| With the acceleration of urbanization process, urbanization not only promote the rapid development of the socio-economic, it also brings many serious social problems, consequently the ecological functions of urban forests is increasingly getting attention. Estimates of the urban forest biomass and carbon storage can provide the scientific basis for using the resources reasonably, sustainable development and management to the forests. This study chose four forest types, and physical and chemical properties of soil, biomass and carbon storage were investigated in Guiyang city, Guizhou province. The main research results showed as following:1. Overstory biomass of different forests was respectively:the25-year-old Poplar forest(Populus.spp) was105.36t·hm-2, of which the aboveground biomass accounted for83.52%in the total forest biomass; the33-year-old Sawtooth Oak (Quercus acutissima Carr.) forest was129.04t·hm-2, the aboveground biomass accounting for76.77%; the10-year-old Betula luminifera(Betula luminifera) and Italian Poplar(Populus euramevicana cv.'I-214') mixed-forests was4.03t·hm-2, the aboveground accounting for84.86%; the38-year-old Black Locust(Robinia pseudoacacia) and Ovate Catalpa (Catalpa ovata)mixed-forests was83.65t·hm-2, the aboveground of which accounted for84.86%.This showed that the aboveground part and the underground part of the biomass of arbor layer presented a roughly ratio, namely the aboveground biomass of the tree layer accounted for about80%, underground part about20%. The proportion of the trunk with the tree bark in the four forests was respectively68.45%,55.34%,59.36%,60.36%, which indicates that the biomass allocation proportion of each organ exists to the highest consistent with the trunk.2. The biomass in Shrub layer of the4forests was respectively7264.14kg·hm-2,1993.28kg·hm-2,6052.19kg·hm-2,4561.61kg·hm-2. This suggests that different forest shrub layer biomass varied larger, and the distribution and size of the understory vegetation biomass related with the characteristics of different forest types.The litter biomass in four stands were5733.52kg·hm-2,5138.32kg·hm-2,2509.87kg·hm-2,2518.80kg·hm-2, and that of the two mixed stands was significantly lower than the other two stands.Biomass of the4forests was respectively: the Poplar forest118.92t·hm-2, Sawtooth Oak forest136.44t·hm-2, Betula luminifera and Italian Poplar mixed-forests16.70t·hm-2, Black Locust and Ovate Catalpa mixed-forests100.22t·hm-2. In addition to Betula luminifera and Italian Poplar mixed-forests, the tree layer biomass of other three forest accounted for more than80%of total forest biomass, and Betula luminifera and Italian Poplar mixed-forests accounted for only24.13%, which related to its stand age and canopy density.3. The average carbon content of tree layer species were:Poplar tree53.23%Sawtooth Oak tree54.55%, Betula luminifera tree54.79%, Italian Poplar tree55.34%, Ovate Catalpa tree54.88%, Black Locust tree2.25%.The order of the tree layer carbon stocks in the4Stands was:the Sawtooth Oak forest (71.60t·hm-2)>the poplar forest (59.84t·hm-2)> the Black Locust and Ovate Catalpa mixed-forests (46.36t·hm-2)> Betula luminifera and Italian Poplar mixed-forests (2.26t·hm-2). And the carbon storage of the aerial parts ranged from1.93t·hm-2to55.68t·hm-2, accounting for about77.77%-85.40%of the total stand carbon storage.Carbon storage of shrub layer in Poplar forest was3932.41kg·hm-2; Sawtooth Oak forest1060.66kg·hm-2; the Betula luminifera and Italian Poplar mixed-forests3109.39kg·hm-2; the Black Locust and Ovate Catalpa mixed-forests2411.01kg·hm-2; and that of the undergrowth herb layer was respectively192.15kg·hm-2,1073.08kg·hm-2,1594.98kg·hm-2,4319.30kg·hm-2. Total carbon storage of the vegetation in the four forests was:63.96t·hm-2,73.73t·hm-2,6.96t·hm-2,53.09t·hm-2.And that of the dead floor layer in the four stands was3267.72kg·hm-2,1959.11kg·hm-2,1046.04kg·hm-2,1145.10kg·hm-2。4. The soils in the four studied forests in Guiyang city were acidic with a mean pH scale of4.68-5.33, Soil water content range from22.94%to40.87%, and the scale of the soil porosity was56.16%--59.72%.Soil organic carbon storage of karst forest in Guiyang city was respectively: Poplar forest121.26t·hm-2; Sawtooth Oak forest75.00t·hm-2; the Betula luminifera and Italian Poplar mixed-forests112.15t·hm-2; the Black Locust and Ovate Catalpa mixed-forests111.00t·hm-2.5. Soil organic carbon storage of Poplar forest in Guiyang city accounted for64.33%, vegetation carbon storage accounting for33.93%, and the proportion of soil organic carbon storage is1.90times than that of vegetation carbon storage and litter carbon stocks accounted for1.73%; Soil organic carbon storage of Sawtooth Oak forest accounted for49.77%, vegetation carbon storage accounting for48.93%, and the proportion of soil organic carbon storage was1.02times than that of vegetation carbon storage and litter carbon stocks accounted for1.30%; In the Betula luminifera and Italian Poplar mixed-forests, the proportion of soil organic carbon storage was93.33%, and it was16.10times than that of vegetation carbon storage, and litter carbon stocks accounted for0.87%; in the Black Locust and Ovate Catalpa mixed-forests, the proportion of soil organic carbon storage was67.23%, and it was2.10times than that of vegetation carbon storage, and the proportion of litter carbon storage was0.69%. Carbon storage of4stands in Guiyang city both showed the following sequential relationship:soil organic carbon pool> vegetation carbon pool> litter carbon pool. It showed that soil is an important carbon repository.Carbon storage of the four forest ecosystems in Guiyang city was respectively: poplar forest188.49t-hm-2, Sawtooth Oak forest150.69t-hm-2, the Betula luminifera and Italian Poplar mixed-forests120.16t-hm-2, the Black Locust and Ovate Catalpa mixed-forests165.52t-hm-2. |
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