Long-term growth, mortality and regeneration of trees in permanent vegetation plots in the Pacific Northwest, 1910 to present

  • PI: Mark E. Harmon
  • Originator: Jerry F. Franklin
  • Other researchers: Robert J. Pabst, Charles B. Halpern, Janneke HilleRisLambers, Andrew J. Larson, James A. Lutz, Mark E. Swanson, James A. Freund, Paul A. Harcombe, Todd M. Wilson, Kenneth J. Bible, Julia A. Jones
  • Dates of data collection: Feb 1 1910 - Sep 15 2016
  • Data collection status: Study continues and further data collection is planned
  • Data access: Online
  • Access constraint: Stands from the Andrews Experimental Forest and from the Hemlock-Spruce series are available except for the most recent remeasurement (5-6 year cycle).
  • Last update: Apr 17 2017 (Version 11)
<Citation>     <Acknowledgement>     <Disclaimer>    
Harmon, M.; Franklin, J. 2017. Long-term growth, mortality and regeneration of trees in permanent vegetation plots in the Pacific Northwest, 1910 to present. Long-Term Ecological Research. Forest Science Data Bank, Corvallis, OR. [Database]. Available: (23 May 2017).
Data were provided by the HJ Andrews Experimental Forest research program, funded by the National Science Foundation's Long-Term Ecological Research Program (DEB 1440409), US Forest Service Pacific Northwest Research Station, and Oregon State University.
While substantial efforts are made to ensure the accuracy of data and documentation, complete accuracy of data sets cannot be guaranteed. All data are made available "as is". The Andrews LTER shall not be liable for damages resulting from any use or misinterpretation of data sets.
A network of more than 130 permanent vegetation plots provides long-term information on patterns and rates of forest succession in most of the major forest zones of the Pacific Northwest. The plot network extends from the coast to the Cascades in western Oregon and Washington and east to ponderosa pine forests in the Oregon Cascades. Most of the permanent plots were established during two intervals: from 1910 to 1948, and from 1970 to 1989. The earlier plots were established by U.S. Forest Service researchers to quantify timber growth in young stands of important commercial species and to help answer other applied forestry questions. The more recent period of plot establishment began under the Coniferous Forest Biome program of the International Biological Program during the 1970s, and continued under the Long-term Ecological Research program. A broader set of objectives motivated plot establishment since 1970, especially quantification of composition, structure, and population and ecosystem dynamics of natural forests. Plots have one of three spatial arrangements: (1) contiguous rectangles subjectively placed within an area of homogeneous forest; (2) circular plots subjectively placed within an area of homogeneous forest; and (3) circular plots systematically located on long transects to sample an entire watershed, ridge, or reserve. Rectangular study areas are mostly 1.0 ha or 0.4 ha (1.0 ac) in size (slope-corrected). Circular plots are 0.1 ha (0.247 ac), not corrected for slope. The tree stratum is the focus of work in closed-forest study areas. All trees larger than a minimum diameter (5 cm for most areas) are permanently tagged. Plots are censused every 5 or 6 years. Attributes measured or assessed at each census include tree diameter, tree vigor, and the condition of the crown and stem. The same attributes are recorded for trees (ingrowth) that have exceeded the minimum diameter since the previous census. In many plots tree locations are surveyed to provide a plot-specific x-y location. A mortality assessment is done for trees that have died since the previous census. The assessment characterizes rooting, stem, and crown condition, obvious signs of distress or disturbance, and the apparent predisposing and proximate causes of tree death.

Study Description Study Site Map Taxonomic Hierarchy Download Study Location Information: (CSV)
Download Full Documentation: (PDF)(EML)
1Initial tree conditions with spatial coordinates (Oct 1 1910 - Apr 1 2010)METADATADATA
2Individual tree remeasurement (Feb 1 1910 - Sep 1 2012)METADATADATA
Table containing periodic remeasurement data of individual trees within reference stands
3Individual tree mortality (Feb 1 1910 - Sep 1 2012)METADATADATA
Table recording individual tree mortality year and contributing conditions and causes of mortality
4Tree heights (Feb 1 1910 - Aug 1 2004)METADATADATA
Height data of selected trees.
5Plot description and establishment year METADATADATA
6Stand characteristics and sampling status METADATADATA
7Stand GPS spatial data METADATAData not online
8Stem tallies in three stands of the Cascade Head EF (Jun 1 1935 - Sep 1 1941)METADATAData not online
9Summaries for density, basal area, volume, biomass, bole npp, and mortalityMETADATAData not online

 Permanent Plots of the Pacific Northwest, USA - An electronic publication series describing preliminary results from long-term permanent vegetation plots
 Ecology of Common Understory Plants in Northwestern Oregon and Southwestern Washington Forests - A summary to key ecological characteristics of the most prominent plant species in the understory of forests in northwestern Oregon and southwestern Washington

 Post-logging community structure and biomass accumulation in Watershed 10, Andrews Experimental Forest , 1974 to present (TP041)
 Ecosystem dynamics in a mature (Hagan block) and old-growth (Watershed 2) forest, Andrews Experimental Forest, 1981 to present (TP091)
 Plant succession and biomass dynamics following logging and burning in Watersheds 1 and 3, Andrews Experimental Forest, 1962 to Present (TP073)
 Plant biomass dynamics following logging, burning, and thinning in Watersheds 6 and 7, Andrews Experimental Forest, 1979 to present (TP114)
 Plant biomass dynamics in old-growth Watersheds 8 and 9 at the Andrews Experimental Forest, 2003 to present (TP115)