Data from: The changing contribution of top-down and bottom-up limitation of mesopredators during 220 years of land use and climate change

Apex predators may buffer bottom-up driven ecosystem change, as top-down
suppression may dampen herbivore and mesopredator responses to increased
resource availability. However, theory suggests that for this buffering
capacity to be realized, the equilibrium abundance of apex predators must
increase. This raises the question: will apex predators maintain
herbivore/mesopredator limitation, if bottom-up change relaxes resource
constraints? Here, we explore changes in mesopredator (red fox Vulpes
vulpes) abundance over 220 years in response to eradication and recovery
of an apex predator (Eurasian lynx Lynx lynx), and changes in land use and
climate which are linked to resource availability. A three-step approach
was used. First, recent data from Finland and Sweden were modelled to
estimate linear effects of lynx density, land use and winter temperature
on fox density. Second, lynx density, land use and winter temperature was
estimated in a 22 650 km2 focal area in boreal and boreo-nemoral Sweden in
the years 1830, 1920, 2010 and 2050. Third, the models and estimates were
used to project historic and future fox densities in the focal area.
Projected fox density was lowest in 1830 when lynx density was high,
winters cold and the proportion of cropland low. Fox density peaked in
1920 due to lynx eradication, a mesopredator release boosted by favourable
bottom-up changes - milder winters and cropland expansion. By 2010, lynx
recolonization had reduced fox density, but it remained higher than in
1830, partly due to the bottom-up changes. Comparing 1830 to 2010, the
contribution of top-down limitation decreased, while environment
enrichment relaxed bottom-up limitation. Future scenarios indicated that
by 2050, lynx density would have to increase by 79% to compensate for a
projected climate driven increase in fox density. We highlight that
although top-down limitation in theory can buffer bottom-up change, this
requires compensatory changes in apex predator abundance. Hence apex
predator recolonization/recovery to historical levels would not be
sufficient to compensate for widespread changes in climate and land use,
which have relaxed the resource constraints for many herbivores and
mesopredators. Variation in bottom-up conditions may also contribute to
context dependence in apex predator effects.