DOI: 10.6073/pasta/7c67241d2ff15de1f82e33164e8655b4
title: Long-term log decay experiments at the Andrews Experimental Forest, 1985 to 2185

description: 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.