Phenological patterns and adaptations in an Artemisia/Agropyron plant community

Abstract

The phenology of 75 plant species belonging to an Artemesia tridentata Nutt./Agropyron spicutum (Pursh.) Scribn. & Smith plant community in southern British Columbia was recorded in 1978 and 1979. Plant species were classified witbin 4 phenological groups that are hypothesized to reflect adaptation to spatial and temporal distribution of soil moisture. Summer Mature taxa (36 species, including 20 perennial forbs and 10 annual grasses and forbs) initiate growth early, fIower rapidly, and mature before or soon after summer drought began. Favorable moisture conditions in the fall may produce some regrowth. Summer Quiescent taxa (27 species, including 8 of 9 perennial grasses) also initiate growth early in spring, develop fairly rapidly, but flower later than Summer Mature taxa, becoming only semidormant during summer drought. Significant regrowth often occurs in response to fall moisture. Protracted Growth taxa (4 species) display delayed spring growth, followed by fall flowering. These deeply rooted shrubs continue to grow and develop slowly throughout the frost-free period. Eight, generally shallowly rooted forbs were classified as Spring Ephemerals that initiate development very early in spring, flower and terminate growth before summer drought, and rarely resprout in fall. These 4 phenological groups provide flushes in botanical composition, forage production, and nutrient availability that should be reflected witbin grazing management and rangeland inventory programs.