Increase in aboveground fresh litter quantity over-stimulates soil respiration in a temperate deciduous forest

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• 作者：Nicolas Chemidlin Pré ; vost-Bouré ; Kamel Soudani ; Claire Damesin ; Daniel Berveiller ; Jean-Christophe Lata ; Eric Dufrê ; ne
• 关键词：Soil CO₂ efflux ; Litter ; Carbon stable isotopes ; Natural abundance ; Priming effect ; Temperate deciduous forest
• 刊名：Applied Soil Ecology
• 出版年：2010
• 出版时间：September 2010
• 年：2010
• 卷：46
• 期：1
• 页码：26-34
• 全文大小：401 K

文摘

In the context of climate change, the amount of carbon allocated to soil, particularly fresh litter, is predicted to increase with terrestrial ecosystem productivity, and may alter soil carbon storage capacities.

In this study we performed a 1-year litter-manipulation experiment to examine how soil CO₂ efflux was altered by the amount of fresh litter. Three treatments were applied: litter exclusion (E), control (C, natural amount: 486 g m⁻²) and litter addition (A, twice the natural amount: 972 g m⁻²).

Litter decomposition rate was not affected by fresh litter amount. However, the addition or exclusion of fresh litter quickly increased or decreased total soil CO₂ efflux (F_S) significantly, but the relative contribution of fresh litter to total soil respiration remained unchanged between the C and A treatments, as determined by laboratory measurements. Variation in F_S among treatments was not related to modification of its temperature sensitivity which was not affected by fresh litter amount (Q₁₀: 3.5 for E, 3.2 for C, 3.6 for A). While litter exclusion was the main cause of the F_S decrease in the E treatment, only 68 % of F_S was directly attributable to litter addition in the A treatment. The remaining 32 % of F_S in the A treatment was related to a real priming effect that appeared to be a long-lasting phenomenon. This priming effect lasting over 1 year may be related to a continuous release of organic compounds from litter to soil because of the progressive decomposition of leaf litter. Q₁₀ estimates and isotopic data lead to the hypothesis that the priming effect corresponded to the activation of the whole soil system.

As a consequence, the increase in ecosystem productivity may lead, via an increase in the amount of litter, to an increase in carbon turnover in soil. Further labelling experiments involving high-frequency carbon stable isotope measurements of CO₂ efflux would help to clarify the relative importance of bulk soil and rhizosphere in the priming effect.