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): M. D. Busse; P. H. Cochran; J. W. Barrett
    Date: 1996
    Source: Soil Science Society of America Journal
    Publication Series: Scientific Journal (JRNL)
    Station: Pacific Southwest Research Station
    PDF: Download Publication  (112.0 KB)


    Competition from understory vegetation for water and nutrients can limit productivity of young forest stands. Less is known of the effect of understory vegetation on long-term stand growth or soil organic properties. The effect of understory vegetation on periodic annual increments (PAIs) of basal area, height, and volume for ponderosa pine (Pinus ponderosa Dougl.) in central Oregon at 4- or 5-yr intervals was examined for a 35-yr period. Soil C, N, and microbial biomass C (MBC) were also quantified after 32 and 35 yr with and without understory vegetation on a sandy loam pumice soil (Xeric Vitricryand). Five tree spacings, ranging from 2.0 to 8.0 m (154–2469 trees ha−1), in combination with two understory treatments (understory vegetation present or continuously absent) were installed in 1959. Total understory vegetation cover averaged 35% between 1959 and 1994 for treatments with understory vegetation present, and was dominated by three shrub species: antelope bitterbrush [Purshia tridentata (Pursh) DC.], greenleaf manzanita (Arctostaphylos patula Green), and snowbrush (Ceanothus velutinus Dougl. ex Hook.). Covariance analyses of PAIs for each successive interval were performed using appropriate stand parameters at the start of each interval as covariates. Tree growth was reduced by competing understory vegetation during the first 12 to 20 yr only; understory vegetation did not reduce the adjusted PAIs during the last 15 yr. Soil C and N were measured incrementally to a depth of 24 cm. Presence of understory vegetation resulted in greater C and N in the O horizon and upper 4 to 12 cm of mineral soil. Seasonal MBC, measured at 14-d intervals from May to November, was greater when understory vegetation was present. The results suggest that understory vegetation plays an important role in maintaining soil quality.

    Publication Notes

    • You may send email to 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.


    Busse, M. D.; Cochran, P. H.; Barrett, J. W. 1996. Changes in ponderosa pine site productivity following removal of understory vegetation. Soil Science Society of America Journal. 60(6): 1614-1621.


    Google Scholar

    Related Search

    XML: View XML
Show More
Show Fewer
Jump to Top of Page