浑善达克沙地黄柳更新特点与规律研究

黄柳作为浑善达克沙地重要的固沙先锋灌木,对沙地生态环境的改善起着十分重要的作用,从天然更新和人工更新两个方面对其特点与规律进行了调查研究。结果表明,黄柳的种子萌发和幼苗生长受多种自然因子的影响,属于r型对策者,但由于种子发芽和幼苗的形成受温度、水分及沙埋情况等多项因子的综合影响,幼苗萌发到第二年的相对保存率只有18.3％,天然更新困难；黄柳长势老化衰退后,可采取人工平茬措施,达到复壮更新的目的。研究表明:平茬灌丛新生枝条长度比未平茬灌丛约长150 cm,最长当年生新枝达277 cm；平茬灌丛新生枝基径也比未平茬的约粗0.5 cm,最粗的为1.32 cm；平茬黄柳灌丛叶片长平均约为8 cm,叶宽平均约为0.6 cm,而未平茬灌丛叶片平均长为5.3 cm,叶片宽平均为 0.4 cm。可见,平茬不但增加了黄柳灌丛的生物量,亦提高了家畜可食部分（叶+嫩茎）的比例,同时增大了郁闭度,增强了防风固沙效果。

Characteristics and Rules of Regeneration of Salix gordejevii in Hunshandak Sandland

Salix gordejevii is a kind of dune-fixing pioneer shrub in Hunshandak Sandland,China.It takes a vital role in improvement of ecological environment.Study on natural regeneration and sprouting regeneration of Salix gordejevii was conducted.Results showed that regeneration of Salix gordejevii belongs to r-countermeasure type,which had much seed,high germination rate and low livability.The regenerate manners of Salix gordejevii had natural seed regeneration and sprouting regeneration,and the former was hard.At the same time,growth of Salix gordejevii would decline when the drifting sand dune was fixed.In order to achieve the purpose of regeneration and restoration,people might adopt shoots cutting measure by making use of its regeneration characteristic.The results also showed that the number,length and diameter of new shoots under different treatments were significantly different.Therefore,not only shoots cutting can increase biomass of shrub,but also can increase edible parts,canopy density and effects of sand-fixing and sand-preventing.