Leaf litter is an important mediator of soil respiration in an oak-dominated forest |
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Authors: | Jared L DeForest Jiquan Chen Steve G McNulty |
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Institution: | (1) Department of Environmental and Plant Biology, Ohio University, Porter Hall 315, Athens, OH 45701–2979, USA;(2) Department of Environmental Sciences, University of Toledo, Mail Stop #604, Toledo, OH 43606–3390, USA;(3) Southern Global Change Program, USDA Forest Service, 920 Main Campus Drive, Venture Center II, Suite 300, Raleigh, NC 27606, USA |
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Abstract: | The contribution of the organic (O) horizon to total soil respiration is poorly understood even though it can represent a
large source of uncertainty due to seasonal changes in microclimate and O horizon properties due to plant phenology. Our objectives
were to partition the CO2 effluxes of litter layer and mineral soil from total soil respiration (SR) and determine the relative importance of changing
temperature and moisture mediating the fluxes. We measured respiration in an oak-dominated forest with or without the O horizon
for 1 year within the Oak Openings Region of northwest Ohio. Mineral soil and O horizon respiration were subtracted from mineral
soil respiration (MSR) to estimate litter respiration (LR). Measurements were grouped by oak phenology to correlate changes
in plant activity with respiration. The presence of the O horizon represented a large source of seasonal variation in SR.
The timing of oak phenology explained some of the large changes in both SR and LR, and their relationship with temperature
and moisture. The contribution to SR of respiration from the mineral soil was greatest during pre-growth and pre-dormancy,
as evident by the low LR:MSR ratios of 0.65 ± 0.10 (mean ± SE) and 0.69 ± 0.03, respectively, as compared to the other phenophases.
Including moisture increased our ability to predict MSR and SR during the growth phenophase and LR for every phenophase. Temperature
and moisture explained 85% of the variation in MSR, but only 60% of the variation in LR. The annual contribution of O horizon
to SR was 48% and the ratio of litter to soil respiration was tightly coupled over a wide range of environmental conditions.
Our results suggest the presence of the O horizon is a major mediator of SR. |
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Keywords: | Litter Oak openings Phenology Soil respiration Temporal variation |
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