<p>There has been a long-term decline in number of cyclic vole populations in boreal Sweden since the 1970s. Several hypotheses have been suggested to explain this decline. Commonly for <i>C. glareolus</i>, <i>C. rufocanus</i> and <i>M. agrestis</i>, the decline has followed upon an increased frequency and severeness of winter declines and has shown up as a drop in spring densities. The spring decline is most pronounced for <i>C. rufocanus</i>. In contrast to other voles, <i>C. rufocanus</i> also show a decline in fall densities, suggesting some additional disturbance in this species. Habitat fragmentation has been suggested as such an additional disturbance and in this thesis the effect of habitat fragmentation on <i>C. rufocanus</i> is explored.</p><p>At first the sampling method was evaluated i.e. whether the decline could be due to destructive sampling when the method in use in the long-term monitoring is snap-trapping. This resulted in a rejection of the destructive sampling hypothesis as a possible cause behind the decline in <i>C. rufocanus</i>. Habitat preference revealed that three habitats at the local scale (trap station) were high quality habitats for <i>C. rufocanus</i>: forest of moist and wet/hydric dwarf-shrub type, in addition to forest/swamp complexes rich in dwarf-shrubs. The occurrence of <i>C. rufocanus</i> at the landscape scale was positively correlated with the amount of boulder fields and a low degree of fragmentation of old-growth pine forests. There was considerable local variation in the decline in vole density among the 58 1-ha sampling plots, with respect to both density and timing of the decline, which suggested that habitat destruction outside sampling plots might be involved. Overall, clear-cuts had a negative influence on vole densities at both the local and landscape scale. A multiple regression analysis suggested that having both a high quality habitat at the local scale and a high proximity among xeric-mesic mires and a low connectivity among clear-cuts at the landscape scale were important for the occurrence of <i>C. rufocanus</i>.</p><p>Initial analysis at the landscape scale were based on landscape data collected from 2.5 x 2.5 km areas centred on the individual vole sampling plots. Further investigations, however, on the patch level suggest that focal forest patch size and quality was of major importance in determining occurrence and persistence of <i>C. rufocanus</i>. Although not tested formally in these studies, the habitat fragmentation hypothesis has so far received support. Currently <i>C. rufocanus</i> seems to be affected negatively by too low patch sizes of suitable habitats in the surrounding landscape suggesting that the amount of suitable habitats could already be below the fragmentation threshold. However, this has to be evaluated further. Work is in progress to establish time-series over local landscape changes, and to evaluate if such changes have been associated with local declines of <i>C. rufocanus</i> and whether habitat loss, true habitat fragmentation or both have been influential.</p>

There has been a long-term decline in number of cyclic vole populations in boreal Sweden since the 1970s. Several hypotheses have been suggested to explain this decline. Commonly for C. glareolus, C. rufocanus and M. agrestis, the decline has followed upon an increased frequency and severeness of winter declines and has shown up as a drop in spring densities. The spring decline is most pronounced for C. rufocanus. In contrast to other voles, C. rufocanus also show a decline in fall densities, suggesting some additional disturbance in this species. Habitat fragmentation has been suggested as such an additional disturbance and in this thesis the effect of habitat fragmentation on C. rufocanus is explored. At first the sampling method was evaluated i.e. whether the decline could be due to destructive sampling when the method in use in the long-term monitoring is snap-trapping. This resulted in a rejection of the destructive sampling hypothesis as a possible cause behind the decline in C. rufocanus. Habitat preference revealed that three habitats at the local scale (trap station) were high quality habitats for C. rufocanus: forest of moist and wet/hydric dwarf-shrub type, in addition to forest/swamp complexes rich in dwarf-shrubs. The occurrence of C. rufocanus at the landscape scale was positively correlated with the amount of boulder fields and a low degree of fragmentation of old-growth pine forests. There was considerable local variation in the decline in vole density among the 58 1-ha sampling plots, with respect to both density and timing of the decline, which suggested that habitat destruction outside sampling plots might be involved. Overall, clear-cuts had a negative influence on vole densities at both the local and landscape scale. A multiple regression analysis suggested that having both a high quality habitat at the local scale and a high proximity among xeric-mesic mires and a low connectivity among clear-cuts at the landscape scale were important for the occurrence of C. rufocanus. Initial analysis at the landscape scale were based on landscape data collected from 2.5 x 2.5 km areas centred on the individual vole sampling plots. Further investigations, however, on the patch level suggest that focal forest patch size and quality was of major importance in determining occurrence and persistence of C. rufocanus. Although not tested formally in these studies, the habitat fragmentation hypothesis has so far received support. Currently C. rufocanus seems to be affected negatively by too low patch sizes of suitable habitats in the surrounding landscape suggesting that the amount of suitable habitats could already be below the fragmentation threshold. However, this has to be evaluated further. Work is in progress to establish time-series over local landscape changes, and to evaluate if such changes have been associated with local declines of C. rufocanus and whether habitat loss, true habitat fragmentation or both have been influential.

