Rocky Mountain Research Station

Title: Drought induced tree mortality and ensuing bark beetle outbreaks in southwestern pinyon-juniper woodlands

Author: Clifford, Michael J.; Rocca, Monique E.; Delph, Robert; Ford, Paulette L.; Cobb, Neil S.

Date: 2008

Source: In: Gottfried, Gerald J.; Shaw, John D.; Ford, Paulette L., compilers. 2008. Ecology, management, and restoration of pinon-juniper and ponderosa pine ecosystems: combined proceedings of the 2005 St. George, Utah and 2006 Albuquerque, New Mexico workshops. Proceedings RMRS-P-51. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 39-51

Station ID: P-RMRS-51

Description: The current drought and ensuing bark beetle outbreaks during 2002 to 2004 in the Southwest have greatly increased tree mortality in pinyon-juniper woodlands. We studied causes and consequences of the drought-induced mortality. First, we tested the paradigm that high stand densities in pinyon-juniper woodlands would increase tree mortality. Stand densities did not impact mortality levels for either tree species, which does not support tree thinning to reduce susceptibility to droughtbark beetle outbreaks. Second, we monitored changes in stand structure and dead woody biomass to test whether altered fuel loads might affect potential fire behavior. Mortality can significantly affect torching index but has little effect on crowning index. Finally, we predicted that ground-dwelling arthropods would be highly responsive to habitat changes resulting from dead trees. Although we found significant responses, they were not as strong as predicted. Together, these results suggest that impacts of drought-induced tree mortality may not appear for years or decades after a major mortality event.

Keywords: pinon-juniper and juniper woodlands, ponderosa pine forests, ecology, management, restoration, southwestern United States

View and Print this Publication (1.06 MB)

Publication Notes: 

• We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
• This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
• You may send email to rschneider@fs.fed.us to request a hard copy of this publication. (Please specify exactly which publication you are requesting and your mailing address.)

 Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility

Citation

Clifford, Michael J.; Rocca, Monique E.; Delph, Robert; Ford, Paulette L.; Cobb, Neil S.  2008.  Drought induced tree mortality and ensuing bark beetle outbreaks in southwestern pinyon-juniper woodlands.   In: Gottfried, Gerald J.; Shaw, John D.; Ford, Paulette L., compilers. 2008. Ecology, management, and restoration of pinon-juniper and ponderosa pine ecosystems: combined proceedings of the 2005 St. George, Utah and 2006 Albuquerque, New Mexico workshops. Proceedings RMRS-P-51. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 39-51.