作 者 ：全国明,毛丹鹃,章家恩,谢俊芳,秦钟

期 刊 ：植物营养与肥料学报 2016年 22卷 2期 页码：439-449

关键词：五爪金龙；南美蟛蜞菊；土壤化学；土壤微生物群落；

Keywords:Ipomoea cairica, Wedelia trilobata, soil chemistry, soil microbial community,

摘 要 ：【目的】五爪金龙(Ipomoea cairica)、 南美蟛蜞菊(Wedelia trilobata)已入侵我国华南地区并造成严重危害。本文研究了五爪金龙入侵群落、 南美蟛蜞菊入侵群落与土著植物类芦(Neyraudia reynaudiana)群落内的土壤养分、 土壤微生物量、 土壤酶活性以及微生物群落代谢活性、 碳源利用特征与功能多样性的变化规律,探讨两种外来植物入侵对土壤生态系统的影响,为揭示其野外入侵机制提供科学依据。【方法】采用野外样方法于2010年1月在广州市东郊的火炉山森林公园设置五爪金龙入侵区、 南美蟛蜞菊入侵区和土著植物类芦区3类样地,测定土壤养分、 土壤酶活性、 土壤微生物量与微生物功能多样性。【结果】1)与土著植物区相比,五爪金龙入侵区土壤有机碳、 全氮、 全磷以及速效氮、 速效磷、 速效钾含量显著提高,增幅达到60.38%~230.01%; 南美蟛蜞菊入侵区土壤有机碳、 全氮、 速效氮、 速效磷含量亦显著提高,增幅达到50.54%~145.52%; 两种外来植物入侵区土壤C/N比显著降低,但对全钾含量的影响不明显。2)两种外来植物能够显著提高入侵地的土壤微生物量,其中五爪金龙、 南美蟛蜞菊入侵区的土壤微生物量碳(C_mic)、 氮(N_mic)、 磷(P_mic)含量分别比土著植物区增加105.00%~152.15%和61.51%~138.27%,但土壤微生物量在两个入侵区之间的差异不明显; 对于土壤微生物熵,南美蟛蜞菊入侵区的C_mic/C_org值显著高于土著植物区,但N_mic/N_t、 P_mic/P_t值3类样地之间差异不显著。3)两种外来植物入侵显著提高土壤脲酶、 蛋白酶、 蔗糖酶和纤维素酶的活性,其中南美蟛蜞菊入侵区的土壤脲酶、 蛋白酶和纤维素酶活性最高,分别比土著植物区增加70.35%、 21.51%和227.86%; 对于蔗糖酶活性,五爪金龙、 南美蟛蜞菊入侵区的增幅则分别达到322.58%和157.14%; 过氧化氢酶活性各处理间的差异较小,差异均不显著。4)两种外来植物入侵能够提高土壤微生物群落的代谢活性,平均孔颜色变化率(AWCD)在整个培育周期内均表现为五爪金龙入侵区＞南美蟛蜞菊入侵区＞土著植物区,其中72 h的AWCD值分别为1.18、 0.88和0.56,差异显著。与土著植物区相比,五爪金龙入侵区6种类型碳源的利用效率显著提高,其增幅高达75.00%~162.86%; 南美蟛蜞菊入侵区碳水化合物类、 羧酸类和聚合物类碳源的利用率亦显著提高,其增幅分别为87.72%、 41.18%和83.72%; 两种入侵植物对不同类型碳源的利用程度存在一定差异,五爪金龙对羧酸类、 胺类碳源的利用率显著高于南美蟛蜞菊。主成分分析显示,PC1与PC2能够解释不同入侵区土壤微生物群落碳源利用数据71.89%的总体变异,其中PC1主要受碳水化合物类、 氨基酸类与聚合物类碳源的影响,PC2则主要受碳水化合物类与羧酸类碳源的制约。两种外来植物入侵对土壤微生物群落的功能多样性产生重要影响,其中入侵地土壤微生物群落的Shannon-Wiener指数(H′)、 Mc Intosh指数(U)、 丰富度指数(S)和Simpson优势度指数(Ds)显著高于土著植物区,但两个入侵区之间的差异较小; 三个处理区的Pielou均匀度指数(E)差异不明显。【结论】五爪金龙、 南美蟛蜞菊两种外来植物能够改善入侵地的土壤营养环境,提高土壤肥力水平,形成对自身生长、 竞争有利的微环境,从而加快入侵扩散。

