Phenological Pattern in the Shortgrass Prairie

Abstract

Data were collected for 1 yr on 34 range plant species and for 2 yr on 6 species to describe phenological timing in the shortgrass prairie of NE Colorado [USA] and to determine whether there were any distinct groups of plants for which a single species could be used as a phenological indicator. Observations were made in 4 [cattle] grazing treatments and 2 water amendment areas (1 with 100 kg/ha mineral N added). Water amendments altered the phenology of some species, while grazing and N treatments had no measurable effects on phenology. Standard cool- and warm-season classification of plants does not adequately describe the phenological dynamics of the shortgrass prairie. For example, Buchloe dactyloides, a warm-season grass, flowers with Agropyron smithii, a cool-season grass, rather than with Bouteloua gracilis, another warm-season grass. Four general categories of plants having different flowering capacities are recognized: blooming only once very early in the growing season; blooming twice with a summer dormancy period; blooming once during midsummer with blooming delayed during drought; and blooming only once late in the growing season.