ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

Maximum daiay temperatures for the two treatments were within Z'C-3'~ of each other,
reaching 63 C on some days. Maximum temperatures at the chip surface were about 10 C
lower. At Lubrecht, mean monthly maximum surface temperatures for the summer period
were 10'~ aower on bare soil than on 1 itter. Differences in daily maximums were as
much as 15 C (fig. 12).
/-'
BARE SOIL SURFACE
20 I ~ l l l l l l l l l l ~
18 19 20 21 22 23 24 25 26 2 3 4
JULY AUG.
DAY AND MONTH
Figure 12.--Maxim daily litter surface and bare soil surface tempmatures
at Lubrecht, for some JuZy and August 1978 days.
Since the surface temperatures differed on 1 i
tter, bare soi 1, burned and chips-
spread areas, we expected temperatures above and below the surface to differ (fig. 13).
Temperatures above the surface (20 cm and 137 cm) at the Wyoming site were nearly the
same for the cleared, burned and chips-spread treatments. Below the surface, however,
temperatures were warmest for the burned treatment and cooler for the cleared and
chips-spread areas (fig. 14 A and B), Burning by removing some of the litter, allows
heat to penetrate faster and deeper. Spreading of the chips insulates sol1 from
extreme surface variations. Clearing leaves a layer of litter deeper than does
burning, but this litter has less of an insulating effect than chips, Figure 15
shows the diurnal progression of temperatures at different heights and depths with
respect to the surface, The daily temperature wave is damped at 20 cm and the range
is small even at 5 cm. Limited data at Lubrecht and Coram reveal the same trend of
temperature with depth for the different surface treaments. Cochran 's (1 969) results
illustrate the same trends.