Title: UPatterns in Understory Vegetation Communities Across Canopy Gaps in Young, Douglas-fir Forests of Western Oregon U.

Canopy gap formation is a major factor contributing to maintenance of overstory species diversity and stand structure in forests and may be integral to development of understory shrub and herb layers as well. Acknowledgement of gap formation as a fundamental feature of natural forests has led to consideration of gaps as an option in forest management regimes. This study examined understory vegetation communities across canopy gaps created as a part of the Density Management Study (DMS), which investigates the effectiveness of a thinning regime in promoting late-successional habitat development in young Douglas-fir forests of western Oregon. Patterns in understory vegetation community composition in and around 0.1 and 0.4ha gaps created as a part of the DMS treatment were investigated. The primary goal of this research was to investigate the potential role of canopy gap creation in fostering heterogeneity in understory vegetation communities, and to examine the extent of gap influence on the surrounding thinned forest matrix. Tree species distributions have been shown to partition across gaps in tropical forest systems through differential responses of species to gradients in resourc