Hollow trees: Rare habitat, rare species

Wainhouse, Matthew 2023. Hollow trees: Rare habitat, rare species. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

The global decline of large old trees coupled with insufficient recruitment to the veteran cohort has led to a loss of hollowing that provides critical habitat for other species. The process of cavity formation and heartwood decomposition is the preserve of a small functionally important group of heart-rot fungi. In spite of their important role in hollowing, research in heart-rot ecology has been largely overlooked. Heartwood decomposition is a slow process. It may take centuries for a fungus to be able to access the heartwood and once there decades more before hollows begin to form. This is problematic as there are no practical interventions that replace the biotic, chemical and structural complexity of a cavity. Inoculating fungi into living trees to accelerate heart-rot development and translocate threatened heart-rot fungi has been suggested as a possible intervention. This thesis explores the ecology and conservation of heart-rot fungi through research in heart-rot inoculation of living trees. Heart-rot inoculation has a pedigree of more than 100 years of research, primarily focussed on understanding colonisation to prevent timber loss. The same approaches can be used in heart-rot conservation. The concept of ‘conservation inoculation’ is introduced as an umbrella term combining ‘veteranising inoculations’, designed to create heart-rot habitat to benefit other taxa, and ‘translocation inoculations’ as a means of species reintroduction for threatened heart-rot fungi. Heart-rot inoculation studies are reviewed in the context of fungal ecology and species conservation to provide guidance on how to design conservation inoculations. Two long-term trials have been established to collect data on the effectiveness of conservation inoculations. This thesis reports on the initial results of tree colonisation by the fungi in these trials. In a veteranising inoculation trial, four species of heart-rot fungi were inoculated into beech trees. After three years, all but one had colonised the tree. In a translocation inoculation trial using a different inoculation method, the threatened fungi Hericium erinaceus and Hericium coralloides were reintroduced to an ancient woodland where they are believed to have been lost. After 2.5 years, both species had colonised the tree. In both trials, naturally colonising species were also identified, including highly combative basidiomycetes in the veteranising inoculation. The results give optimism that conservation inoculations are a viable conservation tool, however long-term monitoring of heart-rot development will be fundamental to establish whether they meet their long terms aims. Interactions drive community structure among saprotrophic basidiomycetes, though outcomes are affected by abiotic factors. Brown-rot and white-rot represent the two broad decay modes of wood decay fungi. A microcosm is used to investigate how species from each guild interact in antagonistic interaction under increasing temperatures. Temperature significantly affected the combative iv hierarchy with brown-rot tending to be more combative at higher temperatures, though its not clear whether this is due positive affect on brown-rot physiology or stress on white-rot physiology. In general, combative ability of brown-rot species increased with temperature while white-rot fell, though there was significant variation between species and even strains. These results help to explain observed frequencies of brown-rot relative to white-rot outside of temperature optima and help to understand how abiotic stresses might promote brown-rot fitness.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Biosciences
Subjects:	Q Science > Q Science (General)
Date of First Compliant Deposit:	26 February 2024
Last Modified:	08 Mar 2024 09:33
URI:	https://orca.cardiff.ac.uk/id/eprint/166549

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