Juniperus Occidentalis
Fire Effects Information System (FEIS) FEIS Home Page Table of Contents • SUMMARY INTRODUCTORY DISTRIBUTION AND OCCURRENCE BOTANICAL AND ECOLOGICAL CHARACTERISTICS FIRE EFFECTS AND MANAGEMENT MANAGEMENT CONSIDERATIONS APPENDICES REFERENCES Figure 1—Western juniper. Photo by Joseph M. DiTomaso, University of California-Davis, Bugwood.org. Citation: Fryer, Janet L.; Tirmenstein, D. 2019 (revised from 1999). Juniperus occidentalis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us/database/feis/plants/tree/junocc/all.html [2019, June 26]. Revisions: The Taxonomy, Botanical and Ecological Characteristics, and Fire Effects and Management sections of this Species Review were revised in March 2019. New primary literature and a review by Miller et al. [145] were incorporated and are cited throughout this review. SUMMARY Western juniper occurs in the Pacific Northwest, California, and Nevada. Old-growth western juniper stands that established in presettlement times (before the 1870s) occur primarily on sites of low productivity such as claypan soils, rimrock, outcrops, the edges of mesas, and upper slopes. They are generally very open and often had sparse understories. Western juniper has established and spread onto low slopes and valleys in many areas, especially areas formerly dominated by mountain big sagebrush. These postsettlement stands (woodland transitional communities) are denser than most presettlement and old-growth woodlands. They have substantial shrub understories in early to midsuccession. Western juniper establishes from seed. Seed cones are first produced around 20 years of age, but few are produced until at least 50 years of age. Mature western junipers produce seeds nearly every year, although seed production is highly variable across sites and years.
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