摘要
【目的】明确森林凋落物、土壤和微生物化学计量特征对氮沉降的响应,厘清三者之间的动态变化及协同作用关系。【方法】以滇中亚热带常绿阔叶林为研究对象,于2019年进行氮沉降模拟试验,设置0(对照,CK)、10(低氮)、20(中氮)和25(高氮)g/(m2·a) 4个氮沉降处理,每2个月采集1次土壤(0~10和10~20 cm)和凋落物(叶和枝)样品,共采集2年,测定凋落物和各土层C、N、P含量,以及各土层微生物C(MBC)和微生物N(MBN)含量、微生物计数和蔗糖酶、脲酶、酸性磷酸酶活性,计算相关化学计量比,并对不同氮沉降处理间各指标进行单因素方差分析与相关性分析。【结果】不同氮沉降处理下,凋落物C、N、P含量较CK分别增加了27.61%~51.89%,19.61%~108.64%和1.99%~71.33%;在第2年施氮期间,凋落物C/N较CK显著降低15.72%~43.24%,N/P则显著增加23.36%~97.65%,凋落叶C/P变化不显著;从不同凋落物组分上看,各氮处理下的凋落物C含量、C/N、C/P和N/P均表现为凋落枝>凋落叶,而N和P含量则为凋落枝小于凋落叶(P<0.05)。土壤C含量、N含量、C/P与CK相比在不同氮沉降处理下总体分别增加7.85%~52.22%,6.48%~44.82%和6.21%~85.37%,低氮和中氮处理下不同土层的C/N、0~10 cm土层的N/P较CK分别增加7.85%~20.24%和10.50%~91.16%,而土壤P含量则降低8.10%~61.89%;从不同土层看,0~10 cm土层土壤C、N含量和N/P显著(P<0.05)高于10~20 cm土层。与CK相比,土壤MBC含量在氮沉降处理下显著降低3.82%~60.15%,MBN含量在中氮和高氮处理下显著降低15.91%~62.31%,0~10 cm土层土壤MBC/MBN仅在低氮处理下显著降低15.70%~20.54%(P<0.05);微生物计数表现为低促高抑;10~20 cm土层土壤的MBC、MBN及MBC/MBN和微生物计数均显著低于0~10 cm土层(P<0.05)。相较于CK,低氮处理显著(P<0.05)增加了土壤蔗糖酶、脲酶和酸性磷酸酶活性,增幅分别为10.93%~30.69%,5.13%~88.11%和11.92%~44.73%(P<0.05),中氮和高氮处理抑制了土壤蔗糖酶和酸性磷酸酶活性而促进了脲酶活性。相关性分析结果显示,凋落物C/N与土壤C和N含量、凋落物C含量与土壤MBC和MBN均存在显著负相关性。【结论】亚热带常绿阔叶林在氮沉降处理下凋落物分解被抑制,土壤N素有效性提高,N限制得到缓解,但养分限制开始向P限制转变。
【Objective】This research aimed to clarify the responses of forest litter,soil and microbial stoichiometric characteristics to nitrogen deposition,and to clarify the dynamic changes and synergies among the three.【Method】Subtropical evergreen broad-leaved forest in Yunnan Province was taken as the research object,nitrogen deposition simulation experiment was conducted in 2019,and 4 treatments were set up:the control(CK,0 g/(m 2·a)),low nitrogen treatment(LN,10 g/(m 2·a)),medium nitrogen treatment(MN,20 g/(m 2·a))and high nitrogen treatment(HN,25 g/(m 2·a)).Meanwhile,soil(0-10 cm and 10-20 cm)and litter(leaves and twigs)samples were collected once a month at the beginning of each month for a total of 24 months.The contents of C,N and P in litters and each soil layers,as well as the MBC,MBN,microbial count,activities of sucrase,urease and acid phosphatase in each soil layer were determined.The relevant stoichiometric ratios were calculated,and one-way ANOVA and correlation ana-lysis were performed for each index.【Result】Under different nitrogen deposition treatments,the contents of C,N and P in litters increased by 27.61%-51.89%,19.61%-108.64%and 1.99%-71.33%compared with CK,respectively.During the second year of nitrogen application,C/N of litter samples significantly decreased by 15.72%-43.24%compared with CK,N/P significantly increased by 23.36%-97.65%,and C/P showed no significant differences.In terms of component analysis,the C content,C/N,C/P and N/P of litter branches under different nitrogen treatments were higher than those of litter leaves,while the N and P contents of litter branches were lower than those of litter