元谋干热河谷冲沟坡度与植物优势种关系

在元谋干热河谷冲沟发育典型的三个样区(沙地村、金雷村、苴林村)采集48条冲沟的植物样方数据和冲沟沟底的坡度数据，运用重要值方法对植被优势种进行判别和筛选，以灌木优势种和草本优势种为主要研究对象，探讨植被优势种与冲沟沟底坡度的关系。结果表明：(1)灌木优势种为车桑子Dodonaea viscosa和山合欢Albizia kalkora，重要值分别为0.486和0.342，占灌木总体的83%；草本优势种为扭黄茅Heteropogon contortus、孔颖草Bothriochloa pertusa和茅草Imperata cylindrica，重要值分别为0.386、0.140及0.196，占草本总体的72%。(2)除草本优势种中的茅草盖度与坡度相关性显著(P<0.05)外，样区冲沟沟底坡度与灌木优势种和草本优势种相关性均不显著(P>0.05)，表明在元谋干热河谷地区，冲沟沟底坡度对植被优势种生长状况影响较小。

Relationship Between Ravine Gradient and Plant Dominant Species in Yuanmou Dry and Hot Valley

With three typical plots (Shadi Village, Jinlei Village, and Julin Village) in the hot-dry valley of Yuanmou as sample areas, 48 plant ditch data about gullies and gully slope were collected, and important value methods were used, the dominant species of vegetation were discriminated and screened. The dominant species of shrubs and herbaceous were the main research objects. The relationship between dominant species of vegetation and gully slope was discussed. The results showed that: (1) The dominant species of shrubs were Dodonaea viscosa and Albizia kalkora, the important values were 0.486 and 0.342, respectively, accounting for 83% of the total shrubs. Herbaceous dominant species were Heteropogon contortus, Bothriochloa pertusa and Imperata cylindrica, the important values were 0.386, 0.140 and 0.196, respectively, accounting for 72% of the total herb. (2) Except for the significant correlation between the slope and coverage degree of I. cylindrica (P<0.05), there was no significant correlation between gully bottom slope and dominant species of shrubs or herbaceous dominant species (P>0.05). The results showed that in the dry-hot valley of Yuanmou area, the gully slope had little effect on growth of dominant species of vegetation.