Pinyon-Juniper Disturbance Effects on Wildlife Active

Background

The expansion of pinyon pine and juniper woodlands into sagebrush ecosystems has been a major focus of restoration for land management agencies in the western U.S. Tree removal treatments are in progress across the region to reduce wildfire fuels and restore habitat for species of conservation concern, especially the greater sage-grouse. However, there are also species that rely on woodlands for habitat, such as the pinyon jay.

In addition, wildfire and drought die-off events can reduce pinyon-juniper woodlands and affect the species that depend on them. While each of these agents of change—tree removal, drought, and wildfire—have been major topics of research on their own, there is a critical need to synthesize and compare their impacts on ecosystems and wildlife.

Assessing how different types of disturbance alter woodlands, and how responses vary across a wide geographic area, is critical to designing and optimizing management strategies for the diverse wildlife species that occupy western rangelands.

Objectives and Methods

Through a systematic review of the scientific literature, we will summarize and analyze what is currently known about pinyon-juniper ecosystem change in response to tree removal treatments, drought, and wildfire.

We are investigating how each disturbance type influences:

1. Stand structures: vertical and horizontal structure of woodlands
2. Fuel loads: amount of vegetative wildfire fuel available, which translates to fire risk
3. Plant community composition: presence and distribution of native and invasive plants
4. Landscape-scale patterns and processes

These observed effects will be compared to known wildlife habitat needs, with a focus on sage-grouse and pinyon jay. This literature review builds upon an existing review that assessed the effects of pinyon-juniper removal treatments on plants, wildlife, and other environmental attributes across the western U.S. By comparing among additional disturbance types, this new review project will help land managers better predict likely outcomes based on management action or inaction.

For example:

• How will tree removal treatments, wildfire, or drought impact exotic annual grass invasion patterns?
• How do the different disturbance types impact the availability of food for sage-grouse and pinyon-jay?
• Do these disturbance effects vary among environmental settings, or in areas with different land use histories?

Where the literature is not adequate to answer all of these types of questions, we will highlight key science gaps, with a focus on those that are most valuable to land managers.