Skip to Main Content
Relationship of stand characteristics to drought-induced mortality in three Southwestern pinyon-juniper woodlandsAuthor(s): M. Lisa Floyd; Michael Clifford; Neil S. Cob; Dustin Hanna; Robert Delph; Paulette Ford; Dave Turner
Source: Ecological Applications. 19(5): 1223-1230.
Publication Series: Miscellaneous Publication
PDF: View PDF (680.13 KB)
DescriptionExtreme drought conditions accompanied by rising temperatures have characterized the American Southwest during the past decade, causing widespread tree mortality in pinon-juniper woodlands. Pinon pine (Pinus edulis Engelm.) mortality is linked primarily to outbreaks of the pinyon ips (Ips confusus (Leconte)) precipitated by drought conditions. Although we searched extensively, no biotic agent was identified as responsible for death in Juniperus L. spp. in this study; hence this mortality was due to direct drought stress. Here we examine the relationship between tree abundance and patterns of mortality in three size classes (seedling/sapling, pre-reproductive, reproductive) during the recent extended drought in three regions: southwest Colorado, northern New Mexico, and northern Arizona. Pinon mortality varied from 32% to 65%, and juniper mortality from 3% to 10% across the three sites. In all sites, the greatest pinon mortality was in the larger, presumably older, trees. Using logistic regression models, we examined the influence of tree density and basal area on bark beetle infestations (pinon) and direct drought impacts (juniper). In contrast to research carried out early in the drought cycle by other researchers in Arizona, we did not find evidence for greater mortality of pinon and juniper trees in increasingly high density or basal area conditions. We conclude that the severity of this regional drought has masked density-dependent patterns visible in less severe drought conditions. With climate projections for the American Southwest suggesting increases in aridity and rising temperatures, it is critical that we expand our understanding of stress responses expected in widespread pinon-juniper woodlands.
- You may send email to email@example.com to request a hard copy of this publication.
- (Please specify exactly which publication you are requesting and your mailing address.)
- 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.
CitationFloyd, M. Lisa; Clifford, Michael; Cob, Neil S.; Hanna, Dustin; Delph, Robert; Ford, Paulette; Turner, Dave. 2009. Relationship of stand characteristics to drought-induced mortality in three Southwestern pinyon-juniper woodlands. Ecological Applications. 19(5): 1223-1230.
Keywordsbark beetles, density-dependent mortality, drought stress, Ips confusus, Juniperus monosperma, Juniperus osteosperma, pinonjuniper woodlands, Pinus edulis, pinyon ips, Southwest USA
- Pinyon-juniper woodlands in Zion National Park, Utah
- Pinyon/juniper woodlands [Chapter 4]
- Biomass of singleleaf pinyon and Utah juniper
XML: View XML