Research On Quantitative Characteristics Of Forest And Grass Vegetation Structure In The Loess Area Of Western Shanxi Province

This paper takes forest and grass vegetation structure as research object in Caijiachuan Watershed of Ji County in shanxi province.Through field investigation and lab analysis to research their Quantitative Characteristics.Tree layer research focus on Diameter Structure and Tree Height Structure , shrub layer and herb layer study on the Species diversity and display the relationship of Species and environment in diagram by DCCA method.The aim of this research is to supply theoretical basis for research district's stand sustainable management and species configuration of forest and grass in vegetation restoration and reconstruction,for low-benefit forest transformation.The conclusion show as following:(1) The analysis of different terrain factor influence in diameter and tree height distribution.1)Diameter value fasten on from 0.5cm to 8.5 cm and the value most from 2.5cm to 3.5cm in shady slope,focus from 0.5cm to 11.5cm in sunny slope and the value most from 5.5 cm to 6.5cm.In 3.75 to 4.25 interval has the most tree height value by overall condition of different slope direction.2) Diameter is dispersed distribute in gentle slope and steep slope zone and the maximum is 22cm, form 0.5cm to16cm in clivus and abrupt slope.the most of tree height value is distribute from 0.45m to 8m, the value is convergence in clivus and abrupt slope.3) Diameter and tree height distribution in different altitude condition.the distribution of diameter centralize from 0.5cm to16cm from 1100m to1200m,form 4cm to 13cm from 1000m to 1100m.the distribution of tree height centralize from 0.45m to 8m from 1100m to1200m.,diameter and tree heigh value is not in a numerical range in other altitude.(2) The distribution fitting of diameter and tree height in different site condition.the diameter fitting by three-parameter weibull distribution has good effect,but the tree height fitting's results is bad. diameter-frequency histogram and tree height-frequency histogram reveal the distribution that is not fit three-parameter weibull distribution and normal distribution and logistic distribution.(3) The distribution character of Advantage shrub and grass species the results shows that: Ostryopsis davidiana, Lespedeza floribunda,Syringa tomentella,Rosa xanthina,Artemisia sacrorum,Dendranthema lavandulifolium,Carex humilis Leyss can adapt to different site environmental. Cotinus coggygria,Celastrus orbiculatus,Lespedeza bicolor,Campylotropis macrocarpa,Forsythia suspensa f. suspense,Rubus parvifolius,Artemisia lavandulaefolia,Artemisia dacunculus L are shade tolerance and pleased wetness species.Lespedeza cuneata and Bothriochloa ischcemum are drought resistance and pleased light species.(4) The result of research on Species diversity shows that: shrub and grass species is symmetrical and steady distribution in different site condition.(5) The relationship of quadrat and species and Terrain factor display intuitive in Two-dimensional ordination diagram of DCCA.