ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

It is logical that if surface temperatures are different for clearcut and uncut
areas then soil temperatures are also different. Data from Solo Creek in July
(fig. 11 ) show soils under the clearcut to be warmer at depths to 20 inches (50 cm).
Data from Coram shows cl earcut temperatures in midsummer to be 6OC-3OC higher from
1-10 inches in depth than those of the uncut stand. Studies at Newman Ridge
(Shearer personal communication) have shown differences of 8OC at 10 inches below
clearcut and uncut areas. Increases in net radiation and consequently heat flux at
the surface of clearcuts produce increases in air temperature. Mean air temperature
at Coram in midsummer at standard height increased 4OC following clearcutting. Other
study results show increased air temperatures close to the surface*
07.
BCD
UNCUT CllT
Mean a
!b' / Mean max.
10 15 20 25 30 35 40
TEMPERATURE (OC)
Figure 11. -- Mean maxim and mean temperature profiles by depth for
July 1978 on uncut and cZearcu;S sites at So20 Cmak. O2 is -the humus
Zayer and BCD is brown crwnbly decayed wood.
Residue treatments and seedbed preparation treatments such as burning and
scarifying have an additional affect on temperature regimes. The placement, color
and thermal properties of surface materials help determine surface temperatures.
Highly reflective and conductive materials have much cooler surfaces than absorbant
materials with low conductivity (Cochran 1969; Fowler 1974; Lowry 1969). Common
forest materials l ike litter, soil, logs, chips, charcoal, rocks, etc. , have con-
siderably different properties (tab1 e 3).
The following equation ill ustrates the relationship between surface properties
and surface temperature:
where AT is the change in temperature, AG is the change in heat flux, k is the thermal
conductivity and cp is the heat capacity.
Surface temperatures at two sites (Lubrecht and Coram) were very similar in both
broadcast bugned and cleared areas. Maximum temperatures on both treatments ranged
from 50 C-60 C, and minimum temperatures were also nearly the same for both treat-
ments. Temperatures at 9,200 feet (2 800 m) in Wyoming followed the same pattern.