The influence of urbanization on forest stand dynamics in Northwestern Oregon |
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Authors: | Nancy E Broshot |
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Institution: | (1) Linfield College, 2255 NW Northrup, Portland, OR 97210, USA |
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Abstract: | Urbanization has been shown to affect forest stand characteristics in nearby natural areas. The purpose of this study was
to examine forest structure in a naturally forested area, Forest Park in Portland, OR and adjacent forested land. Tree community
structure was examined at 25 sites distributed along an urban-rural land use gradient. All trees in three quadrats per site
were identified to species and the diameter at breast height was measured. ANOVA was used to examine differences in species
richness and diversity, and tree density and importance value among four categorical areas. Tree species richness and diversity,
and the density, diameter and importance values of shade-tolerant (later successional) species of trees decreased with urbanization.
Sites nearer the city of Portland had significantly fewer shade tolerant saplings and young trees and were dominated by earlier
successional species of trees as compared with sites at the far end of the study area. The forest structure in the city section
of the park was very similar to that in the significantly younger middle section. The lack of young shade tolerant saplings
and young trees appears to be the result of urbanization, although the mechanisms for such a loss are unknown at this time.
Such a lack of recruitment may interfere with normal successional processes at more urban areas of the park. |
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Keywords: | Forest Urbanization Urban-rural gradient Forest stand structure Succession Regeneration Recruitment Oregon |
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