Landscape patterns of pre-logging forest conditions in western Oregon

by Rasmussen, Mary C.

Abstract (Summary)
Using historical maps and tools provided by GJS, the spatial patterns of

pre-logging forest conditions were quantified for three landscapes in western

Oregon. The spatial coincidence between forest patches and topographic

features was determined for slope gradient, aspect, elevation, and distance

from streams. Pre-logging and current forest compositions were compared.

The pre-logging landscape was dominated by old growth conifer with

less than 10% consisting of early seral disturbance patches. Fire patches

differed in size and shape between the Oregon Coast Range and the Oregon

Cascade Range provinces. The size and variability of fire patches was larger in

the Cascades, with shorter mean distances between fire patches and smaller

perimeter to area ratios compared to fire patches in the Coast Range. Mean

fire return intervals ranged from 170 to 292 years for the Oregon Coast Range.

The most frequent patch size, regardless of patch type and study area, ranged

from 100 to 999 ha. Forest patch types varied predictably by topographic

feature for instance: fewer fire patches occurred on cool, moist aspects while

more occurred on hot, dry, aspects. More burn area and less old growth

conifer than expected occurred within 4000 m of major rivers. Late seral

forest cover has declined dramatically across all three landscapes since 1933.

Bibliographical Information:

Advisor:Ripple, William J.; Means, Joseph; Fiorella, Maria; Kreuger, William

School:Oregon State University

School Location:USA - Oregon

Source Type:Master's Thesis

Keywords:landscape assessment oregon old growth forests aerial photography in forestry


Date of Publication:07/30/1996

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