Skip to Main Content
U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Home > Search > Publication Information

  1. Share via EmailShare on FacebookShare on LinkedInShare on Twitter
    Dislike this pubLike this pub
    Author(s): Emily K. Heyerdahl; Richard F. Miller; Russell A. Parsons
    Date: 2006
    Source: Forest ecology and management. 230(1-3): 107-118
    Publication Series: Miscellaneous Publication
    PDF: View PDF  (676 KB)

    Description

    Over the past century, trees have encroached into grass- and shrublands across western North America. These include Douglas-fir trees (Pseudotsuga menziesii (Mirb.) Franco var. glauca (Beissn.) Franco) encroaching into mountain big sagebrush Nutt. ssp. vaseyana (Rydb.) Beetle) from stable islands of savanna in southwestern Montana. Our objectives were to quantify the relative area occupied by mountain big sagebrush and grasslands versus Douglas-fir savanna in the Fleecer Mountains of southwestern Montana today and in the past, and to identify the historical role of fire and other factors in maintaining this distribution. To do this, we reconstructed a multicentury history of tree establishment and surface fires from 1120 trees sampled on a grid of 50 plots covering 1030 ha of a modern mosaic of sagebrush–grasslands and Douglas-fir trees. We compared these histories to time series of climate and land use, and to spatial variation in topography and soil moisture availability. Beginning in the mid-1800s, Douglas-fir trees established in areas in which trees did not persist historically. In 1855, less than half the plots (42%) had trees whereas today, most plots do (94%). This encroachment was synchronous with the cessation of frequent surface fires, likely caused by the advent of domestic livestock grazing, and perhaps by the start of several decades of relatively dry summers. Douglas-fir savannas historically occurred on fire-safe sites more often than did sagebrush–grass. Our inference that frequent fire excluded Douglas-fir in the past was supported by the results of a simulation model of fire and associated vegetation dynamics. In the continued absence of fire, mountain big sagebrush and grasslands in southwestern Montana are likely to become more homogeneous as Douglas-fir trees continue to encroach.

    Publication Notes

    • You may send email to rmrspubrequest@fs.fed.us 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.

    Citation

    Heyerdahl, Emily K.; Miller, Richard F.; Parsons, Russell A. 2006. History of fire and Douglas-fir establishment in a savanna and sagebrush-grassland mosaic, southwestern Montana, USA. Forest ecology and management. 230(1-3): 107-118

    Keywords

    Artemisia tridentata, mountain big sagebrush, Pseudotsuga menziesii, Douglas-fir, encroachment, fire history, dendrochronology, Montana

    Related Search


    XML: View XML
Show More
Show Fewer
Jump to Top of Page
https://www.fs.usda.gov/treesearch/pubs/27841