Aboveground biomass of glossy buckthorn is similar in open and understory environments but architectural strategy differs

Abstract

The exotic shrub glossy buckthorn (Frangula alnus) is a great concern among forest managers because it invades both open and shaded environments. To evaluate if buckthorn grows similarly across light environments, and if adopting different shapes contributes to an efficient use of light, we compared buckthorns growing in an open field and in the understory of a mature hybrid poplar plantation. For a given age, the relationships describing aboveground biomass of buckthorns in the open field and in the plantation were not significantly different. However, we observed a significant difference between the diameter-height relationships in the two environments. These results suggest a change in buckthorn's architecture, depending on the light environment in which it grows. Buckthorn adopts either an arborescent shape under a tree canopy, or a shrubby shape in an open field, to optimally capture the light available. This architectural plasticity helps explain a similar invasion success for glossy buckthorn growing in both open and shaded environments, at least up to the canopy closure level of the plantation used for this study.