From the simulation of forest plantation dynamics to the quantification of bark-stripping damage by ungulates

Abstract

Large ungulate populations are known to cause economic damage to agriculture and forestry. Bark damage is particularly detrimental to the timber production of certain species, including Picea abies (L.) Karst. (Norway spruce): after bark is wounded, rot often spreads in the trunk base, damaging the most valuable trunk section. Numerous studies have provided valuable information on various aspects of this process but the financial consequences over a full timber production cycle remained poorly quantified and uncertain. To fill this gap, we coupled a forest dynamics model (GYMNOS) with models of damage occurrence and decay spread. We simulated the effect of ranging levels of bark-stripping damage on financial losses. The simulations were repeated for sites of ranging fertility and with different protection measures (fences or individual protections), in Southern Belgium. The net present values of these different simulations were estimated and compared to estimate the cost of the damage and the cost-effectiveness of the damage protections. Protecting plantations against bark-stripping damage with fences was found unlikely to be worthwhile. By contrast, individual protections placed on crop trees could be helpful, particularly in the most fertile stands. Loss of revenue depended greatly on the factors tested: we estimated that the average damage cost could be about 53e/ha/year, reducing timber yield by 19%. A model was built to predict the damage cost for different values of the discount rate, site index and bark-stripping rate. This model could help develop more effective management of Norway spruce plantations and deer populations.

Sampling designs for bark stripping caused by red deer (Cervus elaphus L.): Simulation studies based on nine fully censused stands

“…Stem damages lead to infection with wood decaying fungi (on Picea abies especially Heterobasidion annosum and Stereum sanguinolentum) (Butin, 2011), which make the wood unusable for the sawtimber industry causing high economic losses. For example, in Scandinavia the damage caused by Heterobasidion annosum was quanti ed with 0.5 -1 billion €/year (Rönnberg et al, 2013); more recently, the costs for bark stripping damage were estimated to be 53€/ha/year and the reduction of the timber yield was estimated to be 19% (Ligot, et al, 2023). In Austria, 9.1 % of individual trees are affected by bark peeling (BFW, 2018).…”