Research On Forest Community And The Choice Of Species For The Limestone Mountains In North Of Anhui

The limestone mountain in northern of Anhui was selected and the vegetations was investigated in this paper. According to the survey data from 30 samples, the forest vegetation was divided into 3 vegetation subtypes, 11 formations and 18 associations. The 3 vegetation subtypes were the deciduous broad-leaf forest, the evergreen coniferous forest, the deciduous shrubbery, the result of investigation also showed that Some deciduous species of Fagaceae such as Q.variabilis , Q.acutissima , C.mollissuna, species of Ulmaceae such as P.tatarinowii, species of Rosaceae such as P.betulaefolia and C.speciosa were the main dominant tree species of natural forest, V.negundo, G.biloba , Z. jujuba were the main dominant species of the shrubbery, P. orientalis and R.pseudoacacia were the main species of artificial forest in the study area.The soil and site types in the study area were also investigated. Based on the data of 17 samples, the limestone mountains in the northern of Anhui could be divided into 2 site groups, they are thin layer group and intermediate layer group. The former can be divided into 6 types, and the later can be divided into 2 types, altogether 8 site types.Fallowing the results of community investigation, the seedlings of P.tatarinowii, Q.variabilis, C.sinensis, F.simplex and Amomo were selected to determine the physiological and ecological characteristics. The results showed that:(1)In Spring, the dominant factors affected net photosynthesis rate of the seedlings of P.tatarinowii, Q.variabilis, C. sinensis, F.simplex and A.momo respectively were block temperature, water barometric pressure of leaf surface and water content, intercellular CO₂ concentration and the block temperature, water barometric pressure of leaf surface and the chamber air humidity, stomatal conductance and block temperature; In Summer, the dominant factors affected net photosynthesis rate of the seedlings of the five species respectively were air temperature, leaf temperature and illumination intensity, block temperature and chamber air humidity, water barometric pressure of leaf surface and block temperature, air CO₂ concentration. In Autumn, the dominant factors affected net photosynthesis rate of the seedlings of the five species respectively were stomatal conductance and chamber air humidity, stomatal conductance and air CO₂ concentration, water barometric pressure of leaf surface and air temperature, leaf temperature and illumination intensity, water barometric pressure of leaf surface and illumination intensity. (2) For the seedlings of P.tatarinowii and F.simplex ,the curves of diurnal change in photosynthetic rate were double-peaked at midday in Summer, and were single-peaked in Spring and Autumn; As to the seedlings of the other three species , the curves of diurnal change in photosynthetic rate were double-peaked at midday in Spring and Summer, and were single-peaked in Autumn. The average photosynthetic rate of all the five species was highest in Summer, then Autumn, Spring successively.(3)The light compensation point of P.tatarinowii, Q.variabilis, C. sinensis,F.simplex and Amomo respectively were 77.86μmol·m^-2·s^-1, 90.23μmol·m^-2·s^-1, 177.26μmol·m^-2·s^-1,67.23μmol·m^-2·s^-1and 137.45μmol·m^-2·s^-1, The light saturationpoint respectively were 1072.73μmol·m^-2·s^-1, 1121.25μmol·m^-2·s^-1 , 2693.00μmol·m^-2·s^-1,1276.11μmol·m^-2·s^-1 and 1024.44μmol·m^-2·s^-1.The scope of light which the seedlings of C.sinensis used, from 177.26μmol·m^-2·s^-1 to2693.00μmol·m^-2·s^-1, was widest, next F.simplex, Rtatarinowii and F.simplex, A.momo successively, which showed that the five main seedlings were heliophilous species, and they are adaptive to the environment of limestone.(4)The average water use efficiency of the five species seedlings in Summer respectively were 7.92μmolCO₂/mmolH₂O,5.53μmolCO₂/mmolH₂O,6.77μmolCO₂/mmolH₂O,6.03μmolCO₂/mmolH₂O and 5.91μmolCO₂/mmolH₂O, and those in Summer were highest ,then Spring, the lowest in Autumn. Relatively speaking ,the water use efficiency of the seedlings of Rtatarinowii, C.sinensis and F. simplex were higher and could much more resist to drought than the other species.Considered the economical and ecological effects and based on the datas of the investigation of the community and the results of the physiological and ecological mensuration , proper species were selected for the each site type,they respectively are P. orientalis, Q.variabilis, Q.variabilis,F.simplex and C.coggygria, P. betulaefolia and S.sebiferum, Rtatarinowii and Amomo, C.sinensis and P.betulaefolia, C.mollissuna,Q.variabilis and Rbetulaefolia, Q.variabilis,P. chinesis,Q.acutissima and R.pseudoacacia.