[Estimation of forest vegetation carbon storage in Hunan Province, China based on k-NN method and domestic high-resolution data]. / åŸºäºŽåŸºå‡†æ ·åœ°æ³•å’Œå›½äº§é«˜åˆ†æ•°æ®çš„æ¹–å—çœæ£®æž—æ¤è¢«ç¢³å‚¨é‡ä¼°æµ‹.

To promote the application of domestic high-resolution satellite data in large-scale carbon storage estimation and measurement, a total of 206 high-resolution remote sensing images covering Hunan Province were used as the data source, and the estimated minimum unit was fixed as a 0.06 hm2 square composed of multiple pixels. Through the establishment and purification of the interpretation marks, in the extraction of forest information, the pixel-based method and object-oriented classification method were used to compare. In the estimation of carbon storage of arbor forest, the robust estimate, partial least squares method and k-NN estimate were used to compare. Finally, we estimated forest carbon storage in Hunan Province and generated the distribution map of carbon density levels. The results showed that the interpretation mark based on the automatic extraction of plots could increase the extraction accuracy of arbor forest after purification. For the estimation of forest carbon storage at large-scale, the k-NN algorithm embodied a large advantage in forest information extraction and arbor forest carbon storage modeling. The average classification accuracy of the 206 scene images was 76.8%, the average RMSE was 8.95 t·hm-2, the average RRMSE was 19.1%, and the total carbon stock in Hunan Province was 22.28 Mt. The results provided effective reference for the estimation and measurement of forest carbon storage at the provincial and national scales.

[Estimation of vegetation carbon storage and density of forests at tree layer in Tibet, China.] / 西藏森林植被乔木层碳储量与碳密度估算.

The estimation of vegetation carbon storage and density of forests at tree layer in Tibet Autonomous Region was calculated based on the eighth forest inventory data using the biomass inventory method, as well as other attributes like tree trunk density and carbon content of different species. The results showed that the total carbon storage at tree layer in Tibet forest ecosystem was 1.067×109 t and the average carbon density was 72.49 t·hm-2. The carbon storage at tree layer of different stands was in the order of arbor forest > scattered wood > sparse forest > alluvial tree. The carbon storage of different forest types at tree layer were in the order of shelterbelt > special purpose forest > timber forest > firewood forest. The proportion of the first mentioned two was 88.5%, and the average carbon density of different forest types at tree layer was 88.09 t·hm-2. The carbon sto-rage and its distribution area at tree layer in different forest groups were in the same order, followed by mature forest > over mature forest > near mature forest > middle aged forest > young forest. The carbon storage in mature forests accounted for 50% of the total carbon storage at tree layer in diffe-rent forest groups. The carbon storage at tree layer in different forest groups increased first and then decreased with the increase of stand ages.