Document Type

Thesis

Date of Degree Completion

Spring 2019

Degree Name

Master of Science (MS)

Department

Biology

Committee Chair

Paul W. James

Second Committee Member

Mary E. Poulson

Third Committee Member

Robert J. Hickey

Fourth Committee Member

Eric A. Graham

Abstract

Forest communities are in a constant state of change. Disturbance events can alter the physical landscape and create conditions favorable to some species while negatively impacting others. Fire has been a natural, reoccurring source of disturbance in Pacific Northwest forests. Over the past centuries the fire paradigm has changed in favor of fire suppression. Forest roads permit access provide greater access but further fracture forest community’s continuity. The 2012 Table Mountain Fire and road influence have altered the plant community’s seed rain and vegetation. This study measured dispersed seeds and understory vegetation cover as functions of roads and fire intensity. Significantly more wind dispersed seeds were collected in high intensity fire sites. The peak in seed release was later and more pronounced in the high intensity sites. Road proximity did not significantly affect the seed rain; however nonwind dispersed seeds were significantly higher near the road edge. Fireweed (Epilobium angustifolium) accounted for nearly 48% of the seed rain. When fireweed, the dominant species in both the vegetation cover and the seed rain, was excluded from the total seed rain, there was more seed rain in samples collected nearest to the road edge when compared to other distances from the road, there was no significant difference between the seed rain in sites with differing fire intensity, and the peak seed release in the phenology did not differ between fire intensities.

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