Recently fixed plant carbon (C) being released as rhizodeposits is a major resource fueling soil food webs. Soil microorganisms predominate in incorporating root-derived C and subsequently transfer it to higher trophic levels. However, variation in microbial community structure between cropping systems and its consequences for the incorporation of root-derived C into soil microbivores remain unclear. In the present study, we used ¹³CO₂ to pulse label a crop monoculture (oilseed rape, Brassica napus L.), a mixed grass community (dominated by Lolium perenne L. mixed with clover Trifolium repens L.), and a young tree plantation (willow, Salix schwerinii E.L. Wolf and Salix viminalis L.). During 28 days, we traced the incorporation of root-derived ¹³C into phospholipid fatty acids (PLFAs) of soil microorganisms and neutral lipid fatty acids (NLFAs) of five Collembola species belonging to three functional groups: epedaphic (surface-dwelling), hemiedaphic (litter-dwelling), and euedaphic (soil-dwelling). The contribution of bacterial and fungal channels to the incorporation of root-derived C into Collembola varied considerably between cropping systems. Collembola incorporated more ¹³C from the bacterial channel in rape than in grass and willow, where fungi were the major C source. This corresponded to a similarly higher ¹³C incorporation into bacterial marker PLFAs in rape compared to grass and willow. By contrast, while the proportion of bacterial and fungal biomarkers in Collembola NLFAs was related to the ¹³C incorporation into microbial PLFAs, it did not correlate with the proportion of microbial PLFAs in the different cropping systems. This suggests that Collembola rely on specific microbial pools, presumably related to recent plant inputs. Within the same cropping system, hemiedaphic species incorporated more root-derived ¹³C from the bacterial channel compared to euedaphic and epedaphic species. The results demonstrate the remarkable importance of cropping system for the flux of root C into microorganisms and microbivore soil invertebrates. Changes in root C flux into bacterial and fungal resources among cropping systems resulted in differential utilization of these resources by soil microbivores, suggesting that in particular microorganisms fueled by rhizodeposits are vital resources for the nutrition of higher trophic levels in soil food webs.

最近作为根系沉积物释放的固定植物碳 (C) 是推动土壤食物网的主要资源。土壤微生物在掺入根来源的 C 并随后将其转移到更高的营养水平方面占主导地位。然而，作物系统之间微生物群落结构的变化及其对根源性碳进入土壤微生物的影响仍不清楚。在本研究中，我们使用¹³ CO ₂脉冲标记作物单一栽培（油菜、欧洲油菜）、混合草群落（以多年生黑麦草与三叶草三叶草混合为主）和一棵幼树种植园（柳树、Salix schwerinii EL Wolf 和Salix viminalis L.)。在 28 天内，我们追踪了根源性¹³ C 掺入土壤微生物的磷脂脂肪酸 (PLFA) 和属于三个功能组的五种弹跳虫的中性脂脂肪酸 (NLFA) 中（垃圾居住）和euedaphic（土壤居住）。细菌和真菌通道对根源性 C 掺入跳虫的贡献因种植系统而异。弹尾目从油菜的细菌通道中吸收的¹³ C 比草和柳树中的多，真菌是主要的 C 来源。这对应于同样更高的¹³与草和柳树相比，C 掺入油菜中细菌标记物 PLFAs 中。相比之下，虽然弹尾虫 NLFA 中细菌和真菌生物标志物的比例与¹³ C 掺入微生物 PLFA 相关，但它与不同种植系统中微生物 PLFA 的比例无关。这表明弹尾目依赖于特定的微生物库，可能与最近的植物输入有关。在相同的种植系统中，半食性物种结合了更多的根源性¹³C 来自细菌通道，与 euedaphic 和 epedaphic 物种相比。结果表明，种植系统对于根 C 进入微生物和微生物土壤无脊椎动物的通量具有显着的重要性。作物系统中根 C 流入细菌和真菌资源的变化导致土壤微生物对这些资源的不同利用，这表明特别是由根际沉积物驱动的微生物是土壤食物网中较高营养级营养的重要资源。