leaves(P<0.05).C and N contents and C/P of soil samples increased by 7.85%-52.22%,6.48%-44.82%and 6.21%-85.37%,respectively,compared with CK under different nitrogen deposition treatments.C/N of each soil layers and N/P of 0-10 cm soil layers increased by 7.85%-20.24%and 10.50%-91.16%,respectively,compared with CK under low and medium nitrogen treatment,while P content decreased by 8.10%-61.89%.In different soil layers,the contents of C,N and N/P in 0-10 cm soil layer were significantly(P<0.05)higher than those in 10-20 cm soil layer.Compared with CK,the soil MBC(microbial biomass carbon)content was significantly decreased by 3.82%-60.15%under nitrogen treatments,soil MBN(microbial biomass nitrogen)content was significantly decreased by 15.91%-62.31%under medium nitrogen and high nitrogen treatment,and MBC/MBN in 0-10 cm soil layer was significantly decreased by 15.70%-20.54%only under low nitrogen treatment(P<0.05).The microbial count showed low promotion and high inhibition.The MBC,MBN,MBC/MBN and microbial count in 10-20 cm soil layer were significantly lower than those in 0-10 cm soil layer(P<0.05).Compared with CK,low nitrogen treatment significantly increased the activities of soil sucrase,urease and acid phosphatase by 10.93%-30.69%,5.13%-88.11%and 11.92%-44.73%(P<0.05),respectively.Medium and high nitrogen treatments inhibited the activities of sucrase and acid phosphatase,but promoted the activities of urease.The results of correlation analysis showed that C/N in litters was negatively correlated with soil C and N contents,and C content in litters was negatively correlated with soil MBC and MBN.【Conclusion】Under N deposition treatment,litter decomposition was inhibited,soil N availability was improved,and N limitation was alleviated,but nutrient limitation of P began to appear in subtropical evergreen broad-leaved forest.
作者
王倩
苏连波
王克勤
宋娅丽
张继国
WANG Qian;SU Lianbo;WANG Keqin;SONG Yali;ZHANG Jiguo(College of Ecology and Environment,Southwest Forestry University,Kunming,Yunnan 650224,China;College of Soil and Water Conservation,Southwest Forestry University,Kunming,Yunnan 650224,China;Yangbi Walnut Research Institute,Yunnan Provincial Academy of Forestry and Grassland Sciences,Dali,Yunnan 671000,China;Yuxi Forestry Ecosystem Research Station of National Forestry and Grassland Administration,Yuxi,Yunnan 653100,China)
出处
《西北农林科技大学学报(自然科学版)》
北大核心
2025年第8期84-98,共15页
Journal of Northwest A&F University(Natural Science Edition)
基金
云南省农业基础研究联合专项(202301BD070001-059)
云南省一流学科建设项目(云教发[2022]73号)
云南省大学生创新创业训练计划项目(202210677013)
云南省自然生态监测网络项目云南玉溪森林生态站运行项目(2022-YN-13)
云南玉溪森林生态系统国家长期科研基地项目(2020132550)。
关键词
凋落物-土壤-微生物
生态化学计量特征
氮沉降
常绿阔叶林
litter-soil-microbial
ecological stoichiometric characteristics
nitrogen deposition
evergreen broad-leaved forest
