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Research Project: Understanding Water-Driven Ecohydrologic and Erosion Processes in the Semiarid Southwest to Improve Watershed Management

Location: Southwest Watershed Research Center

Title: Ecohydrology of pinyon and juniper woodlands

item Williams, Christopher - Jason
item Snyder, Keirith
item Pierson Jr, Frederick

Submitted to: Forest Service General Technical Reports
Publication Type: Book / Chapter
Publication Acceptance Date: 12/12/2019
Publication Date: 1/31/2020
Citation: Williams, C.J., Snyder, K.A., Pierson Jr, F.B. 2020. Ecohydrology of pinyon and juniper woodlands. In: Miller, R.F., Chambers, J.C., Evers, L., Williams, C.J., Snyder, K.A., Roundy, B.A., Pierson, F.B., editors. The Ecology, History, Ecohydrology, and Management of Pinyon and Juniper Woodlands in the Great Basin and Northern Colorado Plateau of the Western United States, General Technical Report, RMRS-GTR-403. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. pp. 129-163.

Interpretive Summary: Pinyon and juniper woodlands occupy a substantial component of the western United States and have increased in range dramatically in the past 140+ years. Over the past 75 years, scientists and land managers have made considerable advances in understanding of these ecosystems and their responses to management and disturbances. This publication synthesizes these advancements and provides land managers a reference to the best science when making management decisions regarding these ecosystems. The objectives (1) review best available knowledge for pinyon and juniper woodland ecosystems in the western US and (2) to make this research more available to land managers, researchers, and the interested public. In achieving these objectives, this synthesis provides a useful reference for understanding of and guiding management of these vastly occurring and ecologically important ecosystems throughout the western US.

Technical Abstract: Many dedicated scientists and managers have worked to understand pinyon and juniper woodlands in attempt to provide ecosystem services and to restore ecosystem function. Over the past 75 years we have learned a considerable amount about these woodlands, with many successes and failures. In this synthesis we’ve collected and summarized the literature on the ecological and management history of these semi-arid woodlands in an effort to help managers quickly reference the best science when making decisions about these wooded ecosystems. The primary purpose of this synthesis is to: (1) address the above issues and concerns as we attempt to review our knowledge of pinyon and juniper ecosystems, both for persistent and newly expanded woodlands; and (2) to make the research more available to managers, researches, and interested public. This document provides a resource of information that draws from a large volume of research papers and reports on these semi-arid woodlands. We have cited 1,000 out of over 2,000 papers related to pinyon and juniper woodlands in the American West. The synthesis is divided into five sections. The first section includes a “General Description” of both the Great Basin and northern Colorado Plateau. The “Ecology” section covers woodland and species life histories, biology, and ecology. This section also includes a detailed discussion of climate and the potential consequences of climate change specific to the Great Basin and Colorado Plateau and to the possible future of woodland ecosystems. The third section, “History”, discusses 20,000 years of woodland dynamics, beginning at glacial maximum. This section discusses the magnitude of changes of woodland distribution and structure, and the primary factors attributed to prehistoric woodland dynamics. The end of this section focuses on recent changes (including the past 200-300 years) related to the interactions between climate and anthropogenic disturbance, the extent of the change, and geographic differences among woodland disturbance regimes and resilience. The “Ecohydrology” section, discusses hydrologic processes in woodlands that influence soil conservation and loss; water capture, storage, and release, as well as the effects woodland structure and composition have on these processes. The final section “Restoration and Management”, covers the history of woodland management, the different methods used, the advantages and disadvantages of the different vegetation treatments, and post-treatment vegetation responses. We also discuss successes and failures, and the key components that determine project outcomes that are important considerations for restoring ecosystem function, integrity, and resilience.