摘要
水分含量是与土壤氮转化相关微生物活性的重要影响因素。本研究以黑龙江省北安市的草地和林地土壤为对象,通过室内培养试验,利用^(15)N同位素标记技术和FLUAZ数值优化模型研究60%和100%田间持水量(WHC)条件下土壤氮初级矿化速率、初级固定速率、初级硝化速率和初级反硝化速率,以探讨土壤氮初级转化速率对水分含量变化的响应,阐明不同水分条件下土壤中氮的产生、消耗、保存机制及其生态环境效应。结果表明:土壤水分变化不影响草地和林地土壤氮初级矿化速率和铵态氮固定速率,水分含量由60%WHC增加至100%WHC后显著增加了林地土壤的初级硝化速率,但对草地土壤的初级硝化速率没有显著影响。60%WHC条件下草地和林地土壤的初级反硝化速率可以忽略不计,水分含量增加至100%WHC后土壤初级反硝化速率显著提高,且草地土壤的初级反硝化速率显著低于林地土壤。100%WHC条件下林地土壤初级硝化速率与铵态氮固定速率比值(gn/ia)和N_(2)O排放量均显著高于60%WHC;100%WHC条件下草地土壤的N_(2)O排放量显著高于60%WHC,但两个水分条件下的gn/ia值无显著差异。表明短期内水分含量的增加可能会增加草地和林地土壤氮转化的负面环境效应,且对林地土壤的影响尤为显著。
Soil water content is an important factor driving microbial activities related to soil nitrogen(N) transformation.In this study,^(15)N pair tracing technique combined with the numerical model FLUAZ was used to investigate the gross N mineralization,immobilization,nitrification,and denitrification rates in grassland and forest land soils from Beian City,Heilongjiang Province,China under laboratory condition [60% or 100% water holding capacity(WHC)].The responses of soil gross N transformation rates to soil water content changes,and the mechanisms of N production,consumption,and conservation in soil under different water conditions and its environmental effects were elucidated.The results showed that changes of soil water content did not affect gross rates of N mineralization and NH_(4)^(+) immobilization in the forest land and grassland soils.Increasing soil water content from 60% WHC to 100% WHC significantly increased soil gross nitrification rate in forest land soil,but not affect that in grassland soil.Gross denitrification rates in grassland and forest land soils were close to zero under 60% WHC,and significantly increased under 100% WHC.The rate in grassland soil was significantly lower than that in forest land soil.In forest land soil,the ratio of gross nitrification to NH_(4)^(+) immobilization rates(gn/ia) and N_(2)O emissions under 100% WHC were significantly higher than that under 60% WHC.N_(2)O emission from grassland soil under 100% WHC was significantly higher than that under 60% WHC,but without significant difference in gn/ia between the two water conditions.Our results indicated that increasing soil water content in the short-term may increase the negative environmental effects of nitrogen cycling in grassland and forest land soils,especially in forest land soil.
作者
李平
魏玮
郎漫
LI Ping;WEI Wei;LANG Man(Nanjing University of Information Science&Technology/Jiangsu Key Laboratory of Agricultural Meteorology,Nanjing 210044,China;School of Applied Meteorology,Nanjing University of Information Science&Technology,Nanjing 210044,China)
出处
《应用生态学报》
CAS
CSCD
北大核心
2022年第1期59-66,共8页
Chinese Journal of Applied Ecology
基金
国家自然科学基金项目(41301345,41101284)资助。
关键词
水分含量
林地
草地
^(15)N标记
氮转化
water content
forest land
grassland
^(15)N trace
nitrogen transformation
