外来植物入侵对陆地生态系统地下碳循环及碳库的影响

Impacts of exotic plant invasions on terrestrial ecosystem below-ground carbon cycling and carbon pool

生物入侵是当今全球性重大环境问题之一,是全球变化的主要研究内容。评价外来植物入侵对于生态系统影响的研究多集中在地上部分,对于生态系统地下部分影响的研究相对较少。陆地生态系统地下部分对于生态系统过程的重要性之一体现在它处于生态系统碳分配过程的核心环节。入侵种通过影响群落凋落物的输入数量、质量以及输入时间,影响到对于土壤的碳输入,而入侵种与土著种根系的差异以及入侵种对微生物群落的影响是造成土壤呼吸强度发生变化的主要因素,前者土壤呼吸强度一般比后者高。多数研究表明外来植物入侵对生态系统地下碳循环和碳库产生影响,但由于入侵植物种类较多以及研究地点环境条件的不同,关于外来植物入侵对于土壤碳库和土壤有机碳矿化影响的研究结论并不统一。最后,提出了今后该研究领域应加强的一些建议和方向。

Exotic plant invasions have been identified as one of the most important global problems facing natural ecosystems, where they threaten biodiversity, ecosystem structure and function, and ecosystem stability. In the past little attention has been paid to the potential impacts of exotic species invasion on soil nutrient cycling processes, but recently study in this area have increased and merged as a central issue in invasion ecology. Clearly, below-ground dynamics are a key link in carbon cycling. Invasive species may affect this cycle in a variety of ways ： by changing litter inputs （ amount, litter chemistry, variation in litter components as a result of changed plant morphology, seasonal timing of entry） and altering the root system （added effects of the roots of the invader）. The effects of invasion on soil microbial communities will cause the change of soil respiration. In general, the soil respiration rate of invasive plants is higher than that of indigenous species. Most of the available literature suggests that invasive exotic species can have a potential impact on soil carbon process and the resultant soil carbon pool. However, because of the large the diversity of exotic species and available invasion sites, patterns of difference between invasive and native species are inconsistent trends both soil carbon pools and soil organic carbon mineralization. We conclude that these problems needed further study and present some proposals for further discussion.