## 3 Analyses and Results
### Area Comparison between HJ-1-Based Forest Map and Other Global Products  
The estimated forest area from the three forest maps (HJ-1 2010, GlobCover 2009, and MCD12Q1 2009) is listed in Table 6. Among the three maps, the estimated forest area in Northeast China ranged from 4.25 \(\times\) 10\({}^{5}\) km\({}^{2}\) (MCD12Q1 2009) to 5.0 \(\times\) 10\({}^{5}\) km\({}^{2}\) (HJ-1 2010). The estimated forest area from the MCD12Q1 2009 data and the GlobCover 2009 data were both substantially lower than that of the HJ-1 2010 and national statistics data for forested area (NSF 2010, 4.98 \(\times\) 10\({}^{5}\) km\({}^{2}\)). The forest proportion (40.3%), classified from the HJ-1-based map is more consistent with the forest coverage (40.22%) disseminated by the Ministry of Environmental Protection of the People's Republic of China [62].  
At the provincial level, Heilongjiang had the largest forest area among the four provinces, whereas Liaoning had the smallest forest area (Table 6). The estimated forest area from the MCD12Q1 2009 data in Heilongjiang was slightly lower than that from the HJ-1 2010, GlobCover 2009, and NSF 2010 data. The difference between HJ-1 2010 and NSF 2010 was smallest in the forest area of Heilongjiang province, compared with other datasets. The forest area in Jilin and Inner Mongolia from the MCD12Q1 2009 data was the smallest compared with other datasets and the differences between MCD12Q1 2009 and GlobCover 2009, HJ-1 2010, and NSF 2010 for the forest area of Jilin province are significant. The forest area of Liaoning from the GlobCover 2009 dataset was the smallest among all the forest maps and the forest area from the MCD12Q1 2009 and HJ-1 2010 datasets was approximately twice that of the GlobCover 2009 dataset. The HJ-1-based forest estimates in the four provinces were much closer to the NSF 2010 results and the difference in the total forest area in Northeast China between these two datasets was only 5038 km\({}^{2}\), 1% of the total forest area in the NSF 2010 dataset.  
\begin{table}
\begin{tabular}{c c c c c c} \hline  & **Heilongjiang** & **Jilin** & **Liaoning** & **Inner Mongolia** & **Total** \\ \hline Evergreen needleleaf forest & 4277 & 4000 & 3911 & 2532 & 14,720 \\ Deciduous needleleaf forest & 46,731 & 2358 & 1854 & 47,226 & 98,169 \\ Deciduous broadleaf forest & 126,400 & 67,198 & 49,135 & 102,180 & 344,913 \\ Mixed forest & 20,116 & 9769 & 698 & 2781 & 33,364 \\ Shrubland & 946 & 1593 & 5508 & 3882 & 11,929 \\ Total HJ-1-based forest area & 198,470 & 84,918 & 61,106 & 158,601 & 503,095 \\ Total MCD12Q1 forest area & 187,474 & 33,258 & 74,735 & 129,800 & 425,267 \\ Total GlobCover forest area & 221,999 & 51,052 & 32,477 & 144,328 & 449,856 \\ National statistics of forest & 205,300 [1] & 82,780 [1] & 56,990 [1] & 152,987 [45] & 498,057 \\ area (NSF) & & & & & \\ \hline \end{tabular}  
* \({}^{1}\) from provincial statistics year books (2011).  
\end{table}
Table 6: Provincial estimates of forest area (km\({}^{2}\)) from the HJ-1-based map, GlobCover 2009 and MCD12Q1 2009.  
Figure 6: Forest area of ecological functional zones from HJ-1-based imagery in Northeast China. I: Hulun Buir region; II: Daxing’an Mountains; III: Xiaoxing’an Mountains; IV: Songliao Plain; V: Sanjiang Plain; VI: Changbai Mountains.