Year: 2014
Type: dissertation
Abstract: Under the current biodiversity crisis, there is the need to improve the conservation action. More areas need to be protected to curb biodiversity loss. Also, the methods for selection of both protected areas and management practices have to be well-informed in order to maximise the benefits from the limited resources allocated for conservation. However, because of limited information, decision making procedures are forced to use environmental variables and different species as surrogates of general biodiversity. Moreover, there is a bias towards charismatic and better known species like top predators. It is therefore important to forecast the consequences that favouring certain species might have on other organisms and to evaluate the effectiveness of preserving a subset of species. In this thesis I use empirical data to investigate how avian predators (the Northern Goshawk Accipiter gentilis and the Ural Owl Strix uralensis) associate to biodiversity. The focus is two-fold; First, I investigate the role of species interactions in dictating biodiversity patterns. I show that interactions within the predator assembly can have stronger effect on prey distribution (the Siberian Flying Squirrel Pteromys volans) than landscape attributes. This finding points out that individuals may be able to respond to changes in the structure of the predator assemblage. Additionally, I examine the impact of the Goshawk altering the structure of the forest bird community. I found that not only the raptor conditioned species distribution across space, but that this effect persisted over the years after the Goshawk abandoned the breeding site. Second, I evaluate the potential use of raptors as surrogates to indicate areas of relevant conservation value. On the one hand, I address how the two focal raptor species associate to different biodiversity metrics for birds and polypores (i.e. wood decaying fungi) over a landscape gradient. I found that, while both predator species indicated high biodiversity levels as compared to reference sites, the dominant Goshawk was superior to the Ural Owl. Interestingly, the surrogacy properties remained the same even if the environmental setting changed. On the other hand, I assess the value of preserving raptor nest sites in the context of the existing network of protected areas in the study region. I show that using goshawk nest sites is the most cost-efficient approach if considering only single species. However, combining both predator species further enhanced the conservation output. Concluding, this thesis highlights the idea that avian top predators have a key role on species distributions and shaping community heterogeneity in space and time. Given this disproportionate influence in ecosystems, apex predators might also merit extra conservation commitment. Furthermore, information on the spatial distribution of raptors can indicate, over large areas, locations of disproportional biodiversity value. I show that setting aside raptor nest sites is more cost-effective than other conservation approaches. Additionally, one has to consider that national-wide monitoring schemes already provide raptor nest locations at no extra cost. In the light of these results it is advisable to consider the use of raptors to complement existing and future reserve selection methods.
Source: Työväentutkimus Vuosikirja
Author: Daniel Burgas
Language: English
Topic: Avian ecology and behavior
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
SDG: Life on land
Open Access status: green
OpenAlex ID: W2380160154