Fear of predators alters herbivore regulation of soil microbial community function

Fear of predation can affect important ecosystem processes by altering the
prey traits' expression that, in turn, regulates the quantity and
quality of nutritional inputs to soil. Here, we aimed to assist in
bridging a knowledge gap in this cascading chain of events by exploring
how risk of spider predation may affect grasshopper prey performances, and
the activity of various microbial extracellular enzymes in the soil. Using
a mesocosms field‐experiment, we found that grasshoppers threatened by
spider predation ate less, grew slower, and had a higher body carbon to
nitrogen ratio. Herbivory increased activity of all microbial
extracellular enzymes examined, likely due to higher availability of root
exudates. Predation risk had no effect on C‐acquiring enzymes but
decreased activity of P‐acquiring enzymes. We found contrasting results
regarding the effect of predation on the activity of
N‐acetyl‐glucosaminidase and leucine arylamidase N‐acquiring enzymes,
suggesting that predation risk may alter the composition of N‐inputs to
soil. Our work highlighted the importance of soil microbial enzymatic
activity as a way to predict how changes in the aboveground food‐web
dynamics may alter key ecosystem processes like nutritional‐cycling.