Analysis on the land use and cover change in Tianjin Binhai New Area based on the remote sensing

This paper carries out quantitative analysis on the land use/cover （LU/C） change of 13anjin Binhai New Area in recent 10 years through using land use transition matrix from the three-stage LU/C classification maps of 2000, 2005 and 2010 drafted by means of the National Land Classification System of China based on Landsat TM satellite remote sensing image and the Tianjin Binhai New Area 1：50 000 relief maps. On this basis, the impact of such driving factors as the economy and population on LU/C is further analyzed. The results show that the area of the building land in Binhai New Area has increased significantly over the ten years, and the greenland, wetland, and shoals of high ecological value have been dramatically transformed into the building land and unused land for the development and construction, and the change is more significant in the later five years.

Comparison of CO_(2) Effluxes and Their Driving Factors Between Two Temperate Steppes in Inner Mongolia, China

Soil respiration is a key component of the global terrestrial ecosystem carbon cycle. The static opaque chamber method was used to measure the CO2 effiuxes from soil of a semiarid Aneurolepidium chinense steppe and a Stipa krylovii steppe in the Xilin River Basin of Inner Mongolia, China from March 2002 to December 2004. The results indicated that the soil respiration rates of the semiarid Aneurolepidium chinense steppe and the Stipa krylovii steppe were both relatively high from mid-May to mid-September of each year and remained low during the rest of the year. The minimum value of soil respiration occurred in December or January and negative effiuxes of CO2 appeared for several days during the non-growing season of individual years at the two sampling sites. A high annual variation was found in the two steppes with the coefficients of variance （CV） being over 94%, even high to 131%. The annual sums of soil CO2 effiux of the Aneurolepidium chinense steppe varied between 356.4 gC m^-2 yr^-1 and 408.8 gC m^-2 yr^-1, while those of the Stipa krylovii steppe in the three years were in the range of 110.6 gC m^-2 yr^-1 to 148.6 g Cm^-2 yr^-1. The mean respiration rates of the Aneurolepidium chinense steppe were significantly higher than those of the Stipa krylovii steppe in different statistical periods with the exception of the non-growing season. About 59.9% and 80.6% of the soil respiration variations in both steppes for the whole sampling period were caused by the changes of temperature and soil water content. In the Aneurolepidium chinense steppe, the soil respiration rate has significant or extremely significant positive correlation （r = 0.58 - 0.85, p 〈 0.05 or p 〈 0.01） with air temperature and ground temperature of the topsoil except in 2002; the unique contributions of temperature change to the soil respiration variation of the three years were 53.3%, 81.0% and 58.6%, respectively. But, for the Stipa krylovii steppe in the same time interval, the soil water content （especially that of the 10-20 cm layer） has a greater effect on the change of soil respiration, and the unique contributions of the change of the 10-20 cm soil water content to the variations of soil respiration in 2002 and 2003 were 60.0% and 54.3%, respectively. In 2004, in spite of the higher contribution of temperature than soil water content, the contribution of ground temperature at a depth of 10 cm was only 46.2%, much weaker than that of any single year in the Aneurolepidium chinense steppe.