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Comparison of stream invertebrate response models for bioassessment metric

June 1, 2012

We aggregated invertebrate data from various sources to assemble data for modeling in two ecoregions in Oregon and one in California. Our goal was to compare the performance of models developed using multiple linear regression (MLR) techniques with models developed using three relatively new techniques: classification and regression trees (CART), random forest (RF), and boosted regression trees (BRT). We used tolerance of taxa based on richness (RICHTOL) and ratio of observed to expected taxa (O/E) as response variables and land use/land cover as explanatory variables. Responses were generally linear; therefore, there was little improvement to the MLR models when compared to models using CART and RF. In general, the four modeling techniques (MLR, CART, RF, and BRT) consistently selected the same primary explanatory variables for each region. However, results from the BRT models showed significant improvement over the MLR models for each region; increases in R2 from 0.09 to 0.20. The O/E metric that was derived from models specifically calibrated for Oregon consistently had lower R2 values than RICHTOL for the two regions tested. Modeled O/E R2 values were between 0.06 and 0.10 lower for each of the four modeling methods applied in the Willamette Valley and were between 0.19 and 0.36 points lower for the Blue Mountains. As a result, BRT models may indeed represent a good alternative to MLR for modeling species distribution relative to environmental variables.

Publication Year 2012
Title Comparison of stream invertebrate response models for bioassessment metric
DOI 10.1111/j.1752-1688.2011.00632.x
Authors Ian R. Waite, Jonathan Kennen, Jason T. May, Larry R. Brown, Thomas F. Cuffney, Kimberly A. Jones, James L. Orlando
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of the American Water Resources Association
Index ID 70041952
Record Source USGS Publications Warehouse
USGS Organization California Water Science Center; New Jersey Water Science Center; North Carolina Water Science Center; Oregon Water Science Center; Utah Water Science Center