Journal Article
Biogeosciences, vol. 18, iss. 16, pp. 4773-4789, 2021
Authors
Aditi Sengupta, Sarah J. Fansler, Rosalie K. Chu, Robert E. Danczak, Vanessa A. Garayburu-Caruso, Lupita Renteria, Hyun-Seob Song, Jason Toyoda, Jacqueline Wells, James C. Stegen
Abstract
Abstract. Conceptual frameworks linking microbial community membership, properties,
and processes with the environment and emergent function have been proposed
but remain untested. Here we refine and test a recent conceptual framework
using hyporheic zone sediments exposed to wetting–drying transitions. Our
refined framework includes relationships between cumulative properties of a
microbial community (e.g., microbial membership, community assembly properties,
and biogeochemical rates), environmental features (e.g., organic matter
thermodynamics), and emergent ecosystem function. Our primary aim was to
evaluate the hypothesized relationships that comprise the conceptual
framework and contrast outcomes from the whole and putatively active
bacterial and archaeal communities. Throughout the system we found
threshold-like responses to the duration of desiccation. Membership of the
putatively active community – but not the whole bacterial and
archaeal community – responded due to enhanced deterministic selection (an
emergent community property). Concurrently, the thermodynamic properties of
organic matter (OM) became less favorable for oxidation (an environmental
component), and respiration decreased (a microbial process). While these
responses were step functions of desiccation, we found that in
deterministically assembled active communities, respiration was lower and
thermodynamic properties of OM were less favorable. Placing the results in
context of our conceptual framework points to previously unrecognized
internal feedbacks that are initiated by disturbance and mediated by
thermodynamics and that cause the impacts of disturbance to be dependent on
the history of disturbance.
