UMI  
ProQuest® Dissertations & Theses
The world's most comprehensive collection of dissertations and theses. Learn more...
ProQuest  
 
 
Probabilistic modeling of understory vegetation species in a Northeastern Oregon industrial forest
by Yost, Andrew C., PhD, OREGON STATE UNIVERSITY, 2006, 0 pages; 3190921
 

Abstract: Managing forest ecosystems for sustainable, multiple use requires forest resource managers to understand how species composition and distribution vary across environmental gradients and respond to landscape scale disturbance. A number of statistical modeling tools are available to construct predictive models and maps from response data, a set of predictor variables, and a predefined statistical distribution. Non-Parametric Multiplicative Regression (NPMR) is a probability modeling system that finds the best multiplicative set of predictor variables. The best set maximizes the Bayes Factor value which is a ratio based on modeled estimates and a species' average frequency of occurrence. This study demonstrates predictive vegetation modeling and mapping using NPMR and species presence/absence data collected from 610 plots located across an industrial managed forest landscape in Northeast Oregon. Plots were stratified with a random sampling design. Four modeling approaches were taken to compare the predictive power of spatial coordinates in combination with a set of topographically-derived and stand structural predictor variables. Spatial coordinates were often the most powerful predictors and the modeling approach with physiographic and stand structural variables together was frequently the most improved relative to the average frequency of occurrence. Comparisons between Logistic Regression (LR) and NPMR models were conducted for the species Clintonia uniflora (CLUN) and Pinus ponderosa (PIPO). NPMR performed better for CLUN when the best predictor variables selected by NPMR were used to construct a LR model. For PIPO, the performance of NPMR was comparable to LR when the set of predictor variables used to build the LR model was based on whether the response in probability to each variable was monotonic. Species-level GIS probability maps were produced with the application of the physiographic models and a corresponding set of GIS raster files. GIS overlays of indicator species maps were used to construct plant association group (PAG) maps. Intersections of PAG layers resulted in quantitative mapping of intergrade between types. PAG layers were often significant predictor variables in probability models for 70 understory and five conifer species produced with Logistic Regression (LR) using a forward step-wise process. Potential applications of both NPMR and LR models with the Forest Vegetation Simulator are discussed.

 
Advisor: Maguire, Douglas A.
School: OREGON STATE UNIVERSITY
Source: DAI-B 66/10, p. 5161, Apr 2006
Source Type: PhD
Subjects: Forestry; Environmental science
Publication Number: 3190921
     
Adobe PDF Access the complete dissertation:
 

» Find an electronic copy at your library.
  Use the link below to access a full citation record of this graduate work:
  http://gateway.proquest.com/openurl%3furl_ver=Z39.88-2004%26res_dat=xri:pqdiss%26rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation%26rft_dat=xri:pqdiss:3190921
  If your library subscribes to the ProQuest Dissertations & Theses (PQDT) database, you may be entitled to a free electronic version of this graduate work. If not, you will have the option to purchase one, and access a 24 page preview for free (if available).

 
 
 

About ProQuest Dissertations & Theses
With over 2.3 million records, the ProQuest Dissertations & Theses (PQDT) database is the most comprehensive collection of dissertations and theses in the world. It is the database of record for graduate research.

The database includes citations of graduate works ranging from the first U.S. dissertation, accepted in 1861, to those accepted as recently as last semester. Of the 2.3 million graduate works included in the database, ProQuest offers more than 1.9 million in full text formats. Of those, over 860,000 are available in PDF format. More than 60,000 dissertations and theses are added to the database each year.

If you have questions, please feel free to visit the ProQuest Web site - http://www.il.proquest.com - or call ProQuest Hotline Customer Support at 1-800-521-3042.



Copyright © 2007 ProQuest. All rights reserved. Terms and Conditions

ProQuest