Habitat effects on the breeding performance of three forest-dwelling hawks

PLoS ONE 10(9): e0137877Habitat loss causes population declines, but the mechanisms are rarely known. In the European Boreal Zone, loss of old forest due to intensive forestry is suspected to cause declines in forest-dwelling raptors by reducing their breeding performance. We studied the boreal breeding habitat and habitat-associated breeding performance of the northern goshawk (Accipiter gentilis), common buzzard (Buteo buteo) and European honey buzzard (Pernis apivorus). We combined long-term Finnish bird-of-prey data with multi-source national forest inventory data at various distances (100–4000 m) around the hawk nests. We found that breeding success of the goshawk was best explained by the habitat within a 2000-m radius around the nests; breeding was more successful with increasing proportions of old spruce forest and water, and decreasing proportions of young thinning forest. None of the habitat variables affected significantly the breeding success of the common buzzard or the honey buzzard, or the brood size of any of the species. The amount of old spruce forest decreased both around goshawk and common buzzard nests and throughout southern Finland in 1992–2010. In contrast, the area of young forest increased in southern Finland but not around hawk nests. We emphasize the importance of studying habitats at several spatial and temporal scales to determine the relevant species-specific scale and to detect environmental changes. Further effort is needed to reconcile the socioeconomic and ecological functions of forests and habitat requirements of old forest specialists.Peer reviewe

Simulation of hydraulic disturbances caused by the decay heat of the repository in Olkiluoto

The hydraulic disturbances caused by the decay heat of the repository was studied by a transient simulation of groundwater flow, solute transport and heat transfer. The three phenomena were coupled due to the dependence of density of water on salinity and temperature, and the dependence of viscosity of water on temperature. The construction and operation of ONKALO and repository was not taken into account in the simulations, but the whole tunnel system to a depth of 520 metres was made hydraulically active at the beginning of the simulation and was assumed to be open for 100 years. The simulations continued for 2000 years after present. The results show that the decay heat of spent nuclear fuel rises the temperature of the repository and the surrounding bedrock several tens of degrees for many centuries. During the first 100 years the open ONKALO tunnels dominate the flow conditions in the vicinity of the repository and draw groundwater from all directions in the bedrock. After the closure of the tunnels the temperature rise induces an increasing upward groundwater flow, which for hundreds of years delays the recovery of the flow conditions towards the natural state and rises the salinity of groundwater in the vicinity of the repository