川西亚高山不同海拔森林土壤活性氮库及净氮矿化的季节动态  

Seasonal dynamics of soil labile nitrogen pools and net nitrogen mineralization in subalpine forests along an elevational gradient in western Sichuan,China

作　　者：殷睿[1] 徐振锋[1] 吴福忠[1] 杨万勤[1] 熊莉[1] 肖洒[1] 马志良[1] 李志萍[1] 

机构地区：[1]四川农业大学生态林业研究所林业生态工程重点实验室,成都611130

出　　处：《应用生态学报》2013年第12期3347-3353,共7页Chinese Journal of Applied Ecology

基　　金：国家自然科学基金项目(31170423;31200474;31270498;31000213);"十二五"国家科技支撑计划项目(2011BAC09B05);四川省杰出青年学术与技术带头人培育项目(2012JQ0008;012JQ0059);中国博士后科学基金项目(7013M540714)资助

摘　　要：研究了川西理县毕棚沟不同海拔梯度(3600 m、3300 m和3000 m)森林群落土壤活性氮库及土壤净氮矿化速率的季节动态.结果表明:研究区森林土壤活性氮库(铵态氮、硝态氮、微生物生物量氮和可溶性有机氮)及净氮矿化速率存在明显的季节变化,但不同形态土壤活性氮库的季节动态有一定差异.4个采样时期(非生长季与生长季初期、中期及末期)各海拔土壤硝态氮浓度(8.38~89.60 mg·kg-1)均显著高于铵态氮浓度(0.44~8.43 mg·kg-1).生长季初期各海拔梯度的土壤净氮矿化速率均表现为负值(-0.77^-0.56 mg·kg-1·d-1),而非生长季、生长季中期和末期均为正值.除硝态氮外,不同海拔的土壤铵态氮、微生物生物量氮和可溶性有机氮浓度的差异极显著,海拔对它们的影响与季节变化有关.该区土壤净氮矿化以硝化为主,且氮矿化过程不受海拔梯度的影响.冬季土壤净氮矿化明显(0.42~0.99 mg·kg-1·d-1),早春高的土壤无机氮可能为植物生长提供基础养分,也可能通过淋溶方式从系统中丢失.The seasonal dynamics of soil labile nitrogen pools and net nitrogen mineralization of three subalpine forests along an elevation gradient （3600, 3300 and 3000 m） , western Sichuan, China were examined. Obvious seasonal dynamics were found in soil labile nitrogen pools （ ammoni- um, nitrate, microbial biomass nitrogen and dissolved organic nitrogen） and net nitrogen minerali- zation rate, but the seasonality varied with the measured nitrogen pools. The concentrations of soil nitrate （8.38-89.60 mg~ kg-1 ） were significantly higher than those of ammonium （0.44-8.43 mg ~ kg-1 ） in four sampling periods （ non-growing season, early, middle and late growing season）. Regardless of the elevation, the rate of soil net nitrogen mineralization was negative （ -0.77 to -0.56 mg· kg-1 · d-1 ） early in the growing season, but positive in the other three pe- riods. Except for nitrate, the contents of ammonium, microbial biomass nitrogen and dissolved or- ganic nitrogen varied significantly with elevation and the altitude effects on those pools were depen- dent on seasons. In summary, soil nitrification was the major process of net soil nitrogen mineraliza- tion and soil nitrogen mineralization was not affected by elevational gradient. Soil nitrogen minerali- zation （0.42-0.99 mg· kg-1 · d-1） in winter was considerable in this area. Relatively high inor- ganic nitrogen in early spring might be favorable for vegetation growth, but might also be lost from soil ecosystem through leaching.

关 键 词：亚高山森林 土壤活性氮库 生长季 非生长季 川西 

分 类 号：S714.8[农业科学—林学]