Abstract:【Objectives】Ipomoea cairica and Wedelia trilobata, the two general exotic plants, have invaded successfully in southern China and caused lots of serious damages to native ecosystem. In order to explore impacts of the two weeds invasion on soil ecosystem and provide scientific basis for their invasion mechanism in fields, the changes of soil chemical and microbiological properties, including soil nutrient, soil microbial biomass, soil enzyme and metabolic activity, carbon substrate utilization and function diversity of soil microbial community in I. cairica invaded community, W. trilobata invaded community and Neyraudia reynaudiana native community were investigated by using field plot methods. 【Methods】Three sampling sites were selected, including I. cairica invaded site, W. trilobata invaded site and N. reynaudiana native site in the Huolushan Forest Park of Guangzhou city in January 2010. There were four replicates per sampling site (each replicate plot was 4 m²). Soil samples were collected, and soil nutrient, soil enzyme activity, soil microbial biomass and function diversity of soil microbial community were determined. 【Results】 1) Compared with the native plant plot, the contents of soil organic carbon, total nitrogen, total phosphorus, available nitrogen, available phosphorus and available potassium in the I. cairica plot (increased range is 60.38%-230.01%) and the contents of soil organic carbon, total nitrogen, available nitrogen and available phosphorus in the W. trilobata plot (increased range is 50.54%-145.52%) are significantly increased, while the soil C/N ratios are significantly decreased, and there are no significant differences in the contents of total potassium among the three plots. 2) The two exotic plants could significantly increase soil microbial biomass of the invaded plots. The contents of soil microbial biomass carbon, nitrogen and phosphorus of the I. cairica plot and the W. trilobata plot are 105.00%-152.15% and 61.51%-138.27% higher than those in the native plant plot respectively, while there are no significant differences in the contents of soil microbial biomass between the two invaded plots. The ratio of soil microbial biomass carbon to soil organic carbon (C_mic/C_org) in the W. trilobata plot is significantly higher than that in the native plant plot, but the ratios of soil microbial biomass nitrogen to total soil nitrogen (N_mic/N_t) and soil microbial biomass phosphorus to total soil phosphorus (P_mic/P_t) among the three plots are in the same levels. 3) The two exotic plants invasion could significantly increase the activities of soil urase, protease, invertase and cellulose enzymes. The activities of soil urase, protease and cellulose enzymes of the W. trilobata plot are the highest in all the sampling plots, and are 70.35%, 21.51% and 227.86% higher than those of the native plant plot respectively. The activities of soil invertase of the I. cairica plot and the W. trilobata plot are 322.58% and 157.14% higher than that of the native plant plot respectively, while the activities of hydrogen peroxidase are almost the same among the three plots and no significant differences are found. 4) The two exotic plants could significantly increase the metabolic activities of soil microbial community of the invaded plots. The average well color development (AWCD) of all treatments exhibits an order of I. cairica plot ＞ W. trilobata plot ＞ native plant plot during the whole incubating period. The AWCD values of three sampling plots incubated at 72 hours are 1.18, 0.88 and 0.56 respectively, and the differences are significant. Compared to the native plant plot, I. cairica invasion could significantly improve six carbon substrate utilization of soil microbial community, with the increased ranges reach up to 75.00%-162.86%. W. trilobata invasion also significantly increases the utilizations of carbohydrates, carboxylic acids and polymers, with the increased rates of 87.72%, 41.18% and 83.72% respectively. There are some differences in the utilizations of different carbon substrates between the two invasive plants, and the carboxylic acids and amines/amides utilizations of soil from the I. cairica plot are significantly greater than those in the W. trilobata plot. The principal components analysis (PCI) reveals that 71.89% of the variation of carbon substrate utilization data of soil microbial community in different invasion plots could be explained by the first and second components (PC1 and PC2). Carbohydrates, amino acids and polymers are highly correlated with PC1, while PC2 is mainly affected by carbohydrates and carboxylic acids. The two exotic plants could significantly influence the function diversity of soil microbial community. The indexes of Shannon-Wiener (H′), Mc Intosh (U), substrate richness (S) and Simpson′s dominance (Ds) of soil microbial community in the two invaded plots are significantly higher than those in the native plant plot, but the differences between the two invaded plots are not significant. The Pielou indexes (E) also have not significant differences among all the three treatments. 【Conclusions】 The two exotic plants, I. cairica and W. trilobata, can ameliorate soil nutrition environment in the invaded areas, enhance supply level of soil nutrients, and hence create a favorable microhabitat which can benefit their growth and competitiveness and facilitate their invasion in fields.