Evaluating interactions between soil drainage and seedling performance in a restoration of Pinus sylvestris woodland, Scotland

1 This paper evaluates the role of soil drainage in tree seedling performan ce at a site being restored from Calluna vulgaris moorland to Pinus sylvest ris woodland, in Glen Affric, Scotland. The investigation focuses on the re lationships between height of planted seedlings, type of ground vegetation and drainage conditions. 2 Slope, aspect, and soil depth were assessed as p otential surrogates for direct measures of soil drainage, all of which were derived from digital terrain data. 3 Six variables related to drainage wer e recorded at 58 seedling locations and used in a factor analysis to unders tand links between soil moisture conditions, topographic variables and soil depth characteristics. 4 Factor analysis generated two factors that accoun ted for 70.5% of the variance in the correlation matrix of these variables: Factor 1 correlated strongly with variables that controlled peat accumulat ion and Factor 2 correlated strongly with topographic controls upon drainag e patterns. 5 These two factors explained a significant amount of the variance in heigh t of the Pinus seedlings planted at these locations. Significant difference s were found between the factor scores associated with different types of g round vegetation, as well as between the seedling heights observed at locat ions with different vegetation types. 6 Multiple regressions were developed that indicated that slope, aspect, an d soil depth were significant as independent variables in models where soil moisture content and aerobic soil depth were the dependent variables.