Turning points of ecological resilience: Geostatistical modelling of landscape change and bird habitat provision

Due to field enlargements and removal of landscape elements, intensification of agricultural management is frequently related to the alteration of the landscape structure and composition of elements, resulting in a decreased ecological capability. This study presents a spatially explicit probabilistic approach to model and analyse the effect of landscape elements removal on landscape connectivity and heterogeneity in a case study in North-Eastern Germany. Simulation of stepwise removal of tree elements as potential landscape changes is applied to assess resulting impacts on the related ecological habitat function for the red-backed shrike (Lanius collurio), a representative farmland bird species. The analysis of variograms' parameters identified a turning point in landscape structure constellation, occurring at a removal of nearly 50% of the tree elements, in correspondence of a 21% reduction in heterogeneity and a 20% reduction in elements connectivity. In terms of habitat provision, the turning point appeared at a shifted level, corresponding to a 50% reduction of connectivity, resulting from a ca. 75% reduction in spatial variability. It is argued that at the turning points the agricultural landscape would reach the limits of its resilience in terms of the habitat function associated to the removed elements. Results, displayed as probability maps, highlight that a high probability of tree elements occurrence is not always coupled with a high probability of habitat provision. The approach offers planners the possibility to identify structural and functional resilience thresholds for the management of multifunctional agricultural landscapes.