With a data set of Eurasian forest litter fall based on 471 stands,annual litterfall was estimated to be 6.53Pg dm·a^-1 (1Pg=10^15g;dm,dry matter)in Eurasian forests,of which more than half occurred in tropical a...With a data set of Eurasian forest litter fall based on 471 stands,annual litterfall was estimated to be 6.53Pg dm·a^-1 (1Pg=10^15g;dm,dry matter)in Eurasian forests,of which more than half occurred in tropical and subtropical forests,and a third in the boreal area.With litterfall,around 2.94Pg C per year is transferred from the forest vegetation to the soil on this continent.展开更多
Soil properties were investigated in sites where three succeeding generationsof Chinese fir (Gunning-hamia lanceolata, (Lambert) Hooker) in Nanping, Fujian, China, werecultivated in order to show the impact of a repea...Soil properties were investigated in sites where three succeeding generationsof Chinese fir (Gunning-hamia lanceolata, (Lambert) Hooker) in Nanping, Fujian, China, werecultivated in order to show the impact of a repeated monoculture on site productivity. Compared withthe first generation (FG) stand the soil structure deteriorated in the second generation (SG) andthe third generation (TG) stands. For instance, the destruction rate of the peds increased by 55%-115% in the SG and the TG stands compared to the FG stand. Soil nutrient storage and nutrientavailability also decreased in the SG and the TG stands. For surface soils of 0-20 cm, the organicmatter content, total N and P, and available N and P decreased by 3%-20% relative to those in the FGstand. For many soil parameters, the differences between the FG stand and the SG and the TG standswere statistically significant (LSD test, P < 0.05). Furthermore, with each succeeding generation ofChinese fir, the total number of soil microbes declined, the soil enzyme activity weakened, and thesoil biological activity decreased. In order to maintain sustainable site productivity, newsilvicultural practices need to be developed for management of Chinese fir plantations.展开更多
The CO_2 in the atmosphere is in contact with water vapor and rain droplets forming CO_2·H_2O, HCO -_3 and CO 2- _3. Global precipitation is about 505×10 15 kg/a. Based on theoretical calculation for ...The CO_2 in the atmosphere is in contact with water vapor and rain droplets forming CO_2·H_2O, HCO -_3 and CO 2- _3. Global precipitation is about 505×10 15 kg/a. Based on theoretical calculation for unpolluted air and measurement observations, we estimated that 100—270×10 12 gC/a are scavenged from the air by global precipitation. This roughly equals carbon emissions from volcanic sources or 2—6 per cent of current CO_2 emissions. An inventory-based estimate on carbon removal in northwestern Europe supports the above calculation on global scale. With increasing CO_2 concentration in the air, precipitation scavenging may increase.展开更多
文摘With a data set of Eurasian forest litter fall based on 471 stands,annual litterfall was estimated to be 6.53Pg dm·a^-1 (1Pg=10^15g;dm,dry matter)in Eurasian forests,of which more than half occurred in tropical and subtropical forests,and a third in the boreal area.With litterfall,around 2.94Pg C per year is transferred from the forest vegetation to the soil on this continent.
基金Project supported by the National Natural Science Foundation of China (No. 30170770).
文摘Soil properties were investigated in sites where three succeeding generationsof Chinese fir (Gunning-hamia lanceolata, (Lambert) Hooker) in Nanping, Fujian, China, werecultivated in order to show the impact of a repeated monoculture on site productivity. Compared withthe first generation (FG) stand the soil structure deteriorated in the second generation (SG) andthe third generation (TG) stands. For instance, the destruction rate of the peds increased by 55%-115% in the SG and the TG stands compared to the FG stand. Soil nutrient storage and nutrientavailability also decreased in the SG and the TG stands. For surface soils of 0-20 cm, the organicmatter content, total N and P, and available N and P decreased by 3%-20% relative to those in the FGstand. For many soil parameters, the differences between the FG stand and the SG and the TG standswere statistically significant (LSD test, P < 0.05). Furthermore, with each succeeding generation ofChinese fir, the total number of soil microbes declined, the soil enzyme activity weakened, and thesoil biological activity decreased. In order to maintain sustainable site productivity, newsilvicultural practices need to be developed for management of Chinese fir plantations.
文摘The CO_2 in the atmosphere is in contact with water vapor and rain droplets forming CO_2·H_2O, HCO -_3 and CO 2- _3. Global precipitation is about 505×10 15 kg/a. Based on theoretical calculation for unpolluted air and measurement observations, we estimated that 100—270×10 12 gC/a are scavenged from the air by global precipitation. This roughly equals carbon emissions from volcanic sources or 2—6 per cent of current CO_2 emissions. An inventory-based estimate on carbon removal in northwestern Europe supports the above calculation on global scale. With increasing CO_2 concentration in the air, precipitation scavenging may increase.
