The energy budget and regulating factors were investigated over an estuarine wetland during one year of continuous measurement in 2006.The results show that the seasonal changes of the energy fluxes and Bowen ratio(β) were greatly affected by incoming shortwave radiation and canopy growth.During the non-growing season and early-growing season, sensible heat(H) dominated the energy flux, and β could reach a maximum of 2.5, while during most of the growing season, latent heat dominated the energy flux and β fluctuated from 0.4 to 1.0.The energy budget ratio in growing season was about 0.76, and the value would be higher if heat exchange during tidal flooding was in-cluded.During tidal flooding days, β was slightly higher than that at exposure days in most cases.Vegetation cover seems exert little effect on energy partitioning except in March when the standing dead grass intercepted the incoming radiation that might reach the soil surface and reduce the turbulence between soil and atmosphere, thus suppressing the evaporation from the soil though the soil mositure was high at that time.
Shanghai is a coastal metropolitan city with various types of natural wetlands, which account for 23.5% of its total area. According to the definition of wetland in Ramsar Convention on Wetlands, the wetlands of Shanghai were classified into 4 types: coastal, riverine, lacustrine, and reservoir and pond wetlands. In order to examine the roles of wetlands in the life-support system of Shanghai, we calculated the area of each type of the wetlands using GIS technique, and then measured the ecological service values of different ecosystems in Shanghai based on the classification of ecosystem services proposed by COSTANZA et al. (1997). The estimated annual value of ecosystem services in the study area was 7.3×109US$/a for the total area of 1 356 700ha, among which about 97% was provided by the wetlands. Effective conservation and management of wetlands are therefore crucial to Shanghai’s sustainable development. The limitations of the evaluation method for ecosystem service value were also discussed in the present paper.
利用崇明东滩湿地所建造的通量观测塔,连续监测了2006年生态系统的二氧化碳通量及其相关因子的变化.利用FSAM(Flux Source Area Model)模型,并结合地面测定,对湿地生态系统碳通量贡献区进行了分析.发现通量贡献区范围在各风向均随大气稳定程度的增加而拉长.在稳定的大气条件下,非主风方向上的通量贡献区范围要显著大于主风方向上的通量贡献区,但在非稳定大气条件下,两者相差不大.由FSAM模型所估测的通量贡献区范围表明:所测的碳通量数据可以较好地反映下垫面的通量信息.
