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TitleA process-based boreal ecosystem productivity simulator using remote sensing inputs
AuthorLiu, J; Chen, J M; Cihlar, J; Park, W M
SourceRemote Sensing of Environment vol. 62, issue 2, 1997 p. 158-175,
Alt SeriesEarth Sciences Sector, Contribution Series 20042330
PublisherElsevier BV
Mediapaper; on-line; digital
File formatpdf
SubjectsScience and Technology; Nature and Environment; remote sensing; ecosystems; productivity; modelling; spectral ratios; spectral analyses; evapotranspiration coefficient; boreal ecosystems productivity simulator (BEPS); Leaf Area Index (LAI)
Illustrationsgraphs; formulae; tables; flow charts
Released1997 11 01
AbstractThis paper describes a Boreal Ecosystems Productivity Simulator (BEPS) recently developed at the Canada Centre for Remote Sensing for the need to estimate the carbon budget over Canadian landmass and to assist in natural resources management. BEPS uses principles of Forest-BGC for quantifying the biophysical processes governing ecosystems productivity, but the original model is modified to better represent canopy radiation processes. A set of biological constants are also adjusted for the northern environment. A numerical scheme is developed to incorporate different data types: remote sensing data at 1 km resolution in Lambert Comformer Conic format, daily meteorological data in Gaussian gridded format and soil data at 0.02 degree resolution. The remote sensing inputs to the model are leaf area index (LAI) and land cover type. The meteorological data elements used include daily maximum and minimum air temperatures, total incoming short-wave radiation, precipitation and humidity. The soil data input is the available water-holding capacity. The major outputs of BEPS include NPP and evapotranspiration.

The NPP calculated by BEPS has first been tested against biomass data obtained in Quebec, Canada. A time series of leaf area index (LAI) over the growing season 1993 in Quebec is derived using 10-day composite NDVI images acquired by the Advanced Very High Resolution Radiometer (AVHRR) at 1 km resolution (resampled). Soil polygon data were mosaicked, georeferenced and converted to a raster format in ARC/INFO. Using the process-based model incorporating all major environmental variables affecting plant growth and development, detailed spatial distributions of NPP (annual and four seasons) in Quebec are shown in this paper. The accuracy of NPP calculation is estimated to be 60% for single pixels and 80% for 3*3 pixel areas (9 km2). The modelled NPP ranges from 0.8 kg C/m2/year at the southern border to 0.01 kg C/m2 /year at the northern limit of the province. The total annual NPP in Quebec is estimated to be 0.23 Gt C, which is about 0.3-0.4% of the global NPP.


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