ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

In this paper I examine the effects of harvesting and residue treatments on the
microenvironment. A close consideration of the components of an environment and
certain biophysical principles is necessary to an understanding of the natural com-
plexity of causal relationships. Data resulting from field studies conducted by this
program helps to clarify by quantifying relationships. The work of other researchers
on microenvi ronmental responses, manipulation, and/or predictive models complements
my intent to review possibilites and stimulate a new approach in management.
ENVIRONMENTAL-PHYSIOLOGICAL CONCEPTS
We reap the benefits of spectacular developments in science and technology every
day. Since Geiger's book, The Climate Near the Ground, appeared in 1950, efforts to
apply the principles of natural science and quantative physics to biologic systems
have magnified. Papers and books discuss the principles of environmental physics
with reference to plants (Wijk 1963; Gates 1962; Monteith 1973; f4unn 1966; Rose 1966;
Rosenburg 1974; Lowry 1969; Campbell 1977). As a result the emphasis and approach
concerning the importance of environment to forest growth and uses has changed.
Whi 1 e Toumey and Korstian (1 947) recognized the great importance of environment,
their emphasis was necessarily on qua1 itative determinations of environment-plant
responses. This established the importance of environment, but a predictive under-
standing based on quantitative factors was not available.
We know that shade or drought or genetic factors affect growth, but this does
not explain the process. Environmental processes affect plant processes on1 by
changing the internal processes and conditions (Kramer and Kozlowski l96OeIn
essence, the key to understanding how plants respond to environmental variables
depends on the interaction with physiological processes of the plant. If we are to
manage for a certain species or community, we must know its requirements for survival,
optimal growth, and completion of its life cycle.
Since the environment and physiological processes of organisms are related, how
do we define environment? In the broadest sense the environment 5s the total surroundings
of an organism (Allee and Park 1939), including the direct and indirec t
effects of the surroundings. Spomer (l973), defines the factors that directly a ffect
organisms as the operational environment. This operational environment imp1 ies
factors that interact between an organism's surroundi~gs and the internal condit ions
of the organism. The interaction leads to an internal change in the organism in
response to its environment.
The operational environment is characterized by factors significant to an
organism's internal physiology such as: heat, 1 ight, moisture, nutrients, gases, and
mechanical energy. Indirect factors - pH, aspect, elevation, temperature, soil
texture - describe the potential for exchange. These are important only as they
distinguish between causal factors and those that are correlated. Knowledge of the
exchange 1 eve1 s of causal factors can establ i sh the potential physiological activity
of an organism. With heat, for example, the potential activity depends on the tempera-
ture difference between the organism and its imnediate surroundings. The potential
for change is described by entropy. Temperature is easily measured, but entropy is
not measurable, However, the overall exchange can be closely approximated using
resistance to flow.