Vegetative growth response of black cherry (Prunus serotina) to different mechanical control methods in a biosphere reserve

We assessed the effectiveness of different management strategies against the non-native invasive tree species black cherry (Prunus serotina Ehrh.). The species causes substantial management problems in European forest ecosystems, like the Valle del Ticino Biosphere Reserve in Italy, by suppressing the regeneration of native tree species. This can modify ecological key processes and cause biodiversity loss. Since chemical and biological control has mainly been abandoned in European forest ecosystem management, mechanical control measures are presently the preferred option to proceed against the black cherry but have shown very limited results in the reserve. The aim was to control the success of felling the species and to test other mechanical control methods such as girdling and snapping the trees with regard to their efficiency by quantifying the species' growth reactions. For this purpose, observational studies were conducted in two forest stands of which one was treated in 1996 and the other more recently in 2009. A subsample of resprouting stumps was treated a second time in 2010 to observe the effect of a direct second cutback. An experimental study was implemented in a third forest stand also in 2010 to compare three different mechanical control methods. The results suggest that felling black cherry is ineffective if the objective is to reduce the species' abundance because resprouts occur on 100% of the treated trees and biomass increment is not reduced in the long term. Girdling proved to be the most effective treatment across the diameter classes considered.