昼夜增温对外来入侵植物竞争力的影响

Effects of day and night warming on growth and competitive ability of invasive alien plants

全球存在明显的昼夜不对称增温现象,光合作用只在白天发生,而呼吸作用在白天和晚上都在进行,昼夜增温可能会改变光合作用和呼吸作用之间的平衡,进而影响植物的生长。入侵植物通常具有较强的资源捕获能力与能量利用效率,那么在昼夜增温对外来入侵植物的生长及竞争力有何影响?为此,选取两种严重危害的菊科入侵植物白花鬼针草(Bidens alba)和假臭草(Eupatorium catarium),同时选取本地植物一点红(Emilia sonchifolia)作为对照,设置不同的昼夜增温处理,研究增温对入侵植物和本地植物的生物长、生物量分配及种间竞争的影响。结果表明,白天增温显著提高了入侵植物白花鬼针草和假臭草的总生物量和地上生物量,而全天增温显著提高了本地植物一点红的总生物量和地上生物量;白花鬼针草在全天增温处理下的根冠比显著高于其他增温处理的,而其他2种植物的根冠比在全天增温处理下最低。夜间增温和全天增温加剧了入侵植物对本地植物一点红生长的抑制作用;3种增温模式都不同程度地降低了两种入侵植物对一点红的竞争响应,但不同增温模式之间差异并不显著,说明增温背景下本地植物一点红对入侵植物的竞争响应并未表现出明显的竞争者依赖性。

There is an obvious diurnal asymmetrical warming around the world.Photosynthesis takes place at daytime,while respiration occurs through day and night.Day and night warming may change the balance between photosynthesis and respiration,consequently influencing plant growth.Invasive alien plants usually have stronger resource capture ability and energy use efficiency relative to native plants.What is the effect of day and night warming on the growth and competitiveness of invasive plants?Thus,two invasive plants Bidens alba(also called Bidens pilosa)and Eupatorium catarium,and a native plant Emilia sonchifolia were selected.The effects of warming on plant growth,biomass allocation and inter-competition of invasive plants and native plants were studied.The results showed that daytime warming significantly increased the total biomass and aboveground biomass of the two invasive plants,while whole day warming significantly increased the total biomass and aboveground biomass of the native plants.The root-shoot ratio of B.alba under whole-day warming was significantly higher than that under other warming treatments,while the root-shoot ratio of the other two plants was the lowest under whole-day warming.Night warming and whole day warming promoted the inhibitory effect of invasive plants on native plants.All three warming treatments reduced the competitive response of the two invasive plants to E.sonchifolia,but the difference between different warming treatments was not significant,indicating that the competitive response of native plants to E.sonchifolia did not show significant competitor dependence.