Magistro darbe tiriama pušies ir eglės kirtaviečių paklotės nariuotakojų kompleksų sukcesijos skirtingo ūkininkavimo sąlygomis Darbo objektas - Dubravos eksperimentinėje mokomojoje miškų urėdijoje (EMMU), Vaišvydavos g-joje 2006 m įrengtų 8 tyrimo barelių nariuotakojų kompleksai. Darbo metodas – statistinis nariuotakojų kompleksų tyrimas naudojant Barberio žemės gaudykles. Darbo rezultatai – Atliekant tyrimus nustatyta, kad Iš viso rasta 15 skirtingų nariuotakojų būrių ir klasių atstovų: du iš jų tinklasparniai (Neuroptera) ir blusos (Siphonaptera), rasti tik eglės kirtavietėje, be to blusos pirmą kartą rastos tik 2009 metais. Rasta ir 3(R) - retos rūšyss didysis puošniažygis (Carabus coriaceus) ir žalvarinis puošniažygis (Carabus nitens). Visų sistematinių grupių išskyrus Coleoptera, Aranei, Hemiptera, Orthoptera ir Blattoptera atstovų buvo aptikta daugiau eglyno barelyje, tai rodo, kad pušyno barelis turėjo geresnes sąlygas minėtiems nariuotakojams. Akivaizdūs paklotės nariuotakojų dominantai yra vabalai (Coleoptera), jų rasta virš 27 tūkstančių (2009 m.), jie užima ir daugiausia skirtingų gyvenamų nišų ir trofinių grupių.Visais 2009 metų tyrimų mėnesiais, išskyrus rugsėjį, didžiausias nariuotakojų skaitlingumas buvo eglės kirtavietėje. 2006-2009 metais didžiausias skaitlingumas buvo eglės kirtavietėje, o 2009 metais aptiktų nariuotakojų gausa pasiekė maksimumą. Didžiausias paklotės nariuotakojų skaitlingumas buvo miško bareliuose, mažiausias skaitlingumas buvo tuose... [toliau žr. visą tekstą] / Master thesis examined pine and spruce clear - cut litter arthropod complex succession of different forestry conditions Object of the work - Dubrava experimental teaching forestry enterprise (ETFE) Vaišvydava forestry in 2006 installed eight study plots arthropods complexes. Method of the work- statistical analysis of arthropod complexes using Barber ground traps. The results of the work - The study found that there were found 15 different classes of arthropods, and teams of representatives, two from the Neuroptera (Neuroptera) and flea (Siphonaptera), finding only in spruce clear - cut also flea first was discovered only in 2009. And there were found 3 (R) - rare species, the great ground beetle (C. coriaceus) and bronzed ground beetle (Carabus nitens). All systematic groups except the other than Coleoptera, Arana, Hemiptera, Orthoptera and Blattoptera were discovered more in spruce plot, which shows that the pine forest plot had better access to those arthropods. Obvious litter arthropod dominants are beetles (Coleoptera), they were found over 27 thousand (2009), and they occupy the most different niches and trophic groups. All months of 2009 trials, with the exception of September, had the highest levels of arthropods were in spruce clear - cut. In the period of 2006-2009 had the highest levels in spruce clear - cut, and in 2009 arthropod abundance reached a maximum. The highest number of litter arthropods was in forest plots, the lowest number was in those plots that had... [to full text]

