Long-term log decay experiments at the Andrews Experimental Forest, 1985 to 2185

  • PI: Mark E. Harmon
  • Originator: Mark E. Harmon
  • Other researchers:
  • Dates of data collection: Jan 1 1985 - Oct 15 2001
  • Data collection status: Study continues and further data collection is planned
  • Data access: Online
  • Last update: Nov 25 2015 (Version 8)
<Citation>     <Acknowledgement>     <Disclaimer>    
Harmon, M. 2015. Long-term log decay experiments at the Andrews Experimental Forest, 1985 to 2185. Long-Term Ecological Research. Forest Science Data Bank, Corvallis, OR. [Database]. Available: (22 February 2018) DOI:
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.
These data are collected from six sites within the H. J. Experimental Forest and are part of a 200-year experiment on the decomposition of logs in a terrestrial environment. The taxa being examined in the experiment are Douglas-fir, western hemlock, western redcedar, and Pacific silver fir. The data start in 1985 and are periodically updated as samples are taken. The last collection of data is planned in 2185. Periodically logs are sampled by measuring their diameters and lengths as well as bark cover. Cross-sections are removed with a chainsaw and dissected with a table saw to determine the density of bark and wood samples. These samples systematically sample each cross-section and can be used to reconstruct the spatial pattern of decomposition. Subsamples are ground and nutrient concentrations are determined to calculate nutrient stores. Eleven data tables are associated with this study. A general description of the logs (length, diameters, bark cover) is found in td01401 and can be used to estimate how the log has fragmented over time. The areal extent of tissue types (outer bark, inner bark, sapwood, and heartwood) that are sampled is documented in td01402. The density (dry mass/green volume) of samples is documented in td01403 and based on the weights of individual samples (td01404) as well as their dimensions (td01405). The arrangement of samples into transects (top to bottom, left to right) is documented in td01406. To help explain why some samples may be more dense than other, the area of the sample cross-section is documented in td01407 (knots are more decay resistant and of greater density than wood). The radial thickness of inner and outer bark of the undecayed logs is documented in td01408, and can be used to estimate their thickness of these tissues once extensive decomposition occurs. Given the outer bark can be quite irregular in shape, water displacement was used to determine the volume of this tissue; these data are documented in td01415. The location of the logs at the six sites is stored in td01413, with distances, slope, and bearing from a series of surveyed posts noted. The cell wall chemistry of samples has been analyzed using the proximate method described by Ryan et al. (td01408) and Van Soest (td01412). The number and type of insect galleries present on logs for the first three years is documented in td01410. The number and species of fungal sporocarps growing on logs for the first eight or so years in the autumn is documented in td01414. Nutrient concentrations of dried, ground samples of inner and outer bark, sapwood, and heartwood, as well as sporocarps and insects is stored in td01411. Aside from the density of samples, all the data stored in this set of tables is raw data and not derived.

Study Description Study Site Map Taxonomic Hierarchy Download Study Location Information: (CSV)
Download Full Documentation: (PDF)(EML)
1Log Descriptions (Sep 8 1986 - Oct 5 2001)METADATADATA
2Preliminary cross-sectional area of tissue types (Nov 30 1985 - Nov 30 1985)METADATADATA
3Density(Mar 26 1985 - Oct 25 2001)METADATADATA
4Sample Weights(Nov 25 1985 - Oct 25 2001)METADATADATA
5Regular Wood Block Dimensions(Dec 11 1985 - Oct 25 2001)METADATADATA
6Block Arrangement(Nov 25 1985 - Oct 25 2001)METADATADATA
7Knot Volume Correction (Dec 12 1985 - Oct 15 2001)METADATADATA
8Ryan et al Cell Wall Chemistry(Nov 25 1985 - Oct 25 1993)METADATADATA
9Radial Bark Thickness(Nov 30 1985 - Sep 24 1992)METADATADATA
10Insect Galleries(Sep 9 1986 - Oct 5 1989)METADATADATA
11Nutrient Content(Apr 23 1987 - Feb 20 1994)METADATADATA
12Van Soest Cell Wall Chemistry (Jul 30 1987 - Jun 20 1989)METADATADATA
13Log Survey Notes (Nov 25 1985 - Nov 25 1985)METADATADATA
14Sporocarp Counts (Nov 1 1985 - Nov 30 1992)METADATADATA
15Bark Volumes (Nov 15 1985 - Oct 25 2001)METADATADATA

 Site Descriptions - Elevation, temperature and precipitation for the 6 sites

 Respiration patterns of logs in the Pacific Northwest, 1986-1996 (TD020)
 Nitrogen fixation and respiration potential of conifer logs at Andrews Experimental Forest, 1987 to 2006 (TD018)
 Log decomposition and nutrient release study site locations for 200 yr experiment, Andrews Experimental Forest, 1985 (TD040)