In 1989, the Chisana caribou (Rangifer tarandus) herd in the northern Wrangell Mountains, Alaska, U.S.A., declined substantially in population size and productivity. Grasses, sedges, forbs, and willows (Salix spp.) are critical components of the diet of caribou in spring and summer, and the abundance and quality of forage are influenced by climate. To evaluate effects of climatic variation on caribou forage we conducted a field experiment in subarctic tundra where light, air temperature, and precipitation were manipulated. We used a plastic tarpaulin to increase air temperature and decrease precipitation. We also decreased light intensity with a shade cloth and increased precipitation by adding water to determine climatic effects on [...]
