Discovery of C4 species at high altitude in Qinghai-Tibetan Plateau

Plant specimens are collected from the areas between latitude 27degrees42'N and 40degrees57'N, and longitude 88degrees93'E and 103degrees24'E, with an altitudinal range from 2210 to 5050 m above the sea level in Qinghai-Tibetan Plateau. The stable carbon isotope analysis indicates that two of Chenopodiaceae and six of Poaceae in the samples are C-4 plants. Four of the C-4 plants are found in 11 spots with altitudes above 3800 m, and Pennisetum centrasiaticum, Arundinella yunnanensis and Orinus thoroldii are present in six spots above 4000 m, even up to 4520 m. At low CO2 partial pressure, that sufficient energy of high light improving C-4 plant's tolerance of low temperature and precipitations concentrating in growing season probably are favorable for C-4 plants growing at high altitude in Qinghai-Tibetan Plateau.