基于GIS的关中-天水经济区土地生态系统固碳释氧价值评价

气体调节服务功能是生态服务功能的重要的一部分,生态系统的固碳释氧功能,对于人类社会和整个动物界以及全球气候平衡,都具有重要意义.采用光合作用方程式,利用遥感估算模型,基于植被NPP(第一性生产力)物质量测算结果,测算关中-天水天经济区绿色植物固碳释氧物质量,以此为基础,分别采用造林成本法和工业制氧法测算其价值量,探讨关天经济区生态系统固碳释氧价值的时间变化、空间分布.结果表明:1)1998-2007年关天水经济区年固定CO2的价值量为226.35亿元/a.10a间2005年固定CO2的价值量最高,为301.73亿元/a,2002年最低,为159.06元/a.释放O2价值量取两种测评方法的平均值,年平均价值量为240.45亿元/a,比固定CO2的年均值多14.1亿元/a.2)从各土地利用类型来看,1998年和2007年平均固碳释氧价值排序为:林地＞草地＞耕地＞其他类型.耕地向林地、草地转变时,平均固碳释氧价值分别增加了1614.29、1960.67元·hm-2·a-1,林地、草地向耕地转变时平均固碳释氧价值分别减少了1081.37、1706.60元·hm-2·a-1.3)从空间分布上来看,南部各县的单位面积固定CO2和释放O2价值普遍高于北部各县,总体上分布沿南部向北部逐渐降低.

The value of fixing carbon and releasing oxygen in the Guanzhong-Tianshui economic region using GIS

Quantitatively evaluating the functions of CO₂ fixation and O₂ production is important in the study of ecological systems. This article attempts to measure and evaluate the rate of carbon fixation and oxygen release in terrestrial ecological systems using remote sensing, to provide baseline data for the regional environment. Changing land use and land cover types influence vegetation composition and health, so understanding the effects of these changes on carbon fixation and oxygen production provides an important tool for monitoring ecosystem responses to environmental change. Solar radiation is the primary source for physical and biological processes in the atmosphere and on the surface of the earth. This is the only energy source used by green plants during photosynthesis. Green plants produce all organic assimilates through photosynthesis. Net plant productivity (NPP) is the total amount of organic matter accumulated by vegetation per unit area and time, and equals the difference between the carbon absorbed by photosynthesis and the carbon released by autotrophic respiration NPP reflects not only the productivity of a plant community in its natural environment, but also its ability to sequester carbon. The balance between carbon fixation and oxygen production plays a key role in global biogeochemical carbon cycles. So, carbon flows through an ecosystem are an important determinant of the ecosystem's ability to act as a carbon sink. Using remote-sensing images and precipitation, temperature, and total solar radiation data from1998 to 2007, and a light utilization efficiency model, we studied the effects of changes in these parameters and land use and cover types on the ability of plants to fix carbon and produce oxygen in the Guanzhong-Tianshui economic region. The results show: 1) the economic value of carbon fixation is 22.635 billion yuan/a in the Guanzhong-Tianshui economic region. Over the past ten years, the highest value of carbon fixation was in 2005 at 30.173 billion yuan/a; the minimum was 15.906 billion yuan/a in 2002. By taking an average of the two measuring methods the value of oxygen released, the average value is 24.045 billion yuan/a, more than 1.41 billion yuan a-1 higher than the value of carbon fixation. 2) From the perspective of land use types in the Guanzhong-Tianshui economic region, forestland > grassland > cultivated land > other types. From 1998 to 2007, the value for farmland converted to forest land or grassland for average carbon fixation and oxygen production has increased by 1614.29 yuan·hm^-2·a^-1 and 1,960.67 yuan·hm^-2·a^-1,respectively. Forest land and meadow changed to cultivated land has had the average value for carbon fixation and oxygen production reduced to 1,081.37 yuan·hm^-2·a^-1 and 1706.60 yuan·hm^-2·a^-1, respectively. 3) From a spatial distribution perspective, unit area value of carbon fixation and oxygen production in the southern counties is higher than in the northern counties of the Guanzhong-Tianshui economic region with the value gradually declining from the south to north. By examining the values of carbon fixation and oxygen production based on the NDVI data in various climate scenarios, we were able to explore the influences of land use and cover changes on carbon fixation and oxygen production, as well as the effects of climate change. Carbon fixation and oxygen production in northern China's agriculture and animal husbandry region and the endangered central loess region-which has serious soil erosion and high evaporation rates is-declining in value. Therefore, study of this fragile ecological environment is relevant.