两种沉水植物在不同水深和生长时期对入侵植物的响应

为研究沉水植物在不同水深和生长时期对不同种类入侵植物的响应，选取2种湿地入侵植物凤眼莲Eichhornia crassipes、水盾草Cabomba caroliniana和2种常见本地沉水植物黑藻Hydrillaverticillata、菹草Potamogeton crispus为研究对象，通过模拟试验探究在不同水深（0.2、0.4 m）和生长时期（生长初期和生长旺期）的本地沉水植物对2种入侵植物的响应。结果显示，当水深为0.4 m时更有利于黑藻的生长，并可削弱入侵植物对黑藻生长的消极作用，而水深对菹草的生长无显著影响；入侵植物种类对本地沉水植物的生长无显著影响，但影响方式却存在差异，其中水盾草倾向于直接抑制本地沉水植物的生长，而凤眼莲可以通过降低水体透明度以及总磷含量进而间接抑制本地沉水植物的生长。此外，外来植物在本地沉水植物生长初期入侵对本地沉水植物产生的消极影响较生长旺期入侵时更显著。表明凤眼莲及水盾草入侵对本地沉水植物生长的影响机制存在差异，本地沉水植物在适宜水深和生长旺期对2种入侵植物具有更强的抵抗能力。

Responses of two submerged plants to invasive plants at different water depths and growth periods

In order to investigate the responses of submerged plants to different species of invasive plants in different water depths and growth periods, two wetland invasive plants, Eichhornia crassipes and Cabomba caroliniana, and two common native submerged plants, Hydrilla verticillata and Potamogeton crispus, were selected to investigate the response of native submerged plants to two invasive plants in different water depths (0.2, 0.4 m) and growth periods (early growth and peak growth) through simulation experiments. The results showed that the water depth of 0.4 m was more favorable to the growth of H. verticillata and could weaken the negative effect of invasive plants on the growth of H. verticillata, while the water depth had no significant effect on the growth of minced grass; the invasive plant species did not have a significant effect on the growth of native submerged plants, but there were differences in the mode of influence, in which C. caroliniana tended to inhibit the growth of native submerged plants, while E. crassipes could inhibit the growth of native submerged plants indirectly by decreasing the transparency of the water body and the content of total phosphorus. Total phosphorus content indirectly inhibited the growth of native submerged plants. In addition, the negative impacts of invasive plants on native submerged plants were more pronounced during the early stage of growth than those during the peak growth period of native submerged plants. These results suggested that there were differences in the mechanisms of the invasive effects on the growth of native submerged plants, and that native submerged plants were more resistant to the two invasive plants in the appropriate water depth and during the peak growth period.