2022 Early Hearing Detection & Intervention Virtual Conference

March 13 - 15, 2022

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5/25/2021 | 2:00 PM - 3:30 PM | LIGHT AND DISSOLVED N:P AVAILABILITY AFFECT DEGRADATIVE ENZYME ACTIVITY DURING LEAF LITTER DECOMPOSITION | Virtual Platform

LIGHT AND DISSOLVED N:P AVAILABILITY AFFECT DEGRADATIVE ENZYME ACTIVITY DURING LEAF LITTER DECOMPOSITION

Algae can directly influence leaf litter decomposition by provisioning labile carbon (C) exudates to microbial heterotrophs such as fungi and bacteria. While the intensity of this algal priming effect is highly variable, dissolved nutrients may control priming by constraining degradative enzyme activity. We conducted a flume experiment to test algal priming effects on enzymatic activity and decomposition of Liriodendron tulipifera leaf litter. Litter was incubated under light or dark conditions and low vs. high N:P (amendment molar N:P=1 or 256, respectively) for five weeks. On average, light inhibited decomposition rates, and higher N:P concentrations increased decomposition regardless of light (P<0.001). Activity of the C-acquiring enzyme phenol oxidase was also greater under high dissolved N:P (P<0.05), whereas beta-glucosidase activity was consistently inhibited by light (P<0.001). The C-acquiring enzyme beta-xylosidase showed a light x N:P interaction (P<0.05) in which light inhibited activity more strongly under low N:P as compared to high N:P. Phosphatase activity also showed strong light x N:P interactions (P<0.001). These results provide a mechanistic link between dissolved N and P availability and degradative enzyme activity, which will improve predictions of controls on algal priming during leaf litter decomposition.

Carbon cycle
Decomposition
Stream

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Presenters/Authors

Hal Halvorson (), University of Central Arkansas, halvorso@gmail.com;