Introduction and Early Adaptability of Exotic Alders

Total 54 seedlets (sources) of 11 exotic alder species were tested on field experiment at Fuyang(120°19′ N,30°12′ E),Zhejiang. All of the 3～4 month-old seedlings of 20 seedlets of five species of Alnus viridis,A.crispa, A.sinuata,A.hirsuta and A.jorullensis, died in summer because of being unable to tolerate the higher temperature and arid weather. Other 6 species of foreign alders were able to survive and grow. Of them, European alder (A.glutinosa) displayed the best, no damage in summer was found,the average heigh of its 4 sources reached to 2.18～2.48 m for two year old seedling, the growth speed was equal to Sichuan alder (A.cremastogyne) . The saw-leaf alder (A.serrulata) grew normally and had no damage too. But red alder (A.rubra) and thin-leaf alder (A.tenuifolia) were seriously injured by high temperature and aridity in summer, leaves scorched and shedding,shoot diebacked, even a few plants died in July to August. Glay alder (A.incana) and tooth-leaf alder (A.rugosa) were lightly damaged in summer. In addition,Taiwan alder (A.formosana) had the longest growing time,it grew rapidly,however it was easy to receive the frost injury in northern Zhejiang. Signifficant differences for some physiological indexes were found among alder species. For European alder, saw-leaf alder and grey alder, the authors could select the fine seed sources to expand the experiment of introducing, European alder might be especially hopeful to be popularized in the plain area of middle and lower reaches of Yangtze River.