Exploring soil ecology gradient concepts: sensitivity of ecosystem properties to symbiotic fungi in semiarid prairie

Authors: Reinhart, Kurt; Vermeire, Lance; Penn, Chad; LEKBERG, YLVA - Mpg Ranch

Submitted to: Discover Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/13/2025
Publication Date: 11/16/2025
Citation: Reinhart, K.O., Vermeire, L.T., Penn, C.J., Lekberg, Y. 2025. Exploring soil ecology gradient concepts: sensitivity of ecosystem properties to symbiotic fungi in semiarid prairie. Discover Soil. 2. Article 108. https://doi.org/10.1007/s44378-025-00124-6.
DOI: https://doi.org/10.1007/s44378-025-00124-6

Interpretive Summary: Problem- Drylands with calcareous soils (i.e. subsoils containing carbonates) make up approximately a third of land. In these soils, soil phosphorus binds with calcium and has low solubility and low availability to plants. Plants may use a variety of strategies to acquire insoluble phosphorus that range from using root exudates to mine phosphorus to collaborating with mycorrhizal fungi which effectively scavenge labile phosphorus and trade it with plant roots. We know very little about the phosphorus acquiring strategies of rangeland plants in soils with low phosphorus solubility. Accomplishment- In drylands with calcium-related phosphorus compounds, phosphorus-deficient plants rely more on root-mining strategies than collaborating with mycorrhizal fungi to scavenge labile phosphorus. Our results support the prediction that where inorganic carbon predominates in soil plants will rely on root-mining strategies to acquire phosphorus. Conversely, plants will rely on collaborating with mycorrhizal fungi to acquire phosphorus where soils have more organic than inorganic carbon.

Technical Abstract: In resource-limited environments, plants are predicted to either increase 1) root mining activities or 2) their collaboration with nutritional mutualists (e.g. mycorrhizal fungi). Little is known about in situ effects of arbuscular mycorrhizal fungi (AMF) on semiarid grasslands where soil phosphorus (P) has low solubility. To fill this knowledge gap, we performed a series of experiments and evaluated evidence of AMF effects on plants, plant-plant interactions, plant nutrient limitation, and nutrient acquisition strategy. First, we tested how AMF suppression affected plant biomass, composition, and diversity; lichen and moss abundance; indicators of plant nutrient limitation (i.e. shoot nitrogen-to-phosphorus ratio, N:P) and P acquisition (i.e. shoot manganese concentration, [Mn]); and structure and function of soil with a five-year field experiment. The field study informed pot bioassays. Suppression of fungal symbionts eliminated lichens and increased mosses by 410%. AMF suppression also increased plant biomass by 13% and shifted dominant C3 perennial grasses (more Koeleria macrantha and less Hesperostipa comata). Effects on grass dominance were stronger before and during than after a natural drought. AMF suppression increased a putative indicator of P limitation (increased shoot N:P) of mature K. macrantha and had no effect on N:P of mature H. comata. AMF suppression had no effect on plant diversity, soil structure, and soil function. Pot bioassays tested how dominant grass coexistence was affected by three pairs of soil treatments 1) field soil inoculant (FSI) versus FSI with AMF suppression, 2) FSI versus sterilized FSI, and 3) AMF inoculant versus sterilized AMF inoculant. In 50/50 mixes, K. macrantha outperformed H. comata regardless of treatment, and H. comata was likely P limited as indicated by the 2.5 times greater shoot N:P. Across all experiments, K. macrantha had 2.2 to 4.1 times greater levels of an indicator of root exudation (shoot [Mn]) to mobilize calcium-bound P than H. comata. Sterilization of FSI increased shoot [Mn] of both grasses, suggesting plasticity for inducible root mining. While AMF had small and significant effects on co-dominant C3 grasses, the dryland ecosystem’s plant community composition, soil structure, and soil function were generally resistant (or resilient) to AMF suppression. Our findings add to the understanding of plant P acquisition strategies in drylands where soils with low organic matter and P solubility appear to promote autonomous P-acquisition strategies while moderate soil fertility and P lability may favor collaboration with AMF.