|
|||||
|
|
Estimating forest carbon fluxes for large regions based on process-based modelling, NFI data and Landsat satellite images |
|
| Authors: | S Härkönen A Lehtonen |
| Institution: | a Finnish Forest Research Institute, P.O. Box 68, FI-80101 Joensuu, Finland b Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland c University of Helsinki, Department of Forest Sciences, P.O. Box 27, 00014 University of Helsinki, Finland |
| Abstract: | The aim of this study was to develop and evaluate a new approach for estimating forest carbon fluxes for large regions based on climate-sensitive process-based model, national forest inventory (NFI) data and satellite images. The approach was tested for Central Finland and Lapland with NFI field data and daily weather data from 2004 to 2008.The approach combines (1) a light use efficiency (LUE) model, (2) a process-based summary model for estimating gross primary production (GPP) and net primary production (NPP), and (3) the Yasso07 soil carbon model, which together allow the estimation of net ecosystem exchange (NEE). Landsat TM 5 satellite images were utilized to generalize the carbon fluxes obtained for field sample plots for all forested areas using the k-NN imputation method. The accuracy of the imputations was examined by leave-one-out cross validation and by comparing the imputed and simulated values with Eddy covariance (EC) measurements.RMSE of the k-NN imputations was slightly better in Central Finland than in Lapland, the bias staying at a similar level. Based on the EC comparisons, the approach seemed to work rather well with GPP estimates in both areas, but in the north the NEE estimates were remarkably biased. The main advantages of the approach include its applicability to basic NFI data and a high output resolution (30 m).The method proved to be a promising way to produce carbon flux estimates based on large-scale forest inventory data and could therefore be easily applied to the whole of Northern Europe. However, there are still drawbacks to the approach, such as lacking parameters for peat lands. One of the future goals is to integrate the approach with an interactive mapping framework, which could thereafter be utilized, for example, in climate change research. |
| Keywords: | Carbon fluxes k Nearest neighbour National forest inventory data Process models Satellite images |
| 本文献已被 ScienceDirect 等数据库收录！ | |