ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

Depending on the cutting and treatment, 1,200 to 2,000 ftQw acre (84 to 182
m3/ha) of residue remains on the site. On an oven-dry weight basis, this represents
15 to 35 tons per acre (3.4 to 7.8 kg/m2) of material 3 inches (7.6 cm) and larger.
Fine material - on the ground prior to harvest and crown components lopped or broken
off during harvest - add to another 10 or more tons per acre (2 kg/m2). In the
areas where we measured fine material loadings, there is usually about 2 or 4 tons
per acre (0.4 to 0.9 kg/m2) on the ground prior to harvest. Harvesting increases
by several fold the amount of downed branches, twigs, and foliage.
SUMMARY AND CONCLUSIONS
The data on volumes of residue summarized here are based on utilization practices
and standards that were typical when we began our studies about 5 years ago. Since
that time substantial progress has been made in residue use, particularly standing
dead lodgepole pine for house1 ogs and other products.
The total residues generated each year by logging these six principal forest
types in Montana, Idaho, and Wyoming total 355 million f t 3 (10 million rn3) (figure 5).
Another 110 mill ion ft3 (3.1 mill ion m3) of residues are formed from harvesting other
forest types. Some of this residue volume is already being utilized, but there is
still a large volume of material potentially available. In the past, high cost of
recovery and low-value product potential precluded removal , but current trends in the
demand and value of wood for fiber and energy are rapidly changing the situation. In
the future, more material will be removed from logged areas.
RESIDUES FROM SIX MAJOR TYPES
(OF, WL,LPP,GF.S. AFI
(3. 1 million Ma )
L R E S I DUES FROMr
OTHER FOREST TYPES
Figure 5.-- Wood residues generated annuaZZy from harvesting {n Montana,
Wyoming, and Idaho.