白水江自然保护区植物果实类型组成及垂直分异

Composition and Vertical Differentiation of Fruit Types in Baishuijiang National Nature Reserve in Gansu Province

分析甘肃白水江国家级自然保护区1943种野生被子植物果实类型组成及其沿海拔梯度的变化规律,结果表明:本区干果和肉果分别占65.67%和24.60%,在22种基本果实类型中,居前3位的分别为蒴果(26.56%)、瘦果(12.35%)和核果(12.20%);果实类型及其种数随海拔升高呈先增加后减少的趋势;随着海拔升高,干果比例上升,肉果比例下降并消失于3800m左右,其中蒴果比例在各海拔段均占据显著优势并呈上升趋势,瘦果和颖果比例先下降后上升,核果和浆果比例下降,梨果和翅果比例先上升后下降。聚类结果表明:海拔2000m左右是基本果实类型种数分布的断点。果实类型垂直分异可能是伴随着相应海拔范围内水热条件及其组合特征的改变,以及果实传播方式的不同而产生的。在完善果实分类系统的前提下,可将果实类型的数量对比关系,作为反映某地区气候的生物标志之一。

The compositions of fruit types and their differentiation patterns with elevation of 1 943 wild angiosperms in Baishuijiang National Nature Reserve in Gansu Province were explored. The results show that the proportion of dry fruits is 65.67% and 24.60% in fleshy fruits in the area. The most three are capsule （26.56%）, athene （12.35%） and drupe （12.20%） among 22 basic fruit types. Fruit types and their species numbers increase and then decrease with elevation. The proportion of dry fruits increases and it vanishes at 3 800 m or so in fleshy fruit with elevation. The proportion of capsule is dominant in each elevation segment and increases with elevation. It decreases and then increases in athene and caryopsis. It decreases in drupe and berry. It decreases and then increases in pome and samara. The cluster result shows that the elevation of 2 000 m is the distribution breakpoint of species numbers of basic fruit types. The vertical differentiation of fruit types may have occurred with changing of water and heat condition and their combined characteristic in corresponding altitude range as well as dissemination mode of fruits. Proportion relationship of fruit types can be used as one of the biological marks to reflect the region＇s climax on the premise that the classification system of fruit types can he perfected.