Grigaitis V. 2004. The forest community dynamics in the edges of different age of Vaccinio - myrtillosa pine forests. The Master thesis / superwisor doc. dr. V. Marozas. LŽŪU, Akademija, 98 p.: iliustr. 52. SUMMARY The purpose of work: to study the appearing of the edge effect among cuttings and neighboring with them mature stands by performing clear - cuts in site in the red whortleberry - whortleberry pine forests; the meaningful influece of the edge effect for cuts and the correlation of forest community components of mature stands: for the sprouts of ligneous plants, moss and lichen, herbal plants, underbrush and understorey, the canopy cover in respect of time and space. The subject of work: Kačerginė forest district of Dubrava Forest Enterprise, the forest array of Zapyškis, pine forests of Vaccinio - myrtillosa site types. The total area of the forest district is 2414 ha, of which the forest array of Zapyškis covers 1568 ha. The object is in the Northeastern part of Middle Europe geographically, in regard to plant formation - in the Europe mixed up - forests zone, from the point of geomorphological view forest reserve belongs to East Europe west side part plaines. The methods of work: for the research in pine forests of Vaccinio - myrtillosa site types were sampled five clear - cut tracts of different cut age, neighboring with conditionally of the same age pine stands of Vaccinio - myrtillosa site types. In the each cut and mature stand group( in the couple)... [to full text]

Forest clearings can potentially be an important resource for pollinators. Land use history has previously been shown to be important for the number of species and individuals of butterflies in clearings, with a larger number where it historically was meadows, even after a generation of production forest. Plant species richness has also been shown to be influenced by land use history. In this study, pollinators were collected with pan traps on clear-cuts that had at least one generation of production forest, which in the 1870s was either meadow or forest. The results showed that there was no difference in species numbers and individual number between the two types of clear-cuts when it comes to Bombus spp, Syrphinae spp, Lepturinae spp, Cetoniidae spp and Trichius spp. The result is surprising because there is a greater frequency of herbs in clearings that previously had been meadow and the expectations was therefore that there should be more pollinators there. There are indications that the catchability when it comes to the pan trap method is inversely proportional to the floral richness, and the lack of differences could therefore be due to sampling bias.

The aim of this thesis was to investigate the processes behind an unexpected runoff behaviour after a clear-cut in a boreal forest in northern Sweden (Balsjö). The risks of increased flooding, erosion, nutrient leakage and changes in the local ecosystems are some reasons why it is important to fully understand the effect of clear-cuts on the water balance. In northern boreal forests the snow is of great importance as it results in the main hydrological event of the year, the spring flood. In general, open areas accumulate more snow, have a lower evapotranspiration and therefore maintain a higher runoff than a forest. In a recent paired catchment study at Balsjö the expected pattern after a clear-cut was only shown in three out of five years (2007-2011). The expected increase in runoff did not occur in 2010 and 2011. Two hypothesized alternatives were year-to-year variation of ET or changes in soil water storage. In order to investigate this further the rainfall-runoff model HBV was used. First, the model was calibrated for the forest catchment (Ref) and the clear-cut catchment (CC), using observed data from Balsjö. To account for parameter uncertainty the calibration was performed using parameter optimization, resulting in 100 different parameter sets. Model results were evaluated using observed snow data from Balsjö and ET from Flakaliden, a nearby forest. Both the simulated snow and ET were quite consistent with the observed values. Finally the annual and the spring water balance were studied, using the simulated data. The simulated results did not detect the unexpected runoff behavior for the two years as clearly as the observations. The reason for this was that the model was calibrated for all five years, which meant that annual variations were not taken into account. The hypothesis, that higher ET could be the reason for the unexpected runoff behavior, could neither be dismissed nor confirmed by this thesis. This was because there were no observed data for the clear-cut area and limitations within the HBV model, which meant that sublimation and interception processes could not be analyzed separately. The model results indicated that the change in soil water storage was a more likely explanation for the unexpected runoff behavior. The simulation result showed that the meltwater was stored in the soil water storage. However, this theory does not seem likely since a clear-cut is normally wetter than a forest. The results of this thesis are consistent with other studies as they indicate that clear-cut effects should be studied seasonally as well as annually. The special feature of this thesis was the opportunity to study observed ET and investigate its influence on the water balance.

