Plant species richness patterns along a gradient of landscape modification intensity in Lower Saxony, Germany

Several concepts of landscape modification, landscape naturalness and hemeroby have been put forward to quantify the extent of human activities and impact on landscapes. However, despite numerous studies on the human influence on landscapes, the relationship between these concepts and biodiversity has rarely been tested. On a grid of 1386 lat/long cells (landscape units, c. 30 km2) we used simple information on land cover and easily measurable landscape metrics to identify a gradient of landscape modification for the model region of Lower Saxony, Germany. We linked the gradient of landscape modification intensity to richness patterns of eight groups of vascular plants that were aggregated using residence and threat status and habitat preferences of the species. Using k-means cluster analysis a gradient of six landscape modification levels ranging from highly-fragmented urban landscapes to little-fragmented landscapes with large proportions of forest was followed. Richness of the eight species groups considered in the analysis differed significantly along the gradient. For the total and native species pools, for forest, low-nutrient indicating and threatened plants richness peaked at both ends of the modification intensity gradient. For neophytes, urban plants and high-nutrient indicators, richness decreased along the gradient from urbanised to less modified landscapes. Due to its simplicity and coarse scale, our approach may easily be applied to other study areas without comprehensive data on land cover. Furthermore, following proper interpretation by experts, it can be used to identify and preselect priority landscapes for nature conservation planning.