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With increasing pressure from policymakers and the general public to conduct alternative forest management throughout the European Union (EU), Sweden needs to find ways to best prioritize the implementation of this alternative management. Alternative management is a term used to describe alternative management methods to clear-cut rotation forestry and can include silvicultural methods such as continuous cover forestry, management increasing proportion tree diversity and presence of broadleaves, and extended rotation lengths. Riparian buffers are one possible location for this management that may provide a win-win solution for meeting EU goals of increasing conservation of productive forests and use of alternative management, as well as benefiting water quality and biodiversity. Riparian buffers can protect the ecological functioning of a stream, typically by leaving a strip of unharvested trees in place around the stream, but in Sweden these buffers are often narrow (5-7m) and are dominated by a single tree species. Implementation of alternative forest management that would promote a diversity of tree species in wide riparian buffers could benefit streams, as well as assist Sweden in meeting EU goals. To determine the amount of forest land contained within buffers under 5 m, 15 m, 30 m, and 60 m buffer width scenarios I conducted a GIS analysis of 11 study areas throughout Sweden. I also examined the current tree species composition in these potential buffer zones and analysed the area around both natural channels, and forest ditches. I found that there is a significant latitudinal gradient in species composition within the buffer zones from north to south, with total tree volume, deciduous tree volume, and spruce tree volume increasing from north to south, whereas the proportion of pine is highest in northern study regions. This latitudinal trend was not seen in terms of the proportion of forest land contained within the buffers that was productive forest land; ho

At present, there are no clear guidelines for when and where ditch network maintenance (DNM) should be performed in Sweden. Recently there have been attempts to create tools that indicate the need for DNM, one of these tools is the Ditch Flow Tracker (DFT). The DFT determines the catchment area (CA) and soil type to predict if a ditch segment does not need DNM. The tool is based on the hypothesis that ditches with small CA’s do not need maintenance because they do not function to drain enough water to improve tree growth. The overall goal of this study was to ground truth the DFT by testing how well the CA, soil type and water flow divided into category can predict ditch function in terms of tree growth. Since the decision of DNM should take into account the ecological impacts the ability of the DFT to predict biodiversity of plants was also tested. A field study was conducted in the Krycklan Catchment Study at 18 drained sites with different CA’s and soil types. At each site, different ditch characteristics were measured as well as forest variables at different distances from the ditch. The analyses indicated that soil type had an effect on the increase in tree growth caused by ditches. Ditch segments in till soils had a higher volume in plots closest to the ditch as well as a higher volume overall compared to peat soils. Contrary to my hypothesis, CA did not affect the effectiveness of a ditch segment. Instead, water flow divided into categories seemed to effect the growth effect from drainage. Ditch segments with a high water flow had the highest standing volume as well as had a gradient of decreasing volume away from the ditch. CA did however indicate the biodiversity of plants within a ditch segment. The analysis showed that ditches with larger CA (1-2 ha) had a significantly higher plant diversity than the ditches with smaller CA’s. Neither soil type nor CA showed any influence on the long term growth effect of ditching when tree rings were examined. However t, Det finns idag inga riktlinjer för när och var underhåll av diken bör utföras i det svenska skogslandskapet. För att underlätta beslutet om dikesunderhåll har flera verktyg utvecklats. Ett av dessa verktyg är ”Ditch Flow Tracker” (DFT) som kan indikera om ett dikessegment är i behov av underhåll genom att avgöra dikets avrinningsområde och jordart. Verktyget DFT baseras på teorin att ett mindre avrinningsområde inte behöver underhållas då det inte dränerar tillräckligt med vatten för att förbättra trädens tillväxt. Målet med denna studie var att utvärdera verktyget DFT genom att testa hur avrinningsområde, jordart och vattenflöde indelat i kategorier kan förutse ett dikessegments funktion. Eftersom beslut att utföra dikesunderhåll även bör baseras på hur åtgärden påverkar de ekologiska förutsättningarna, testades även DFT’s möjlighet att indikera ett dikessegments biodiversitet. En fältstudie utfördes inom Krycklans avrinningsområde på 18 områden med olika storlek på avrinningsområde och jordarter. Inom varje område mättes dikets egenskaper samt skogliga variabler på olika avstånd från diket. Analyser av fältdata indikerade att jordarten påverkade dikenas effekt på trädens tillväxt. Dikessegment i morän påvisade en högre volym, både nära diket och generellt, jämfört med torvmark. I motsats till hypotesen hade avrinningsområdets storlek ingen påverkan på ett dikessegments effektivitet. På grund av detta ersattes avrinningsområdets storlek med variabeln vattenflöde indelat i tre kategorier. Dikessegment med högst vattenflöde hade den högsta stående volymen och en avtagande stående volym med ökande avstånd till diket. Däremot kunde avrinningsområdets storlek ge en indikation om ett dikessegments biodiversitet. Diken med större avrinningsområde (1-2 ha) hade signifikant större artdiversitet bland de undersökta växterna. Varken avrinningsområde eller jordart påverkade dikenas långsiktiga tillväxteffekt. Detta resultat var dock baserat på endast 10 av de totalt 18 områden