云南松与旱冬瓜混交林林地土壤养分及细根、叶片养分特征

Soil Nutrients in Mixed Forest of Pinus yunnanensis-Alnus nepalensis and Nutrient Content of Leaves and Fine Roots of the Two Tree Species

为了探讨云南松与旱冬瓜混交对养分的利用情况,对云南松纯林、云南松与旱冬瓜混交林分、旱冬瓜纯林3种林分类型进行了林地土壤及叶片、根系养分质量分数的测定分析。结果表明:云南松与旱冬瓜混交林地土壤表层土的有机质、有效磷、水解氮、有效钾、全氮、全磷、全钾、交换性钙、镁离子等肥力指标都比纯林高,pH值也发生了变化,介于云南松纯林与旱冬瓜纯林林地土壤的pH值之间,为4.93～5.15。云南松与旱冬瓜混交提高了2树种细根的养分质量分数,提高了云南松叶片的养分质量分数,云南松叶片的m(N)∶m(P)<14,研究区普遍受氮养分限制,且在夏季混交林比纯林受氮养分限制更明显。云南松与旱冬瓜混交提高了林地土壤养分质量分数,尤其是有效养分的质量分数,对改良土壤和防止地力衰退具有重要的作用。

An experiment was conducted to determine soil nutrient contents in a pure Pinus yunnanensis forest,a pure Alnus nepalensis forest and a mixed forest of P.yunnanensis-A.nepalensis.And nutrient contents of leaves and fine roots of P.yunnanensis and A.nepalensis were also studied.Results showed that the contents of soil organic matter,available phosphorus,hydrolyzable nitrogen,available potassium,total nitrogen,total phosphorus,total potassium,exchangeable calcium and magnesium in the soil of the mixed forest were higher than those of the purity forests.Soil pH of the mixed forest was intermediate（4.9-5.2） between the pH values of the pure P.yunnanensis forest and the pure A.nepalensis forest.Moreover,nutrient contents of fine roots and leaves of P.yunnanensis and A.nepalensis in the mixed forest all increased.N∶P ratio of P.yunnanensis was less than 14,indicating that the growth of P.yunnanensis in the study area was limited by nitrogen.There was a more obvious shortage of soil nitrogen in the mixed forest than in the pure forests in summer.P.yunnanensis mixed with A.nepalensis could enhance soil nutrient content,especially the contents of available nutrients.