| The rising of greenhouse gas concentration caused global warming, which has become a challenge for human. Forests as the main terrestrial ecosystem, play an important regulatory role in global carbon cycle. However, because of the complexity of forest ecosystems and the limitations of human cognition, now on the study of forest carbon, there are still many uncertainties. In order to explore the effects of stand age on forest carbon pool, Chinese pine (25a,65a and 105a) and Oriental arborvitae (12a,32a and 51a) forests in different ages were studied. This paper facilitated calculation of Chinese pine and Oriental arborvitae plantation carbon pools in Beijing mountainous area and provided a theoretical and technical basis for the study of forest plantation carbon pools. Results showed that:(1) Power model with tree diameter as a single input variable is the best biomass prediction equations for the most component biomass of Chinese pine and Oriental arborvitae, but except roots biomass of Oriental arborvitae. When foliage biomass of Chinese pine and all components biomass of Oriental arborvitae are predicted, effects of ages should be considered.(2) With age increasing, all of biomass in each tree component of Chinese pine and Oriental arborvitae increased. Total tree biomass of Chinese pine and Oriental arborvitae ranged from 40.284-202.136 t·hm-2 and 10.241～51.679 t-hm-2, respectively.(3) For Oriental arborvitae plantation forests, ratio of root to shoot biomass increased from 0.241 in the 12 year old stand to 0.319 in 51 year old stand, however, for Chinese pine, ratio of root to shoot biomass was steadily around 0.2 with increasing stand age.(4) Both of the forest type and age affected the biomass of understories. For Chinese pine plantation forests, shrub and herb biomass decreased with stand age increasing, total of them decreased from 8.680 t·hm-2 in 25 year old stand to 3.533 t·hm-2 in 105 year old stand; on the contrary, shrub and herb biomass of Oriental arborvitae increased with stand age increasing, total of them increased from 2.399 t·hm-2 in 12 year old stand to 6.274 t·hm-2 in 51 year old stand.(5) The carbon content of different issues of Chinese pine ranged from 0.485 to 0.567, and the carbon content of different issues of Oriental arborvitae ranged from 0.495 to 0.577. Weighted mean of carbon contents for both Chinese pine and Oriental arborvitae biomass were steadily with stand age increasing.(6) The total vegetation carbon density of Chinese pine plantation forests increased from 24.470 t·hm-2 in 25 year old stand to 105.326 t·hm-2 in 105 year old stand; similarly, the total vegetation carbon density of Oriental arborvitae plantation forests increased from 6.389 t·hm-2 in 12 year old stand to 30.137 t·hm-2 in 51 year old stand.(7) Carbon content of litter fall increased with stand age increasing. Total soil organic carbon content increased with stand age increasing in three soil horizon of Chinese pine plantation forests and 0-20cm soil horizon of Oriental arborvitae plantation forests, however, decreased with soil depth increasing. Total soil carbon organic density of Chinese pine plantation forests increased from 59.637 t·hm-2 to 102.195 t·hm-2 with stand age increasing. Similarly, total organic carbon density of Oriental increased from 49.420 t·hm-2 in 12 year old stand to 69.663 t·hm-2 in 51 year old stand.(8) Changing patterns of soil labile organic carbon contents is in agreement with that of total soil organic carbon with stand age increasing. Soil liable organic carbon was significantly related to total soil organic carbon, and the relationship between soil particulate organic carbon and soil dissolve organic carbon was also significant. |
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