Fertilizing western rangelands for ungulate conservation: An assessment of benefits and risks

Abstract

ABSTRACT Intensive natural gas development causes habitat loss that reduces nutritional carrying capacity for ungulates and other species of conservation concern. To offset habitat loss from energy development, wildlife managers are experimenting with large‐scale sagebrush fertilization on western public rangelands. We synthesize what is known about basic sagebrush ecosystem biogeochemistry and ungulate nutritional ecology to anticipate the benefits and risks of this emerging mitigation tool. Under some environmental conditions, fertilization can temporarily increase sagebrush biomass, and potentially, the nutritional carrying capacity of mule deer limited by digestible energy. However, nitrogen additions are costly and pose environmental risks when applied to arid and semi‐arid systems. Fertilization may promote weed invasions, changes to biogeochemical cycles, and potentially irreversible ecosystem shifts that reduce shrub communities. Fertilization also creates excess nitrogen at 2–8 × natural background levels and increases greenhouse gases, ozone pollution precursors, downwind nitrogen deposition, and freshwater degradation. Considering these risks and recognizing that potential benefits are short‐term, uncertain, and expensive to achieve, the practice of sagebrush fertilization may pose a net conservation cost. © 2015 The Authors. Wildlife Society Bulletin published by The Wildlife Society.

Keywords

• Artemisia spp
• Bromus tectorum
• energy mitigation
• fertilization
• mule deer
• nitrogen