Anthropogenic change in the Great Plains of North America within the past two centuries has facilitated extensive woody encroachment by eastern redcedar (Juniperus virginiana, hereafter redcedar). Conversion of grassland to redcedar woodland occurs rapidly as a result of the interaction between changing disturbance and land use patterns. In addition, redcedar encroachment causes compositional shifts in grassland floral and faunal assemblages, and may alter abiotic factors such that grassland restoration efforts are limited. The objectives of this study were to: 1) track vegetation and faunal assemblages in grasslands along a gradient of redcedar encroachment, 2) assess the capacity for experimental tree removal to promote re-colonization of grasslands by associated flora and fauna, and 3) examine the influence of scale on spatial relationships between small-mammal abundance and redcedar cover. During the first phase of my study, I examined herbaceous vegetation, woody vegetation, and small-mammal assemblages at grassland sites along a redcedar encroachment gradient in north-central Oklahoma. I noted hump-shaped trends in the capture rate, species diversity, and species evenness of small mammals along the redcedar encroachment gradient. In addition, higher levels of encroachment were associated with compositional shifts from grassland- to woodland-associated small mammals. Characteristics of the small-mammal assemblage along the gradient corresponded to increases in redcedar cover and the frequency of episodic management events within the past two decades. Experimental redcedar removal during the second phase of my study generally increased vegetation and faunal diversity in 2 years following treatment, and treatment sites having the highest pre-treatment levels of redcedar cover exhibited the greatest responses to tree removal. The results of my study suggested that within the time frame I examined, redcedar encroachment had altered the biotic characteristics of this system, but did not facilitate abiotic shifts capable of constraining rapid grassland recovery. Tree removal also appeared to modulate the effects of consecutive drought and flood years on small-mammal diversity during post-treatment. During the third phase of my study, I examined the strength of association between differences in percent redcedar cover and spatial abundance patterns of 4 common small-mammal species. I examined small-mammal abundance at three relatively small spatial scales (38, 154, and 616 m2) to determine how redcedar-mammal associations were stronger with increases in spatial scale. In addition, I determined whether the influence of spatial scale on redcedar-mammal associations varied along a gradient of redcedar encroachment. The strength of redcedar-mammal associations increased with spatial scale, but was strongest at sites having the lowest levels of encroachment. These results corresponded to variation in the spatial distribution of redcedar cover and compositional differences in the small-mammal species assemblage along the encroachment gradient. Studies examining the effects of woody encroachment will extend our understanding of successional processes and ensure that appropriate management is implemented in the conservation of these imperiled grassland ecosystems.

Siktröjning är en viltolycksförebyggande åtgärd som används för att skapa bättre siktförhållanden för trafikanter och djur genom att gallra träd och röja sly längs vägkanten. Förutom ökad sikt medför även åtgärden att vägen torkar upp snabbare eftersom att solstrålarna når vägen bättre när skymmande träd avlägsnas. En siktröjning kan utformas som en total avverkning eller en utglesning av skogen i vägkanten och bedöms minska risken för viltolyckor med ca 23%. Riksväg 25 går mellan Kalmar och Halmstad och mellan orterna Eriksmåla och Lessebo i Kalmar och Kronobergs län har väg 25 en standard som inte betraktas vara god i förhållande till trafikeringen som råder på vägen. I framtiden förväntas därför vägsträckan breddas och byggas om till en mötesseparerad väg. Eftersom detta beräknas ske längre fram i tiden spekuleras det kring om en tillfällig säkerhetshöjande åtgärd kan genomföras fram till ombyggnationen. Syftet med denna studie var att utreda om och hur en siktröjning hade kunnat genomföras på den här sträckan samtidigt som det skulle göras en avvägning mellan andra viltolycksförebyggande alternativ som främst inriktades på viltstängsel.I undersökningen skulle det utredas vilka förutsättningar som råder och hänsyn till ekonomiska och tidsmässiga perspektiv skulle tas. En relevant aspekt var hur markåtkomst kunde erhållas för att gallra träd och röja sly längs vägen. I studien användes juridisk metod, analys av litteratur samt semi-strukturerade intervjuer där ett flertal sakkunniga som besitter god kunskap beträffande viltolycksförebyggande åtgärder och förutsättningarna som råder på vägsträckan deltog. Utöver det intervjuades även sakkunniga inom markåtkomst, viltfrågor, fastighetsvärdering och skogliga åtgärder. Resultatet visar att markåtkomst för siktröjning kan erhållas med både nyttjanderätt enligt jordabalken och vägrätt enligt väglagen, men att markåtkomst mest sannolikt behöver ske genom frivilliga överenskommelser. Siktröjning kan utformas som en successiv utglesning och stamkvistning av skogen längs vägen där en total avverkning sker cirka tio meter ifrån vägkanten och en gallring sker ytterligare tio meter in. Denna utformning skapar ett mindre omfattande underhåll och mildrar konsekvenserna av singelolyckor. Det går inte med säkerhet går att fastställa vilken viltolycksförebyggande åtgärd som är mest fördelaktig på den här vägsträckan utan för det krävs mer omfattande utredningar. / Removal of trees along the road is a measure used to reduce the risk of wildlife accidents. It is used to create better view for motorists and animals by reducing the amount of trees and bushes along the roadside. Except better view the mesure will also entail faster drying of the road since removal of obscuring trees and vegetation will let the sunbeams reach the road to a greater extent. The measure can be formed as a total removal of trees or a thinning of the forest and may reduce the risk of wildlife accidents by 23 %. Highway 25 runs between the cities Kalmar and Halmstad and between the villages Eriksmåla and Lessebo, where the road section is regarded as a poor standard relative to the amount of traffic. In the future there is an expected reconstruction of the road by broaden it to a 2+1 road including a median barrier. Since this may accure further into the future there are speculations around a temporary measure that raises security on the road. The purpose of this study was to investigate if and how a removal of trees along the road could be performed on this road section and at the same time there would be a comparison with alternative measures, especially wildlife fencing. The study would investigate which are the conditions on this road section and take economic and time-consuming perspectives into account. One important aspect was to investigate how to obtain land access to be able to remove trees along the road. In the study qualitative methods were used, which included legal method, analysis of literature and semi-structured interviews, where several persons who possesses good knowledge concerning measures that reduces wildlife accidents and the conditions of this road section attended. Beyond this experts in land access, wildlife issues, property valuation and forest issues were interviewed. The results show that land access can be obtained in two different types of access rights in the Swedish legislation and that the most realistic is that it should happen in voluntary agreements with land-owners. Removal of trees can be performed as a successive thinning and branch pruning of the forest along the road where a total removal of trees is performed ten meters from the roadside and an additional area of ten meters is thinned out. This configuration can be maintained less often and makes the consequences of single vehicle accidents less severe by broadening the safety zone. It can not be determined which measure to reduce wildlife accidents that is most suitable on this road section and further investigations must be performed for this purpose.

No description available.