"The differences in soil microbial diversity between forest systems could potentially result in the exposure of kauri fragments to introduced microbial communities which now have kauri within their range," she added.
The introduction of invasive species into native ecosystems through non-native trees was a recognised driver of disease in forests, Ms Byers wrote, a risk that was particularly high for Phytophthora species, with the plant nursery trade being identified as a vector for introduction and dispersal into new ecosystems globally.
Kauri dieback is caused by Phytophthora agathidicida.
Dr Amanda Black, who is one of Ms Byers' supervisors, and a co-author of the study, said the results showed more research was needed into the relationship between fragmented kauri forests and the pine and pasture ecosystems surrounding them.
"We have just 7500 ha of original kauri forest left, and it exists as fragments, surrounded by 60,000ha of plantation forests and regenerating kauri forest," Dr Black said.
"We need to understand what part this plays in the spread of kauri dieback."