Sovremennye problemy distantsionnogo zondirovaniya Zemli iz kosmosa, 2008, Issue 5, Vol. 2, pp. 339-346
Estimation of carbon balance in drylands of Kazakhstan by integrating
remote sensing and field data with an ecosystem model
P.A. Propastin
1, M. Kappas
2, N.R. Muratova
31 Department of Geography, Georg-August University Gцttingen
Laboratory of Remote Sensing and Image Analysis, Kazakh Academy of Science, Goldschmidtstr. 5, 37077,
Gцttingen, Germany
Shevchenko Street, 15, 480040, Almaty, Kazakhstan
2 Department of Geography, Georg-August University Gцttingen, Goldschmidtstr. 5, 37077,
Gцttingen, Germany
3 Laboratory of Remote Sensing and Image Analysis, Kazakh Academy of Science, Shevchenko Street, 15, 480040, Almaty, Kazakhstan
A monitoring system based on the use of the remotely sensed derived data and quantitative information from
field investigations was developed for estimation of carbon balance in drylands of Kazakhstan. In this system, carbon
fluxes were derived from the combination of incoming solar radiation, the fraction of the photosynthetically
active radiation (PAR) absorbed by plant canopies (fPAR), and a biological conversion factor known as Light Use
Efficiency (LUE) which describes the ability of vegetation to convert light energy into biomass. The amount of
incoming solar radiation and PAR was computed from the variables of Earth-Sun distance, solar inclination, solar
elevation angle, geographical position and information on clouds at localities at a daily time-step and than summed
to 10-day values. The product of this calculation was corrected for slope and aspect using a Digital Elevation Map.
The fPAR was estimated from 10-day maximum values of the Normalized Difference Vegetation Index (NDVI)
derived from the SPOT-VG satellite. A LUE value for every vegetation type was obtained through calibration of
peak biomass data collected from a number of test sites against the amount of PAR computed for each of these
locations. The LUE was reduced from the computed optimum value by modifiers dependent on atmospheric vapour
pressure deficits and temperature. Separation of above-ground and under-ground biomass production was made
using a root-shoot ratio computed from field measurements for each vegetation type. Autotrophic respiration was
estimated by a quantitative approach described in recent literature. All modelling results were converted to carbon
amounts using factor 0.47. The end outputs of the monitoring system were maps of carbon fluxes with a spatial
resolution of 1-km and 10-day time-step. The regional monitoring system allows detailed information on an areawide
carbon balance to be extracted using remote sensing and ground truth data.
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