【摘要】 沙地樟子松在沙地上持续进行的天然更新对退化生态系统的植被恢复与重建,沙地生态系统各种效益的持续发挥,以及我国北方绿色生态屏障的建立都具有重要意义。本文通过调查发现,在呼伦贝尔沙地,天然分布的沙地樟子松更新状况良好,经常可以见到10~20龄的更新苗群丛。在不受干扰的情况下,樟子松单株下常见不同龄级的幼苗和幼树,其中6~10龄所占的比例最大,1~5龄次之,这与近年来干旱加剧和过度放牧的关系密切。随着林木单株的生长发育,从幼年期经青年期、壮年期到老年期,单株下方更新苗的密度逐渐增加,成熟单株下方更新苗的密度达到最大,以后渐趋平缓。过熟单株的结实率依然较高,但林下更新苗的数量略有减少。通过对沙地樟子松单株下的更新苗进行分布型计算,认为樟子松更新苗呈集群分布的格局。在不考虑樟子松单株的龄级和其生境特殊性的情况下,沙地樟子松单株下的更新苗集中分布在林冠下北偏东方向的一个扇形区域内,产生这种现象的主要原因是光照和风向的共同作用产生的。更多还原

【Abstract】 The natural regeneration process of Mongol Scotch Pine in the sandy land is important to vegetation rehabilitation,degraded ecosystems reconstruction,sustainable sandy ecosystem benefit development,as well as the establishment of green ecological barriers in north of China.Results show that in Hunlun Buir Sandyland it is common to find the 10~20 years old Mongol Scotch Pine seedling association.Under the environment without all kinds of disturbance,there are lots of seedlings distribute around the mature individual plant,and 6~10 years old seedlings take an advantage percentage,1~5 years old seedlings take the secondary percentage,which related to the recently drought climate and local overgrazing.With the individual plant growth from young to aging,the seedling density under the individual plant gradually increased,and seedling density is highest under the mature individual growth.After the calculating the seedling distribution type index,results show that Mongol Scotch Pine seedlings is clusted distribution pattern.Without the considering of the individual plant age class and its habitat spatial heterogeneity,the seedlings distribute assembly in a fan-shape region located in north to east direction below the mature growth crown.更多还原