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. 持续气候变化引发的暖干化环境，将加剧全球干旱区植物与菌根真菌（mycorrhizal fungi）所面临的非生物胁迫，进而可能降低植被覆盖与生产力，加剧土地退化与荒漠化风险。根际微生物互作及其反馈过程是关键调控环节，既可以缓解干旱区植被对未来气候变化的脆弱性，也可能加剧这一风险。
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实验，以评估增温（约2.5℃，W处理）、减雨（约30%，RR处理）及其组合（W+RR处理）对本土灌木鳞叶半日花（Helianthemum squamatum）及其伴生菌根真菌生长表现的影响。
3. 尽管气孔导度同步提升约33%，增温处理（W与W+RR组）仍使鳞叶半日花的净光合速率下降约31%，导致水分利用效率大幅降低约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%，且在干旱年份降低了W与W+RR组植株的存活率。减雨组（RR）植株的光合速率、气孔导度与地上生长仅出现10%~20%的中等程度下降。
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，并通过高通量测序大幅降低了EMF序列的相对丰度，这一响应与宿主植物叶片氮、磷及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序列相对丰度并未受到气候操控处理的显著影响。
5. 综合分析：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（plant-soil feedbacks）机制对预测干旱区植被响应未来干旱化趋势的重要性。植物与外生菌根真菌对增温和减雨的协同响应，可能会形成植被生产力与养分库规模的有害反馈循环，进而加剧气候变化对以EMF为主导的干旱区生态系统功能的不利影响。