Relationship between soil conditions and declining growth rate of aged Pinus tabulaeformis at Jietai Temple of Beijing

The relationship between soil conditions and the low growth rate of famous aged Pinus tabulaeformis in Jietai Temple was studied.Results showed that these famous aged pine trees grew on soils containing low organic matter,total nitrogen and readily available phosphorus but with enough available potassium,iron, copper and zinc.A suitable total soil porosity but with high capillary porosity and very low non-capillary porosity of 1.1%-6.4% was found for tree growth.High soil moisture in topsoil (25%) along with a very low permeability may lead to oxygen shortage in the roots.Soil pH was higher than 8 in all layers.In topsoil, water-soluble sodium was higher than 100mg/kg which may be toxic to the pine trees,and easily reducible materials were higher than 1.5% which may put the roots in a reduction condition.Suggestion was made to scientifically monitor the habit of the old pine trees and to investigate the chemical and physical properties of soil,soil moisture,mechanical harm and environmental pollutants so as to control them in the suitable ranges.