strength of congruence in species turnover patterns, and the relative contributions of abiotic environmental factors and biotic interaction towards this congruence, remain poorly understood. Secondly, our current understanding of factors driving changes in the highly diverse species assemblages of mountainous agricultural landscape is generally limited. Especially the role of landscape scale factors, relative to the regional scale and plot scale factors that effect biodiversity. The impact of landscape structures on biodiversity are commonly based on the analysis between landscape and species data at the same time. Because the time lagged response of species, it requires comparing the influence of different period’s landscape structure on present species distribution pattern. Meanwhile, the most studies of the impact of the spatial landscape changes on biodiversity may not be a good substitute for the impact of temporal landscape changes on biodiversity changes.In view of the above problems, we have carried out the spatial and temporal research in Bashang, Hebei province and Qianjiang, Hubei province in China, respectively. In the Bashang area, four different altitudinal study sites were selected. Three habitat types were selected in each study site, with four replicates of each type for sampling of vascular plants, geometrid and arciinid moths, and carabid, and investigated environmental factors at different scales. Cross-taxon congruence in species composition turnover patterns and the relative effects of environmental factors at different scales on their species composition were analyzed. In the Qianjiang area, combined with the previous five period’s landscape maps and carabid and spider data, we re-sampled and analyzed the impact of landscape structure of different periods on biodiversity, and the imfluence of temporal landscape changes on temporal changes of carabid and spider diversity.In the spatial study of Bashang, there were significant cross-taxa congruences among the four species compositional patterns caused by the altitude gradient. Due to the vegetation structure and associated microclimatic condition provided favorable niche for the carabid, there was a strong cross-taxon congruence between vascular plants and carabid. Although moths and plants have a direct feeding relationship, moth assemblages appeared to be dominated by generalist species whose turnover was weakly associated with vegetation changes. The variations in the species composition of vascular plants and carabids were more closely linked to plot-level characteristics than to regional-level factors, while the opposite trend was observed for the two moth taxa due to the stronger flight. Overall, the variations in the species composition of different taxa can be explained by varying sets of environmental variables acting at different spatial scales, and the relative role of these variables is highly taxon-specific. Although the landscape extent of 100m × 100m is too small, the proportion of semi-natural habitat has a significant effect on plants and carabids. Thus, the effect of factors within landscape scale cannot be neglected.For the study of Qianjiang area at different temporal scales, we confirmed the time lag response as past landscape metrics independently affected species composition in 1995. Moreover, both past and present landscape structure simultaneously determined current species richness in 1995 or species composition in 2013. It was due to not only the correlation between past and present landscape, but also various time response process of different species to landscape change. Historically stable landscape structures and the recent dramatic changes in built area can explain the current pattern of species distribution. The coexistence of extinction debt and colonization credit implied the complicated process of species response to landscape change in time and space. Although built area increased from 6.3% in 1993 to 32% in 2013, the overall species richness did not decline. Urbanization had negative effect on large or brachipterous carabid, but the effects on small or macropterous species have been positive. In contrary to these adverse influences, the increase grassland significantly increased the species richness of predatory carabids. The change in semi-natural land proportion was also positively correlated with change in ratio of weaver spider individuals. Species composition of large, predatory or brachipterous carabid and weaver or large spider was more sensitive to landscape change than small, omnivorous or macropterous carabid and small or gourd hunter spider.Thus, the spatial and temporal pattern of agricultural landscape significantly affected the diversity of different farmland biological groups. The measures of multi spatial and temporal scale, such as considering the differences in environmental requirements of different species, arranging several protected areas in the large spatial scale, increasing the semi-natural habitats in the landscape scale, maintaining crop diversity and plant diversity in the plot scale, and considering landscape history, maintaining the landscape stability, increasing the semi-natural habitat in the suburbs around the city, and planning the appropriate patch size, need integrated to better protect the biodiversity, especially the specialist species in the agricultural landscape. Future studies of between agricultural landscape and biodiversity should take into account multi-taxa or multi-functional groups, multi-scale environmental factors, and the time lag of species response in dynamic agricultural landscape.