School of Geographical Sciences, Fujian Normal University, Fuzhou, China.
Environ Res. 2011 Oct;111(7):909-16. doi: 10.1016/j.envres.2011.05.023. Epub 2011 Jun 25.
We compared the influence of invasion by an alien invasive species (Spartina alterniflora, smooth cordgrass) and a native aggressive species (Phragmites australis, common reed) as they have expanded into the native Cyperus malaccensis (shichito matgrass)-dominated wetland ecosystem in the Min River estuary of southeast China. S. alterniflora is a perennial grass native to North America, which has spread rapidly along the southeast coast of China since its introduction in 1979. Our study compared the above and belowground biomass, net primary production, litter decomposition, plant nutrient stocks and soil organic carbon storage of the grasses in three ecosystems: (1) the native ecosystem dominated by C. malaccensis; (2) ecosystems previously dominated by C. malaccensis but presently replaced by P. australis; and (3) ecosystems previously dominated by C. malaccensis but presently replaced by S. alterniflora. Our results demonstrate that the recent invasion (3 years) of the exotic invasive species S. alterniflora has already significantly increased live aboveground biomass and aboveground plant nutrient stocks. However, there was no significant difference in these variables between native aggressive species P. australis and native C. malaccensis. The majority of belowground root Carbon (C), Nitrogen (N) and phosphorus (P) stocks of the three plant species were all distributed in the upper surface layer and there was a decrease with soil depth. There was little difference in litter decomposition rates among the three grass species; they were ranked in the following order: C. malaccensis>S. alterniflora>P. australis. Litter element concentration showed similar patterns for the three species. However, important differences were found between N and P; the litter N concentrations in each of the three species were greater at the end of the 280 days decomposition than at the start, but P concentrations followed a fluctuating pattern during the decomposition period. Soil organic carbon stocks (0-50cm) under S. alterniflora, P. australis and C. malaccensis stands were statistically indistinguishable, which may be due to the invasion of S. alterniflora having been a relatively recent phenomenon. Thus, recent invasion of the exotic species S. alterniflora has already altered the nutrient cycle of C. malaccensis in the ecosystem in the Min River estuary.
我们比较了外来入侵物种（互花米草，光滑大米草）和本地侵略性物种（芦苇，普通芦苇）的影响，因为它们已经扩展到中国东南闽江河口的本地 Cyperus malaccensis（席地茅）占主导地位的湿地生态系统。互花米草原产于北美洲，自 1979 年引入以来，已迅速沿中国东南沿海扩散。我们的研究比较了三个生态系统中草的地上和地下生物量、净初级生产力、凋落物分解、植物养分储量和土壤有机碳储存：（1）以 C. malaccensis 为主导的本地生态系统；（2）以前由 C. malaccensis 主导但现在由 P. australis 取代的生态系统；（3）以前由 C. malaccensis 主导但现在由 S. alterniflora 取代的生态系统。我们的结果表明，外来入侵物种互花米草的最近入侵（3 年）已经显著增加了活地上生物量和地上植物养分储量。然而，本地侵略性物种芦苇和本地 C. malaccensis 之间在这些变量上没有显著差异。三种植物的大部分地下根系碳（C）、氮（N）和磷（P）储量都分布在上表层，随土壤深度而减少。三种草的凋落物分解速率差异不大；它们的排序如下：C. malaccensis>S. alterniflora>P. australis。凋落物元素浓度对三种物种的模式相似。然而，在 N 和 P 之间发现了重要差异；在三种物种的每一种中，凋落物 N 浓度在 280 天分解结束时都大于开始时，但 P 浓度在分解期间呈波动模式。互花米草、芦苇和 C. malaccensis 林分下（0-50cm）的土壤有机碳储量在统计学上没有区别，这可能是由于互花米草的入侵是一个相对较新的现象。因此，外来物种互花米草的最近入侵已经改变了闽江河口生态系统中 C. malaccensis 的养分循环。
