Network formation by rhizomorphs of Armillaria lutea in natural soil: their description and ecological significance

• Published in: FEMS microbiology ecology Vol. 62; no. 2; pp. 222 - 232
• Main Authors: Lamour, Angelique, Termorshuizen, Aad J, Volker, Dine, Jeger, Michael J
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.11.2007; Blackwell Publishing Ltd; Oxford University Press
• Subjects: Agaricales - growth & development; Agaricales - physiology; Amputation; Apexes; Armillaria; Armillaria rhizomorphs; basidiomycete linear organs; cepistipes; Changing environments; colonization; connectedness; Disruption; dynamics; ecological persistence; Ecology; Ecosystem; Environmental changes; Graph theory; hypholoma-fasciculare; mellea; Microbiology; mycelial cord systems; Mycorrhizae - growth & development; Mycorrhizae - physiology; Network formation; network structure; Nutrients; phanerochaete-velutina; physiology; Picea; Picea abies; Pine trees; Pinus; Pinus - microbiology; Pinus nigra; Planting density; Rhizomorphs; robustness; Soil mapping; Soil Microbiology; Soil surfaces; Soils; translocation; robustness; connectedness; graph theory; network structure; ecological persistence; rhizomorphs
• ISSN: 0168-6496; 1574-6941
• DOI: 10.1111/j.1574-6941.2007.00358.x

Armillaria lutea rhizomorphs in soil were mapped over areas of 25 m² at a Pinus nigra (site I) and a Picea abies (site II) plantation. Rhizomorph density was 4.3 and 6.1 m m⁻² soil surface with 84% and 48% of the total rhizomorph length in the mapped area interconnected in a network at site I and site II, respectively. At site I there were only two network attachments to Pinus stumps, but at site II many more to Picea roots and stumps. Anastomoses of rhizomorphs resulted in cyclic paths, parts of the network that start and end at the same point. Connections between different rhizomorph segments were shown to allow gaseous exchange. The network at site I consisted of 169 rhizomorphs ('edges'), and 107 rhizomorph nodes ('vertices'). Disruption of two critical edges ('bridges') would lead to large parts (13% and 11%) being disconnected from the remainder of the mapped network. There was a low probability that amputation of a randomly chosen edge would separate the network into two disconnected components. The high level of connectedness may enhance redistribution of nutrients and provide a robust rhizomorph structure, allowing Armillaria to respond opportunistically to spatially and temporally changing environments.