Distribution of Solar Energy in Agriculture Landscape: Comparison Between Wet Meadow and Crops

This study examines the impact of plant cover on water and energy exchange between land and atmosphere in the Třeboň Biosphere Reserve, Czech Republic. Energy fluxes, evapotranspiration and evaporative fraction were determined over typical crops of agriculture landscape and compared with fluxes in an adjacent wet meadow. The results show distinct differences in heat and water exchange between these ecosystems. Diurnal average difference in evapotranspiration rates for days with high irradiance over the wet meadow and arable crops ranged from 1.1 mm day−1 to 3.4 mm day−1. Furthermore, the evapotranspiration differences between C3 (rapeseed) and C4 (cornfield) was about 2.3 mm day−1. Analysis of thermovision pictures showed that temperature variation reached about 9 °C between the ploughed field and meadows at the time of maximum intensity of solar radiation. Heat exchange (sensible heat flux) was greater over arable lands, while water exchange (latent heat flux) was stronger over the wet meadow. The evaporative fraction displayed that more than 100 % of available energy was released by the wet meadow through evapotranspiration due to the advection of dry air from the surroundings. Wetlands show equal or even inverse temperature in vertical profile, whereas corn and wheat show noticeable higher temperature at soil surface in comparison with plant stand surface. Therefore, we suggest that introduction of wetlands to agricultural land is one of the most important instruments for the management of water and heat balance of the landscape.