ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

MICROENVIRONMENTAL RESPONSE TO HARVESTING AND RESIDUE MANAGEMENT
Roger D. Hungerford
Research Forester, USDA Forest Service,
Intermountain Forest and Range Experiment station
ABSTRACT
The concept of energy balance is useful in analyzing the environ-
mental changes and in predicting biological responses that follow
timber harvesting and residue management. The physical properties
of the surface have a large effect on the surface environment.
Surface conditions such as radiation load and temperature have
reached lethal levels following harvesting on several sites.
Harvesting also aggravates and creates frost pockets that severely
1 imit seedling establ ishment. Some predictive models are discussed
that aid in prediction of environmental conditions and relate to
biological imp1 ications. Methods of using residue manipulation to
alter the microenvirontnent are suggested.
KEYWORDS: 1 ogging residue, temperature, net radiation, operational
environment, energy budget
INTRODUCTION
Harvesting has specific effects on the mi croenvi ronrnent which in turn influence
the subsequent development of the site. The condition of a microsite within several
meters of the surface can vary considerably over space and time. When extreme condi-
tions are created by harvesting they may hamper seedling establishment and cause
successional development to take an undesirable path. The magnitude, frequency, and
duration of any harvest-related changes are the crucial factors in relation to seed-
ling requirements. Quantitative infornlation based on these factors precedes the
creation of practical model s : model s based on fundamental physical princl ples may be
appl ied to a wide range of habitat types and harvest situations. Although universally
accepted relationships are not yet fully developed, research aims at modeling bio-
physical responses to harvesting in pursuit of predictive model s for land managers.