THE RELATION AMONG ECOLOGICAL FACTORS AND DIAMETER GROWTH OF PLATYCLADUS ORIENTALIS IN THE SOUTH OF NORTHERN SHAANXI PROVINCE

Using grey association analysis and quantificatlon method I,the relation among 7 clamatic factors, 3 topographic factors and diameter growth of Platycladus orientalis in 3 areas in the south of northern Shaanxi Province were analysed. The effects ofeach clamatic factor in these 3 areas are different,but annual rainfall and humidity arethe most important factors. The effect of position on slope is the prime important in topographic factors. Further analysis revealed that the aforementioned results are consistent. In addition,the growth of Platycladus orientalis in different communities and different soil conditions were discussed. The result Indicated that Quercus liaotungensis has detrimental effect on growth of Platycladus orientalis,while Pinus tabulaeformis and P.bungeana have not. It also revealed that soil moisture and soil organic matter are significant positive correlation with growth of Platycladus orientalis.