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Monitoring change in exotic plant abundance after fuel reduction/restoration treatments in ponderosa pine forests of western Montana

Author(s): Erich K. Dodson
Year Published: 2004

Exotic species were monitored following treatments designed to reduce wildfire hazard and initiate restoration of forest structure and process in ponderosa pine (Pinus ponderosa)/Douglas-fir (Pseudotsuga mensiezii) forests to compare response among treatments. Treatments included: no treatment (control), prescribed burning, comprehensive cutting (thinning), and thinning followed by burning. Each treatment was replicated three times in a randomized block design. Frequency, richness, and cover of exotic species were sampled at multiple scales (1 m2, 100 m2, and 1000 m2) in 10 modified Whittaker plots per treatment unit. Data were collected before treatment, one growing season after burning, and two growing seasons after thinning. Special emphasis was given to a subset of harmful exotic species, which were considered undesirable. Non-metric Multidimensional Scaling (NMS) revealed that several thin/burn plots were different in exotic species abundance and composition than plots in any other treatment. Blocked Multi-Response Permutation Procedures (BMRPP) detected significant treatment differences in exotic and undesirable species abundance at each scale. The thin/burn treatment consistently had the highest levels of overall undesirable and exotic abundance. Indicator Species Analysis revealed several exotic species became significant indicators of the thin/burn after treatment. Responses of individual exotic species differed depending on the scale sampled, with more significant differences in abundance being detected at larger scales. Regression models showed that exotic species richness increased with canopy openness, fire severity, and increased native richness, and decreased with sapling density, supporting a resource limitation model of exotic invasion.

Citation: Dodson, Erich K. 2004. Monitoring change in exotic plant abundance after fuel reduction/restoration treatments in ponderosa pine forests of western Montana. Master's Thesis. Missoula, MT: University of Montana. 99 p.
Topic(s): Fire Ecology, Invasive Species, Fire Effects, Ecological - Second Order
Ecosystem(s): Montane dry mixed-conifer forest, Ponderosa pine woodland/savanna
Document Type: Dissertation or Thesis
NRFSN number: 11279
FRAMES RCS number: 844
Record updated: May 24, 2018