不同土壤水分和养分条件下喜旱莲子草与同属种生长状况的比较研究

喜旱莲子草(Alternanthera philoxeroides)入侵已在中国造成巨大的生态和经济损失。为揭示喜旱莲子草成功入侵的生态机制并预测其种群扩张趋势及其与环境因子的关系, 作者比较了喜旱莲子草与其同属的外来弱入侵种刺花莲子草(A. pungens)以及土著种莲子草(A. sessilis)在不同土壤水分、养分条件下的生长状况。结果显示: 在高水高肥条件下, 喜旱莲子草的生物量要高于刺花莲子草和莲子草, 而在低水低肥条件下却不如这两个同属种; 弱入侵种刺花莲子草在低水条件下的生物量要高于强入侵种喜旱莲子草和土著种莲子草, 说明植物的入侵性受环境条件的影响。另外, 强入侵种喜旱莲子草形态学性状的可塑性较高, 在各种条件下都具有较高的比叶面积, 暗示这两个指标可作为莲子草属外来植物入侵性的预测指标。

Comparison of morphological traits between alligator weed and two congeners under different water and nutrient conditions

Alligator weed (Alternanthera philoxeroides), a worldwide noxious weed, has caused enormous ecological and economic losses in China. To better understand the species’ successful invasion, and to predict relationships between expansion of its population and environmental conditions, we compared morphological traits of alligator weed with two closely related species, i.e. the geographically restricted alien A. pungens and the native A. sessilis, under different water and nutrient conditions in a common garden experiment. Compared to A. pungens and A. sessilis, alligator weed produced more biomass with high availability of water and nutrients, but did not in conditions of low water availability. These results suggest that the invasiveness of alligator weed may be influenced by environmental conditions. In addition, alligator weed had marginally greater specific leaf area (SLA) and phenotypic plasticity than its congeners. Phenotypic plasticity and SLA may thus have predictive value for invasiveness of alien species under multiple environmental conditions.