胡杨（Populus euphratica）在额济纳绿洲三种生境内的根蘖繁殖特性

以额济纳荒漠绿洲胡杨根蘖幼苗为研究对象，通过对绿洲内胡杨分布的3种主要生境内根蘖幼苗的调查，得出如下结论。近年来绿洲内胡杨种群的更新几乎完全依赖于无性繁殖更新，种子萌发产生的幼苗在调查地内没有发现。河岸沙丘地及胡杨林下地的根蘖幼苗中，3龄幼苗所占比重最大，龄级越小的根蘖苗在群落中的数量越少；在河水漫灌后的林间空地，2龄幼苗的数量最多。水漫灌后的林间空地中根蘖幼苗密度显著大于其余两生境内根蘖幼苗密度，同时该生境内每段胡杨根系萌生出的不定芽也大于另两生境。随着龄级增加，未枯枝根蘖幼苗的比率逐渐减小。根蘖幼苗的萌发点分布于土层30cm以内的根系上，分布深度大于30cm的根系不能萌发出根蘖幼苗。

The charactertics of root suckers of Populus euphratica Oliv. in three habitats of Ejina oasis

The characteristics of root suckers of Populus euphratica. in Ejina oasis were studied in this research. The field investigation of root suckers in three habitats were carried out in the research areas. The results indicated that the asexual reproduction was the main regeneration approach for Populus euphratica in the last several years, there had no seed reproduced seedlings in the sample plots. In the habitats of sand dune and forest floor, 3-year-old root suckers had the higher proportion compared with the number of 1-year-old and 2-year-old suckers. The younger the root suckers were, the less proportion the root sucker occupied. In the habitat of seasonal flooding area, the 2-year-old suckers were with the largest number. The root suckers density in the the seasonal flooding area was obviously higher than the density in other two habitats, as well as the number of adventitious buds per root. Along with the root sucker aging, the proportion of the suckers without dead branches declined. The root suckers regeneration all happened in the root systems which distributed in soil layer above 30 cm underground, there had no root suckers recruited under 30cm.