Drying and Wetting Effects on Carbon Dioxide Release from Organic Horizons

• Published in: Soil Science Society of America journal Vol. 67; no. 6; pp. 1888 - 1896
• Main Authors: Borken, W., Davidson, E. A., Savage, K., Gaudinski, J., Trumbore, S. E.
• Format: Journal Article
• Language: English
• Published: Madison Soil Science Society 01.11.2003; Soil Science Society of America; American Society of Agronomy
• Subjects: Agronomy. Soil science and plant productions; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Carbon dioxide; Chemical, physicochemical, biochemical and biological properties; Deciduous forests; Decomposition; Drying; Forest soils; Forestry; Forests; Fundamental and applied biological sciences. Psychology; General forest ecology; Generalities. Production, biomass. Quality of wood and forest products. General forest ecology; Mixed forests; Organic matter; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Respiration; Simulated rainfall; Soil science; Soil temperature; Soils; Synecology; Temperate forests; Terrestrial ecosystems; Water; Water content; United States; North America; Massachusetts; America; USA, Massachusetts; Deciduous forest; Organic matter; Gas emission; Carbon dioxide; Quercus rubra; Forest soil; Aceraceae; Acer rubrum; Dicotyledones; Ecosystem; Angiospermae; Soil science; Hardwood forest tree; Terrestrial environment; Litter; Soil moisture; O horizon; Ecology; Fagaceae; Biological activity; Carbon cycle; Biogeochemistry; Soil horizons; Forestry; Soil biology; Spermatophyta; Wetting drying cycle; Respiration
• ISSN: 0361-5995; 1435-0661
• DOI: 10.2136/sssaj2003.1888

Drying and wetting cycles of O horizon in forest soils have not received much attention, partly due to methodological limitations for nondestructive monitoring of the O horizon water content. The objective of this study was to determine the importance of moisture limitations in the O horizon of a temperate forest on summertime soil respiration. We measured soil respiration in three replicated plots in a mixed deciduous forest at Harvard Forest, Massachusetts, weekly from May to October 2001. Direct Current (DC) half‐bridge sensors that had been calibrated using destructive samples of the Oi and Oe/Oa horizons were placed in the Oi and Oe/Oa horizons to record hourly changes of gravimetric water contents. Soil temperature explained 47% of the variation in soil respiration using the Arrhenius equation. The residuals of the temperature model were linearly correlated with gravimetric water content of the Oi horizon (r2 = 0.72, P < 0.0001) and Oe/Oa horizon (r2 = 0.56, P < 0.001), indicating that temporal variation in soil respiration can be partly explained by water content of the O horizon. Additionally, a laboratory study was performed to evaluate drying/wetting cycles of the O horizon at constant temperature. Even small simulated rainfall amounts of 0.5 mm significantly increase CO2 flux from dry O horizon within a few minutes. The duration of CO2 pulses increased with the amount of applied water, lasting from a few hours to days. A strong correlation between CO2 release and water content of the O horizons demonstrates a clear regulatory role of litter water content on decomposition within the O horizons.