Vegetation of the Mima Mounds Washington State, USA

Del Moral, Roger; Deardorff, David

The vegetation patterns on the undulating topography of the Mima Mounds, Washington, USA exist on at least three scales. At the smallest scale the distribution of individuals is determined primarily by microtopographic features which provide small, but significant habitat variation. An Intermediate scale is dependent upon exposure and elevation. Mounds alter drainage and insolation to create moisture gradients to which all species respond. The largest scale involves the shift of species distributions with respect to mounds as one moves from the prairie to a zone of Pseudotsuga menziesii invasion. Conditions become more mesic as a consequence of reduced insolation and wind in this ecotone, resulting in an increase in mesophytes and a decrease in xerophytes. Both ordination and classification methods are applied in this study. The analyses are complementary and provide insight into the nature of factors controlling vegetation. A method of detailed mapping is proposed which involves the description of a small sample of the area to be mapped, preliminary clustering, the application of discriminant analysis to perform reallocation of samples, and the construction of a key to the resultant associations. The key is used in the field to assign samples to the proper association.

Vegetation of the Mima Mounds Washington State, USA

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