石灰岩山地侧柏纯林非生长季土壤氮矿化研究

Soil Nitrogen Mineralization of Platycladus orientalis(L.) Franco Plantation During Non-growing Season on Limestone Mountains

为探明石灰岩山地侧柏纯林非生长季土壤氮矿化能力,采用PVC管原位培养法对济南南部山区石灰岩山地人工恢复不同年限(5,10,25年)的侧柏纯林土壤的氮矿化能力进行研究。结果表明:3种不同恢复年限侧柏纯林NO3--N含量先升高后降低然后再有所升高,NH4+-N含量变化没有明显的规律性。其净硝化速率和净氮矿化速率均在11月份达到最大值,分别为(0.07±0.04)mg/(kg.d),(0.11±0.01)mg/(kg.d),(0.15±0.02)mg/(kg.d)和(0.15±0.04)mg/(kg.d),(0.29±0.02)mg/(kg.d),(0.33±0.03)mg/(kg.d)。石灰岩山地侧柏纯林土壤的净氮矿化速率与土壤湿度表现为二次函数关系,但随湿度增加,土壤净氮矿化能力降低。土壤净氮矿化与土壤pH值呈显著负相关(r=-0.452,p=0.018),与土壤有机碳含量、微生物量碳含量和C/N比均呈正相关关系,但相关性不显著(r=0.076,p=0.707;r=0.374,p=0.055;r=0.337,p=0.086)。非生长季石灰岩山地侧柏纯林土壤有较强的氮转化能力,气温变化所导致的土壤环境因素对氮矿化有显著影响。

In order to explore nitrogen mineralization of the Platycladus orientalis（L.） Franco plantation during non-growing season on limestone mountains.By employing an intact soil core in-situ situ incubation technique with PVC tubes,the soil nitrogen mineralization in P.orientalis（L.） Franco plantation for different restoration years（5 years,10 years,25 years） was studied.The results demonstrated that NO-3-N content was increased first,then it decreased and increased in the research months.However,the NH＋4-N content had no obvious regularity.The net nitrogen nitrification rates and mineralization rates reached maximum in November and they were（0.07±0.04） mg/（kg·d）,（0.11±0.01） mg/（kg·d）,（0.15±0.02） mg/（kg·d） and（0.15±0.04） mg/（kg·d）,（0.29±0.02） mg/（kg·d）,（0.33±0.03） mg/（kg·d） in three restored forest soil,respectively.The soil net nitrogen mineralization rate showed quadratic function relation with soil moisture as well as significantly negative correlation with the soil pH value（r=-0.452,p=0.018）.The net nitrogen mineralization reduced with the increasing soil moisture.Besides,the soil net nitrogen mineralization rate had positive correlation with the soil organic carbon content,microbial biomass carbon content and C/N ratio,but the correlations were not significant（r=0.076,p=0.707;r=0.374,p=0.055;r=0.337,p=0.086）.There was strong nitrogen transform in the soil of Platycladus orientalis（L.） Franco plantation during no-growing seasons.The changes of soil condition resulted from temperature had significant effects on the soil nitrogen mineralization.