Browsing by discipline "Metsäekologia"

Rapid changes in the environment due to human actions have highlighted the need to better understand the functioning of ecosystems and the underlying mechanisms. Biodiversity and ecosystem functioning (hereafter, BEF) research has mainly concentrated on studying the effects of biodiversity on ecosystem functioning in experiments using grassland species. Moreover, the focus of these studies has been in determining how a single ecosystem process (e.g. productivity) is affected by the changes of biodiversity. Evaluating how the forest ecosystems’ successional gradient and species functional traits are related to each other still remains a major challenge for ecologists. The aim of this study was to find out the relations between different forest successional stages and plant species functional traits and if there were traits that were favoured along the successional gradient. This was investigated by using a direct plant species trait approach called the fourth-corner method. Also, the vertical vegetation structure of the successional stages was studied. The field measurements were conducted in 31 study sites in the southern boeal vegetation zone during summer 2011. The study sites were divided into three groups according to their successional stage and time since last management activities. Ten of the sites were young forests stands with normal management activities; eleven were mature stands that have had silvicultural activities (e.g. thinnings) within the last 25 years and the rest were also mature forest stands but without management activities since 1985. From these sites the understory vegetation was inventoried and general stand characteristics (e.g. mean height or the DBH of the living trees) were measured. Clear patterns of trait associations with the successional stages emerged from the analysis. The young stands were characterized with species that are shade intolerant, able to expand extensively also but also have abundant production of small seeds. These traits are typical for so-called pioneer species. Species traits associated with the mature, recently managed forests were chameaphytes with erect leafy stems and had a scarce seed production. For the mature nonrecently managed stands, a positive correlation was found for shade tolerant species. Species abundant in these stands had significantly longer seeds that were mainly dispersed by ants. Species occurring in these stands had also a semi-abundant seed production. The vertical vegetation structure showed, that the vegetation structure of both mature stands was similar and that the management activities could affect the natural successional trajectories. The results showed that the fourth-corner method could indeed give insight on which plant species functional traits are affected by environmental factors (such as forest succession or management activities). With this method it is possible for example to identify traits associated with valuable forest stands and practice forest management activities targeted in preserving the ecosystems’ key functions.

Conflicts are concern for the coexistence of wolves (Canis lupus) and humans, and injuries and deaths of domestic animals (i.e. depredations) are a concrete part of the conflicts. Even though wildlife researchers have studied characteristics, risk factors, and prevention methods of depredation for decades, the diversity and complexity of depredation phenomenon has ensured that there is still a long way to go before the knowledge and management of depredations reach a satisfactory level. The thesis is consisted of three parts that have a broader theme in the description of the depredation phenomenon from slightly different perspectives and so to serve the purpose of increasing the capacity of understanding and managing the depredation. The first part of the thesis gives a literature-based introduction to the problem of depredation and the factors that are likely to contribute to the depredation risk in general. The aim of the first part was to provide a foundation for the second and third parts. The second part of the thesis focuses on the large-scale depredation characteristics by surveying depredation records of Europe and North America via a literature review and personal data requests. The aims of the second part were to generalize the depredation characteristics on the large scale, to compare depredation datasets between study areas, and to study the relationship between depredations and possible large-scale explanatory factors of depredation. The third part of the thesis represents a collective study of wolf attacks on bear-hunting dogs in the states of Michigan and Wisconsin, US. The aim of the third part was to study the relationship between dog depredation rates and bear-hunting practices and to exemplify the benefits of the transregional research approach. The second part of the thesis represented depredation characteristics from 20 study areas in Europe and the US. Small- or medium-sized domestic animals dominated the depredation records. The percentages of depredated livestock stayed small. Sheep and goat depredations occurred more often than expected and bovine and equine depredations less than expected by the occurrence of the animals in the live population. The second part showed also that despite the large variability between the depredation datasets, the composition and number of depredations were geographically clustered. Europe was defined by extensive sheep and goat depredations whereas the US was defined by moderate bovine depredations. The results also showed that wolf abundance and domestic animal densities correlated significantly with the number of depredations and depredation rates (depredations/wolf) whereas the human population density and the forest and farmland coverages correlated less significantly with the depredation rates. The third part of the thesis showed that the depredation rates of bear-hunting dogs in Michigan and Wisconsin are partly influenced by the bear-hunting permits sold per wolf and hunter method. The greater dog depredation rates in Wisconsin compared to Michigan could be affected by the longer duration of bear-baiting and more concurrent timing of baiting with dog training in Wisconsin. The differences in the compensation schemes could also contribute to the differences in depredation rates between the states. In conclusion, the results of the second part indicated that some characteristics of depredation that have been previously identified on the more local scales are applicable also on the large scales. More research is needed to clarify the role of wolf abundance and domestic animal densities in determining the depredation likelihood on the large scales. The depredation records were highly variable in relation to the data collection procedures, and it would be important to set minimum standards for the depredation data. The depredation research and management should be improved also by increasing the transparency and availability of depredation records. The third part of the thesis showed how the differences in natural resources management between the states might have a significant role in defining depredation rates for hunting dogs. The study exemplifies well how the depredation research and management can benefit from the collection and distribution of depredation data across the administrative borders. As the depredation information hopefully increases in the future, the large-scale picture of the depredation characteristics across Europe and North America will also be further defined.