Provisional tree and shrub seed zones for the Great Plains
1975
Cunningham, Richard A.
"Seed collection zones are subdivisions of land areas established to identify seed sources and to control the movement of seed and planting stock. Seed zones are needed for many species because of the genetic variation associated with their geographic distribution. Zone boundaries may be delineated from experimental data that identify genetic variation, or by analysis of the environmental factors that most likely acted as selective forces in creating such genotypic variation."
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书目信息
出版者 Rocky Mountain Forest and Range Experiment Station, Forest Service, U.S. Dept. of Agriculture | Fort Collins, Colo. : Rocky Mountain Forest and Range Experiment Station, Forest Service, U.S. Dept. of Agriculture, 1975