Pasi Reunanen

Spatially dynamic forest management to sustain biodiversity and economic returns

Production of marketed commodities and protection of biodiversity in natural systems often conflict and thus the continuously expanding human needs for more goods and benefits from global ecosystems urgently calls for strategies to resolve this conflict. In this paper, we addressed what is the potential of a forest landscape to simultaneously produce habitats for species and economic returns, and how the conflict between habitat availability and timber production varies among taxa. Secondly, we aimed at revealing an optimal combination of management regimes that maximizes habitat availability for given levels of economic returns. We used multi-objective optimization tools to analyze data from a boreal forest landscape consisting of about 30,000 forest stands simulated 50 years into future. We included seven alternative management regimes, spanning from the recommended intensive forest management regime to complete set-aside of stands (protection), and ten different taxa representing a wide variety of habitat associations and social values. Our results demonstrate it is possible to achieve large improvements in habitat availability with little loss in economic returns. In general, providing dead-wood associated species with more habitats tended to be more expensive than providing requirements for other species. No management regime alone maximized habitat availability for the species, and systematic use of any single management regime resulted in considerable reductions in economic returns. Compared with an optimal combination of management regimes, a consistent application of the recommended management regime would result in 5% reduction in economic returns and up to 270% reduction in habitat availability. Thus, for all taxa a combination of management regimes was required to achieve the optimum. Refraining from silvicultural thinnings on a proportion of stands should be considered as a cost-effective management in commercial forests to reconcile the conflict between economic returns and habitat required by species associated with dead-wood. In general, a viable strategy to maintain biodiversity in production landscapes would be to diversify management regimes. Our results emphasize the importance of careful landscape level forest management planning because optimal combinations of management regimes were taxon-specific. For cost-efficiency, the results call for balanced and correctly targeted strategies among habitat types.

Aggregate dispersion of birds after encountering a predator: experimental evidence

Animals may join flocks to gain protection against predation. In this experiment we investigated how predation risk affects the spatial distribution of forest birds during breeding time. We manipulated the perceived risk of predation by showing stuffed avian predators and by playing the warning signals of some of the passerine species in experimental areas. The spatial distribution of the bird individuals in both experimental and control areas was investigated by censusing birds and marking the locations of all individuals on maps both before and after the simulated appearance of a predator. We predicted that the distances between heterospecific individuals would be reduced in the experimental areas compared with those in control plots because of a perceived increased risk of predation. After predator presentation individuals in experimental areas were closer to heterospecifics than in control areas. Predation risk is one possible cause of clumped distribution of species and mixed-species foraging flocks in boreal breeding bird communities.

Cost-effective strategies to conserve boreal forest biodiversity and long-term landscape-level maintenance of habitats

Setting aside parcels of land is the main conservation strategy to reduce the rate of biodiversity loss worldwide. Because funding for biological conservation is limited, it is important to distinguish the most efficient ways to use it. Here, we assess implications of alternative measures to conserve biodiversity in managed boreal forest landscapes. We calculated four alternative spatio-temporal scenarios and compared these to the current management regime over 100-year time period. In the alternative scenarios, a fixed amount of funding was invested in (1) permanent large reserves (each tens of ha in size), (2) permanent small reserves (each a few ha in size), (3) temporary small reserves (based on 10-year contracts with private land owners), and (4) green-tree retention (small groups of trees retained on clear-cuts). To assess biodiversity implications, we used habitat suitability indices to calculate overall habitat availability for five groups of red-listed and habitat-specific species associated with decaying spruce logs. The possibilities for timber harvests did not differ among the scenarios, but biodiversity performance was different. The scenarios with permanent reserves tended to outperform other scenarios, suggesting that conservation policies based on permanent reserves are the most cost-efficient in the long term. Results, however, varied among time scales and species groups. In the short term, a strategy of investment in temporary small reserves was the most efficient. Habitat for species associated with old spruce dead-wood and preferring shade was rare throughout all simulations, and therefore, it is likely that these species cannot be sustained in managed forests. Species that live on fresh dead-wood and are associated with forest edges coped well in all scenarios suggesting that such species will persist in managed landscapes without additional conservation efforts. Explicit definition of conservation objectives and time frames for conservation action are thus prerequisites for successful conservation planning.

The effects of small-scale disturbance on forest birds: a meta-analysis

Small-scale disturbance is a significant process in all major forest biomes. Some silvicultural practices, particularly group selection harvesting, intend to emulate natural small-scale disturbance by harvesting small clearcuts in the continuous forest. We conducted a meta-analysis on the effects of small-scale harvesting on North American breeding forest birds. We extracted species richness and relative abundance of several functional bird groups and guilds from published studies and compared them between gap-dominated and unlogged forest as a function of forest type and the size and age of the gap. The abundance of many bird groups was higher in the gap-dominated than in the continuous forest. Species preferring interior parts of the forest had the most negative association with the presence of gaps but this relationship was not statistically significant. Abundances of many bird groups increased with increasing gap size, while its effect on abundance of some bird groups disappeared quickly. Our review s...

Regional Landscape Patterns and Distribution of the Siberian Flying Squirrel Pteromys volans in Northern Finland

Distribution of the Siberian flying squirrel Pteromys volans in northern Finland, at the edge of its global range, is fairly distinctive: the species is apparently absent in the western part of the region (Pohjanmaa), occurs regularly in the central part (Koillismaa), and only sporadically further east closer to the Russian border (northern Kainuu). In this study, we examined landscape structure in these three regions using geographic information system (GIS) and multi-source land use and cover data to identify key characteristics in landscape structure that are linked to the observed distribution pattern of the Siberian flying squirrel in northern Finland. We analysed landscape structure by studying habitat type proportions in nature reserves and in large-scale landscape samples within the regions. In addition, landscape configuration and connectivity were analysed within larger landscape sample plots. Our results suggest that the observed distribution pattern is associated with natural patterns in landscape structure at local and regional scales. Open peat lands, bogs and non-forested habitats dominate the landscape in the western part of the region and possibly account for the absence of the Siberian flying squirrel. More subtle differences between the central and eastern parts of the region indicate regional scale landscape responses of the species. The relatively high amount of spruce-dominated mixed forests in the central part was associated with the regular occurrence of the Siberian flying squirrel, whereas the increasing dominance of pine forests towards the east was associated with the low number of sightings. Forest management history is much alike in the different parts of the region, but the effects of forest management on the actual range of the species cannot be estimated owing to a lack of knowledge on accurate population trends in northern Finland. However, human-caused fragmentation and large-scale habitat degradation may have long-term effects on the persistence of the species in northern Finland.

Spatial Context of Breeding Ponds and Forest Management Affect the Distribution and Population Dynamics of the Great Crested Newt

Intensive forest management and landscape degradation are threats to amphibian populations. We modelled and compared the extinction and colonization dynamics of the great crested newt in four different spatial contexts that describe landscape change from past to present and future forest landscapes in eastern Finland. In future landscape scenarios, we explored the effects of two forest use intensities with different logging rotation times. The introduction of fish into breeding ponds has been the main cause of local extinctions of the great crested newt. In the future, intensifying land-use and shorter logging rotation will decrease the connectivity between ponds the most. In conservation planning, more attention should be paid to the spatial arrangement of habitat patches, especially if the intensity of human impact will increase. Conservation effort must be targeted towards securing source ponds in the core area and towards enhancing connectivity.