米槠次生林内4种植物叶片DOM的数量和质量特征

选取福建省三明市米槠次生林内的4种植物,即米槠(CAC),木荷(SCS),山杜英(ELS),芒萁(DID)为研究对象,对其叶片进行了室内淋溶处理,并分析了淋溶液中的可溶性有机碳(DOC)和可溶性有机氮(DON)含量及pH值,芳香性指标(AI)和荧光效率指数(Feff)等,以揭示其淋溶液中可溶性有机质(DOM)的数量和质量特征。结果表明:4种植物叶片DOM含量总体随淋溶次数的增加逐渐减小,其中首次淋溶后淋溶液中的DOC和DON含量最大,分别占总淋溶量的平均值为67.90%和44.51%;淋溶液中前3次DOC和DON淋溶量总和分别占10次淋溶总量的87.40%~94.77%和68.46%~72.49%;且前3次淋溶次数间呈极显著差异(P0.01),其后差异性不显著。DOM的pH值和光谱指标随着淋溶次数的增加逐渐上升.总体上乔木树种DOM的数量和质量比林下植被要高,这是由于乔木树种的DOM含有更多的养分和芳香类和腐殖化的高分子量化合物,而林下植被的DOM含有较多低分子量化合物和易分解组分。

Quantities and Qualities of Leaf-leached DOM of Four Species in A Secondary Castanopsis carlesii Forest

times of extraction , 67.90%of total DOC and 44.51%of total DON were obtained by the first extrac-tion, and most of the nutrients （87.40%~94.77% and 68.46%~72.49% for DOC and DON re-spectively ） were obtained by the first three extractions .The DOC and DON concentrations among the first three extractions differed significantly （ P＆lt;0.01 ） , while there was no significant difference among the following extractions .With increasing leaching times , the pH values and the AI increased slightly , and the Fef and Fmax increased markedly , which suggested that the amount of easily degradable materi-als decreased and the proportion of humic substances bearing aromatic rings increased .The concentra-tions of DOC and DON were much higher for the overstory species （ CAC, SCS, ELS） than for under-growth species （ DID） .Our results indicated that DOM derived from the overstory species contained more DOC and DON , with more condensed aromatic and humified compounds , while DOM from the understory vegetation contained more labile compounds .