三叶鬼针草与不同本地植物竞争对土壤 微生物和土壤养分的影响

入侵植物三叶鬼针草(Bidens pilosa)对我国农牧业生产造成了重大的损失。本文主要研究三叶鬼针草入侵与不同本地植物竞争对土壤微生物群落结构和土壤养分的影响。利用磷脂脂肪酸方法(phospholipid fatty acids, PLFAs)测定土壤微生物群落组成, 同时测定土壤养分和酶活性, 并利用Canoco4.5软件分析了土壤微生物、土壤养分和土壤酶活性的相关性。结果表明: (1)三叶鬼针草对革兰氏阳性菌、革兰氏阴性菌、丛枝菌根真菌等土壤微生物具有较强的聚集能力, 且其根际土壤聚集的微生物类群与本地植物种类密切相关。(2)三叶鬼针草入侵显著增加了入侵地土壤的有机碳含量, 降低了铵态氮的含量; 土壤中的速效钾、速效磷和硝态氮的含量则与本地植物种类密切相关。(3)相关性分析表明, 16:00和16:1 ω5c对铵态氮的含量影响较大, 而三叶鬼针草入侵地16:00和16:1 ω5c的含量显著高于裸土对照, 进而推测这一状况导致了铵态氮含量的降低。(4) 15:1 anteiso A和18:1 ω5c与速效钾的含量呈显著正相关, 而其含量在狗尾草(Setaria viridis)中显著高于其他处理, 三叶鬼针草与狗尾草混种处理中土壤中速效钾的含量高于其他处理。以上结果说明, 三叶鬼针草通过改变土壤微生物群落结构影响了土壤酶活性和土壤养分, 且这种改变与入侵地本地植物种类有关。

Effects of rhizosphere soil microorganisms and soil nutrients on competitiveness of Bidens pilosa with different native plants

The invasive plant Bidens pilosa has caused losses to agriculture and livestock. We studied the effects of B. pilosa on rhizosphere soil microorganisms and soil nutrients of different native species. The soil microbial species were examined using phospholipid fatty acid (PLFA), and the concentrations of soil nutrients and the activities of soil enzyme activities were measured. Correlation analysis of soil microbial, soil nutrients, and soil enzyme activities was used in Canoco 4.5. Results showed that B. pilosa had a strong ability to aggregate soil microorganisms such as gram-positive bacterium (G⁺), gram-negative bacterium (G^-), and arbuscular mycorrhizal fungi (AMF). The microbial species in the rhizosphere soil of B. pilosa was closely related to the native plant species. Bidens pilosa significantly increased the concentration of organic carbon, while decreasing the concentration of ammonium. The concentrations of available potassium, available phosphorus, and nitrate were strongly related to the native plant species. Correlation analysis showed that 16:00 and 16:1ω5c had a significant influence on the concentration of ammonium. The concentrations of 16:00 and 16:1 ω5c in the rhizosphere soil of B. pilosa were significantly higher than that in the soil of the control, which may lead to the decrease of the concentration of ammonium in the rhizosphere soil of B. pilosa. The concentrations of 15:1 anteiso A and 18:1 ω5c were significantly positively correlated with the concentration of available potassium, and its content were significantly greater than the other treatments in Setaria viridis. The concentration of available potassium in the competition treatment between B. pilosa and S. viridis was significantly higher than the other treatments. The above results show that the invasive plant B. pilosa affected soil enzyme activities and soil nutrients via altering microbial communities, and these changes impacted the native plant species.