Data from: Mycorrhizas influence functional traits of two tallgrass prairie species

Over the past decade, functional traits that influence plant performance and thus, population, community, and ecosystem biology have garnered increasing attention. Generally lacking, however, has been consideration of how ubiquitous arbuscular mycorrhizas influence plant allometric and stoichiometric functional traits. We assessed how plant dependence on and responsiveness to mycorrhizas influence plant functional traits of a warm-season, C4 grass, Andropogon gerardii Vitman, and the contrasting, cool-season, C3 grass, Elymus canadensis L. We grew both host species with and without inoculation with mycorrhizal fungi, across a broad gradient of soil phosphorus availabilities. Both host species were facultatively mycotrophic, able to grow without mycorrhizas at high soil phosphorus availability. A. gerardii was most dependent upon mycorrhizas and E. canadensis was weakly dependent, but highly responsive to mycorrhizas. The high dependence of A. gerardii on mycorrhizas resulted in higher tissue P and N concentrations of inoculated than noninoculated plants. When not inoculated, E. canadensis was able to take up both P and N in similar amounts to inoculated plants because of its weak dependence on mycorrhizas for nutrient uptake and its pronounced ability to change root-to-shoot ratios. Unlike other highly dependent species, A. gerardii had a high root-to-shoot ratio and was able to suppress colonization by mycorrhizal fungi at high soil fertilities. E. canadensis, however, was unable to suppress colonization and had a lower root-to shoot ratio than A. gerardii. The mycorrhiza-related functional traits of both host species likely influence their performance in nature: both species attained the maximum responsiveness from mycorrhizas at soil phosphorus availabilities similar to those of tallgrass prairies. Dependence upon mycorrhizas affects performance in the absence of mycorrhizas. Responsiveness to mycorrhizal fungi is also a function of the environment and can be influenced by both mycorrhizal fungus species and soil fertility.

过去十年来，影响植物生长表现，进而作用于种群、群落与生态系统生物学过程的功能性状，已受到学界日益广泛的关注。但目前仍普遍缺失的是，针对无处不在的丛枝菌根（arbuscular mycorrhizas）如何调控植物异速生长与化学计量学功能性状的相关研究。本研究以暖季型C4草本植物（C4 grass）大须芒草（Andropogon gerardii Vitman），以及性状特征相对的冷季型C3草本植物（C3 grass）加拿大披碱草（Elymus canadensis L.）为研究材料，探究植物对菌根的依赖性与菌根响应如何影响其功能性状。我们在跨度较广的土壤磷有效性梯度下，分别对接种与未接种菌根真菌的两种宿主植物开展栽培实验。两种宿主植物均为兼性菌根营养型，在土壤磷有效性较高的条件下，可脱离菌根独立完成生长过程。其中大须芒草对菌根的依赖性较强，而加拿大披碱草依赖性较弱，但对菌根的响应程度更高。大须芒草对菌根的高依赖性导致接种组植物的组织磷、氮浓度显著高于未接种组；未接种条件下，加拿大披碱草可凭借较弱的菌根养分吸收依赖性，以及显著调整根冠比的能力，获取与接种组相当的磷、氮吸收量。与其他高菌根依赖性物种不同，大须芒草本身具有较高的根冠比，且可在土壤肥力较高的条件下抑制菌根真菌的定殖；反观加拿大披碱草则无法抑制菌根定殖，且根冠比低于大须芒草。两种宿主植物的菌根相关功能性状，或可解释其在自然生境中的生长表现：二者在与高草草原（tallgrass prairies）土壤磷有效性相近的条件下，均可从菌根共生中获得最大的响应收益。对菌根的依赖性会影响无共生条件下的植物生长表现；而对菌根真菌的响应程度同时受环境因子调控，亦会受到菌根真菌种类与土壤肥力的共同影响。