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Abstract
A modified light use efficiency (LUE) model was tested in the grasslands of central Kazakhstan in terms of its ability to characterize spatial patterns and interannual dynamics of net primary production (NPP) at a regional scale. In this model, the LUE of the grassland biome (ϵn) was simulated from ground-based NPP measurements, absorbed photosynthetically active radiation (APAR) and meteorological observations using a new empirical approach. Using coarse-resolution satellite data from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), monthly NPP was calculated from 1998 to 2008 over a large grassland region in Kazakhstan. The modelling results were verified against scaled up plot-level observations of grassland biomass and another available NPP data set derived from a field study in a similar grassland biome. The results indicated the reliability of productivity estimates produced by the model for regional monitoring of grassland NPP. The method for simulation of ϵn suggested in this study can be used in grassland regions where no carbon flux measurements are accessible.
Acknowledgements
This research work has been carried out as part of the research project ‘Dry Lands Management in Kazakhstan’, which was funded by the World Development Bank and the Government of Kazakhstan. The work of the first author was supported by a grant from the Space Research Institute of the Science Academy of Kazakhstan. We thank all colleagues of the Space Research Institute and particularly the Head of the Institute Dr N.R. Muratova for the field data provided and helpful recommendations and approvals.