Data from: The effects of moose- and pine density on browsing damage in Swedish pine forests

Moose (Alces alces) is a culturally and economically important game
species in Sweden, but their browsing on regenerating Scots pine trees
(Pinus sylvestris) often causes extensive damage to the production and
quality of timber. Forest- and wildlife managers are faced with the
dilemma of how to reduce damage to timber trees while also supporting
moose populations and hunting opportunities. The proportion of damaged
trees can be reduced by decreasing the number of moose, but also by
increasing the number of pines. However, the relative effectiveness of
these two approaches is debated and has not been conclusively determined.
Here we addressed this question by analyzing the effects of moose- and
pine density on pine damage based on yearly data from almost all of
Sweden’s moose management areas (MMAs) over 10 years, 2015-2024 (718
observations). We developed a mechanistic model to realistically represent
the browsing process and used regression with mixed models to account for
variable vulnerability (damage at a common number of moose per pine tree)
among MMAs in the statistical analysis. The model explained 53% of the
variation in the proportion of damaged trees and showed that, on average,
the relative damage reduction effect of a decreased moose population was
~1.5x larger (25%) than the effect of increased pine density (17%).
Vulnerability to browsing varied substantially among MMAs and between
years within each MMA, especially in areas with low pine density. This
variability prevents reliable predictions of management effects at the
individual MMA level for most MMAs. Such local predictions may be improved
in the future by incorporating longer time series of observations and
additional variables, such as alternative forage sources, browsing by
other deer species, and snow cover and duration.