Variations in the natural 13C and 15N abundance of plants and soils under long-term N addition and precipitation reduction:interpretation of C and N dynamics

查看全文 作　　者：Guoyong [1,2,3]Yan;Shijie [4]Han;Mingxin [5]Zhou;Wenjing [3]Sun;Binbin [2]Huang;Honglin [2]Wang;Yajuan [1,2]Xing;Qinggui [1,2,3]Wang 机构地区：[1]School of Life Sciences,Qufu Normal University,Qufu 273165,Shandong,China;[2]College of Agricultural Resource and Environment,Heilongjiang University,74 Xuefu Road,Harbin 150080,Heilongjiang,China;[3]School of Forestry,Northeast Forestry University,26 Hexing Road,Harbin 150040,Heilongjiang,China.;[4]School of Life Sciences,Henan University,Kaifeng 475004,Henan,China.;[5]Heilongjiang Institute of Construction Technology,999 Xueyuan Road,Harbin 150025,Heilongjiang,China 出　　处：《Forest Ecosystems》索引2020年第7卷第4期,共13页 基　　金：from National Natural Science Foundation of China(Grant Nos:41773075,41575137,31370494,31170421). 摘　　要：Background:The nitrogen isotope natural abundance(δ^(15)N)provides integrated information on ecosystem N dynamics,and carbon isotope natural abundance(δ^(13)C)has been used to infer how water-using processes of plants change in terrestrial ecosystems.However,howδ^(13)C andδ^(15)N abundances in plant life and soils respond to N addition and water availability change is still unclear.Thus,δ^(13)C andδ^(15)N abundances in plant life and soils were used to investigate the effects of long-time(10 years)N addition(+50 kg N·ha^(−1)·yr^(−1)and precipitation reduction(−30%of throughfall)in forest C and N cycling traits in a temperate forest in northern China.Results:We analyzed theδ^(13)C andδ^(15)N values of dominant plant foliage,litterfall,fungal sporophores,roots,and soils in the study.The results showed thatδ^(15)N values of foliage,litterfall,and surface soil layer’s(0–10 cm)total N were significantly increased by N addition,whileδ^(15)N values of fine roots and coarse roots were considerably decreased.Nitrogen addition also significantly increased theδ^(13)C value of fine roots and total N concentration of the surface soil layer compared with the control.The C concentration,δ^(13)C,andδ^(15)N values of foliage andδ^(15)N values of fine roots were significantly increased by precipitation reduction,while N concentration of foliage and litterfall significantly decreased.The combined effects of N addition and precipitation reduction significantly increased theδ^(13)C andδ^(15)N values of foliage as well as theδ^(15)N values of fine roots andδ^(13)C values of litterfall.Furthermore,foliarδ^(15)N values were significantly correlated with foliageδ^(13)C values,surface soilδ^(15)N values,surface soil C concentration,and N concentrations.Nitrogen concentrations andδ^(13)C values of foliage were significantly correlated withδ^(15)N values and N concentrations of fine roots.Conclusions:This indicates that plants increasingly take up the heavier 15N under N addition and the heavier 13C and 15N under precipitation reduction,suggesting that N addition and precipitation reduction may lead to more open forest ecosystem C and N cycling and affect plant nutrient acquisition strategies. 关 键 词：δ^(13)C δ^(15)N N addition Precipitation reduction Nutrient acquisition strategies