Data and R code for “Tree growth response to shifting soil nutrient economy depends on mycorrhizal associations”, New Phytologist, 2019.

The mycorrhizal-associated nutrient economy hypothesis proposes a strong connection between plant and fungal traits and the dominant form of soil nutrients. If true, then shifting from an organic to an inorganic nutrient economy should benefit arbuscular mycorrhizal (AM) trees because they are more suited to acquiring inorganic forms of nutrients and have limited decomposing capabilities when compared to ectomycorrhizal (ECM) trees. An inorganic nutrient economy was experimentally promoted by applying inorganic phosphorus (P) fertilizer and/or elevating soil pH with lime in three Allegheny Plateau mixed mesophytic forests. Trees were measured over seven growing seasons to determine how growth responded to the treatments based on mycorrhizal association. AM-associated trees showed increased growth in response to increased inorganic nutrients, but ECM tree growth was suppressed when compared to the control. We also observed that understory and mid-story trees responded to the treatments, but large overstory trees showed no significant growth response. Results support the hypothesis that AM trees respond positively to an inorganic nutrient economy. While raising pH in acidic soils can be detrimental to ECM tree growth, the exact mechanism for this response is unclear

菌根关联养分经济假说（mycorrhizal-associated nutrient economy hypothesis）提出，植物与真菌性状和土壤养分的主导形态之间存在紧密关联。若该假说成立，则由有机养分经济模式向无机养分经济模式的转变，将对丛枝菌根（arbuscular mycorrhizal, AM）树种更为有利——相较于外生菌根（ectomycorrhizal, ECM）树种，丛枝菌根树种更擅长获取无机形态养分，且自身分解能力相对有限。研究人员在3处阿勒格尼高原中生混交林中，通过施加无机磷（phosphorus, P）肥料、或施用石灰提升土壤pH值，人为构建了无机养分经济环境。研究者在7个完整生长季内对样地树木开展监测，以明确基于菌根共生类型的树木生长对各处理措施的响应规律。监测结果显示，丛枝菌根关联树种在无机养分供给提升的条件下生长量显著增加，而外生菌根关联树种的生长则较对照组受到抑制。此外，研究还观察到林下与林中层树木对处理措施存在显著响应，但大径级上层林木未表现出明显的生长变化。本研究结果支持“丛枝菌根树种对无机养分经济模式存在正向响应”这一假说。尽管酸性土壤的pH提升可能对於外生菌根树种的生长产生不利影响，但该生长响应的确切调控机制目前仍不明确。