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arid soil, semiarid soil, manipulation experiment, climate change, initial soil formation,
bacterial community
Abstract:
The microbiota is attributed to be important for initial soil formation under
extreme climate conditions, but experimental evidence for its relevance is scarce.
To fill this gap, we investigated the impact of in situ microbial communities and
their interrelationship with biocrust and plants compared to abiotic controls
on soil formation in initial arid and semiarid soils. Additionally, we assessed
the response of bacterial communities to climate change. Topsoil and subsoil
samples from arid and semiarid sites in the Chilean Coastal Cordillera were
incubated for 16 weeks under diurnal temperature and moisture variations to
simulate humid climate conditions as part of a climate change scenario. Our
findings indicate that microorganism-plant interaction intensified aggregate
formation and stabilized soil structure, facilitating initial soil formation.
Interestingly, microorganisms alone or in conjunction with biocrust showed
no discernible patterns compared to abiotic controls, potentially due to watermasking
effects. Arid soils displayed reduced bacterial diversity and developed
a new community structure dominated by Proteobacteria, Actinobacteriota,
and Planctomycetota, while semiarid soils maintained a consistently dominant
community of Acidobacteriota and Proteobacteria. This highlighted a sensitive
and specialized bacterial community in arid soils, while semiarid soils exhibited
a more complex and stable community. We conclude that microorganism-plant
interaction has measurable impacts on initial soil formation in arid and semiarid
regions on short time scales under climate change. Additionally, we propose that
soil and climate legacies are decisive for the present soil microbial community
structure and interactions, future soil development, and microbial responses.
