Bezemer T Martijn, Harvey Jeffrey A, Kowalchuk George A, Korpershoek Hanna, van der Putten Wim H
Netherlands Institute of Ecology (NIOO-KNA W), Centre for Terrestrial Ecology, P.O. Box 40, 6666 ZG Heteren, The Netherlands.
Ecology. 2006 Aug;87(8):2002-13. doi: 10.1890/0012-9658(2006)87[2002:ibsjap]2.0.co;2.
To elucidate the factors that affect the performance of plants in their natural environment, it is essential to study interactions with other neighboring plants, as well as with above- and belowground higher trophic organisms. We used a long-term field experiment to study how local plant community diversity influenced colonization by the biennial composite Senecio jacobaea in its native range in The Netherlands in Europe. We tested the effect of sowing later-succession plant species (0, 4, or 15 species) on plant succession and S. jacobaea performance. Over a period of eight years, the percent cover of S. jacobaea was relatively low in communities sown with 15 or 4 later-succession plant species compared to plots that were not sown, but that were colonized naturally. However, after four years of high abundance, the density of S. jacobaea in unsown plots started to decline, and the size of the individual plants was smaller than in the plots sown with 15 or 4 plant species. In the unsown plots, densities of aboveground leaf-mining, flower-feeding, and stem-boring insects on S. jacobaea plants were lower than on plants in sown plots, and there was a strong positive relationship between plant size and levels of herbivory. In a greenhouse experiment, we grew S. jacobaea in sterilized soil inoculated with soil from the different sowing treatments of the field experiment. Biomass production was lower when S. jacobaea test plants were grown in soil from the unsown plots than in soil from the sown plots (4 or 15 species). Molecular analysis of the fungal and bacterial communities revealed that the composition of fungal communities in unsown plots differed significantly from those in sown plots, suggesting that soil fungi could have been involved in the relative growth reduction of S. jacobaea in the greenhouse bioassay. Our results show that, in its native habitat, the abundance of S. jacobaea depends on the initial composition of the plant community and that, on a scale of almost a decade, its interactions with plant and soil communities and aboveground invertebrates may influence the dynamics of this colonizing species.
为了阐明影响植物在自然环境中表现的因素，研究其与其他邻近植物以及地上和地下更高营养级生物的相互作用至关重要。我们进行了一项长期田间试验，以研究当地植物群落多样性如何影响两年生菊科植物千里光在其欧洲荷兰原生范围内的定殖情况。我们测试了播种演替后期植物物种（0、4或15种）对植物演替和千里光表现的影响。在八年的时间里，与未播种但自然定殖的地块相比，播种了15种或4种演替后期植物物种的群落中，千里光的覆盖百分比相对较低。然而，在经历了四年的高丰度之后，未播种地块中千里光的密度开始下降，且单株植物的大小比播种了15种或4种植物物种的地块中的要小。在未播种地块中，千里光植株上的地上食叶、食花和蛀茎昆虫的密度低于播种地块中的植株，并且植物大小与食草水平之间存在很强的正相关关系。在温室试验中，我们将千里光种植在接种了田间试验不同播种处理土壤的灭菌土壤中。当千里光试验植株种植在未播种地块的土壤中时，其生物量产量低于种植在播种地块（4种或15种）土壤中的产量。对真菌和细菌群落的分子分析表明，未播种地块中真菌群落的组成与播种地块中的显著不同，这表明土壤真菌可能参与了温室生物测定中千里光相对生长减少的过程。我们的结果表明，在其原生栖息地，千里光的丰度取决于植物群落的初始组成，并且在近十年的时间尺度上，其与植物、土壤群落以及地上无脊椎动物的相互作用可能会影响这种定殖物种的动态变化。
