Carbon sequestration status of forest ecosystems in Ningxia Hui Autonomous Region.

Based on the data of Ningxia Hui Autonomous Region forest resources inventory, field investigation and laboratory analysis, this paper studied the carbon sequestration status of forest eco-systems in Ningxia region, estimated the carbon density and storage of forest ecosystems, and analyzed their spatial distribution characteristics. The results showed that the biomass of each forest vegetation component was in the order of arbor layer (46. 64 Mg·hm^-2 ) > litterfall layer (7. 34 Mg·hm^-2) > fine root layer (6. 67 Mg·hm^-2 ) > shrub-grass layer (0. 73 Mg·hm^-2 ). Spruce (115. 43 Mg·hm^-2) and Pinus tabuliformis (94. 55 Mg·hm^-2 ) had higher vegetation biomasses per unit area than other tree species. Over-mature forest had the highest arbor carbon density among the forests with different ages. However, the young forest had the highest arbor carbon storage (1. 90 Tg C) due to its widest planted area. Overall, the average carbon density of forest ecosystems in Ningxia region was 265. 74 Mg C·hm^-2, and the carbon storage was 43. 54 Tg C. Carbon density and storage of vegetation were 27. 24 Mg C·hm^-2 and 4. 46 Tg C, respectively. Carbon storage in the soil was 8. 76 times of that in the vegetation. In the southern part of Ningxia region, the forest carbon storage was higher than in the northern part, where the low C storage was mainly related to the small forest area and young forest age structure. With the improvement of forest age structure and the further implementation of forestry ecoengineering, the forest ecosystems in Ningxia region would achieve a huge carbon sequestration potential. [ABSTRACT FROM AUTHOR]