Roadside vegetation in boreal South Yukon and adjacent Alaska
Lausi, D.; Nimis, P. L.
This paper gives an account of a recent study (1983) of roadside vegetation along the main highways of Central and Southern Yukon (Canada) and Southeastern Alaska (USA). A sample of 101 phytosociological relevés from systematic sampling (1 relevé every 15 km) along the main roads crossing the survey area has been submitted to multivariate analysis. The results revealed that: The floristical variation in roadside vegetation is related to environmental differences among different portions of the survey area. The main factor underlying floristical variation in roadside vegetation is climate, chiefly precipitation. A definite correlation exists between the floristic composition of weed stands and adjacent natural vegetation. This is mainly due to the colonization of wastelands by native species occurring in adjacent natural stands, chiefly grasslands, xeric woods and forest edge. The ecological and compositional gradient is correlated with variation in the frequencies of different phytogeographical elements. Life-form types are correlated with climatic differences along the gradient. Three community-types were recognized for the purpose of classification. These are geographical vicariants within the survey area.