Abstract:
AIMS : Anthropogenic activities disturb forests and their associated mycorrhizal fungi. The combination of climate
change and habitat fragmentation are linked to increased incidence of a canker disease in a Mediterraneantype
forest tree in Western Australia. As changes in communities of mycorrhizal fungi could predispose these
Mediterranean-type forest trees to decline, we investigated how two aspects of mycorrhizal fungal community
structure, soil propagules and resident communities on mature trees, respond to habitat fragmentation.
METHODS : Roots were collected from a forest tree (Corymbia calophylla) across a disturbance gradient. Soil collected
from the same disturbance gradient was used in a glasshouse bioassay with C. calophylla as the bioassay
host (i.e., soil propagule community). After four months, we harvested the seedlings and collected roots. DNA
was extracted from the field roots (resident community) and glasshouse roots (propagule community), amplified
with fungal specific primers, labelled with specific barcodes and subjected to 454 pyrosequencing.
RESULTS : Mycorrhizal fungal community composition overlapped substantially between the soil propagule and
resident communities. However, the resident community had greater mycorrhizal fungal richness than the soil
propagule community. Habitat fragmentation had a similar effect on each community structure: communities
along highly fragmented areas had different community compositions than communities in a healthy forest.
CONCLUSION : With the increased mortality of C. calophylla forest trees in recent years along edge habitats, understanding
the effects habitat fragmentation has on communities of mycorrhizal fungi will further elucidate
host-mutualist interactions in these forest ecosystems. The changes in community composition of mycorrhizal
fungal species in both propagule and resident pools can have cascading effects on future tree establishment and
health by predisposing forest trees to other abiotic or biotic factors.
