ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

Recognizable brown-cubical decayed wood in the field is usually in the form of
dead fallen trees or logging residues greater than 0.5 m in diameter or large
enough to maintain a reasonable degree of recognizability through the processes of
decay, weathering, and physical dispersion. Residues of lesser dimension are
subject to spreading, dispersion, and downhill movement in steep terrain. Thus, the
larger residues tend to collapse and spread during the deterioration process,
appearing somewhat ellipsoidal in profile at the soil surface. Tabl es 3 and 4
summarize the more important properties and characteristics of soil wood. Ryp'aFek
and Ryp'ac'kova (1975) note that humic substances isolated from wood decomposed by
brown rot fungi exhibit properities sSmi1ar to those of soil humus, and that dif-
ferences are dependent on the degree of wood decomposition.
Tabl e 3 .--Summary of brown-cubical decayed soil wood properties and
characteristics.
Volume 5-25 pct 0.5-0.8 KgN/ha/YR - N2 Fixation
Persistence 500 + 12-fold increase in N compared to un-
decayed wood
Moisture 300 pct + 5-fold increase in P
CEC 45-90-MEQ Appreciabl e niacroel ement content
Per
100 gm
Low pH 4-5.5 Lignin content 68 pct
Tabl e 4.-- Mean percent 1 ignin, ash and carbohydrate contents, based on
odw of brown cubical decayed wood from Coram Experimental
Forest, Montana, 1975.
---
Number Ash Ligni n Carbohydrate
sampl es content content content
...........................................................................
" NONDECAY" ACTIVITIES
In addition to the two major kinds of decay associated with biodegradation of
woody residues, other activities of fungi may be considered nondegradative in the
sense that they are not responsible for major volume or weight reductions in
residues. Ecologically, these fungi appear early in the biodegradative sequence of
plant materials, They are the primary colonizers with the ability to metabolize
the readily available low-molecular-weight carbon and nitrogen sources that are '
available in fresh residues. Fungal numbers gradually decrease with time, an increase
in extractive content and, perhaps, increasing acidity of substrates. Their abil i ty
to rapidly form large amounts of biomass within short periods of time is noticeable
in figures 10 and 11.