Spatiotemporal monitoring of rare and elusive saproxylic beetles - A pheromone based approach

Sammanfattning: Forest ecosystems are under severe pressure from global environmental changes and increasing demands of wood-related products. During the last century, intensified management regimes have led to the decline of many previously common forest habitats, with catastrophic effects for biodiversity. Many saproxylic beetles, which often play important roles as decomposers and food sources in natural ecosystems, are suffering population declines due to the losses and degradation of their forest habitats. As many of the species have become increasingly rare, or appear cryptic and elusive, it is often challenging to study their genuine distributions and habitat demands. In recent years, pheromone-based methodologies have begun to be applied for surveying such rare and threatened insects. In this thesis, I first identified the aggregation-sex pheromone components of three saproxylic beetles of Swedish conservation interest. In a second step, I utilised pheromone-based trapping methodologies to investigate how beetles with varying substrate and habitat demands fare in the Swedish forest landscape. By setting up large-scale monitoring studies across their distribution ranges in Southern Sweden, I was able to evaluate both their spatial and temporal population fluctuations. My results reveal large variability in species’ responses to modern forestry practices, seemingly dependent on differences in their spatiotemporal ecology. Through the high accuracy sampling, I was significantly able to alter our perception of the presence and abundance of several species within their distribution ranges. Overall, this work demonstrates the need for efficient monitoring methodologies for conservation of forest biodiversity.

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