Prescribed fire has now become the usual management practice in the Chinese fir （Cunninghamia lanceolata （Lamb.） Hook.） plantation in southern China. Heat generated during fire may affect carbon （C） dynam- ics i...Prescribed fire has now become the usual management practice in the Chinese fir （Cunninghamia lanceolata （Lamb.） Hook.） plantation in southern China. Heat generated during fire may affect carbon （C） dynam- ics in soils. We investigated the microbial biomass C （MBC） and microbial respiration in two Chinese fir forest soils （one is not exposed to fire for the past 88 years, and the other is recently exposed to prescribed fire） after soil heating （100 and 200 ℃） under three moisture regimes [25, 50 and 75 % of water holding capacity （WHC）]. For both soils, significant reduction in MBC with increasing heating temperature was found. Soils without exposing to fire previously had significantly greater MBC concentra- tion than the fire-exposed soils when heated at 100 or 200 ℃. Lower soil water content resulted in higher MBC concentrations in both soils. In contrast, both soils had the highest soil microbial respiration rate at 50 % WHC. Soils without exposing to fire previously had the greatest microbial respiration rates at 200 ℃, while the fire-ex- posed soils when heated at 100 ℃ had greatest microbialrespiration rates. During 14-days post-heat incubation, soil MBC in both soils was greatest after heating at 200 ℃ and 25 % WHC. However, soil previously exposed to fire had the lowest CO2 evolution when incubated at 25 % WHC.展开更多
To address the corrosion and dendrite issues of lithium metal anodes, a protective layer was ex-situ constructed by P4S10 modification. It was determined by X-ray photoelectron spectroscopy and Raman spectra that the ...To address the corrosion and dendrite issues of lithium metal anodes, a protective layer was ex-situ constructed by P4S10 modification. It was determined by X-ray photoelectron spectroscopy and Raman spectra that the main constituents of the protective layer were P4S10, Li3PS4 and other LixPySztype derivatives. The protective layer was proved to be effective to stabilize the interphase of lithium metal. With the modified Li anodes, symmetric cells could deliver stable Li plating/stripping for 16000 h;Li–S batteries exhibited a specific capacity of 520 m A h g-1 after 200 cycles at 1000 m A g-1 with average Coulombic efficiency of 97.9%. Therefore, introducing LixPySzbased layer to protect Li anode provides a new strategy for the improvement of Li metal batteries.展开更多
Various nanostructured architectures have been demonstrated to be effective to address the issues of high capacity Si anodes. However, the scale-up of these nano-Si materials is still a critical obstacle for commercia...Various nanostructured architectures have been demonstrated to be effective to address the issues of high capacity Si anodes. However, the scale-up of these nano-Si materials is still a critical obstacle for commercialization. Herein, we use industrial ferrosilicon as low-cost Si source and introduce a facile and scalable method to fabricate a micrometer-sized ferrosilicon/C composite anode, in which ferrosilicon microparticles are wrapped with multi-layered carbon nanosheets. The multi-layered carbon nanosheets could effectively buffer the volume variation of Si as well as create an abundant and reliable conductivity framework, ensuring fast transport of electrons. As a result, the micrometer-sized ferrosilicon/C anode achieves a stable cycling with 805.9 m Ah g-1 over 200 cycles at 500 mA g-1 and a good rate capability of455.6 mAh g-1 at 10 A g-1. Therefore, our approach based on ferrosilicon provides a new opportunity in fabricating cost-effective, pollution-free, and large-scale Si electrode materials for high energy lithium-ion batteries.展开更多
Mid-subtropical forests are the main vegetation type of global terrestrial biomes, and are critical for maintaining the global carbon balance. However, estimates of forest biomass increment in mid-subtropical forests ...Mid-subtropical forests are the main vegetation type of global terrestrial biomes, and are critical for maintaining the global carbon balance. However, estimates of forest biomass increment in mid-subtropical forests remain highly uncertain. It is critically important to determine the relative importance of different biotic and abiotic factors between plants and soil, particularly with respect to their influence on plant regrowth. Consequently,it is necessary to quantitatively characterize the dynamicspatiotemporal distribution of forest carbon sinks at a regional scale. This study used a large, long-term dataset in a boosted regression tree（BRT） model to determine the major components that quantitatively control forest biomass increments in a mid-subtropical forested region（Wuyishan National Nature Reserve, China）. Long-term,stand-level data were used to derive the forest biomass increment, with the BRT model being applied to quantify the relative contributions of various biotic and abiotic variables to forest biomass increment. Our data show that total biomass（t） increased from 4.62 9 106 to 5.30 9 106 t between 1988 and 2010, and that the mean biomass increased from 80.19 ± 0.39 t ha-1（mean ± standard error） to 94.33 ± 0.41 t ha-1in the study region. The major factors that controlled biomass（in decreasing order of importance） were the stand, topography, and soil. Stand density was initially the most important stand factor, while elevation was the most important topographic factor. Soil factors were important for forest biomass increment but have a much weaker influence compared to the other two controlling factors. These results provide baseline information about the practical utility of spatial interpolationmethods for mapping forest biomass increments at regional scales.展开更多
基金financed by the National Natural Science Foundation of China(No.31370615 and 31130013)National Key Basic Research Program of China(2014CB954003)
文摘Prescribed fire has now become the usual management practice in the Chinese fir （Cunninghamia lanceolata （Lamb.） Hook.） plantation in southern China. Heat generated during fire may affect carbon （C） dynam- ics in soils. We investigated the microbial biomass C （MBC） and microbial respiration in two Chinese fir forest soils （one is not exposed to fire for the past 88 years, and the other is recently exposed to prescribed fire） after soil heating （100 and 200 ℃） under three moisture regimes [25, 50 and 75 % of water holding capacity （WHC）]. For both soils, significant reduction in MBC with increasing heating temperature was found. Soils without exposing to fire previously had significantly greater MBC concentra- tion than the fire-exposed soils when heated at 100 or 200 ℃. Lower soil water content resulted in higher MBC concentrations in both soils. In contrast, both soils had the highest soil microbial respiration rate at 50 % WHC. Soils without exposing to fire previously had the greatest microbial respiration rates at 200 ℃, while the fire-ex- posed soils when heated at 100 ℃ had greatest microbialrespiration rates. During 14-days post-heat incubation, soil MBC in both soils was greatest after heating at 200 ℃ and 25 % WHC. However, soil previously exposed to fire had the lowest CO2 evolution when incubated at 25 % WHC.
