【摘要】 目前灌丛沙堆研究主要集中在干旱半干旱区的沙质草原和沙漠边缘,对亚热带湿润区灌丛沙堆的形成、演变过程并不清楚。以鄱阳湖沙地为研究区,通过样方调查和地统计学的方法,研究不同沙化程度下蔓荆灌丛沙堆的形态特征及分布格局。结果表明:鄱阳湖沙地蔓荆沙堆的形态以盾形为主,其冠幅变化幅度为1.2—18.2 m~2,固定和半固定沙地显著高于流动沙地;对灌丛沙堆的形态参数来说,其长轴与短轴在固定和半固定沙地上呈极显著的线性相关关系,流动沙地上呈二次函数关系;半固定和流动沙地上沙堆底面积与沙堆高度呈二次函数关系(r>0.6);3种类型沙地上灌丛底面积与沙堆体积之间极显著线性相关,其中半固定沙地线性函数的斜率最大;除固定沙地的沙堆高度和半固定沙地的灌丛高度外,3种沙地上蔓荆灌丛与沙堆的其他形态参数间均极显著相关,说明随着沙地的固定,蔓荆灌丛有利于沙堆水平尺度的增长;3种沙地上蔓荆沙堆均呈随机分布。更多还原

【Abstract】 Studies of nebkhas focus mainly on the vegetation of sandy grasslands or desert edges in arid and semi-arid areas, whereas the formation and development processes of nebkhas in subtropical humid areas remains unknown. The goal of this study was to reveal the morphological characteristics and distribution patterns of Vitex trifolia nebkhas under different degrees of desertification in the sandy areas of Poyang Lake. The nebkhas pile of V. trifolia was primarily shield shaped, and the crown breadth ranged from 1.2 m~2 to 18.2 m~2, and the breadth in shifting sands was smaller than that in both fixed and semi-fixed sands. Relationships between the long axis and the short axis of nebkhas were linear in the fixed and semi-fixed sands, but showed a quadratic relationship in shifting sands. The projected areas of nebkhas in semi-fixed and shifting sands were quadratically related with their heights(r > 0.6). For all types of sands, there was a an extremely significant linear correlation between the projected area of thickets and the volume of nebkhas, the slope of which was highest in semi-fixed sands. Except for the height of nebkhas in fixed sand and the thicket height in semi-fixed shrubs, there were significant correlations between the morphological parameters of the thickets and nebkhas in the three types of sands. The results showed that with sandy land being fixed, the shrub was advantageous to increases in the horizontal scale of V. trifolia nebkhas. V. trifolia nebkhas was randomly distributed on sandy lands.更多还原