A Nutrition-Based Approach for Elk Habitat Management on Intensively Managed Forestlands

Abstract

We present an elk (Cervus elaphus) habitat management approach to guide timber harvest on managed forestlands. Forest managers consider many constraints when selecting stands to cut, but we suggest additional consideration for elk habitat. The Muckleshoot Indian Tribe's 93,000-ac Tomanamus Forest in western Washington is managed as a working forest, with the challenges of providing income along with ensuring sustainable plant and animal resources relied on by tribal members. We partition the Forest into smaller Elk Management Areas (EMA) and seasonal ranges related to distinct elk groups. Within each EMA, we calculate an Elk Forage Index (EFI) that uses canopy cover and hardwood variables to predict biomass and dietary digestible energy to meet yearly adult cow elk nutritional needs. We propose EFI targets within EMAs that can be used as a variable in a decision model to guide forest planning and evaluate alternative management options that include elk. Management and Policy Implications Our EFI approach is intended as one of many variables to guide harvest management for the Tribe's 100-year forest plan. Timber harvest patterns often produce periods of surplus and deficits in big game forage needs. The spatial distribution of big game habitat resources is often clumped, a pattern created by historical harvest patterns that were based on ease of access and stand age. EFI integrates curvilinear relationships among forest cover, hardwoods, and forest zone into an index that can be used to assess the nutritional value of an area to elk, and help managers evaluate the effects of timber harvests. A goal is to reduce fluctuations in forage resources to generate a managed landscape that can support stable elk numbers. We partition the Tribe's forest into analysis areas based on known elk movements and distribution, and then use the EFI to inform the redistribution of clearcuts on the Forest. The EFI can be among many constraints in a decision model to meet owner objectives. Treatments to improve elk nutrition and increase EFI include modification of overhead canopy such as clearcutting or thinning or promoting diverse hardwood stands. Managers have the flexibility to diversify stand arrangement based on other harvest and management goals.