EFFECTS OF CLIMATE ON PLANT-FOOD AVAILABILITY AT HIGH ALTITUDE IN THE COLORADO FRONT RANGE, U.S.A

Abstract

Forty plant species and groups of related species were identified as potential food sources in the alpine tundra and subalpine forest of the Colorado Front Range. Emergence, flowering, and ripening schedules were monitored from 1994 to 2004, a period that included years with marked differences in precipitation, growing-season temperature, and snowbank­meltout dates. Late-lying snow is a critical limiting factor in the high-mountain environment, delaying the emergence of edible greens and the blooming of root-food species by as much as 2½ to 3 months in extreme years. Fruit and seed production are unreliable at high altitude because favorable moisture and temperature conditions rarely exist at all stages in the developmental process. Ethnographic data from arctic and subpolar regions with ET (effective temperature) values similar to those of the study area suggest that plant foods comprised less than 20% of the high-altitude summer diets of Front Range hunter-gatherers. Percentages would have been lower during cold, snowy intervals such as the Little Ice Age. Visitors to the alpine region, however, spent much of the year in warmer environments. On an annual basis they were not plant-food deprived.