Effects of ectomycorrhizal fungi on alleviating the decline of Pinus sylvestris var.mongolica plantations on Keerqin sandy land
外生菌根真菌对科尔沁沙地樟子松人工林衰退的影响

Based on the observations of air temperature,soil temperature,and root systems of Pinus sylvestris var.mongolica plantations on southeastern Keerqin sandy land,the decline mechanisms of the plantations were analyzed from the aspect of the effects of temperature on the growth and survival of ectomycorrhizal fungi(ECM).The results indicated that ECM could hardly survive with in 0-5 cm soil layer because of its high temperature environment,but the temperature condition in 20-40 cm soil layer was suitable for the survival and growth of ECM.78% of the roots of 13-42 years old P.sylvestris var.mongolica tress were distributed in 20-40 cm soil layer,which suggested that the existence of ECM in this soil layer inhibited or alleviated the decline of the P.sylvestris var.mongolica plantations,and was not the inducing factor of the plantations' top withering,low growth rate,and tree death.The lack of ECM in surface soil layer(0-5 cm) could be one of the main reasons leading to the death of seedlings root systems,and thus,the failure of P.sylvestris var.mongolica plantations' regeneration.