中等强度收割对菹草和伊乐藻种间竞争的影响

Effects of moderate-intensity harvesting on interspecific competition between Potamogeton crispus and Elodea nuttallii

以取代系列实验方法研究了中等强度收割对菹草（Potamogeton crispus）和伊乐藻（Elodea nuttallii）种间竞争的影响。竞争攻击力、相对产量、相对竞争强度、相对拥挤系数等指标表明：收割前后伊乐藻的种间竞争能力强于菹草;收割前单独培养和混合培养的菹草在盖度方面较伊乐藻占有明显优势（P〈0.05）,但收割后菹草的盖度分别显著降低了33.5%和45.3%（P〈0.05）,而伊乐藻的盖度显著提高（P〈0.05）,最终伊乐藻在盖度方面略占优势;收割前,单独培养和混合培养的菹草的株均干重显著地大于伊乐藻（P〈0.05）,但收割后菹草的株均干重有所下降,伊乐藻的株均干重增长显著（P〈0.05）;收割后,两种方式培养的菹草的株均干重显著地小于伊乐藻（P〈0.05）;中等强度收割抑制了0~25cm和25 cm以上部位菹草的分枝和干物质的累积,但促进了伊乐藻在各层分枝和干物质的累积,这将有利于伊乐藻在竞争中取胜;此外,菹草与伊乐藻的种间竞争对植物根的生长影响较小。

A replacement series experiment was carried out to analyze the effects of moderate-intensity harvesting on interspecific competition between Elodea nuttallii and Potamogeton crispus. Competition indices such as aggressivity, relative yield, relative competitive intensity and relative crowding coefficient showed that E. nuttallii was the stronger competitor before and after harvesting. P. crispus outcompeted E. nuttallii significantly （P〈0.05） in coverage in both the mono- culture and the mixed culture before harvesting. However, harvesting resulted in a significant reduction in coverage of P. crispus by 33.5% in the monoculture and 45.3% （P〈0.05） in the mixed culture, respectively, and a significant increase in coverage of E. nuttallii （P〈0. 05 ）. The result showed that E. nuttallii surpassed slightly over P. crispus in terms of coverage. The mean dry weight per plant of P. crispus was greater than that of E. nuttallii in both the monocul- ture and the mixed culture before harvesting （P 〈 0.05 ）. However, the mean dry weight per plant of P. crispus was obviously lower than that of E. nuttallii after harvesting in both the culti- vation modes （ P〈0.05 ）. The moderate-intensity harvesting produced inhibition effects on P. crispus but promotion effects on E. nuttallii in branching and dry matter accumulation in layers of 0-25 cm and above, which would be beneficial for E. nuttallii to win the competition with P. crispus. In addition, the results also showed that root growth was less affected by the interspecific competition.