Spatio-temporal infestation patterns of Ips typographus (L.) in the Bavarian Forest National Park, Germany

Abstract

The Bavarian Forest National Park in Germany has experienced infestations of bark beetle (Ips typographus L.) since the 1980s, resulting in considerable ecological loss due to the destruction of almost 5800ha of spruce forests. Although there have been numerous investigations on the physiology and ecology of the bark beetle, until now the spatio-temporal infestation and dispersal dynamics of the bark beetle over a longer period have still not been satisfactorily understood. The understanding of the structure and the dispersal of bark beetle infestations is however of significant importance for forest management systems in order to predict the risk of outbreaks, especially in the face of climate change.The aim of this investigation was therefore (I) to analyse and describe the long term spatio-temporal infestation patterns of I. typographus in the Bavarian Forest National Park, Germany on the landscape scale, (II) to conduct investigations on spatio-temporal shifts of the focal points of bark beetle infestations from 1988 to 2010 and (III) to compare the quantitative spatio-temporal infestation patterns obtained at the landscape level with the dispersal patterns of the spatially explicit agent-based simulation model (SAMBIA) for I. typographus (Fahse and Heurich, 2011).The results of the study show that a shift in the infestation pattern of I. typographus from 1988 to 2010 occurs at different time intervals both undirectionally as well as directionally. Furthermore, the dispersal pattern of the bark beetle was recorded quantitatively and described extensively over a period of 23 years on the landscape scale.The quantification of the presence and dispersion pattern of I. typographus in the Bavarian Forest National Park allows us to gain a better understanding of the distribution pattern of the bark beetle on the landscape scale. In this way, both the pattern and structure of infestation patterns obtained for I. typographus serve as: (a) a basis for the criteria to improve the parameters of spatio-temporal simulation models, (b) a better understanding of the bark beetle pattern and existing processes such as disturbance patterns or damage patterns in the food web of spruces due to climate change, (c) a test for the hypotheses on the relationships between the presence of bark beetle and relevant habitat variables as well as (d) the compilation of forecast models on the dispersal of bark beetle. These predictions can help with the implementation of specific management strategies to prevent the dispersal of bark beetle.