氮沉降对喀斯特森林土壤氮循环及酶活性的影响  

Effects of nitrogen deposition on soil nitrogen cycling and associated enzyme activities in a karst forest

作　　者：王伟[1,2] 梁燕 罗绮婷 吴芳兰 蒙姿玉 段敏 WANG Wei;LIANG Yan;LUO Qiting;WU Fanglan;MENG Ziyu;DUAN Min(Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection,Ministry of Education,Guilin,Guangxi 541006,China;College of Life Sciences,Guangxi Normal University,Guilin,Guangxi 541006,China;Guangxi Key Laboratory of Landscape Resources Conservation and Sustainable Utilization in Lijiang River Basin,Guilin,Guangxi 541006,China)

机构地区：[1]珍稀濒危动植物生态与环境保护教育部重点实验室,广西桂林541006 [2]广西师范大学生命科学学院,广西桂林541006 [3]广西漓江流域景观资源保育与可持续利用重点实验室,广西桂林541006

出　　处：《森林与环境学报》2023年第4期346-355,共10页Journal of Forest and Environment

基　　金：国家自然科学基金项目“漓江流域岩溶区森林土壤关键磷循环过程及其对氮沉降的响应机制研究”(42067023);广西科技基地和人才专项“模拟氮沉降对喀斯特生态脆弱区森林土壤氮循环的影响机制”(桂科AD20159055);广西漓江流域景观资源保育与可持续利用重点实验室主任基金“漓江流域岩溶区森林植被不同恢复阶段土壤关键磷循环过程研究”(LRCSU21Z0208);国家级大学生创新创业训练计划项目“喀斯特森林土壤磷循环过程对氮沉降的响应机制研究”(202110602069)。

摘　　要：为阐明氮沉降对喀斯特森林土壤氮循环影响的短期效应,以典型喀斯特森林采集的土壤为研究对象,用硝酸钾(KNO_(3))和硫酸铵[(NH_(4))_(2)SO_(4)]分别模拟氧化态和还原态氮沉降,设置对照(CK)、低量氧化态氮沉降(Oxi⁃L,氮添加量40 mg·kg^(-1))、低量还原态氮沉降(Red⁃L,氮添加量40 mg·kg^(-1))、高量氧化态氮沉降(Oxi⁃H,氮添加量80 mg·kg^(-1))和高量还原态氮沉降(Red⁃H,氮添加量80 mg·kg^(-1))5个处理,在氮添加后的0、1、3、7、14、30、60 d测定土壤的氮相关指标,计算土壤净氮转化速率。结果表明:氮沉降量对喀斯特森林土壤净硝化速率没有显著影响,但对土壤净氨化速率和净氮矿化速率的影响与沉降形态和沉降时间有关;氧化态氮沉降在氮添加后的前7 d显著降低了喀斯特森林土壤净硝化速率和净氮矿化速率(P<0.05),但对土壤净氨化速率没有显著影响;还原态氮沉降显著降低了喀斯特森林土壤净氨化速率和净氮矿化速率(尤其是在氮添加后的前7 d,P<0.05),显著提高了土壤净硝化速率(P<0.05);还原态氮沉降显著提高了土壤微生物生物量碳(MBC)含量(P<0.05),而氧化态氮沉降对土壤MBC含量没有显著影响;高量氧化态氮沉降显著降低了土壤微生物生物量氮(MBN)含量(P<0.05),高量还原态氮沉降显著提高了土壤MBN含量(P<0.05);氮沉降对喀斯特森林土壤脲酶活性没有显著影响,氮沉降量和沉降形态对喀斯特森林土壤硝酸还原酶活性的影响受沉降时间的调控,氮沉降量对喀斯特森林土壤亚硝酸还原酶活性没有显著影响,但氮沉降形态对土壤亚硝酸还原酶活性有一定影响;喀斯特森林土壤净氮转化速率主要受土壤总氮、可溶性有机碳、可溶性有机氮、MBC以及铵态氮和硝态氮的调控,受土壤脲酶、硝酸还原酶以及亚硝酸还原酶活性的影响较小。A simulated nitrogen deposition experiment was conducted to examine the effects of nitrogen deposition on nitrogen cycling in karst forest soils.The experiment comprised five treatments in total:control(CK),oxidized nitrogen deposition with a low rate(Oxi⁃L,nitrogen addition rate of 40 mg·kg^(-1)),reduced nitrogen deposition with a low rate(Red⁃L,40 mg·kg^(-1)),oxidized nitrogen deposition with a high rate(Oxi⁃H,80 mg·kg^(-1)),and reduced nitrogen deposition with a high rate(Red⁃H,80 mg·kg^(-1)).Soil nitrogen indices were determined at 0 and 1,3,7,14,30,and 60 days after nitrogen addition,and the net transformation rates of soil nitrogen were calculated to determine the short⁃term effects of nitrogen deposition on soil nitrogen cycling in karst forests.The results showed that the application rates had no significant effect on the soil net nitrification rate.However,the effects of nitrogen deposition rates on soil net ammonification and nitrogen mineralization rates were related to the form of nitrogen deposition and incubation time.Oxidized nitrogen deposition had no significant effect on the soil net ammonification rate in the karst forest,but significantly reduced the soil net nitrification and nitrogen mineralization rates in the first 7 days of incubation(P<0.05).Reduced nitrogen deposition significantly reduced soil net ammonification and nitrogen mineralization rates(P<0.05),particularly in the first 7 days of incubation,and it significantly increased the soil net nitrification rate(P<0.05).Reduced nitrogen deposition significantly increased soil microbial biomass carbon content(P<0.05),whereas oxidized nitrogen deposition had no significant effect on it.High nitrogen deposition significantly reduced the soil MBN content(P<0.05),whereas high reduced nitrogen deposition significantly increased the soil MBN content(P<0.05).Nitrogen deposition had no significant effect on the soil urease activity.The effects of the form and rate of nitrogen deposition on soil nitrate reductase activity were regul

关 键 词：氧化态氮 还原态氮 氮沉降 土壤氮循环 土壤酶活性 净硝化速率 净氨化速率 净氮矿化速率 

分 类 号：S718.5[农业科学—林学]