Search for: All records

Abstract Under drought conditions, arbuscular mycorrhizal (AM) fungi may improve plant performance by facilitating the movement of water through extensive hyphal networks. When these networks interconnect neighboring plants in common mycorrhizal networks (CMNs), CMNs are likely to partition water among many individuals. The consequences of CMN-mediated water movement for plant interactions, however, are largely unknown. We set out to examine CMN-mediated interactions amongAndropogon gerardiiseedlings in a target-plant pot experiment, with watering (watered or long-term drought) and CMN status (intact or severed) as treatments. Intact CMNs improved the survival of seedlings under drought stress and mediated positive, facilitative plant interactions in both watering treatments. Watering increased mycorrhizal colonization rates and improved P uptake, particularly for large individuals. Under drought conditions, improved access to water most likely benefited neighboring plants interacting across CMNs. CMNs appear to have provided the most limiting resource within each treatment, whether P, water, or both, thereby improving survival and growth. Neighbors near large, photosynthate-fixing target plants likely benefited from their establishment of extensive hyphal networks that could access water and dissolved P within soil micropores. In plant communities, CMNs may be vital during drought, which is expected to increase in frequency, intensity, and length with climate change. 

Abstract Although it is known that arbuscular common mycorrhizal networks (CMNs) mediate below‐ground interactions between one or two species, little is understood about their role in mediating interactions among multiple, co‐occurring plant species.We investigated the CMN‐mediated interactions among two Central European species,Inula conyzaeandCrepis bienniswithin pots and the impact of a third plant, an invasiveEchinops sphaerocephalus, on these relationships. We examined changes in C‐to‐P exchange within a CMN formed byFunneliformis mosseaesourced from Central Europe by tracking plant C cost with¹³C signatures of 16:1ω5 and P acquisition to hosts with³³P only accessible to CMNs.When only native plants were present, the C cost was consistent for both species, despite CMNs favouringC. bienniswith P uptake. In the presence ofE. sphaerocephalus, CMNs also favouredC. bienniswith P, but whileC. biennisandE. sphaerocephalusprovisioned similarly large portions of¹³C,I. conyzaeprovided less. Mycorrhizal P acquisition, therefore, was the costliest forE. sphaerocephalus, which likely mitigated someI. conyzae's C cost even though both received a low proportion of³³P from CMNs.Echinops sphaerocephalusaltered mineral nutrient and C exchange proportions between native plants and their CMN, suggesting that this species alters below‐ground plant interactions and that not only specific characteristic of plant host and fungal partner but also the wider plant community mediates resource exchanges between CMNs and individual plants. Read the freePlain Language Summaryfor this article on the Journal blog.