title: Arctic foxes as ecosystem engineers: increased soil nutrients lead to increased plant productivity on fox dens.
abstract: Top predators can provide fundamental ecosystem services such as nutrient cycling, and their impact can be even greater in environments with low nutrients and productivity, such as Arctic tundra. We estimated the effects of Arctic fox (Vulpes lagopus) denning on soil nutrient dynamics and vegetation production near Churchill, Manitoba in June and August 2014. Soils from fox dens contained higher nutrient levels in June (71% more inorganic nitrogen, 1195% more extractable phosphorous) and in August (242% more inorganic nitrogen, 191% more extractable phosphorous) than adjacent control sites. Inorganic nitrogen levels decreased from June to August on both dens and controls, whereas extractable phosphorous increased. Pup production the previous year, which should enhance nutrient deposition (from urine, feces, and decomposing prey), did not affect soil nutrient concentrations, suggesting the impact of Arctic foxes persists >1 year. Dens supported 2.8 times greater vegetation biomass in August, but δ(15)N values in sea lyme grass (Leymus mollis) were unaffected by denning. By concentrating nutrients on dens Arctic foxes enhance nutrient cycling as an ecosystem service and thus engineer Arctic ecosystems on local scales. The enhanced productivity in patches on the landscape could subsequently affect plant diversity and the dispersion of herbivores on the tundra.
authors.affiliation: Department of Biological Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, Manitoba R3T 2N2, Canada.
authors.forename: Tazarve
authors.initials: T
authors.lastname: Gharajehdaghipour
authors.affiliation: Department of Biological Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, Manitoba R3T 2N2, Canada.
authors.forename: James D
authors.initials: JD
authors.lastname: Roth
authors.affiliation: Department of Biological Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, Manitoba R3T 2N2, Canada.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Fafard
authors.affiliation: Department of Biological Sciences, University of Manitoba, 50 Sifton Road, Winnipeg, Manitoba R3T 2N2, Canada.
authors.forename: John H
authors.initials: JH
authors.lastname: Markham
mesh_terms: D000818:Animals; D044822:Biodiversity; D018533:Biomass; D002170:Canada; D005589:Foxes; D009584:Nitrogen / Q000737:chemistry; D010758:Phosphorus / Q000737:chemistry; D010944:Plants; D006109:Poaceae; D011157:Population Dynamics; D011235:Predatory Behavior; D012621:Seasons; D012987:Soil / Q000737:chemistry*; D065929:Tundra
chemical_list: D012987:Soil; D010758:Phosphorus; D009584:Nitrogen