The data of field studies about mineral nutrient content in the biomass components of young birch stands （9-15 years old） in different forest growing conditions and soil types have been analyzed. In forest growing c...The data of field studies about mineral nutrient content in the biomass components of young birch stands （9-15 years old） in different forest growing conditions and soil types have been analyzed. In forest growing conditions on fertile soils （ASG, TSC and SP） the total amount of biomass produced by young birch stands divides into fractions as follows： stem wood 51.8%-59.5%; branch wood 9.8%-12.4%; foliage 5.7%-6.8%; stump wood and roots 25%-30%. In forest types on lean soils （TP） the same indices are 32.3%-41.8%, 18.2%-24.2%, 13.2%-16.1% and 26.8%-27.4%, respectively. The stand performance closely correlates with the basic nutrient （P, N, K, C and Mg） availability in forest soils. In lean typicpodzol soils （TP） the content of mineral nutrients is no higher than 20%-48% of that in more fertile soils （ASG, TSC and SP）. In young birch stands the take-up of mineral nutrients from 0-40 cm soil layer for developing the above-ground biomass makes a fairly small proportion of the total： up to 4.8%-6.2% for P; 4.9%-12.2% for N; 1.1%-4.1% for K; 11.6% for Ca; 0.8%-7.7% for Mg; in leaner soils the same indices are P 0.1%-0.4%, N 1%-1.5%, K 0.2%-0.6%, Ca 0.1%-0.9%, Mg 0.1%-0.8%, respectively. The analyses of pest damages in young birch stands confirm a hypothesis that the degree of pest damage depends on the stand vitality as described by the site index.展开更多
We investigate the growing condition dependences of magnetic and electric properties of the La2/3Sr1/3MnO3 thin films grown on SrTiO3（001） substrates.With reducing the film thickness and growth pressure,the Curie te...We investigate the growing condition dependences of magnetic and electric properties of the La2/3Sr1/3MnO3 thin films grown on SrTiO3（001） substrates.With reducing the film thickness and growth pressure,the Curie temperature（Tc）drops off,and the magnetism and metallicity are suppressed.At an appropriate deposition temperature,we can obtain the best texture and remarkably enhance the magnetic and electrical properties.However,the resistivity of film cannot be modulated by changing the dc current and green light intensity.This result may be induced by the coherent strains in the epitaxially grown film due to its lattice mismatching that of the SrTiO3 substrate.Furthermore,we show that the relations between the magnetism and the resistivity for the typical films with different thickness values.For the 13.4-nm-thick film,the R-T curve presents two transition behaviors：insulator-to-metal and metal-to-insulator in the cooling process：the former corresponds to magnetic transition,and the later correlates with thermal excitation conduction.展开更多
Crop yield is mainly affected by weather condition, inputs, and agriculture policies. In the crop yield estimation, farmers＇ perception on weather conditions lead to the assessment of how well yield would be compared...Crop yield is mainly affected by weather condition, inputs, and agriculture policies. In the crop yield estimation, farmers＇ perception on weather conditions lead to the assessment of how well yield would be compared to the previous seasons. This paper applies Bayesian estimation method to estimate crop yield with farmers＇ appraisal on weather condition. The paper shows that crop yield estimation with farmers＇ appraisal on weather condition takes into account risk proportionally to climate change. In light of the United Nations efforts aimed to build a consolidated agriculture statistical system across countries, the statistical model developed here should provide an important tool both for the crop yield estimation and food price analysis.展开更多
文摘The data of field studies about mineral nutrient content in the biomass components of young birch stands （9-15 years old） in different forest growing conditions and soil types have been analyzed. In forest growing conditions on fertile soils （ASG, TSC and SP） the total amount of biomass produced by young birch stands divides into fractions as follows： stem wood 51.8%-59.5%; branch wood 9.8%-12.4%; foliage 5.7%-6.8%; stump wood and roots 25%-30%. In forest types on lean soils （TP） the same indices are 32.3%-41.8%, 18.2%-24.2%, 13.2%-16.1% and 26.8%-27.4%, respectively. The stand performance closely correlates with the basic nutrient （P, N, K, C and Mg） availability in forest soils. In lean typicpodzol soils （TP） the content of mineral nutrients is no higher than 20%-48% of that in more fertile soils （ASG, TSC and SP）. In young birch stands the take-up of mineral nutrients from 0-40 cm soil layer for developing the above-ground biomass makes a fairly small proportion of the total： up to 4.8%-6.2% for P; 4.9%-12.2% for N; 1.1%-4.1% for K; 11.6% for Ca; 0.8%-7.7% for Mg; in leaner soils the same indices are P 0.1%-0.4%, N 1%-1.5%, K 0.2%-0.6%, Ca 0.1%-0.9%, Mg 0.1%-0.8%, respectively. The analyses of pest damages in young birch stands confirm a hypothesis that the degree of pest damage depends on the stand vitality as described by the site index.
基金supported by the National Natural Science Foundation of China(Grant Nos.111374348,11134007,11174345,and 111474341)the National Basic Reaearch Program of China(Grant Nos.2013CB921700,2011CB921801,and 2012CB933000)
文摘We investigate the growing condition dependences of magnetic and electric properties of the La2/3Sr1/3MnO3 thin films grown on SrTiO3（001） substrates.With reducing the film thickness and growth pressure,the Curie temperature（Tc）drops off,and the magnetism and metallicity are suppressed.At an appropriate deposition temperature,we can obtain the best texture and remarkably enhance the magnetic and electrical properties.However,the resistivity of film cannot be modulated by changing the dc current and green light intensity.This result may be induced by the coherent strains in the epitaxially grown film due to its lattice mismatching that of the SrTiO3 substrate.Furthermore,we show that the relations between the magnetism and the resistivity for the typical films with different thickness values.For the 13.4-nm-thick film,the R-T curve presents two transition behaviors：insulator-to-metal and metal-to-insulator in the cooling process：the former corresponds to magnetic transition,and the later correlates with thermal excitation conduction.
文摘Crop yield is mainly affected by weather condition, inputs, and agriculture policies. In the crop yield estimation, farmers＇ perception on weather conditions lead to the assessment of how well yield would be compared to the previous seasons. This paper applies Bayesian estimation method to estimate crop yield with farmers＇ appraisal on weather condition. The paper shows that crop yield estimation with farmers＇ appraisal on weather condition takes into account risk proportionally to climate change. In light of the United Nations efforts aimed to build a consolidated agriculture statistical system across countries, the statistical model developed here should provide an important tool both for the crop yield estimation and food price analysis.
