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Title: CHANGES IN THE ALASKA WEED FLORA OVER A 20 – YEAR TIME PERIOD

Author
item Conn, Jeffery
item Beattie, Katherine

Submitted to: Weed Science Society of America Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 9/20/2005
Publication Date: 2/1/2006
Citation: Conn, J.S., Beattie, K.L. 2006. Changes in the Alaska weed flora over a 20-year time period. Weed Science Society of America Meeting Proceedings.

Interpretive Summary:

Technical Abstract: Agricultural fields were surveyed in 2004 near Palmer, Fairbanks, and Delta Junction, Alaska. A similar study had been performed in 1984, which allowed us to determine if new weed species had been introduced to Alaskan agriculture and to find changes in environmental and management variables underlying weed species distribution. Ten 1-m2 quadrats were sampled in each field and percent cover was determined for each weed species. For each field we determined field age (time since clearing), herbicides used, crop grown, elevation, surrounding vegetation type, and percent of photosyntheticly active radiation reaching the soil surface. Detrended correspondence analysis was used to ordinate fields based on weed vegetation. Multiple linear regression was used to determine which of the environmental and management variables was most highly correlated with field ordination x and y axis locations. Six new weed species were found: large mouse ear chickweed (Cerastium fontanum), horseweed (Conyza Canadensis), charlock mustard (Sinapsis arvensis), bladder champion (Silene latifolia), perennial sow thistle (Sonchus arvensis), narrow-leaf hawksbeard (Crepis tectorum), and orange hawkweed (Hieracium aurantiacum).