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

Abstract

Abstract This paper evaluates the role of soil drainage in tree seedling performance at a site being restored from Calluna vulgaris moorland to Pinus sylvestris woodland, in Glen Affric, Scotland. The investigation focuses on the relationships between height of planted seedlings, type of ground vegetation and drainage conditions. Slope, aspect, and soil depth were assessed as potential surrogates for direct measures of soil drainage, all of which were derived from digital terrain data. Six variables related to drainage were recorded at 58 seedling locations and used in a factor analysis to understand links between soil moisture conditions, topographic variables and soil depth characteristics. Factor analysis generated two factors that accounted for 70.5% of the variance in the correlation matrix of these variables: Factor 1 correlated strongly with variables that controlled peat accumulation and Factor 2 correlated strongly with topographic controls upon drainage patterns. These two factors explained a significant amount of the variance in height of the Pinus seedlings planted at these locations. Significant differences were found between the factor scores associated with different types of ground vegetation, as well as between the seedling heights observed at locations with different vegetation types. Multiple regressions were developed that indicated that slope, aspect, and soil depth were significant as independent variables in models where soil moisture content and aerobic soil depth were the dependent variables.