| A carbon sink is known to be effective for reducing greenhouse gas emissions, which is defined as a process, an activity, or a mechanism of removing greenhouse gases, aerosols and their precursors from the atmosphere. Forest ecosystem carbon pool plays an important role in studying the carbon sink globally as its characteristic of large area, complex structure, quickcarbon cycle. Quantities of studies on regional, national, or global forest carbon sink are done continually. However, these researches in large scales are based on survey data in fine scales.Therefore, this study evaluated the forest carbon storage of Changjiang reservoir forest reserve in Zhongshan city by on-site investigation and sample collection and analysis, using the established model of biomass and carbon storage, and discussed the relationship, distribution and influence factors in the forest carbon pools using statistical analysis. The main conclusions were as follows.(1) Some correlations were obtained among forest carbon densities. Significant and positive correlations were found between tree and vegetation carbon density, between shrub and understory carbon density, and among soil layers organic carbon densities; whereas negative correlation was found between tree and understory carbon density and significantly negative correlation was found between litter and soil. Moreover, positive correlation and significantly positive correlation were found between vegetation and forest ecosystem and between soil and forest ecosystem carbon density respectively; whereas negative correlation was found between litter and forest ecosystem.(2) The highest carbon storage in forest was found in soil, followed by vegetation and litter. Tree showed the highest carbon storage in vegetation, followed by shrub and herb, while forest soil organic carbon density decreased with deeper soil layers.(3) Forest carbon pool changed as forest grow, on the other hand, it was dynamic with time. Tree carbon density increased with forest growth while soil carbon density decreased, but the forest ecosystem carbon density did not show a clear trend.(4) The composition and structure of forest community influenced forest carbon pool. All vegetationlayers of mixed conifer and deciduous forest showed the highest carbon density of all 3 types(lucidophyllous forest, mixed conifer and deciduous forest and conifer forest), while the carbon densities of all soil layers were in the order of lucidophyllous forest > mixed conifer and deciduous forest > conifer forest. The carbon densities of vegetation, soil and ecosystem in mixed forest were all higher than those in pure forest. Moreover, the higher biodiversity of tree increased the soil and the forest ecosystem carbon densities, while the higher biodiversity of understory plant decreased the biomass of forest litter and contributed to increase the soil and the ecosystem carbon densities.(5) The soil carbon density of natural forest is higher than planted forest. High altitude showed the highest soil organic carbon density, followed by low altitude and intermediate altitude. The carbon densities in vegetation and litter were higher in gentle slope, compared to steep hill. From shady slope to semi-shady slope, and to semi-sunny slope, the vegetation carbon density decreased gradually. The soil carbon density decreased with lower slop position except the peak. The carbon densities of vegetation, soil and forest ecosystem decreased with heavier human activities.(6) The forest ecosystem carbon storage of changjiang reservoir forest reserve was 582.678 Gg C, with the vegetation carbon storage of 255.952 Gg C(43.9%), the litter carbon storage of 7.562 Gg C(1.3%), and the soil carbon storage of 319.164 Gg C(54.8%). The total carbon storage of all kinds of vegetation types in this reserve was 608.695 Gg C approximately. The overall mean carbon density of forest ecosystem in this reserve was 135.377 Mg C·hm-2. The forest ecosystem carbon density in this reserve, especially in the soil carbon density was low. |
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