两种不同生境对豚草入侵影响的实验研究

什么样的生境更有利于外来植物入侵,一直是入侵生态学重点关注的问题。本研究以豚草为实验入侵植物,探讨生境与豚草入侵的关系。通过人工草地群落试验发现,豚草入侵物种多样性水平为1、4、9、16四个不同人工植物群落与入侵有土壤种子库的裸地生境相比,其生物量平均减少590 g·m^-2、植株高度平均降低43.7 cm、成活率平均降低21.4%,其在群落中的优势度平均降低0.695。说明已有植物群落定居的生境对豚草的入侵有强烈的抵御作用。由此推断豚草入侵裸地时,生境中存在大量的空余生态位,豚草很容易成为单优势物种,而豚草入侵已有植物群落的生境时,现有植物物种已占据了大量的生态位空间,其入侵性明显降低。研究结果揭示,对外来入侵植物的管理和防控上应采取以预防为主的策略,营造多样化的本地植物群落,减少人为裸地存在时间,可阻挡或延缓外来植物的入侵。

Effect of Two Different Habitats on Ragweed Invasion

Identifying the sensitive habitats with high invasibility is critical for management of biological invasion. Ragweed (Ambrosia artemisiifolia Linn.) has been identified as one of the most dangerous invasive exotic species in many countries throughout the world. The experiment took ragweek as a model invader to reveal the community invisibility of different habitats. Compared with bare plots, the biomass, plant height, survival rate, and community dominance of ragweed were reduced by 590 g·m^-2, 43.7 cm, 21.4% and 0.695 respectively when they invaded communities with four resident species richness (species richness level: 1, 4, 9, 16). The results suggested that the presence of native species had strong negative effects on the performance of the invader species. The presence of native species occupied the niche space and left few empty niches for the colonization of the invaders. The results revealed that planting native species in bare soils, and maintaining the native communities with high diversity, was effective strategies to control the invasion of exotic species.