种植不同树种对土壤可溶性有机质渗滤液组成和光谱特征的影响

Composition and Spectral Characteristics of Soil Dissolved Organic Matter Leachate From Different Planted Tree Species

可溶性有机质(DOM)是森林生态系统重要的活性碳库和养分库,其性质受到植物种类、土壤性质、水文状况等因素影响。为探究树种对土壤可溶性有机质(DOM)渗滤液组成和光谱性质的影响,在根箱中间种植1年生米槠(CC)、杉木(CL)、花榈木(OP)幼苗,并设置不种植对照(NT)处理。于2021年8月的一场暴雨后收集根箱土壤(0~60 cm)渗滤液DOM,测定其理化性质及光谱特征。结果表明:(1)种植杉木幼苗土壤渗滤液中溶解性有机碳(DOC)含量显著高于种植花榈木和米槠幼苗(p<0.05)。(2)米槠土壤渗滤液DOM芳香化指数(SUVA254)最高,杉木土壤渗滤液DOM疏水指数(SUVA260)最低,各树种土壤渗滤液DOM相对分子量大小(SUVA280)无显著差异。(3)三种树种和未种树根箱土壤渗滤液DOM荧光指数(FluI)、新鲜度指数(Frl)、生物源指数(BIX)均无显著性差异,各处理渗滤液DOM腐殖化指数(HIX)均小于1,且种植米槠、花榈木的土壤渗滤液DOM的HIX显著高于未种树对照处理(p<0.05)。本研究土壤渗滤液DOM主要由类富里酸和类腐殖酸物质(C1),类腐殖酸物质(C2)和溶解性类微生物产物(C3)三种成分组成。相比于花榈木和杉木土壤渗滤液DOM,米槠土壤渗滤液DOM中C1、C2组分的贡献率较高,C3组分贡献率较低。(4)Pearson相关分析表明,DOC浓度与紫外指数(SUVA254、SUVA260、SUVA280)、二维荧光指数FluI及三维荧光组分C2呈负相关,与C3呈正相关关系(p<0.05)。本研究结果对亚热带树种土壤养分流动和生物地化循环研究提供一定的参考。

Dissolved organic matter(DOM)is a labile carbon and nutrient pool inforest ecosystems and its properties are affected by plant species,soil properties,hydrological conditions and other factors.To investigate the effects of tree species on the composition and spectral properties of soil DOM leachate,one-year-old seedlings of Castanopsis carlesii(CC),Cunninghamia lanceolata(CL),and Ormosia Henryi(OP)were planted in the root boxes(0~60 cm),and no planting was set as the control.After a rainstorm in August 2021,soil DOM leachate in the root box was collected to determine its composition and spectral characteristics.The results show that:(1)The content of dissolved organic carbon(DOC)in soil leachate of Cunninghamia lanceolata seedlings was significantly higher than those of Ormosia Henryi and Castanopsis carlesii seedlings(p<0.05).(2)The value of the aromatic index(SUVA254)in the soil leachate of Castanopsis carlesii was the highest,and that of the hydrophobic index(SUVA260)in soil leachate of Cunninghamia lanceolata was the lowest.There was no significant difference in the molecular weight(SUVA280)in the soil leachate of different tree species.(3)There were no significant differences in the DOM fluorescence index(FluI),freshness index(Frl)and biogenic index(BIX)of soil leachate among the three tree species and no-tree species in the root box soil leachate.The DOM fluorescence humification index(HIX)of soil leachates in all treatments was less than one,and the HIX of soil DOM leachates of Ormosia Henryi and Castanopsis carlesii were significantly higher than that of no-tree control(p<0.05).Soil DOM leachate was mainly composed of three components,fulvic and humic acid-like(C1),humic acid-like(C2)and soluble microbial products(C3).Compared with the soil DOM leachates of Ormosia Henryi and Cunninghamia lanceolata,the proportions of C1 and C2 in the soil DOM leachate of Castanopsis carlesii was higher,while the proportion of C3 was low.(4)Pearson correlation analysis showed that DOC concentration was negatively correlated with UV index(SUVA254,SUVA260,SUVA280),two-dimensional fluorescence index FluI,and three-dimensional fluorescence component C2,while positively correlated with C3(p<0.05).The results of this studyprovide some reference value for the study of soil biogeochemical cycles in the subtropical region.