The use of birch tar in the prevention of moose damage in young Scots pine stands

Abstract

Moose (Alces alces L.) browsing causes economically significant damage in young Scots pine (Pinus sylvestris L.) stands in Finland. Various methods and devices have been used in attempts to prevent moose damage to Scots pine in young sapling stands. Our aim was to test the effectiveness of birch tar, a new innovation as repellent, under controlled experiments in young Scots pine stands frequently browsed by moose. Experiments were conducted during winter 2007/2008. In experiment A, each of the four experimental stands was divided into two treatments: (1) a treated block where all the top shoots and current-year shoots in the first whorl were treated with birch tar, and (2) an untreated block, i.e. a control area. In experiment B, the effect of birch tar was tested as an odorous repellent, i.e. small sacks with wooden pellets were dipped in the repellent liquid and placed around and inside three young Scots pine stands. In experiment A, there were no differences in the measured stand characteristics and the damage variables between the treated and untreated blocks. In experiment B, no significant differences in the measured variables were found between the protected and control stands. In conclusion, it seems that birch tar does not have a sufficient repellent effect when used against moose browsing.