The role of fire in pinyon and juniper woodlands: a descriptive analysis

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Among the most pronounced vegetation changes in the past 130 years has been the increase in both distribution and density of juniper (Juniperus spp.) and pinyon (Pinus spp.) across the Intermountain West. Juniper and pinyon species between the Canadian and Mexican borders occupy over 30 million ha throughout this region. Prior to European settlement, woodland species were primarily confined to rocky ridges or surfaces where sparse vegetation limited fire. Woodlands now occupy more productive sites with deeper well-drained soils. Woodland species began their unprecedented and ongoing rates of increase during the late 1800s. Replacement of sagebrush shrub steppe, riparian, and aspen (Populus spp.) communities by pinyon and juniper species is largely attributed to the reduced occurrence of fire. An important sagebrush type that has been impacted by recent woodland expansion is mountain big sagebrush (Artemisia tridentata var. vaseyana). Prior to settlement, mean fire return intervals for a large portion of this cover type were 12–25 years. At present, fire return intervals in this cover type have increased to >100 years. As trees gain dominance and shrubs and herbaceous vegetation decline, fuel structure changes, which contributes to significant increases in the length of mean fire return intervals. Fire-safe communities successionally replace fire-dependent communities. However, in the central and southern portions of the Intermountain West, particularly where pinyon is dominant, dense tree-canopied woodlands are now becoming susceptible to intense crown fires. The intensity of these fires can lead to dominance by exotics, further altering the successional dynamics of the site. During the past, juniper and pinyon woodlands have been treated to control the expansion. However, wildlife and environmental concerns, and different perceptions of the intrinsic values of these environments, have recently limited treatment of woodlands, including the use of prescribed fire. During the early to middle stages of development when woodlands contain understories of native shrubs and herbs, they can successfully be treated by various methods, particularly fire. However, once communities become tree-dominated woodlands, treatment becomes difficult and expensive.

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ELECTRONIC FILE - Ecology

Suggested citation: Miller, R. F., and R. J. Tausch. 2001. The role of fire in pinyon and juniper woodlands: a descriptive analysis. Pages 15-30 in K.E.M. Galley and T.P. Wilson (eds). Proceeding of the Invasive Species Workshop: the Role of Fire in the Control and Spread of Invasive Species. Fire Conference 2000: the First National Congress on Fire Ecology, Prevention, and Management. Miscellaneous Publication No. 11, Tall Timbers Research Station, Tallahassee, FL.

SWAP (2/19/2016) citation (with conference title added):
Miller RF, Tausch RJ. 2001. The role of fire in pinyon and juniper woodlands: a descriptive analysis. In: Galley KEM, Wilson TP, editors. Proceedings of the Invasive Species Workshop: the Role of Fire in the Control and Spread of Invasive Species. Fire Conference 2000: the First National Congress on Fire Ecology, Prevention, and Management; Tallahassee, FL. Tall Timbers Research Station. p. 15–30. Miscellaneous Publication No. 11. [accessed 2015 Nov 20]. http://www.sagestep.org/educational_resources/bibliographies/articles/20...

Additional info: Supported by the Joint Fire Science Program. The Oregon State University URL might be better to use; it provides conference name information.