Complexity-dependent responses in ecosystem processes to low-frequency electromagnetic disturbance

Through an experimental approach aimed at evaluating the propagation of disturbance across a hierarchical progression of ecological systems, we demonstrated the coupling between low frequency electromagnetic fields (1st mode of Schumann resonances) and system functioning at different levels of complexity. The alterations of ecological dynamics elicited by interfering anthropogenic electromagnetic fields were demonstrated to depend on system complexity, with increasingly clearer responses in moving from organisms to ecosystems. Here, focusing at the ecosystem level, we aimed at evaluating how the complexity of functionally coupled processes may modulate the responses to electromagnetic disturbances. To this end, we studied the effects on litter decomposition of Schumann resonances variably interfered by 7.83 Hz – 15 ± 2 µT artificial fields. To highlight potentially small effects, the study was carried out under controlled conditions for up to 216 days, by exposing litter bags with holm oak leaves in mesocosms for different times (0, 15’, 30’), using a coil purposefully developed via finite element modelling. Decomposition was investigated in terms of rates of mass loss and of involved processes, i.e. microbial activity by means of CO2 evolution and enzyme activities, estimating the effects through Bayesian multilevel modelling. Results highlight that disturbance to Schumann resonances differentially affects enzyme activities and microbial respiration, with the type and amplitude of responses dependent upon process complexity. The interaction among these processes, each with specific dynamics, elicits non-linear, hormetic responses in litter decomposition that are buffered, in terms of amplitude, in respect to the underlying processes. On the one hand, our research confirms the coupling between low frequency electromagnetic fields and the functioning of ecological systems. On the other hand, it sheds light on the role of complexity in modulating the propagation of disturbances among interacting processes and in buffering the effects they may elicit on ecosystem processes.