Hazel (Corylus avellana L.) is a common feature of meadows and pastures where it can grow in large populations and become very old. Is it possible to use the size of hazel stools for age determination and is it possible to use the size distribution of a population to provide information about how the land has been used? Hazel populations on ground where the lake-water level had been lowered, has been studied to validate an already developed growth model of hazel clones. Different hazel populations, on wooded meadows affected by mowing or grazing or overgrown meadows, were studied to evaluate the method utilizing hazel as land use indicator. The growth model was used to compare the size distributions of hazel populations with historical periods, which has been important for changes in agriculture or demography. The results show that the current growth model needs to be refined, but the method itself with a growth model based on the circumference of hazel bushes seems feasible. Additional studies about the influence of, for example, soils of different fertility are needed. The results also show that the size distribution in a population depends on how much meadows have been affected by mowing or grazing and that areas with similar land use have similar size distribution. Finally, some examples are reported about how a growth model can be used to compare historical periods of changes in agriculture, for example reduced livestock, with variations of the size distribution in a hazel population.

I investigated the role of land use in structuring benthic invertebrate assemblages in agricultural streams in the French Broad River drainage in western North Carolina. I sampled six agricultural streams (3 with cleared headwaters and 3 with forested headwaters) at three points along a gradient (headwaters, a midpoint, and a downstream site). At each site, I measured a variety of physico-chemical parameters, including temperature, chlorophyll a, discharge, nutrients, and suspended solids. Invertebrates were sampled at all sites in October 1996 and April 1997. Riparian vegetation was assessed for each site at mutiple spatial scales using GIS data from the 1950s, 1970s, and 1990s. Forested agricultural (FA) streams had more riparian vegetation than cleared agricultural (CA) streams in both the 1950s and the 1970s. Cleared agricultural streams had less organic matter, more primary production, higher nitrates, and warmer temperatures than FA streams. Total and EPT taxa richness was greater in FA streams. Pollution-sensitive Plecoptera were relatively more abundant in FA streams, while tolerant Diptera were more abundant in CA streams. High diversity and Plecoptera abundance was related to high habitat quality, more riparian vegetation, low nitrates, and low summer temperatures. Higher invertebrate diversity was related to the land use 25-50 years as well as the current land use (forested, moderate agriculture, or heavy cattle impact). These results indicate a long-term legacy of agricultural influences on stream invertebrate assemblages. / Master of Science

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.

Kalkbarrskogar är en sällsynt och artrik skogstyp i Sverige. Stora arealer finns i Jämtland. Skogstypen kalkbarrskog är prioriterade för områdesskydd och det finns därför ett behov att undersöka den. Studien genomfördes i samarbete med Länsstyrelsen i Jämtland. 45 prioritetsobjekt undersöktes genom GIS-baserade analyser. Målet var att undersöka objektens brukningshistorik för att undersöka eventuell påverkan på naturvärdena. Syftet var att utreda behovet av formellt områdesskydd. Samtliga objekt har fram till nutid aldrig blivit kalavverkade. 80 % var historiskt brukade med skogsbete och virkesuttag, vilket kan ha hållit skogarna glesa fram till 1960-talet. Studien kan inte visa om brukningshistoriken påverkat dagens naturvärden. Naturvärdena kan funnits innan brukandet startat, samt att andra miljöparametrar kan haft större betydelse. Idag är en femtedel av objekten helt eller delvis avverkade och en fjärdedel avverkningsanmälda. Studien kan styrka behovet av formellt områdesskydd på kalkbarrskogar i Jämtland eftersom det är ett motiverat alternativ för att naturvärdena bibehålls.