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International Journal of Forestry Research
Volume 2012 (2012), Article ID 263953, 16 pages
http://dx.doi.org/10.1155/2012/263953
Research Article

Structural Equation Modeling: Theory and Applications in Forest Management

1Department of Forest Engineering, Resources and Management, College of Forestry, Oregon State University, 204 Peavy Hall, Corvallis, OR 97331, USA
2Division of Forest Management, Department of Forest and Climate Change, Korea Forest Research Institute, 57 Hoegiro, Dongdaemun-gu, Seoul 130-712, Republic of Korea

Received 18 October 2011; Accepted 27 January 2012

Academic Editor: Hubert Sterba

Copyright © 2012 Tzeng Yih Lam and Douglas A. Maguire. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Forest ecosystem dynamics are driven by a complex array of simultaneous cause-and-effect relationships. Understanding this complex web requires specialized analytical techniques such as Structural Equation Modeling (SEM). The SEM framework and implementation steps are outlined in this study, and we then demonstrate the technique by application to overstory-understory relationships in mature Douglas-fir forests in the northwestern USA. A SEM model was formulated with (1) a path model representing the effects of successively higher layers of vegetation on late-seral herbs through processes such as light attenuation and (2) a measurement model accounting for measurement errors. The fitted SEM model suggested a direct negative effect of light attenuation on late-seral herbs cover but a direct positive effect of northern aspect. Moreover, many processes have indirect effects mediated through midstory vegetation. SEM is recommended as a forest management tool for designing silvicultural treatments and systems for attaining complex arrays of management objectives.