The aim of this thesis was to test and evaluate whether parameter regionalization of a hydrological model can be used to model the impact of forest clearcutting on streamflow in Sweden. This is an important task to be able to perform water management and impact assessments adequately. The HBV conceptual rainfall-runoff model was applied for 218 Swedish catchments of different sizes that were spread across the country and covered a wide range of different forest cover percentages. The modelling approach included calibration of the model for each catchment using a genetic algorithm and then associating the resulting optimal parameter values with the percentage of forest cover. The obtained relationship between different model parameters and forest cover was validated with help of a paired catchment study site in northern Sweden where a clear cut was done in 2006: calibrated optimal parameter sets of pre- and post-clearcutting conditions were compared to parameter sets obtained from the Sweden-wide analysis. Correlations were found for about half of the fifteen hydrological model parameters, but the validation with the paired catchment study site could only partially confirm these obtained relationships. The results suggest that the adopted parameter regionalization approach is too basic. However, some of the results seem promising and emphasize the need for further research and development of the approach to provide a more reasonable method to model the impact of forest clearcutting on streamflow. / Det huvudsakliga målet med detta examensarbete var att testa och utvärdera om parameterregionalisering av en hydrologisk modell kan vara en lämplig metod för att modellera och kvantifiera påverkan från skogsavverkning på vattenbalansen i Sverige. Detta är en viktig uppgift för att kunna hantera våra vattenresurser och utföra konsekvensanalyser på ett tillfredsställande sätt. En konceptuell hydrologisk modell tillämpades på 218 avrinningsområden av olika storlekar och som var geografiskt utspridda i hela Sverige där även andelen skog i avrinningsområdena hade ett brett spektrum. Den använda modelleringsmetoden innefattade kalibrering av varje avrinningsområde genom att använda en genetisk algoritm, varefter de optimala parametervärdeana korrelerades mot andelen skog i avrinningsområdet. Idén med denna metod är att använda dessa potentiella samband för att justera modellparametrarna och därmed simulera en skogsavverkning. De erhållna sambanden mellan modellparametrarna och skogstäcket validerades med hjälp av data från en försöksstudie i norra Sverige där en skogsavverkning gjordes under 2006. Skillnaden mellan de bäst fungerande parametervärdena före och efter skogsavverkningen jämfördes med de tidigare sambanden från andra avrinningsområden i Sverige. Signifikant korrelation hittades för ungefär hälften av de 15 hydrologiska modellparametrarna, men valideringen mot den riktiga skogsavverkningen kunde bara delvis bekräfta de erhållna sambanden. Resultaten visar att detta sätt att använda parameterregionalisering antagligen är för grundläggande. Vissa resultat är ändå lovande och fortsatt forskning och utvidgning av metoden är nödvändig för att kunna tillhandahålla en rimlig metod för att kvantifiera en skogsavverknings effekter på vattenbalansen.

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