养分增加提高大狼耙草入侵种群的生长和竞争能力

为了探讨大狼耙草的入侵风险,该文通过同质种植园实验,研究了不同养分水平下大狼耙草河北、江苏、江西和广西4个入侵种群在单种和各种群与近缘本地植物金盏银盘混种时的生长和竞争响应。结果表明:(1)单种时4个种群的株高、分枝数和总生物量在高养分下显著高于低养分下,繁殖比在低养分下显著高于高养分下(江苏种群除外); 混种时4个种群各生长参数的竞争响应在高养分下小于低养分下的。(2)各养分下,广西和江西种群的株高和总生物量显著高于河北种群,广西种群的分枝数最多低、中和高养分下分别为(12±0.86)、(16.83±0.95)和(21.83±1.14)]; 河北种群的繁殖比在低养分 (47.33±3.29)%]和高养分 (25.74±2.82)%]下最高,且显著高于同养分下的广西种群 低养分为(30.92±1.78)%和高养分为(19.77±1.22)%]。中养分下,河北种群总生物量的竞争响应(-0.51±0.04)显著大于广西种群(-0.35±0.06),繁殖生物量的竞争响应(-0.46±0.03)也显著大于广西种群(-0.28±0.07)。综上表明,高养分提高大狼耙草的生长和竞争能力,生长和竞争能力在种群间有差异,养分增加和入侵种群间基因流可能会潜在地提高大狼耙草的入侵风险,该研究结果有助于预测入侵植物的入侵风险。

Increased nutrients enhance the growth and competitive ability of invasive populations of Bidens frondosa

In order to explore the potential of Bidens frondosa to become invasive, we tested the growth and competitive response of B. frondosa by planting four introduced populations of B. frondosa alone and together with the native congener B. biternata under three nutrient levels. The results were as follows:(1)When grown alone under high nutrient, B. frondosa had significantly higher values for plant height, branch number and total biomass compared with those grown under low nutrient. The reproductive ratios of all the populations under low nutrient were significantly greater than those under high nutrient except for Jiangsu Population. When grown with four populations together, the competitive responses of the growth parameters of each population of B. frondosa under high nutrient were significantly lower than those under low nutrient, indicating that this invasive weed was suppressed less under high nutrient compared with that under low nutrient conditions.(2)Under all nutrient conditions, Guangxi and Jiangxi populations significantly grew higher and had a greater total biomass than Hebei Population. Guangxi Population had the highest number of branches among the four populations when grown at low, medium and high nutrients (12±0.86),(16.83±0.95)and(21.83±1.14), respectively]. The reproduction ratios of Hebei Population grown under low and high nutrients (47.33±3.29)% and(25.74±2.82)%, respectively] were significantly greater than those of Guangxi Population when grown under comparable conditions (30.92±1.78)% and(19.77±1.22)%, respectively]. In addition, the competitive response of total biomass were significantly greater for Hebei Population(-0.51±0.04)than for Guangxi Population(-0.35±0.06)under medium nutrient. The competitive response of reproductive biomass of Hebei Population(-0.46±0.03)was also significantly greater than that of Guangxi Population(-0.28±0.07)under medium nutrient. Our results indicate that nutrient addition can enhance the growth and competitive ability of B. frondosa, there are variations in the growth and competitive response among the introduced populations, and increasing nutrient and gene flow among populations may enhance the potential risks of invasion by B. frondosa, the results will help to predict the invasion risk of alien plants.