Carbon Storage Of The Different Urban Communities In Huanchen Park In Hefei

Urban forest in Huanchen Park is like a green ring surrounding Hefei. The Park has a various micro-topography with different community types. The study on distribution characteristics of carbon storage in urban forest was conducted in Huanchen Park in Hefei by plot sampling method and biomass estimation method based on stem volume. In this study, a comparative analysis was conducted for the capacity of carbon storage in different communities and their surface soil organic carbon storage. In addition, the characteristics, daily and seasonal patterns of soil respiration in the different communities were also studies by using Li-6400-09 CO₂ analyzer. The effects of soil temperature and water content on soil respiration was analysed. The main results obtained are as follows.(1) The results showed that the biomass carbon storage in urban forests averaged 24.97 kg/m² with a range from 1.41 kg/m² to 142.04 kg/m² in Huanchen Park,. This suggests that the carbon storage in this urban forest is not great, which could be attributed to a large proportion of young and middle forest. Therefore, the carbon storage capacity of urban forest in this park is relatively low.(2) According to the characteristics of community structure and tree composition, the urban forests in Huanchen Park could be divided into four types: broadleaved stand, conifer-broadleaved mixture, coniferous stand, sparse tree stand. The capacity of carbon storage was differed greatly for the different communities. The order of the biomass carbon storage for the different urban forests in Huanchen Park was: broadleaved stand > conifer-broadleaved mixture > coniferous tree stand > sparse tree stand.(3) Within the 21 sampling stands, the contents of soil organic carbon (SOC) ranged from 3.9 g/kg to 64.7 g/kg for 0-10cm mineral layer, and from 2.2 g/kg to 45.2 g/kg for 10-20cm mineral layer. There existed a significant difference in SOC content amongst the different stands. The order of SOC content for 0-10cm mineral layer was: conifer-broadleaved mixture > broadleaved stand > coniferous stand > sparse tree stand, while for 10-20cm mineral layer it ranked as broadleaved stand > conifer-broadleaved mixture > coniferous stand > sparse tree.(4) Community type has a certain influence on soil carbon storage. Soil organic carbon (SOC) storage for the different forests ranged from 0.84 to 9.36 kg/m², in which a great SOC storage was appeared in broadleaved stand and conifer-broadleaved mixture while low in coniferous stand and sparse tree stand. The order of SOC storage for the different forests was as broadleaved stand > conifer-broadleaved mixture > coniferous stand > sparse tree stand.(5) Soil bulk density and moisture content also have a certain influence on SOC content. The regression analysis result showed that SOC content was negatively correlated with soil bulk density (r = -0.382). To some content, SOC content decreased with the increasing of soil bulk density.(6) The in situ measurement shows that the annual average rate of soil respiration ranged from 1.99 to 4.03μmol/m²/s. The maximum rate of daily soil respiration appeared in the summer, and the minimum in winter. The average soil respiration rate in summer reached 5.01μmol/m²/s, and was only 1.11μmol/m²/s in winter. The order of average rates of soil respiration for the different urban forests was: sparse tree stand > broadleaved stand > conifer-broadleaved mixture > coniferous stand.(7) The result from the regression analysis showed that soil respiration was significantly correlated with surface soil temperature. The correlation coefficients were from 0.35 to 0.92. Soil water content also had an influence on soil respiration. The interaction between soil temperature and water content showed clear influence on soil respiration.