Ecohydrological Optimality in Northeast China Transect
Qinshu Li1,2, Zhentao Cong1,2, Kangle Mo1,2, and Lexin Zhang1,21Department of Hydraulic Engineering, Tsinghua University, Beijing, 100084, China 2State Key Laboratory of Hydroscience and Engineering, Beijing, 100084, China
Received: 21 May 2016 – Accepted for review: 03 Jun 2016 – Discussion started: 06 Jun 2016
Abstract. Northeast China Transect (NECT) is one of International Geosphere-Biosphere Program (IGBP) terrestrial transects. In this transect area, there is a significant precipitation gradient from east to west, as well as a vegetation transition of forest-grasslands-dessert. In this paper, we use vegetation cover as an index to describe the properties of vegetation distribution and dynamics in NECT. Normalized Difference Vegetation Index (NDVI) is used to derive the actual vegetation cover M, while Eagleson's ecohydrological optimality theory is applied to calculate the optimal canopy cover M* along NECT. The result indicates that the theoretical M* fits the actual M well (for forest, M* = 0.822 while M = 0.826; for grassland, M* = 0.353 while M = 0.352; the correlation coefficient between M and M* is 0.81). Water balance are also calculated using Eagleson's theory. The result is compared to the field measured data and shows a relative good match, which further demonstrates the reliability of the ecohydrological optimality theory in this area. M* increases with the decrease of LAI, stem fraction, temperature, and the increase of leaf angle and precipitation amount. The ecohydrological optimality method offers a quantitative way to analyse the impacts of climate change to canopy cover quantitatively, thus providing advices for eco-restoration projects.
Li, Q., Cong, Z., Mo, K., and Zhang, L.: Ecohydrological Optimality in Northeast China Transect, Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-235, in review, 2016.