| Ecological public welfare forest (EPWF) is an important part of ecological construction for regional forestry. Under global warming and the continually worsening of eco-environment, health management and promoting carbon fixation efficiency of EPWF has become especially important. Therefore, it is of great significance for EPWF’s management by analyzing its carbon storage and distribution pattern. In this study, we chose and investigated 101 plots in the size of 20mx20m for 9 types of EPWF (evergreen broad-leaf forest, deciduous broad-leaf forest, mixed forest, pine forest, Cunninghamia lanceolata forest, Cupressus funebris forest, Phyllostachys pubescens forest, mixed bamboo forest and shrub) in Ningbo, Zhejiang Province. We studied community characteristic of each EPWF type, and estimated biomass and carbon storage of EPWF based on developing local biomass models and measuring the carbon content of dominant species. The purpose of this study is to find out the characteristic and the distribution pattern of carbon storage of EPWF in Ningbo, providing data basis and scientific basis for EPWF construction. The results showed that:1、Evergreen broad-leaf forest, mixed forest and pine forest were the dominant forest types of EPWF in Ningbo, covering 75% area. Totally,172 woody plants were recorded in this research. The richness of dominant species in tree layer was small and similar among the plots within the same type. While the species richness in shrub layer was relatively high.2、The power function (Biomass=a(DBH)b) was the best fitting model for biomass models of main species of EPWF in Ningbo. By comparing the estimated value of models with measured value, it was found that the relative error was 2.55% and 0.86% for shrub layer and tree layer respectively. The average carbon content of main species was 0.47. The carbon content of coniferous species was much bigger than that of broad-leaf species, and the stem carbon content of Phyllostachys pubescens was much bigger than that of broad-leaf tree.3、 With increasing stand age, biomass per unit area of each EPWF type showed different variation tendency. Biomass per unit area of evergreen broad-leaf forest increased linearly, and that of mixed forest increased fast in the late period and over evergreen broad-leaf forest when reaching the status of mature forest. While biomass of pine forest and Cunninghamia lanceolata forest increased relatively slowly. During all standing ages, biomass per unit area of evergreen broad-leaf forest and mixed forest were bigger than deciduous broad-leaf forest, Cupressus funebris forest, Phyllostachys pubescens forest, mixed bamboo forest and shrub.4、 The total carbon storage of EPWF in Ningbo was 1176.83×04t·C. Mixed broad-leaf forest (603.24×04t·C), evergreen broad-leaf forest (196.74×04t·C), pine forest (181.31×04t·C), Phyllostachys pubescens forest (126.21×04t·C) and Cunninghamia lanceolata forest (44.25×04t·C) were the main contributor, occupied 98%. For EPWF with different stand ages, young EPWF has a carbon storage of 679.74×04t·C, occupied 58%; following half-mature EPWF (262.71 ×04t·C,22%), near-mature EPWF (116.74×04t·C,10%), mature EPWF (115.98×04t·C,10%), over-mature EPWF 0.88×04t·C, less than 1%. Generally, average carbon density of EPWF in Ningbo was 55.26 t·C·hm-2. For each EPWF type, carbon density increased with stand age, reaching the maximum at the mature stage of EPWF and then decreased.5、The average carbon density of EPWF in Ningbo was higher than that of central Zhejiang and that of the whole Zhejiang. As most of broad-leaf forest was in the young stage or half-mature stage, its carbon density was much lower than that of coniferous forest. Therefore, we suggested to increase forest succession by tending management of young forest and transformation of forest, to increase the carbon storage of EPWF in Ningbo. |
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