卧龙巴郎山川滇高山栎群落植物叶特性海拔梯度特征

Leaf-form characteristics of plants in Quercus aquifolioides community along an elevational gradient on the Balang Mountain in Wolong Nature Reserve, Sichuan,China

川滇高山栎林是中国植被非常特殊的亚高山硬叶栎林类型,广泛分布在横断山地区。为了阐明植物群落植物叶型组成对海拔梯度的响应,对卧龙自然保护区巴朗山阳坡川滇高山栎群落植物叶型特征随海拔梯度(15海拔梯度,海拔2200—3600 m)的变化进行了研究。卧龙自然保护区巴朗山各个梯度川滇高山栎群落维管束植物的叶级以小型叶为主,占总种数的平均百分率为36.09%;细型叶和中型叶的维管束植物比例相当,分别为25.64%,25.22%;大型叶和巨型叶维管束植物分别占6.82%—9.94%和0.00%—0.71%;微型叶植物比例在1.28%—5.59%;小型叶维管束植物的比例随海拔先降低后升高再降低,最低值出现在海拔3000 m左右。各个海拔梯度川滇高山栎林内维管束植物的叶型以单叶为主,平均占总种数的75.89%,其余为复叶植物,占总种数的24.11%;维管束单叶型植物物种比例随海拔升高变幅较小,在73.84%—78.78%之间,但在海拔2500 m有一个最低值,其比例为73.85%;复叶维管束植物在各海拔梯度群落物种数比例在21.21%—26.15%之间。各海拔川滇高山栎林内维管束植物的叶质以纸叶型为主,平均占总种数的46.03%,其次为薄叶植物(29.17%),革质(22.00%)和厚革质植物(2.79%)。川滇高山栎群落内纸质与厚革质维管束植物种类的比例随海拔升高而降低;革质与薄叶型维管束植物种类的比例随海拔升高而升高。全缘维管束和非全缘维管束植物种类分别占总数的50.50%和49.50%;全缘类维管束植物随海拔升高呈正二项式分布,而非全缘维管束植物则呈相反的分布格局。

The evergreen oak （ Quercus aquifolioides Rehder ＆ E.H. Wilson） forests are widely distributed in the subalpine zone on the Hengduan Mountains, southwestern China. To understand plant responses to elevational gradient,we studied the leaf-form characteristics of vascular plants growing in 15 Q. aquifolioides community along an elevational gradient from 2200 to 3600 m.a.s.1, on the Balang Mountain,Wolong Nature Reserve, SW China. The majority of the plant species occurring in Q. aquifolioides populations belonged to the microphyll leaf size class （36.09% of the total plant species recorded）. Plants with nanophyll- and mesophyll-sized leaf had a proportion of 25.64% and 25.22%, respectively. Plants with macrophyll-andmegaphyll-sized leaves accounted for 6.82%--9.94% and 0.00--0.71%, respectively. Plants with macrophyll-sized leaves of the total plant species recorded in the populations across the elevational transect. Plants belonging to the leptophyll leaf size class had a proportion of 1.28%--5.59% only. The proportion of plants with microphyll-sized leaves decreased then increased and then decreased again with increasing elevation, with the lowest proportion at 3000 m a.s. 1. Single-leaved plants had a proportion of 75.52% （ranging from 73% to 78%） with a minimum value of 57.23% at 2700 m a. s. 1. Compound-leaved plants accounted for 24.48% ranging from 21% to 26% across the Q. aquifolioides populations investigated. Membranous plants were abundant with a proportion of 46.03% ,followed by orthophyll （29.17%）, sclerophyll （22.00%） , and thick sclerophyll （2.79%）. Proportions of plants with membranous and thick sclerophyll leaves decreased, but those with orthophyll and sclerophyll leaves increased with increasing elevation. Entire-leaved plants （50.50%） and unentire-leaved plants （49.50%） had the same proportion in Q. aquifolioides populations, but the former changed with increasing elevation following a positive binomial distribution, and the latter following a negative binomial distribution.