Data from: The differential impact of a native and a non-native ragwort species (Senecioneae) on the first and second trophic level of the rhizosphere food web

Whereas the impact of exotic plant species on above-ground biota is relatively well-documented, far less is known about the effects of non-indigenous plants on the first and second trophic level of the rhizosphere food web. Here, rhizosphere communities of the invasive narrow-leaved ragwort Senecio inaequidens and the native tansy ragwort Jacobaea vulgaris, co-occurring in three semi-natural habitats are compared. For both species, two life stages were taken into consideration. Quantitative PCR assays for the analyses of bacterial and fungal communities at a high taxonomic level were optimized, and it was investigated whether changes in the primary decomposer community were translated in alterations in bacterivorous and fungivorous nematode communities. In contrast to J. vulgaris, small but significant reductions were observed for Actinobacteria and Bacteroidetes (both p < 0.05) in case of the invasive S. inaequidens. More pronounced changes were detected for the overall nematode community density, and, more specifically, for the bacterivorous genus Anaplectus and the family Monhysteridae (both p < 0.05), as well as the necromenic Pristionchus (p < 0.001). At high taxonomic level, no differences were observed in fungal rhizosphere communities between native and non-native ragwort species. The impact of plant developmental stages on rhizosphere biota was prominent. The overall bacterial and fungal biomasses, as well as a remarkably consistent set of constituents (Actinobacteria, α- and β-Proteobacteria and Bacteroidetes) were negatively affected by plant stage for both ragwort species. Although later developmental stages of plants generally coincided with lower levels for individual nematode taxa, densities of the fungivorous genera Diphtherophora and Tylolaimophorus remain unaltered. Hence, even at a high taxonomic level, differential effects of native and non-native ragwort could be pinpointed. However, plant developmental stage has a more prominent impact and this impact was similar in nature for both native and non-native ragwort species.尽管外来植物对地上生物群的影响已有较为充分的研究记录，但针对非本土植物对根际食物网（rhizosphere food web）第一、第二营养级的影响，目前的认知仍十分有限。本研究选取在3种半自然生境中共存的入侵性狭叶千里光（Senecio inaequidens）与本土款冬状千里光（Jacobaea vulgaris），对二者的根际群落开展对比分析。针对这两种植物，本研究均纳入了两个生长发育阶段作为研究变量。本研究优化了用于高分类阶元下细菌与真菌群落分析的定量PCR（qPCR）实验体系，并探究了初级分解者群落的变化是否会传递至食细菌线虫（bacterivorous nematode）与食真菌线虫（fungivorous nematode）群落中。与本土的J. vulgaris不同，入侵性S. inaequidens的根际放线菌门（Actinobacteria）与拟杆菌门（Bacteroidetes）丰度出现了小幅但显著的下降（两者p值均<0.05）。线虫群落总密度则呈现出更为显著的变化，具体而言，食细菌线虫属Anaplectus、单齿线虫科（Monhysteridae）（两者p值均<0.05）以及食尸性Pristionchus属（p<0.001）的丰度均发生了显著改变。在高分类阶元层面，本土与外来千里光属植物的根际真菌群落未出现显著差异。植物发育阶段对根际生物群（rhizosphere biota）的影响则十分显著。对于两种千里光而言，总细菌与真菌生物量，以及一组稳定性极高的群落组分（放线菌门、α-变形菌纲、β-变形菌纲与拟杆菌门）均会受到植物发育阶段的负面影响。尽管植物后期发育阶段通常伴随着单个线虫类群丰度的下降，但食真菌线虫属Diphtherophora与Tylolaimophorus的密度并未发生改变。因此，即便在高分类阶元层面，仍可明确本土与外来千里光属植物对根际生物群的差异化影响。但相较而言，植物发育阶段对根际生物群的影响更为显著，且该影响在本土与外来千里光属植物中表现出相似的本质特征。