自然生境下北美车前和车前竞争策略的选择性差异

竞争是显著影响植物生长速度和产量的重要因素,外来植物优越的竞争能力和竞争策略,被认为是其成功入侵新栖息地的一个重要机制。本研究分析了不同生长模式和密度下北美车前和车前的生殖投资和竞争特性,探讨其竞争策略的选择性差异。结果表明:土著种车前的根冠比显著高于外来种北美车前的,但其生殖投资则与此相反,且其净生殖投资受到竞争带来的显著影响而降低;而外来植物北美车前则可以在竞争中保持甚至提高净生殖投资,并降低根冠比。生殖投资和竞争指数分析结果均表明,在竞争环境中,北美车前通过提高种子的竞争力、而车前则通过提高根系的竞争力来维持竞争平衡。这种土著种与外来种竞争策略的选择性差异,促使外来植物能够较好的与土著种在同一群落中共存,也可能是北美车前提高入侵能力,并获得入侵成功的一种机制。

DIFFERENCES IN THE SELECTIVITY OF COMPETITIVE STRATEGY BETWEEN PLANTAGO VIRGINICA AND R ASIATICA IN NATURAL HABITATS

Competition is the main factor which significantly affects plant growth and yield. The superior competitive ability and strategy of exotic plants is considered to be an important mechanism of alien plant species to successful invade in new habitats. In this paper it was analyzed that the characteristics of reproductive investment and competitive traits of Plantago virginica and P. asiatica in different growth patterns and densities, and the differences in the selectivity of competitive strategy were discussed. The results showed that： The root-shoot ratio of native species P. asiatica was significantly higher than that of P. virginica, but their total reproductive investment is to the contrary. The net reproductive investment of P. asiatica deceased significantly by the impact of competitive press. In the competition, the exotic species P. virginica could maintain or even increase its net reproductive investment, and decreased its root-shoot ratio. The results of reproductive investment and competitive indices analysis showed that, in a competitive environment, they could maintain competitive balance by different way. P. virginica improved the competitiveness of seeds, while P. asiatica increased the competitiveness of roots. These differences in the selectivity of competitive strategy between P. virginica and P. asiatica promoted exotic plant and native plant species to better coexist in the same community. It could be a mechanism ofP. virginica to improve competitiveness and invasion successfully.