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

  • Creator(s): Jerry F. Franklin, Mark E. Harmon
  • PI(s): Mark E. Harmon
  • Originator(s): Jerry F. Franklin
  • Other researcher(s): Jay M. Sexton, Becky Fasth, Jack Booth, John Moreau, Timothy D. Schowalter, John D. Lattin, Rick G. Kelsey, Elaine R. Ingham
  • Dates of data collection: Mar 26 1985 - Aug 24 2016
  • Data collection status: Study continues and further data collection is planned
  • Data access: Online
  • DOI:
  • Last update: Jun 13 2018 (Version 10)
<Citation>     <Acknowledgement>     <Disclaimer>    
Franklin, J.; Harmon, M. 2018. 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: Accessed 2024-05-21.
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.
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 and the fraction of their length in contact with the ground. Cross-sections are removed with a chainsaw and dissected with a table saw or other means 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. Twenty one 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) and zones of rotten wood from cross-sections is documented in td01418 and td01419. The position of the pith in each cross-section, a useful indicator of volume loss, is documented in td01420. 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) within the cross-sections is documented in td01406. To help explain why some samples may be more dense than others, the area of the sample cross-section covered by knots 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 td01409, and can be used to estimate the original thickness of these tissues once extensive decomposition occurs. Given that 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 in the autumn for the first eight years is documented in td01414. Concentrations of nutrient elements such as nitrogen, phosphorus, calcium, and potassium of dried, ground samples of inner and outer bark, sapwood, and heartwood, as well as fungal sporocarps and insects is stored in td01411. Parameters for regression models derived from these data that describe the temporal pattern of decomposition is stored in td01421.

Study Description Study Site Map Taxonomic Hierarchy Download Study Location Information: (CSV)
Ecological Metadata Language: (EML)
1Whole Log Descriptions (Sep 8 1986 - Aug 24 2016)METADATADATA
A general description of the logs (length, diameters, bark cover); used to estimate how the log has fragmented over time
3Sample volume, moisture, and density (Mar 26 1985 - Dec 9 2015)METADATADATA
4Sample Wet and Dry Weights (Nov 25 1985 - Oct 1 2016)METADATADATA
5Wood and Bark Sample Outer Dimensions (Dec 11 1985 - Oct 1 2015)METADATADATA
6Block and Sample Arrangement in Cross-sections (Nov 25 1985 - Oct 1 2015)METADATADATA
The arrangement of samples into transects (top to bottom, left to right)
7Knot Volume Correction Estimate for Wood Samples (Dec 12 1985 - Oct 21 2005)METADATADATA
8Ryan et al Cell Wall Chemistry of Bark and Wood Samples (Nov 25 1985 - Oct 25 1993)METADATADATA
9Radial Bark Thickness(Nov 30 1985 - Sep 24 1992)METADATADATA
The radial thickness of inner and outer bark of the undecayed logs
10Insect Galleries(Sep 9 1986 - Oct 5 1989)METADATADATA
11Nutrient Content of Bark, Wood, Fungal, and Insect Samples (Apr 23 1987 - Feb 20 1994)METADATADATA
12Van Soest Cell Wall Chemistry of Wood and Bark Samples (Jul 30 1987 - Jun 20 1989)METADATADATA
13Log Location Survey Notes (Nov 25 1985 - Nov 25 1985)METADATADATA
Used to Produce Maps
14Sporocarp Counts from Logs (Nov 1 1985 - Nov 30 1992)METADATADATA
15Bark Sample Volumes from Water Displacement (Nov 15 1985 - Jul 6 2016)METADATADATA
16Entire cross-section method: data for tissue dimensions, total mass, total volume, and density (Sep 20 2005 - Oct 21 2015)METADATADATA
17Entire cross-section method: data for subsample dimensions, mass, and density (Sep 20 2005 - Oct 21 2015)METADATADATA
18Areas of sound and rotten tissues based on digitized photographic slides of cross-sections (Nov 25 1985 - Oct 5 2001)METADATADATA
19Computed diameter and areas of sound and rotten tissues based on digitized photographic slides of cross-sections (Nov 25 1985 - Oct 5 2001)METADATADATA
Derived from digitized data (entity 18)
20Polar coordinate (distance and angle) location of pith relative to the outer surface of cross-sections (Nov 25 1985 - Sep 24 1992)METADATADATA
Distance and angle data for pith to external parts of cross-section. See related file: Idealized cross-section diagram
21Decomposition equation summary data (Nov 25 1985 - Sep 18 2015)METADATADATA

 Site Descriptions - Elevation, temperature and precipitation for the 6 sites
 Idealized cross-section diagram - Diagrams the measured components of the cross-section
 Bearing system diagram - Diagram of bearing system used to survey log locations

 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)

 Harmon, Mark E. 1992, Long-term experiments on log decomposition at the H.J. Andrews Experimental Forest (Pub. No: 1045)