The importance of wetlands in the energy balance of an agricultural landscape

• DOI: 10.1007/s11273-013-9334-2
• Publication Date: 2013-12-23T16:36:07Z
• Authors: Hanna Huryna; Jakub Brom; Jan Pokorny
• Keywords: 2. Zero hunger; 13. Climate action; 15. Life on land; 01 natural sciences; 7. Clean energy; 6. Clean water; 0105 earth and related environmental sciences

Energy fluxes, including net radiation, latent heat flux and sensible heat flux were determined on clear days during the vegetative period in four types of land cover: wet meadow, pasture, arable field, and an artificial concrete surface. The average net radiation ranged between 123 W m−2 at the concrete surface and 164 W m−2 at the wet meadow. The mean maximum daytime latent heat ranged between 500 and 600 W m−2, which corresponds to an evapotranspiration rate of about 0.2 g m−2 s−1 under the prevailing conditions of the wet meadow. The results demonstrated that the wet meadow dissipated about 30 % more energy through evapotranspiration than the field or the pasture, and up to 70 % more energy than the concrete surface. The evaporative fraction indicated that more than 100 % of the energy released by the wet meadow was dissipated through evapotranspiration; this was attributed to local heat advection. Wetland evapotranspiration thus contributes significantly to the cooling of agricultural landscapes; the energy released can reach several 100 MW km−2. Wetland evapotranspiration has a double ‘air conditioning’ effect through which it equalises temperature differences: (1) surplus solar energy is bound into water vapour as latent heat; (2) The vapour moves towards cooler portions of the atmosphere where the energy is released. The air-conditioning effect of wetlands plays an important role in mitigating local climate extremes; this ecosystem service tends to be disregarded in relation to other better-known wetland functions such as nutrient retention and provision of high biodiversity.