to investigate the responses of some physiological and morphological traits to different soil temperature and phosphorus supply under current and doubled carbon dioxide concentration ([co2]), white birch (betula papyrifera mash) seedlings were exposed to three soil temperatures (tsoil) (7, 17 and 27c) and three levels of phosphorus (p) (241, 493 and 951 mg/l) under current and doubled carbon dioxide concentration.