LUOMA, D. L. and THIES, W. G. 1994. Effects of live tree fumigation on nontarget vegetation. Can. J. For. Res. 24: 2384-2389

Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco) trees, both healthy and infected by Inonotus sulphurascens (Pil‡t) M. J. Larsen, Lombard, & J. W. Clark (Phellinus weirii sensu lato), were fumigated with chloropicrin or methylisothiocyanate at a site in the Oregon Coast Range. Ten growing seasons later, vegetation cover on plots around treated and untreated individuals was evaluated to determine fumigant effects on nontarget plants. Total plant cover and individual species cover for Berberis nervosa Pursh, and Stokesiella oregana (Sull.) Robins were significantly reduced in the chloropicrin treatment plots. The dominant shrub, Gaultheria shallon Pursh, was little affected in chloropicrin plots. Slightly greater species richness and Rubus ursinus Cham. & Schlecht. cover in chloropicrin plots were attributed to higher light levels and other factors associated with reduced shrub cover on the treated plots. Multivariate analysis showed little overlap in plant community structure between chloropicrin treated and control plots. Detection of effects due to the methylisothiocyanate treatment was hindered by the lack of strictly paired control trees. The results are discussed in relation to the retrospective nature of the study.