Data from: Poor plant performance under simulated climate change is linked to mycorrhizal responses in a semiarid shrubland

1.Warmer and drier conditions associated with ongoing climate change will increase abiotic stress for plants and mycorrhizal fungi in drylands worldwide, thereby potentially reducing vegetation cover and productivity and increasing the risk of land degradation and desertification. Rhizosphere microbial interactions and feedbacks are critical processes that could either mitigate or aggravate the vulnerability of dryland vegetation to forecasted climate change.

2.We conducted a four-year manipulative study in a semiarid shrubland in the Iberian Peninsula to assess the effects of warming (~2.5°C; W), rainfall reduction (~30%; RR) and their combination (W+RR) on the performance of native shrubs (Helianthemum squamatum) and their associated mycorrhizal fungi.

3.Warming (W and W+RR) decreased the net photosynthetic rates of H. squamatum shrubs by ~31% despite concurrent increases in stomatal conductance (~33%), leading to sharp decreases (~50%) in water use efficiency. Warming also advanced growth phenology, decreased leaf nitrogen and phosphorus contents per unit area, reduced shoot biomass production by ~36% and decreased survival during a dry year in both W and W+RR plants. Plants under RR showed more moderate decreases (~10-20%) in photosynthesis, stomatal conductance and shoot growth.

4.Warming, RR and W+RR altered ectomycorrhizal fungal (EMF) community structure and drastically reduced the relative abundance of EMF sequences obtained by high-throughput sequencing, a response associated with decreases in the leaf nitrogen, phosphorus and dry matter contents of their host plants. In contrast to EMF, the community structure and relative sequence abundances of other non-mycorrhizal fungal guilds were not significantly affected by the climate manipulation treatments.

5.Synthesis: Our findings highlight the vulnerability of both native plants and their symbiotic mycorrhizal fungi to climate warming and drying in semiarid shrublands, and point to the importance of a deeper understanding of plant-soil feedbacks to predict dryland vegetation responses to forecasted aridification. The interdependent responses of plants and ectomycorrhizal fungi to warming and rainfall reduction may lead to a detrimental feedback loop on vegetation productivity and nutrient pool size, which could amplify the adverse impacts of forecasted climate change on ecosystem functioning in EMF-dominated drylands.

1. 伴随气候变化持续发生的暖干化环境，将加剧全球旱地生态系统中植物与菌根真菌（mycorrhizal fungi）所承受的非生物胁迫，进而可能降低植被覆盖度与生产力，并提升土地退化与荒漠化的发生风险。根际微生物互作与反馈过程是关键调控环节，既可以缓解也会加剧旱地植被对未来气候变化的脆弱性。
2. 我们在伊比利亚半岛的半干旱灌丛中开展了一项为期四年的操控性实验，以评估增温（约2.5℃，W）、减雨（约30%，RR）及其组合处理（W+RR）对本土灌木鳞叶半日花（Helianthemum squamatum）及其关联菌根真菌生长表现的影响。
3. 尽管气孔导度同步提升约33%，但增温处理（W及W+RR组）使鳞叶半日花的净光合速率降低约31%，进而导致水分利用效率大幅下降约50%。增温还提前了植株的生长物候期，降低了单位叶面积的氮、磷含量，使地上生物量减少约36%，并在干旱年份降低了W与W+RR组植株的存活率。减雨处理组的植株则表现出更温和的变化：光合速率、气孔导度与地上生长量均下降约10%~20%。
4. 增温、减雨及其组合处理均改变了外生菌根真菌（ectomycorrhizal fungi, EMF）的群落结构，并使经高通量测序（high-throughput sequencing）获得的EMF序列相对丰度大幅降低，该响应与宿主植物叶片氮、磷与干物质含量的下降显著相关。与外生菌根真菌不同，其他非菌根真菌功能群的群落结构与相对序列丰度均未受到气候操控处理的显著影响。
5. 研究总结：本研究结果凸显了半干旱灌丛中本土植物及其共生菌根真菌对气候暖干化的脆弱性，同时指明深入解析植物-土壤反馈过程，对于预测旱地植被对未来干旱化的响应至关重要。植物与外生菌根真菌对增温及减雨的相互依存响应，可能会形成损害植被生产力与养分库规模的负面反馈环路，进而加剧预测中气候变化对以EMF为主导的旱地生态系统功能的不利影响。