额济纳胡杨林林分结构与更新初探

Study on Forest Structure and Renew of Pouplur euphratica Oliv. in Ejna

通过研究胡杨林分结构和更新,阐述了胡杨林在恶劣环境中维持生存的生态学机制。应用-3/2自疏定律对胡杨天然林进行研究,结果表明:1)过熟林林内存在高度自疏现象,树冠枯死严重,郁闭度低。2)成熟林生长正常,树冠郁闭度高,有少量枯枝,存在自疏现象;3)幼龄林林木生长未受抑制,但林内存在着激烈的空间竞争。胡杨胸径小于20 cm为快速生长期,超过20 cm的所有大径阶胡杨都有枯梢现象,高生长受到抑制。个体生长是通过控制林冠大小,降低树高和增加幼苗更新来适应恶劣的环境。额济纳胡杨的生存策略是成熟及过熟木放弃林木冠层复壮而将有限的资源分配到萌蘖新苗,从而达到林分不断更新。

By studying the structure and renew of Populus euphratica Oliv., the paper is intended to illustrate elabo- rated poplar maintain ecological mechanism to survive in harsh environments. Natural Populus euphratica Oliv. for- est in Ejina, including young forest, mature forest and over - mature forest. Application of - 3/2 self - thinning law on natural Populus euphratica Oliv. forest, the results showed that： 1 ） Highly thinning phenomenon, severely died crown and low forest canopy closure were observed in over - mature forest. 2） The growth of mature forest can- opy is fast and showed high crown density, on the other hand, mature forest displayed a small amount died bran- ches and high self - thinning phenomenon. 3 ） The growth of young forest is very quickly, but space competition is fairly intense. Rapid growth was observed in Populus euphratica Oliv. which diameter at breast height （DBH） is less than 20 cm, on the contrary, the growth was restricted and appeared lager amount withered little phenomenon in Populus euphratica Oliv. which diameter at DBH is more than 20 era. The individual tree adapted to the harsh environment by controlling the size of the canopy, reducing height and increasing seedling renewal. Therefore the survival strategy of Populus euphratica Oily. forest are abandoned canopy rejuvenation for mature forest and over - mature forest, which the limited resources were allocated to sprout trees emerging and forest renewal.