Effects of Complexity in Floor Reflectance on Carbon and Water Fluxes in an Urban Park

Monday, 15 December 2014
Hyungsuk Kimm1, Youngryel Ryu1, Hideki Koayashi2, Keunmin Lee3, Je-woo Hong3 and Jinkyu Hong3, (1)Seoul National University, Department of Landscape Architecture and Rural Systems Engineering, Seoul, South Korea, (2)Japan Agency for Marine-Earth Science and Technology, Department of Environmental Geochemical Cycle Research, Yokohama, Japan, (3)Yonsei University, Department of Atmospheric Sciences, Seoul, South Korea
Urban parks account for great portion of urban vegetation that could partially contribute to carbon uptake. However, the complex land surface reflectance have limited our understanding on canopy photosynthesis in urban parks. In this study, a 3-D canopy radiative transfer model, Forest Light Environment Simulator (FLiES), is coupled with a 1-D biophysical model, CANOAK, to investigate effect of floor reflectance on canopy-scale photosynthesis and evapotranspiration in an urban park, Seoul Forest Park (Seoul, the Republic of Korea). Through a series of intensive field works, we prepared model input data such as tree positions, crown shapes, leaf area index, photosynthetic parameters such as Vcmax and Jmax. Meteorological data were derived from flux tower observations.

We first evaluate the modelled net ecosystem exchange and latent heat flux against flux measurements from the eddy covariance system in the park. Then, we test the effects of floor reflectance on canopy photosynthesis and evapotranspiration using the model with different scenarios. Finally, we propose several design guidelines for urban park to increase carbon uptake by plants. The model simulation uncertainties are also discussed. We expect the usage of 3-D RTM would give better understanding of ecological processes in a complex space.