增温、增雨对荒漠草原植物和土壤总氮及稳定氮同位素的影响  

Effects of warming and increasing precipitation on total nitrogen and stable nitrogen isotopes of plants and soil in the desert steppe

作　　者：吕广一 贺梦婷 徐学宝 王成杰 LÜGuangyi;HE Mengting;XU Xuebao;WANG Chengjie(Key Laboratory of Grassland Resources of the Ministry of Education/College of Grassland,Resources and Environment,Inner Mongolia Agricultural University,Hohhot 010011,China)

机构地区：[1]草地资源教育部重点实验室/内蒙古农业大学草原与资源环境学院,呼和浩特010011

出　　处：《生态学报》2023年第10期4167-4175,共9页Acta Ecologica Sinica

基　　金：国家自然科学基金项目(31960357);内蒙古自治区“科技兴蒙”国际合作引导项目(2021CG0020);内蒙古自治区自然科学基金项目(2019MS03065)。

摘　　要：剖析气候变化下植物和土壤氮含量关系,有助于了解植物—土壤氮循环,揭示植物群落和土壤演替趋势。收集了增温(环境温度、增温2℃和4℃)增雨(自然降水量、降水量增加25%和50%)6年析因实验处理后荒漠草原优势物种和土壤样品,通过对叶片和土壤的总氮(Total nitrogen,TN)、有效氮(Available nitrogen,AN)以及稳定氮同位素(Stable nitrogen isotopes,δ^(15)N)测定分析,探究了增温增雨后荒漠草原植物和土壤氮含量变化趋势以及控制植物—土壤氮循环的主要因子。结果表明:(1)单独增温和同时增温增雨使土壤TN、AN和δ^(15)N值升高但不显著(P>0.05);单独增雨显著降低了土壤AN(P<0.05)。(2)单独增温使短花针茅(Stipa breviflora)和栉叶蒿(Neopallasia pectinata)叶片TN升高,而冷蒿(Artemisia frigida)和蒙古葱(Allium mongolicum)叶片TN降低;单独增雨和同时增温增雨显著降低了4个物种叶片TN(P<0.05),这可能是受到了土壤AN的调控。(3)增温会使叶片δ^(15)N值富集,增雨会使叶片δ^(15)N值贫化,叶片δ^(15)N受温度、降水、土壤δ^(15)N值和植物叶片TN的共同调节。因此,本研究认为增温刺激了荒漠草原物种间的氮竞争,有助于短花针茅和栉叶蒿对氮的吸收和积累,这可能会增加其在植物群落中的占比。此外,降水量对荒漠草原植物—土壤氮循环有主导作用,频发的降水事件可能会加剧荒漠草原的氮限制。Dissecting the relationship between plant and soil nitrogen(N)content under climate change is helpful to understand the plant-soil N cycle and reveal the change trend of plant community and soil.This study collected dominant species and soil samples in desert steppe under the six years of factorial experiment of warming(ambient temperature,warming 2℃and warming 4℃)and increasing precipitation(natural precipitation,increasing precipitation by 25%and 50%).By measuring and analyzing the total nitrogen(TN),available nitrogen(AN)and stable nitrogen isotopes(δ^(15)N)of leaves and soils,we explored the change trend of N content of plants and soil in desert steppe after warming and increasing precipitation,and revealed the main factors controlling the plant-soil N cycle.The results show that:(1)warming and the interaction of warming and increasing precipitation insignificantly increased the TN,AN andδ^(15)N of soil(P>0.05).Increasing precipitation significantly reduced the AN of soil(P<0.05).(2)Warming activated nitrogen competition among species,which increased the leaves TN of Stipa breviflora and Neopallasia pectinata and decreased the leaves TN of Artemisia frigida and Allium mongolicum.Increasing precipitation and the interaction of warming and increasing precipitation significantly reduced the leaves TN of four species,which may be regulated by soil AN.(3)Warming enriched theδ^(15)N of leaves,and increasing precipitation depleted theδ^(15)N of leaves.Theδ^(15)N of leaves was regulated by temperature,precipitation,theδ^(15)N of soil and the TN of leaves.Therefore,warming stimulated the N competition among species in desert steppe,which contributed to the absorption and accumulation of N by Stipa breviflora and Neopallasia pectinata,which may increase their proportion in plant communities.In addition,precipitation plays a leading role in the plant-soil N cycle of desert steppe and frequent precipitation events may exacerbate nitrogen limitation in desert steppe.

关 键 词：气候变化 荒漠草原 植物和土壤 总氮 稳定氮同位 

分 类 号：S812[农业科学—草业科学]