滨海新区土地利用变化对土壤碳密度空间分布及生态风险的影响

Influence of the spatial LUCC on the SOC density distribution and the ecological hazards in New Binhai Area

利用土壤类型法估算了天津滨海新区不同土地利用类型土壤的有机碳密度,并基于滨海新区1979年的TM和2009年的SPOT影像资料,利用GIS技术,获取区域30 a的土地利用转移信息图及土壤碳密度的空间分布图,构建区域土地利用变化对土壤碳汇的生态风险影响评价等级,获取区域土壤碳汇的生态风险等级空间分布图。结果表明:作为滨海新区主要碳汇的土地利用类型是城市绿地和林地,而裸地和建设用地是主要的碳源地类;滨海新区30年间50%以下的区域生态风险影响程度没发生变化,位于城市绿地和林地向建设用地过渡边缘地带的区域生态风险增加程度最大。基于低碳理念和土地利用总体规划的原则,提出相应的建议,促进滨海新区低碳化建设。

The present article takes it as its goal to apply low-carbon idea and ecological hazard assessment method to evaluate the land use program of the New Binhai Area of Tianjin. As is known, low-carbon economy has been proposed to promote the sustainable development with LUCC as an important factor in the soil carbon cycle. The SOC density analysis and the hazards ranking assessment we suggested can be done to reflect the influence of land use change. The assessment we have initiated is aimed at estimating the organic carbon density of different soils in the Area by means of the soil-type identification. Based on the remote sensing TM image in 1979 and the SPOT image in 2009, as well as GIS technology, we have created a program ofland-use and map-cover so as to obtain the land-use situation-change information and the spatial distribution data of the organic carbon density during the past 30 years, i.e. from 1979 to 2009. Having es- tablished the ecological hazards assessment rank （from the value - 3 to 3, totally 7 levels） of the organic carbon distribution in the soil un- der the local land-cover change, we have finally confirmed the eco- logical hazards ranking data. The results of our investigation show that the increase of the urban green land and forest area can distinctly help to increase the carbon reduction whereas the bare land and building land are the main carbon pollution sources. Since the low carbon distribution in the air helps to protect the urban green land and forest restoration, about 50% of the total area of the place proves not to be free from the ecological hazards influence change, indicating that the rate of hazards increase and decrease were between 28.8 % and 29.8 % respectively. However, the places located in the bound- ary zones where stands the marginal transfer of the urban green land and forest land to the building sites, such as Nangang industry devel- opmental zone and Tanggu economic technological zone, suffers the ever-growing ecological hazards. From what is said above, it can be concluded that a proper land use program should help to integrate the low-carbon indexes and adopt necessary measures to control the land abuse and waste.