Analysis on carbon stock distribution patterns of forest ecosystems in Shaanxi Province

Aims The objective of this study was to understand the distribution patterns of carbon stock in forest ecosystems in Shaanxi Province following the implementation of the ecological restoration project―the Grain for Green―in the 90’s of 20th century for combating the severe soil erosion and other environment problems. Methods Based on forest resources inventory data and field measurements, we estimated carbon storage of tree, shrub, herb, litter, and soil layer within each forest ecosystem of Shaanxi Province. Important findings Forest ecosystems in Shaanxi Province stored a total of 790.75 Tg C, and the proportion occupied by soil, vegetation and litter carbon were 72.14%, 26.52% and 1.34%, respectively. Carbon storage within Quercus spp. was the highest (44.17%) among all forest types. Given the large proportion of the areas occupied, the young and middle-aged forests accounted for almost half of the total carbon stores in forest ecosystems. The average carbon density of forest ecosystem was 123.70 t·hm^–2. Similar to the patterns among carbon pools, carbon density was also highest in soil, lowest in litter, and medium in vegetation for each forest type. Carbon density increased with stand age for natural and planted forest ecosystems, and was higher in the natural forest ecosystems than in the planted forests within the same stand ages. Differences in the spatial patterns between carbon stores and density indicate that carbon storage is related not only to forest quality, but also to forest areas. Therefore we could select tree species with high carbon concentration for reforestation and afforestation, and improve forest management practices to increase carbon sequestration potential, which would be beneficial to mitigation of global climate change.