Leaf litter presence in the non‐growing season prolongs plant legacy effects on soil fungal communities and succeeding plant growth

Soil microbes can profoundly affect species coexistence and alien plant invasion via plant–soil feedbacks (PSFs). Theoretically, plants can modify soil biotic communities (e.g. fungal and bacterial communities) sequentially via rhizo‐inputs in the growing season and via litter decomposition in the non‐growing season, and in this way affect the performance of plant individuals that establish in the same soil in the following growing season. However, how plants affect soil microbes via sequential rhizosphere and litter inputs and how these soil microbial legacies feedback to subsequent plants remains unclear. Here, we first explored the sequential effects of living individuals and their leaf litter on soil fungal communities, using 42 common alien and native species in China, and then estimated their PSF effects on three common test species. Our results show that living plants growing in field soil developed distinct rhizosphere fungal communities within one season. After the removal of conditioning plants, the fungal communities in these conditioned soils changed more dramatically in the absence than in the presence of leaf litter, suggesting that leaf litter inputs prolonged the species‐specific legacies that conspecific living individuals exerted in the soil. Moreover, leaf litter induced general negative effects on all test species in the second growing season. Conditioning plant origin (native vs. alien) and life cycle (annual vs. perennial), respectively, had a slight or no impact on fungal community composition, and conditioning plant origin did not affect PSF responses of the test species. Synthesis : These findings show that leaf litter prolongs soil fungal legacies of conspecific living individuals, which can lead to carryover effects on heterospecific plant growth in the next season. Our findings highlight the importance of leaf litter for plant–soil interactions and thereby stress the potential importance of plant litter as a driver of plant community dynamics. 土壤微生物通过植物‐土壤反馈(PSF)可能影响物种共存和外来植物入侵。理论上，植物可以通过根际分泌物(生长季)和凋落物分解(非生长季)依次调节土壤微生物群落(例如真菌和细菌群落)，进而影响后期生长于相同土壤的植株。然而，植物如何依次通过根际分泌物和凋落物分解影响土壤微生物和反馈作用，目前仍不清楚。有鉴于此，本研究采用新的植物‐土壤反馈作用研究框架(包括2个土壤驯化阶段)，选用42种中国常见的外来和本土物种开展了控制实验，探讨了植物生长和叶凋落物对土壤真菌群落的影响，测试了驯化土壤对三种常见物种的PSF作用。结果发现经过一个生长季，活体植物显著改变了土壤真菌群落结构。然而经过一个非生长季(冬季)且没有叶片凋落物时，驯化土壤中真菌结构显著改变。然而，在叶片凋落物存在时，驯化土壤中真菌结构在非生长季变化幅度显著降低，表明叶片凋落物显著延长了活体植株的土壤遗留效应。在第二个生长季，与种植于无叶片凋落物驯化土壤比较，植株种植于有叶片凋落物驯化土壤时地上生物量较低。驯化植物来源(本土或外来)对土壤真菌群落结构和PSF作用仅有较弱的影响。上述结果表明:叶片凋落物延长了活体植物的土壤真菌遗