Mycorrhizal networks: a review of their extent, function, and importance

Abstract

It is well known from laboratory studies that a single mycorrhizal fungal isolate can colonize different plant species, form interplant linkages, and provide a conduit for interplant transfer of isotopic carbon, nitrogen, phosphorus, or water. There is increasing laboratory and field evidence that the magnitude and direction of transfer is influenced by physiological source–sink gradients between plants. There is also evidence that mycorrhizal fungi play a role in regulating transfer through their own source–sink patterns, frequency of links, and mycorrhizal dependency. Although it is plausible that connections are extensive in nature, field studies have been hampered by our inability to observe them in situ and by belowground complexity. In future, isotopic tracers, morphological observations, microsatellite techniques, and fluorescent dyes will be useful in the study of networks in nature. Mycorrhizal networks have the potential to influence patterns of seedling establishment, interplant competition, plant diversity, and plant community dynamics, but studies in this area are just beginning. Future plant community studies would benefit from concurrent experimental use of fungal network controls, isotopic labeling, direct observation of interplant linkages, and long-term observation in the field. In this paper, we review recent literature on mycorrhizal networks and interplant carbon transfer, suggest future research directions, and highlight promising scientific approaches.Key words: common mycorrhizal network, carbon transfer, source–sink, establishment, competition, diversity.

Fungal loop transfer of N depends on biocrust constituents and N form

“…However, fungi may be more than just passive conduits and exert control over resources due to their own sink-source resource needs (Simard and Durall 2004). 302…”

Inoculación con hongos micorrízicos y fertilización con urea de plantas de Fraxinus uhdei en acrisoles provenientes de sitios degradados

“…Se sabe que la simbiosis micorrízica estimula el crecimiento vegetal debido principalmente al efecto benéfi co sobre la nutrición mineral y el aporte de agua hacia las plantas (Simard y Durall, 2004;Pringle et al, 2009), sin embargo, debe tenerse en cuenta que hay asociaciones distintas que se establecen entre el hongo y su hospedante, y que cada combinación puede tener efectos distintos sobre el crecimiento de la planta. En ese sentido, en este estudio se observó que a pesar de que Fraxinus udhei puede formar asociaciones simbióticas tanto con Rhizophagus intraradices (endomicorriza) como con Pisolithus tinctorius (ectomicorriza), las plantas respondieron de manera distinta a cada especie.…”

Mycorrhizal networks and complex systems: Contributions of soil ecology science to managing climate change effects in forested ecosystems

“…4). To help visualize this, consider mycorrhizal networks from a phytocentric point of view, where fungi form links between plants of the same or different species (representing nodes or hubs) (Francis and Read 1984;Simard and Durall 2004;Southworth et al 2005;Selosse et al 2006). The mycorrhizal networks may function in resource (carbon, nutrients or water) transfer between plants (Simard et al 1997a), or as mycorrhizal colonization vectors (Nara and Hogetsu 2004).…”

“…Ectomycorrhizal fungi (EMF) play a fundamental role in seedling establishment by colonizing roots and exchanging available soil resources for plant carbon. Increasingly recognized, however, is the functional significance of EMF at higher levels of biological organization, including their role in facilitating forest regeneration and succession (Nara and Hogetsu 2004;Simard and Durall 2004;Selosse et al 2006;McGuire et al 2007). In this section, I describe research we have been conducting on the role of mycorrhizal networks in interior Douglas-fir stand dynamics.…”

“…Mortality can be managed in a manner that conserves ecosystem legacies, however, providing structure and processes that ease the transition from one forest type to another. It is well established that nutrients can transfer directly through mycorrhizal networks between healthy plants (Simard and Durall 2004;Selosse et al 2006), but other studies suggest that even larger amounts may transfer from dying to healthy roots Pietika¨inen and Kyto¨viita 2007). Alternatively, organic compounds exuded from senescing roots may be rapidly immobilized by the rhizosphere microbial community and, through turnover, increase nutrient availability in the soil pool for microbial or plant uptake.…”