Fungi vital for native beech reforestation
THE OTAGO UNIVERSITY RESEARCH TEAM HAS, FOR the last two years, been working on the restoration of native forests. A pilot study in 2018, funded by the NZ Bioheritage National Science Challenge and the QEII National Trust, led to the threeyear partnership grant with the Ministry for Primary Industries under Te Uru Rakau’s 1 Billion Trees Programme.
The object of the Ngā Kākano Whakahau project is to optimise methods for re-establishing native forest using seeds and beneficial fungi. The large-scale trials are being conducted on High Peak Station, Canterbury, and on Motatapu Station, Otago, part of the Soho Properties QEII National Trust covenant of nearly 55,000 ha.
Both areas were historically dominated by Beech forest and a vital booster for Beech restoration is the availability of native ecto-mycorrhizal fungi.
Led by Professor Janice Lord, the research team based in the University’s Botany Department has been working on techniques to reintroduce beneficial native fungi during native re-afforestation.
Beech tree roots needed to be colonised by ecto-mycorrhizal (EM) fungi to attain enough phosphorus and nitrogen in naturally nutrientlimited soils.
She explains where native forest had been taken out by pastoral farming, burned or invaded by exotic vegetation, native fungi that have a mutualistic relationship with the trees, had disappeared.
Research is now comparing methods for introducing fungal spores to seeds. It has found that the most common EM mushrooms collected from Manuka and Beech forests were from the genus Cortinarius, which is the most important EM genus in New Zealand. Like all EM fungi, the fungal hyphae of Cortinarius can be seen growing on the outside of their host’s roots and are particularly diverse in mature Beech forest.
Under normal conditions, Beech roots cannot acquire enough phosphorus and nitrogen unless they are infected with ecto-mycorrhizal fungi (ecto = outside, mycor =fungus, rhiza=root i.e. fungus coats the outside of the root, commonly referred to as EM fungi). The fungi network is far more efficient at gathering these nutrients from the soil and supplies them to the Beech roots. In turn the fungi gains sugars from the beech. This mutualism is common worldwide and well-known to the forestry industry, as pines and eucalypts also rely on EM fungi.
Among NZ native trees, Beech (all five species) are the only trees that obligately rely on EM fungi. Manuka and Kanuka can form associations with EM fungi but can also manage with just the more common AM (arbuscular mycorrhizal) fungi (that most other native trees form associations with).
The research group is currently optimising methods for spore extraction, storage and viability testing. Professor Lord says that while fresh spores show the highest viability, cool or dry storage for later use is feasible. However, pioneer EM fungi may be more suitable for Beech restoration projects than fungi from mature forests. In line with these findings, the project also includes work on large-scale establishment of Manuka from seed. Manuka can host some EM fungi that benefit Beech and establishes more rapidly from seed, leading to a pioneer community with potential for economic return, while facilitating Beech reforestation over time.
NZL