Abstract
We performed continuous and manual in situ measurements of CO2 efflux from the leaf litter layer (R LL) and water content of the leaf litter layer (LWC) in conjunction with measurements of soil respiration (R S) and soil water content (SWC) in a temperate forest; our objectives were to evaluate the response of R LL to rainfall events and to assess temporal variation in its contribution to R S. We measured R LL in a treatment area from which all potential sources of CO2 except for the leaf litter layer were removed. Capacitance sensors were used to measure LWC. R LL increased immediately after wetting of the leaf litter layer; peak R LL values were observed during or one day after rainfall events and were up to 8.6-fold larger than R LL prior to rainfall. R LL declined to pre-wetting levels within 2–4 day after rainfall events and corresponded to decreasing LWC, indicating that annual R LL is strongly influenced by precipitation. Temporal variation in the observed contribution of R LL to R S varied from nearly zero to 51%. Continuous in situ measurements of LWC and CO2 efflux from leaf litter only, combined with measurements of R S, can provide robust data to clarify the response of R LL to rainfall events and its contribution to total R S.
Highlights
Efflux of CO2 from the soil surface, which is the sum of respiration by autotrophs and heterotrophs, is an important component of total CO2 efflux from forest ecosystems [1,2,3]
In forest ecosystems, heterotrophic respiration consists of CO2 efflux from various sources and their rates are controlled by their specific environmental condition such as water content (WC) and temperature [8], physical properties of the substrate [9,10], and chemical properties [11,12]
To continuously measure CO2 efflux from the L-layer only, in parallel with measurement of RS, we developed an approach for measuring RLL using an automated chamber method in a treatment area from which all CO2 sources except for the litter layer (Llayer) were removed
Summary
Efflux of CO2 from the soil surface (soil respiration; RS), which is the sum of respiration by autotrophs and heterotrophs, is an important component of total CO2 efflux from forest ecosystems [1,2,3]. In forest ecosystems, heterotrophic respiration consists of CO2 efflux from various sources (e.g., leaf and root litter, woody debris, soil organic matter) and their rates are controlled by their specific environmental condition such as water content (WC) and temperature [8], physical properties of the substrate (e.g., density and structure) [9,10], and chemical properties (e.g., labile and recalcitrant carbon) [11,12]. A variety of methods for separating components of heterotrophic respiration and for determining their contribution to total RS have been developed [9,13]
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