Stand age characteristics and soil properties affect species composition of vascular plants in short rotation coppice plantations

Abstract

Woody biomass plantations on agricultural sites are an attractive source of biomass for bioenergy, but their effects on local biodiversity are unclear. This study's objective was to evaluate the influences of light availability, plantation age, and soil properties on phytodiversity in short rotation coppice (SRC) plantations. Ground vegetation mapping, irradiance measurement (PAR), and surface soil analyses were conducted in 15 willow and poplar SRC plantations in Central Sweden and Northern Germany. We performed different multivariate statistical methods like cluster analysis (CA), principal component analysis (PCA), and canonical correspondence analysis (CCA) in order to analyze species composition and the influence of irradiance, age, and soil properties on phytodiversity. CA revealed highest species composition similarities in SRC plantations in close proximity. PCA identified humus quality/essential plant nutrients, plantation age/irradiance effects, soil acidity and shoot age as the four principal components of the recorded parameters. The ground vegetation cover was negatively correlated with the plantation age component and positively with the nutrient component. With an increase in the plantation age component, a shift in species composition was proven towards more forest habitat species, more nutrient-demanding species, and increasing occurrence of indicator species for basic soils. Applying Ellenberg indicator values, basic soil indicator species corresponded in occurrence to increasing nutrient availability. However, species richness was not related to any of our studied site variables. Judged from CCA, species composition in SRC plantations was influenced by plantation age/ irradiance, and nutrient availability; soil acidity and shoot age had no significant influence. Young poplar and willow SRC plantations showed greatest variation in photosynthetically active radiation (PAR). Our findings suggest that phytodiversity in SRC plantations depends mainly on plantation age and thus shifts over time. © Sarah Baum et al.