Plant biomass dynamics following logging, burning, and thinning in Watersheds 6 and 7, Andrews Experimental Forest, 1979 to present

  • Creator(s): Mark E. Harmon, Kari B. O'Connell, David Bell
  • PI(s): David Bell
  • Originator(s): Kari B. O'Connell
  • Other researcher(s): Robert J. Pabst, Suzanne M. Remillard, Andrew Bluhm, Frederick J. Swanson, James H. Mayo
  • Dates of data collection: Jul 9 1979 - Sep 2 2021
  • Data collection status: Study continues and further data collection is planned
  • Data access: Online
  • DOI:
  • Last update: Jan 12 2023 (Version 8)
<Citation>     <Acknowledgement>     <Disclaimer>    
Harmon, M.; O'Connell, K.; Bell, D. 2023. Plant biomass dynamics following logging, burning, and thinning in Watersheds 6 and 7, Andrews Experimental Forest, 1979 to present. Long-Term Ecological Research. Forest Science Data Bank, Corvallis, OR. [Database]. Available: Accessed 2024-06-15.
Data were provided by the HJ Andrews Experimental Forest research program, funded by the National Science Foundation's Long-Term Ecological Research Program (DEB 2025755), 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.
Watersheds 6 (WS06) and 7 (WS07) at the HJ Andrews are part of a three-watershed study initiated in the 1970’s to examine the response of hydrology and forest vegetation to logging. In 1974, Watershed 6 was clearcut logged; Watershed 7 was shelterwood cut, leaving 75-100 overstory trees per hectare (comprising about 40% of the original basal area). A nearby watershed (WS08) serves as an unlogged control. In 1975, all of Watershed 6 and the portion of WS07 below the road were broadcast-burned. In 1976, both watersheds were planted with Douglas-fir seedlings. Natural regeneration of Douglas-fir and western hemlock also established. In 1984, the remnant overstory trees in WS07 were harvested, and in 2001 the young stand in WS07 was thinned to about 550 trees per hectare. The thinning was not planned but provides an interesting twist to the study. The watersheds are located along the northern boundary of the HJA off the 327 and 328 roads, at elevations ranging from 850 to 1,160 m. Initial vegetation measurements were taken in the summer of 2002 in watersheds 6 and 7 for the purpose of characterizing plant succession after thinning in a small, high-elevation watershed. Understory vegetation plots are remeasured at approximately 6 year intervals.

Study Description Study Site Map Taxonomic Hierarchy Download Study Location Information: (CSV)
Ecological Metadata Language: (EML)
1Individual tree remeasurement (Jun 1 2002 - Aug 20 2014)METADATADATA
These data are managed with PSP tree measurement data and served through a view from TV010 entity 2
2Stump data (Jun 18 2002 - Jul 23 2002)METADATADATA
stump species and diameter within the plot
3Tree Core data (Jun 18 2002 - Jul 23 2002)METADATADATA
bark and sapwood thickness measurements from tree cores
4Ground Surface Cover Types (Jun 18 2002 - Sep 2 2021)METADATADATA
Percent canopy cover and ground surface cover types for specific cover types
5Understory Vegetation Cover (Jun 18 2002 - Sep 2 2021)METADATADATA
Resurrected plots after original logging and measurements with new sampling protocol
6Biomass Measurements (Jul 1 2002 - Sep 2 2021)METADATADATA
biomass measurements for particular species rooted in the quadrat
7Whole plot species list (Jun 18 2002 - Sep 2 2021)METADATADATA
list of all species occurring within the plot
8Plot level data (Jul 9 1979 - Jul 23 2002)METADATADATA
Listing of all plots (old and resurrected) in each watershed, the transect line where the plot lays, the plot type (terrestrial or riparian), and slope for the resurrected plots
9Vegetation cover estimates (Jul 9 1979 - Dec 18 1995)METADATADATA
Original understory vegetation cover
10Tree heights and crown data (Jun 18 2014 - Jul 7 2014)METADATADATA
total tree heights, height to the base of the live crown, and crown diameters in selected trees

 WS6 and WS7 Vegetation Research and History - Report based on original study plan and establishment report for vegetation research in watersheds 6 and 7.
 WS6 and WS7 plot layout - Schematics of various plot layouts for given measurements
 WS6 and WS7 original maps - Original maps of watersheds with transect and plot layouts, including riparian areas.

 Long-term growth, mortality and regeneration of trees in permanent vegetation plots in the Pacific Northwest, 1910 to present (TV010)
 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 in old-growth Watersheds 8 and 9 at the Andrews Experimental Forest, 2003 to present (TP115)