不同营养水平对外来物种凤眼莲生长特征及其竞争力的影响

入侵种凤眼莲(Eichhorniacrassipes)在中国的泛滥不仅与其强大的适应力和繁殖能力有关,还与水体的富营养化有很大的关系。作者通过盆栽实验比较了三个营养水平的模拟富营养条件下凤眼莲的生长特征和对当地种黄花水龙(Ludwigiapeploidesssp.stipulacea)和黑藻(Hydrillaverticillata)两个不同生长型的影响。结果表明:富营养条件增强了凤眼莲的生长繁殖能力,使其平均每母株克隆分株数、平均株高以及总生物量极大的增加。凤眼莲的生长优势导致了其竞争优势,对黄花水龙和黑藻都发生了明显的竞争效应。迅速繁殖的凤眼莲覆盖大量水面,通过排挤作用抑制了黄花水龙的生长(低营养水平除外);黑藻因光照缺乏,导致正常光合作用受阻,生物量急剧下降。凤眼莲对黑藻的竞争效应较黄花水龙更强。富营养化的水体为凤眼莲的成功入侵提供了优越条件,因此解决当前水体的富营养化状况能有效控制凤眼莲入侵,同时也有利于本地生物多样性的保护。

Effects of nutrient levels on growth characteristics and competitive ability of water hyacinth (Eichhornia crassipes), an aquatic invasive plant

Water hyacinth (Eichhornia crassipes), a noxious invasive species, has infested vast aquatic ecosystems. Besides its extraordinary adaptive ability and clonal growth, the eutrophication of water bod-ies also account for its rapid spread. Based on a series of pot experiments, we examined the growth char-acteristics of water hyacinth at three different nutrient levels, as well as its competitive effects on two na-tive plants Ludwigia peploides ssp. stipulacea and Hydrilla verticillata. Our results showed that the mean number of ramets, mean height and total biomass of water hyacinth significantly increased with increase of nutrient level, indicating that nutrient-enriched water accelerated the growth and propagation of water hya-cinth, which, as a result, reduced the growth of L. peploides ssp. stipulacea and H. verticillata. This suggests that eutrophication further boosts the competitive advantages of water hyacinth over native plants, and thus facilitates the invasion of this weed in water bodies. Thus, alleviating water pollution is a key method for controlling the spread of water hyacinth in order to protect native biodiversity and ecosys-tem function.