Data: Foxes fertilize the subarctic forest and modify vegetation through denning

Ecosystem engineers modify habitats through processes other than trophic
interactions, such as by regulating soil nutrients, and can influence
resource availability and quality for other organisms. Predator-mediated
elemental cycling may be especially important in determining plant
diversity and growth in ecosystems where soil fertility and primary
productivity are low. Red foxes (Vulpes vulpes L.), top predators
in the Subarctic, could engineer local ecosystems through denning, which
could create biogeochemical hotspots of nutrients due to continual input
of feces, urine and prey remains. We examined soil and vegetation
characteristics on red fox dens and paired control sites in woodland
habitats near the Arctic treeline in Manitoba, Canada. The organic soil
layer on den sites had 81% more inorganic nitrogen and 250% more
extractable phosphorus than in control areas. Denning also increased soil
respiration and pH in the organic layer, suggesting improved soil quality
and nutrient availability for plants. By enriching nutrients and
disturbing soils through digging, den sites had a higher plant
species ß-diversity and a greater cover of erect woody
shrubs (Salix spp.), grasses (Leymus mollis (Trinius)
Pilger) and weedy ephemerals compared to control sites, resulting in a
regional increase in plant species richness. Our research
highlights the importance of considering impacts of predators other than
through their consumption of prey, and provides insight into the role of
red foxes in modifying plant diversity and productivity in the Subarctic.