石羊河下游7种沙生灌木的构型比较

为了明确比较相同环境下不同灌木的构型特征,揭示其防风固沙机理,也为仿真模拟研究提供基础数据,该研究对石羊河下游的相同环境下,高度相似的梭梭(Haloxylon ammodendron)、油蒿(Artemisia ordosica)、沙蒿(A.arenaria)、花棒(Hedisarum scoparium)、沙拐枣(Calligonum mongolicum)、白刺(Nitraria tangutorum)、红砂(Reaumuria kaschgarica)7种灌木的分枝角度、枝长和分枝数等构型指标进行测量分析。结果表明:(1)7种灌木中有6种的平均分枝角度自冠层内部向外逐渐变大,枝序级可分为四级,除油蒿外,其余灌木的冠层外枝均较长。(2)分枝分维数以红砂最大,其次为梭梭和白刺,沙拐枣和花棒最小;除梭梭外,其余灌木的总体分枝率都小于1。(3)除沙拐枣外,其余灌木的侧影面积随高度增加而增加,达到最大值后又逐渐减少。研究认为,生长在相似环境的灌木形成了不同构型,红砂、白刺、油蒿和花棒可归为密生枝型灌木,梭梭、沙拐枣和沙蒿则可定为疏生枝型灌木。

A Comparison on Architecture of 7 Psammophyte Shrubs at Lower Reaches of Shiyang River Basin

The objective is to compare the different shrub architecture and uncover mechanism of controlled moving sand,also to provide the basic data for simulation research of simulated fixed-sand shrub.The crotch angles,branch length,branch number and architecture of Haloxylon ammodendron,Artemisia ordosica,A.arenaria,Hedisarum scoparium,Calligonum mongolicum,Nitraria tangutorum,Reaumuria kaschgarica were measured and analyzed at the lower reaches of Shiyang River Basin.The results showed that:(1)the mean of crotch angle measured seven shrubs increased gradually from inside to outer position of canopy with four branching ranks.It was only A.ordosica that the length of outer twigs was longer than that of inside twigs of canopy.(2)The number of branching fractal dimension of R.kaschgarica was bigger than that of the other 6 shrubs.Second one of branching fractal dimension was H.ammodendron and N.tangutorum,the least one was C.mongolicum and H.scoparium.The branch-stem ratio was less than one except H.ammodendron.(3)Except C.mongolicum,the number of upwind projected area increased with height of canopy,and gradually decreased at the maximizing point of upwind projected area.R.kaschgarica,N.tangutorum,A.ordosica and H.scoparium were as dense branch shrubs,as sparse branch shrubs of H.ammodendron,C.mongolicum and A.arenaria.