Patterns of Denitrification and Methanogenesis Rates from Vernal Pools in a Temperate Forest Driven by Seasonal, Microbi
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GENERAL WETLAND SCIENCE
Patterns of Denitrification and Methanogenesis Rates from Vernal Pools in a Temperate Forest Driven by Seasonal, Microbial Functional Gene Abundances, and Soil Chemistry Paul A. Ayayee 1,2
&
Joseph Taura 2 & Alescia A. Roberto 2 & Christopher B. Blackwood 2 & Laura G. Leff 2
Received: 30 April 2019 / Accepted: 12 September 2019 # The Author(s) 2020
Abstract Due to their relatively small sizes, temperate forest vernal pools are less studied than other wetlands, despite being potential biogeochemical hotspots in landscapes. We investigated spatial and temporal factors driving N2O and CH4 emission rates from vernal pools in a temperate forest. We determined higher N2O (3.66 ± 0.53 × 10−6, μg N2O/m2/h) and CH4 (2.10 ± 0.7 × 10−3, μg N2O/m2/h) rates in spring relative to fall (~50% and 77% lower for N2O and CH4 rates, respectively) and winter (~70% and 94% lower for N2O and CH4 rates, respectively). Soil organic matter, nitrate content and bacterial 16S rDNA, nirS, and norB gene abundances emerged as significant drivers of N2O rates, whereas, soil pH, organic matter content and mcrA abundance were significant drivers of CH4 rates. Denitrification gene abundances were negatively correlated with N2O rates, whereas mcrA abundance correlated positively with CH4 rates. Results suggest that CH4 rates may be directly coupled to methanogen abundance, whereas N2O rates may be directly impacted by a variety of abiotic variables and indirectly coupled to the abundance of potential denitrifier assemblages. Overall, additional studies examining these dynamics over extended periods are needed to provide more insights into their control. Keywords Vernal pools . Denitrification . Methanogenesis . norB . mcrA . Biogeochemistry
Introduction Vernal pools are ephemeral wetlands formed in relatively small permanent basins/depressions (less than 2 m deep) that experience periodic inundation and drying (Zedler 2003). Vernal pools are variable in size, depth, and volume (Brooks and Hayashi 2002). The relatively shallow depths, small to medium sizes, and ephemeral nature of vernal pools results in considerable mixing between upper (water column) and lower (soil and organic matter) layers during periods of Electronic supplementary material The online version of this article (https://doi.org/10.1007/s13157-019-01225-z) contains supplementary material, which is available to authorized users. * Paul A. Ayayee [email protected] 1
Department of Ecosystem Science and Management, University of Wyoming, Laramie, WY, USA
2
Department of Biological Sciences, Kent State University, Kent, OH, USA
inundation that differ from larger wetland systems. This mixing changes biotic and abiotic variables at the oxic and anoxic interface (Zedler 2003; Carrino-Kyker and Swanson 2007; Holgerson and Raymond 2016) and impacts biogeochemical processes. Several abiotic factors impact biogeochemical processes in terrestrial wetland systems. Elevated soil moisture (and reduced soil aeration) (Liu et al. 2011; Signor and Cerri 2013; Butterba
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