Heterogeneity of wood decay classes within hardwood logs 1 This paper is Scientific Contribution No.

Abstract As forest floor coarse woody debris (CWD) decays, it changes from solid wood to material without a recognizable origin. Decaying logs provide a progression of woody habitat substrates that contribute to the diversity of species and ecological processes in the forest. For studies of the habitat values of logs, decaying logs typically are assigned to one of the five classes with Class V being highly decayed logs that have lost their cylindrical shape and are composed primarily of powdery wood. In a study made in Quercus hardwood and mixed hardwood stands of the University of Connecticut Forest, near Storrs, CT, we examined the range and variability in actual decay classes present within logs assigned to decay class groups I, II, III, or IV. The proportions of all the decay classes found in each of 125 logs were estimated from measurements of the length and diameters of each different sector of decay within a log. The homogeneity of within-log decay classes varied by overall decay class group with the decay class III logs and group being the most variable. We compare our results to an idealized continuum of decay and conclude that by virtue of being in the middle of the decay sequence, class III is expected to be the most variable. We recognize that although the overall pattern of our results may be considered typical relative to the idealized continuum, the specific proportion of decay class variability from any one study represents site- and time-specific conditions not likely to typify `average' conditions in a broader geographic area. Our results indicate that variability of decay state within a given log is generally to be expected, and, from this we infer within-log variability in species and ecological functioning.

[1]  J. Trappe,et al.  Hypogeous fungal production in mature Douglas-fir forest fragments and surrounding plantations and its relation to coarse woody debris and animal mycophagy , 1994 .

[2]  J. Trappe,et al.  The Seen and Unseen World of the Fallen Tree , 1984 .

[3]  R. B. Smith,et al.  Fungal deterioration of second-growth Douglas-fir logs in coastal British Columbia , 1970 .

[4]  M. Harmon,et al.  Ecology of Coarse Woody Debris in Temperate Ecosystems , 1986 .

[5]  S. A. Graham.  The Felled Tree Trunk as an Ecological Unit , 1925 .

[6]  R. N. Mack,et al.  VARIATION IN DEMOGRAPHY OF JUVENILE TSUGA HETEROPHYLLA ACROSS THE SUBSTRATUM MOSAIC , 1984 .

[7]  Russell T. Graham,et al.  Managing coarse woody debris in forests of the Rocky Mountains. Forest Service research paper , 1994 .

[8]  M. Harmon,et al.  COMMUNITIES OF FILAMENTOUS FUNGI AND YEAST IN DECOMPOSING LOGS OF PSEUDOTSUGA MENZIESII , 1990 .

[9]  R. Sinsabaugh,et al.  Wood decomposition over a first-order watershed : mass loss as a function of lignocellulase activity , 1992 .

[10]  P. Sollins,et al.  First-year survival of Tsuga heterophylla without mycorrhizae and subsequent ectomycorrhizal development on decaying logs and mineral soil , 1982 .

[11]  B. Berg,et al.  Nitrogen and phosphorus release from decomposing litter in relation to the disappearance of lignin , 1989 .

[12]  M. Larsen,et al.  N2 fixation associated with wood decayed by some common fungi in western Montana. , 1978 .

[13]  C. Elton.  Dying and Dead Wood , 1966 .

[14]  E. Fager.  The Community of Invertebrates in Decaying Oak Wood , 1968 .

[15]  T. Schowalter.  Heterogeneity of decomposition and nutrient dynamics of oak (Quercus) logs during the first 2 years of decomposition , 1992 .

[16]  Jerry F. Franklin,et al.  Tree Seedlings on Logs in Picea‐Tsuga Forests of Oregon and Washington , 1989 .

[17]  J. Franklin,et al.  Ecological characteristics of old-growth Douglas-fir forests. , 1981 .

[18]  Richard S. Miller,et al.  The Ecological Survey of Animal Communities: With a Practical System of Classifying Habitats by Structural Characters , 1954 .

[19]  J. Means,et al.  Biomass and nutrient content of Douglas-fir logs and other detrital pools in an old-growth forest, Oregon, U.S.A. , 1992 .

[20]  Suzanne D. McAlister.  SPECIES INTERACTIONS AND SUBSTRATE SPECIFICITY AMONG LOG-INHABITING BRYOPHYTE SPECIES' , 1995 .

[21]  D. Coates,et al.  FUNGAL POPULATION AND COMMUNITY DEVELOPMENT IN CUT BEECH LOGS: III. SPATIAL DYNAMICS, INTERACTIONS AND STRATEGIES. , 1985, The New phytologist.

[22]  P. Sollins,et al.  Changes in organic components for fallen logs in old-growth Douglas-fir forests monitored by 13C nuclear magnetic resonance spectroscopy. , 1990 .

[23]  James K. Brown.  Handbook for inventorying downed woody material , 1974 .

[24]  Charlotte Pyle,et al.  A rapid system of decay classification for hardwood logs of the eastern deciduous forest floor , 1998 .

[25]  L. Boddy,et al.  Fungal decomposition of attached angiosperm twigs , 1991 .

[26]  O. Hendrickson.  Abundance and activity of N2-fixing bacteria in decaying wood , 1991 .

[27]  H. E. Savely.  Ecological Relations of Certain Animals in Dead Pine and Oak Logs , 1939 .

[28]  A. B. Carey,et al.  Small mammals in managed, naturally young, and old-growth forests. , 1995 .

[29]  D. A. Crossley,et al.  Biodiversity and coarse woody debris in southern forests , 1996 .

[30]  D. Coates,et al.  FUNGAL POPULATION AND COMMUNITY DEVELOPMENT IN CUT BEECH LOGS: I. ESTABLISHMENT VIA THE AERIAL CUT SURFACE. , 1985, The New phytologist.