Unravelling changes in the Pinus radiata root and soil microbiomes as a function of aridity

Rising aridity is becoming a major consequence of climate change,
impacting terrestrial ecosystems worldwide. Forest biomes are especially
at risk due to their long lifespan and immobility, making them vulnerable
to shifting environmental conditions. Over time, microbiomes have evolved
alongside plants, fostering mutual benefits. However, rapid environmental
changes and plant domestication may disrupt the ability of plants to
recruit beneficial microbial partners that enhance stress tolerance. This
study examines how aridity influences the symbiotic relationship between
tree roots and microbes, focusing on the widely planted Pinus radiata. By
analyzing samples across a broad geographic range and varying
environmental conditions, we explore how aridity, soil properties, and
climate factors shape microbial communities in P. radiata roots and
surrounding soils. Our findings show that while aridity plays a major role
in shaping microbial community assembly, factors like soil pH and organic
carbon strongly influence bacterial diversity. Certain bacterial and
fungal taxa were found to be conditionally associated with aridity,
emphasising their potential role in Pinus radiata resilience
under increasing environmental stress. As mesic ecosystems shift toward
arid conditions due to climate change, the presence of these
aridity-associated taxa varies in bulk soils expected to become drier.
This raises concerns that these beneficial microbes may need to be
recruited through alternative mechanisms to support tree adaptation.