基金financially supported by the National Key Research and Development Program of China(no.2016YFB0100200)Beijing Municipal Science and Technology Project(no.Z181100004518001)。
文摘To address the corrosion and dendrite issues of lithium metal anodes, a protective layer was ex-situ constructed by P4S10 modification. It was determined by X-ray photoelectron spectroscopy and Raman spectra that the main constituents of the protective layer were P4S10, Li3PS4 and other LixPySztype derivatives. The protective layer was proved to be effective to stabilize the interphase of lithium metal. With the modified Li anodes, symmetric cells could deliver stable Li plating/stripping for 16000 h;Li–S batteries exhibited a specific capacity of 520 m A h g-1 after 200 cycles at 1000 m A g-1 with average Coulombic efficiency of 97.9%. Therefore, introducing LixPySzbased layer to protect Li anode provides a new strategy for the improvement of Li metal batteries.
基金the National Natural Science Foundation of China(No:21703285)。
文摘Various nanostructured architectures have been demonstrated to be effective to address the issues of high capacity Si anodes. However, the scale-up of these nano-Si materials is still a critical obstacle for commercialization. Herein, we use industrial ferrosilicon as low-cost Si source and introduce a facile and scalable method to fabricate a micrometer-sized ferrosilicon/C composite anode, in which ferrosilicon microparticles are wrapped with multi-layered carbon nanosheets. The multi-layered carbon nanosheets could effectively buffer the volume variation of Si as well as create an abundant and reliable conductivity framework, ensuring fast transport of electrons. As a result, the micrometer-sized ferrosilicon/C anode achieves a stable cycling with 805.9 m Ah g-1 over 200 cycles at 500 mA g-1 and a good rate capability of455.6 mAh g-1 at 10 A g-1. Therefore, our approach based on ferrosilicon provides a new opportunity in fabricating cost-effective, pollution-free, and large-scale Si electrode materials for high energy lithium-ion batteries.
基金supported by National Forestry Public Welfare Foundation of China(201304205)National Science Foundation of China(31470578 and 31200363)+2 种基金Fujian Provincial Department of S&T Project(2016Y0083,2013YZ0001-1,2014J05044 and 2015Y0083)Xiamen Municipal Department of Science and Technology(3502Z20130037 and 3502Z20142016)Youth Innovation Promotion Association CAS
文摘Mid-subtropical forests are the main vegetation type of global terrestrial biomes, and are critical for maintaining the global carbon balance. However, estimates of forest biomass increment in mid-subtropical forests remain highly uncertain. It is critically important to determine the relative importance of different biotic and abiotic factors between plants and soil, particularly with respect to their influence on plant regrowth. Consequently,it is necessary to quantitatively characterize the dynamicspatiotemporal distribution of forest carbon sinks at a regional scale. This study used a large, long-term dataset in a boosted regression tree（BRT） model to determine the major components that quantitatively control forest biomass increments in a mid-subtropical forested region（Wuyishan National Nature Reserve, China）. Long-term,stand-level data were used to derive the forest biomass increment, with the BRT model being applied to quantify the relative contributions of various biotic and abiotic variables to forest biomass increment. Our data show that total biomass（t） increased from 4.62 9 106 to 5.30 9 106 t between 1988 and 2010, and that the mean biomass increased from 80.19 ± 0.39 t ha-1（mean ± standard error） to 94.33 ± 0.41 t ha-1in the study region. The major factors that controlled biomass（in decreasing order of importance） were the stand, topography, and soil. Stand density was initially the most important stand factor, while elevation was the most important topographic factor. Soil factors were important for forest biomass increment but have a much weaker influence compared to the other two controlling factors. These results provide baseline information about the practical utility of spatial interpolationmethods for mapping forest biomass increments at regional scales.
