In all three species, clonal selection for growth and commercial biomass production, coppice stem number (not plant sex, longest stem length or corresponding basal stem diameter) was the best criteria for selecting superior willow clones. Case in point is the coppice dune formation resulting from woody shrub encroachment into native grasslands throughout the arid and semi-arid regions of south-western US and globally (e.g., Gibbens et al., 2005 Nickling. This indicated that a zero sum model in which reproductive and vegetative structures compete for assimilates was not supported by our results. Coppice dunes are often associated with areas having degraded soil and vege-tation resulting from anthropogenic disturbances. Female COR plants were often slightly larger than male plants in this dioecious species, but these differences were not statistically significant, and provided no evidence of a reproductive cost expressed as a differential reduction in subsequent vegetative growth in female vs. Stem number showed strong positive relationships to stem dry mass in 1- and 3-year-old coppices.

Each species varied significantly in coppice structure and growth. Additionally, a systematic study on the roles of dune geometry, morphology and hydrological processes in relation to sediment grain-size. Geographic region, populations within regions, and clones within populations all accounted for large portions of total variation in coppice growth traits that were compared with two other willows commonly used for biomass production, S. The formation of coppice dunes (nebkhas) has been attributed to both aeolian and hydrological processes, however, the interactions between these processes and vegetation dynamics are poorly understood. In a common garden study, clones from the eastern and southwestern regions of Ontario, Canada, outperformed those from northern populations. (COR) has proved to be one of the most productive and useful for woody biomass production. Coppice dunes treated with herbicide in 1979 to kill mesquite (Prosopis glandulosa) had the same frequency of occurrence of the shrub as the untreated dunes. Among eight native North American willow species examined for coppice growth performance, the sand dune willow, Salix cordata Michx.