Document


Title

Recent changes (1930s-1990s) in spatial patterns of interior northwest forests, USA
Document Type: Journal Article
Author(s): Paul F. Hessburg; B. G. Smith; R. Brion Salter; Roger D. Ottmar; Ernesto Alvarado
Publication Year: 2000

Cataloging Information

Keyword(s):
  • Abies grandis
  • Arceuthobium americanum
  • arthropods
  • bark
  • catastrophic fires
  • change detection
  • coniferous forests
  • conifers
  • cover
  • cover type
  • cover type conversion
  • croplands
  • crown fires
  • diseases
  • disturbance
  • disturbance regimes
  • ecosystem dynamics
  • ecosystem health
  • fire dependent species
  • fire exclusion
  • fire exclusion
  • fire regimes
  • forest health
  • forest management
  • fuel loading
  • herbaceous vegetation
  • histories
  • Idaho
  • insects
  • landscape assessment
  • landscape ecology
  • light
  • Montana
  • mountains
  • Oregon
  • overstory
  • Pinus ponderosa
  • plant diseases
  • Pseudotsuga menziesii
  • reference variation
  • rivers
  • shrublands
  • smoke management
  • spatial patterns
  • species diversity (plants)
  • succession
  • trees
  • Washington
  • watersheds
  • wildfires
Record Maintained By:
Record Last Modified: February 13, 2019
FRAMES Record Number: 37943
Tall Timbers Record Number: 12467
TTRS Location Status: In-file
TTRS Call Number: Fire File
TTRS Abstract Status: Fair use, Okay, Reproduced by permission

This bibliographic record was either created or modified by the Tall Timbers Research Station and Land Conservancy and is provided without charge to promote research and education in Fire Ecology. The E.V. Komarek Fire Ecology Database is the intellectual property of the Tall Timbers Research Station and Land Conservancy.

Description

We characterized recent historical and current vegetation composition and structure of a representative sample of subwatersheds on all ownerships within the interior Columbia River basin and portions of the Klamath and Great Basins. For each selected subwatershed, we constructed historical and current vegetation maps from 1932 to 1966 and 1981 to 1993 aerial photos, respectively. Using the raw vegetation attributes, we classified and attributed cover types, structural classes, and potential vegetation types to individual patches within subwatersheds. We characterized change in vegetation spatial patterns using a suite of class and landscape metrics, and a spatial pattern analysis program. We then translated change in vegetation patterns to change in patterns of vulnerability to wildfires, smoke production, and 21 major forest pathogen and insect disturbances. Results of change analyses were reported for province-scale ecological reporting units (ERUs). Here, we highlight significant findings and discuss management implications.Twentieth century management activities significantly altered spatial patterns of physiognomies, cover types and structural conditions, and vulnerabilities to fire, insect, and pathogen disturbances. Forest land cover expanded in several ERUs, and woodland area expanded in most. Of all physiognomic conditions, shrubland area declined most due to cropland expansion, conversion to semi- and non-native herblands, and expansion of forests and woodlands. Shifts from early to late seral conifer species were evident in forests of most ERUs; patch sizes of forest cover types are now smaller, and current land cover is more fragmented. Landscape area in old multistory, old single story, and stand initiation forest structures declined with compensating increases in area and connectivity of dense, multilayered, intermediate forest structures. Patches with medium and large trees, regardless of their structural affiliation are currently less abundant on the landscape. Finally, basin forests are now dominated by shade-tolerant conifers, and exhibit elevated fuel loads and severe fire behavior attributes indicating expanded future roles of certain defoliators, bark beetles, root diseases, and stand replacement fires. Although well intentioned, 20th Century management practices did not account for landscape-scale patterns of living and dead vegetation that enable forest ecosystems to maintain their structure and organization through time, or for the disturbances that create and maintain them. Improved understanding of change in vegetation spatial patterns, causative factors, and links with disturbance processes will assist managers and policymakers in making informed decisions about how to address important ecosystem health issues. © 2000 Elsevier Science B.V. All rights reserved.

Citation:
Hessburg, P. F., B. G. Smith, R. B. Salter, R. D. Ottmar, and E. Alvarado. 2000. Recent changes (1930s-1990s) in spatial patterns of interior northwest forests, USA. Forest Ecology and Management, v. 136, no. 1-3, p. 53-83.