According to the natural ecology and socio-economic conditions in Henan Province, a land use regionalization index system with 6 factors and 24 factor layers was constructed by combining with the characteristics of la...According to the natural ecology and socio-economic conditions in Henan Province, a land use regionalization index system with 6 factors and 24 factor layers was constructed by combining with the characteristics of land use in Henan Province. Expert scoring method was used to determine the weights of the indicators. Based on the similarities and differences of these factors in the index system at county （city, district） levels, hierarchical clustering method was used to make the quantitative analysis to the land use regionalization in Henan Province. And constrastive analysis and qualitative analysis were made to the regionalization scheme by combining with the acutal conditions in the counties （cities, districts）, and finally, Henan Province was classified into 6 regions.展开更多
It was hypothesized that soil respiration can be affected by canopy composition. Hence, admixture of trees as a common forest management practice may cause significant change in the carbon cycling. This study was cond...It was hypothesized that soil respiration can be affected by canopy composition. Hence, admixture of trees as a common forest management practice may cause significant change in the carbon cycling. This study was conducted in a mixed spruce-beech stand at Solling forest in central Germany to investigate the effect of canopy composition on soil respiration. The canopy cover was classified in four major canopy classes （pure beech, pure spruce, mixed and gap）, and the area under each canopy class was identified as a sub-plot. Soil respiration in each sub-plot （n=4） was measured monthly from Jun 2005 to July 2006. Results show significant difference in annual soil respiration between the beech （359g·m^-2·a^-1 C） and gap （211 g·m^-2·a^-1 C） sub-plots. The estimation of the total below-ground carbon allocation （TBCA） based on a model given by Raich and Nadelhoffer revealed considerably higher root CO2 production in the beech sub-plot （231 g·m^-2·a^-1 C） compare to the gap sub-plot （51 g·m^-2·a^-1 C ）. The contribution of the root respiration to the total soil respiration was higher in the soil under the beech canopy （59%） compared with the soil in the gap （29%）. The findings suggested that the condition under the beech canopy may cause more desirable micro-site for autotrophic respiration and consequently higher CO2 release into the atmosphere.展开更多
Based on China National Standard of Soil Engineering Classification (GB/T 50145-2007) and the Unified Soil Classification System of American Society for Testing Materials (ASTM D-2478), two kinds of soil laboratory en...Based on China National Standard of Soil Engineering Classification (GB/T 50145-2007) and the Unified Soil Classification System of American Society for Testing Materials (ASTM D-2478), two kinds of soil laboratory engineering classification methods were discussed and analyzed from the aspects of the definition in particle fraction, classification of soil type and evaluation standard for soil gradation. There is a same limit of fine grains fraction in the two standards, and there are three main types of soil in GB/T 50145-2007 and two in ASTM D-2487. Different evaluation standards of gradation are put forward for gravels and sands in ASTM D-2487. Same criteria of A line, B line and controlling value of plastic index are in the plasticity chart of both standards.展开更多
基金Supported by the Study on the Farmland Quality Evolution and Protection Mechanism based on Rapid Urbanization~~
文摘According to the natural ecology and socio-economic conditions in Henan Province, a land use regionalization index system with 6 factors and 24 factor layers was constructed by combining with the characteristics of land use in Henan Province. Expert scoring method was used to determine the weights of the indicators. Based on the similarities and differences of these factors in the index system at county （city, district） levels, hierarchical clustering method was used to make the quantitative analysis to the land use regionalization in Henan Province. And constrastive analysis and qualitative analysis were made to the regionalization scheme by combining with the acutal conditions in the counties （cities, districts）, and finally, Henan Province was classified into 6 regions.
文摘It was hypothesized that soil respiration can be affected by canopy composition. Hence, admixture of trees as a common forest management practice may cause significant change in the carbon cycling. This study was conducted in a mixed spruce-beech stand at Solling forest in central Germany to investigate the effect of canopy composition on soil respiration. The canopy cover was classified in four major canopy classes （pure beech, pure spruce, mixed and gap）, and the area under each canopy class was identified as a sub-plot. Soil respiration in each sub-plot （n=4） was measured monthly from Jun 2005 to July 2006. Results show significant difference in annual soil respiration between the beech （359g·m^-2·a^-1 C） and gap （211 g·m^-2·a^-1 C） sub-plots. The estimation of the total below-ground carbon allocation （TBCA） based on a model given by Raich and Nadelhoffer revealed considerably higher root CO2 production in the beech sub-plot （231 g·m^-2·a^-1 C） compare to the gap sub-plot （51 g·m^-2·a^-1 C ）. The contribution of the root respiration to the total soil respiration was higher in the soil under the beech canopy （59%） compared with the soil in the gap （29%）. The findings suggested that the condition under the beech canopy may cause more desirable micro-site for autotrophic respiration and consequently higher CO2 release into the atmosphere.
基金Supported by Projects of National Natural Science Foundation of China ( Nos. 40902077,41111120084,41172236)
文摘Based on China National Standard of Soil Engineering Classification (GB/T 50145-2007) and the Unified Soil Classification System of American Society for Testing Materials (ASTM D-2478), two kinds of soil laboratory engineering classification methods were discussed and analyzed from the aspects of the definition in particle fraction, classification of soil type and evaluation standard for soil gradation. There is a same limit of fine grains fraction in the two standards, and there are three main types of soil in GB/T 50145-2007 and two in ASTM D-2487. Different evaluation standards of gradation are put forward for gravels and sands in ASTM D-2487. Same criteria of A line, B line and controlling value of plastic index are in the plasticity chart of both standards.
