A forest carbon （C） sequestration project was conducted to evaluate the economic incentives that would be required by landowners to engage in C trading under different management regimes. Costs associated with joint...A forest carbon （C） sequestration project was conducted to evaluate the economic incentives that would be required by landowners to engage in C trading under different management regimes. Costs associated with joint management for C sequestration and timber would be valuable for establishing sound forest C trading systems. In this study, we calculated the C yield and amortized value of three Wyoming, ponderosa pine stands. The management practices examined were, unmanaged, even-aged （regeneration after clear-cut） and uneven-aged （selectively harvested）. Costs and revenues associated with three stands were converted into 2006 real dollars using the all commodity producer price index to facilitate a comparison among the net revenues of three stands. Net revenues were annualized using a conservative annual interest rate of 4.5%. Our even-aged stand bad the highest annual average C yield of 2.48 Mg·ha^-1·a^-1, whereas, the uneven-aged stand had the lowest C accumulation （1.98Mg·ha^-1·a^-1）. Alternatively, the even-aged stand had the highest amortized net return of S276·ha^-1·a^-1 and the unmanaged stand had the lowest net return of S64·ha^-1·a^-1. On the plots examined, an annual payment of S22 for each additional Mg of C sequestered would encourage a change from uneven aged management to an unmanaged stand that sequesters additional C, in the absence of transactions costs.展开更多
We demonstrate that the near-infrared （NIR） absorptivity of semiconducfing single-walled carbon nanotubes （s-SWCNTs） can be harnessed in blended heterojunctions with the fullerene derivative [6,6]-phenyl-C61-butyr...We demonstrate that the near-infrared （NIR） absorptivity of semiconducfing single-walled carbon nanotubes （s-SWCNTs） can be harnessed in blended heterojunctions with the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester （PCBM）. Photogenerated charge separation is efficiently driven by the ultrahigh interracial area of the blends and the favorable energy offsets between the two materials. NIR-sensitive photovoltaic and photodetector devices utilizing the stack （indium tin oxide/ca. 10 nm s-SWCNT：PCBM/100 nm CJ10 nm 2,9- dimethyl-4,7-diphenyl-],10-phenanthroline （BCP）/Ag） were fabricated with NIR power conversion efficiencies 〉1.3% and peak, zero bias external quantum efficiency of 18% at λ = 1205 nm.展开更多
The tradeoffs and optimizations of ecosystem services are the key research fields of ecology and geography.It is necessary to maximize the overall benefit of timber production and carbon storage for forest ecological ...The tradeoffs and optimizations of ecosystem services are the key research fields of ecology and geography.It is necessary to maximize the overall benefit of timber production and carbon storage for forest ecological development in China.We selected the Huitong National Research Station of Forest Ecosystem as our study area,and used In VEST model to evaluate timber production and carbon storage quantitatively.The results showed that:(1)While timber production increased with harvesting intensity over the planning horizon,carbon storage decreased.There were tradeoffs between timber production and carbon storage according to the significant negative relationship.(2)While the overall benefit of timber production and carbon storage increased with harvesting intensity,the value of tradeoffs decreased.T1 and T2 scenarios,with harvesting intensity of 10%–20% every 10 years,are the optimum management regimes for the two ecosystem services to gain more benefit and less tradeoffs.(3)The current harvesting intensity in Huitong County was slightly higher than the optimum harvesting intensity.On practical dimension,these findings suggested that obvious objectives are needed to formulate the corresponding countermeasures of tradeoffs,in order to realize the improvement of ecosystem services and the optimization of ecosystem structures.展开更多
Considering the uncertainty of kelp-abalone-sea cucumber population, an interval model of carbon sink fisheries with multi-trophic levels is proposed. The equilibria of the model are identified and the corresponding s...Considering the uncertainty of kelp-abalone-sea cucumber population, an interval model of carbon sink fisheries with multi-trophic levels is proposed. The equilibria of the model are identified and the corresponding stabilities are discussed. And the existence of bionomic equilibrium of the model is investigated. Next the optimal controller is designed to obtain the optimal harvest using Pontryagin＇s maximum principle. Numerical simulations are carried to prove the results.展开更多
文摘A forest carbon （C） sequestration project was conducted to evaluate the economic incentives that would be required by landowners to engage in C trading under different management regimes. Costs associated with joint management for C sequestration and timber would be valuable for establishing sound forest C trading systems. In this study, we calculated the C yield and amortized value of three Wyoming, ponderosa pine stands. The management practices examined were, unmanaged, even-aged （regeneration after clear-cut） and uneven-aged （selectively harvested）. Costs and revenues associated with three stands were converted into 2006 real dollars using the all commodity producer price index to facilitate a comparison among the net revenues of three stands. Net revenues were annualized using a conservative annual interest rate of 4.5%. Our even-aged stand bad the highest annual average C yield of 2.48 Mg·ha^-1·a^-1, whereas, the uneven-aged stand had the lowest C accumulation （1.98Mg·ha^-1·a^-1）. Alternatively, the even-aged stand had the highest amortized net return of S276·ha^-1·a^-1 and the unmanaged stand had the lowest net return of S64·ha^-1·a^-1. On the plots examined, an annual payment of S22 for each additional Mg of C sequestered would encourage a change from uneven aged management to an unmanaged stand that sequesters additional C, in the absence of transactions costs.
基金Acknowledgements The authors acknowledge the assistance of Frederick C. Prehn in sample preparation. This work was supported by the National Science Foundation （Grant No. DMR- 0905861）.
文摘We demonstrate that the near-infrared （NIR） absorptivity of semiconducfing single-walled carbon nanotubes （s-SWCNTs） can be harnessed in blended heterojunctions with the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester （PCBM）. Photogenerated charge separation is efficiently driven by the ultrahigh interracial area of the blends and the favorable energy offsets between the two materials. NIR-sensitive photovoltaic and photodetector devices utilizing the stack （indium tin oxide/ca. 10 nm s-SWCNT：PCBM/100 nm CJ10 nm 2,9- dimethyl-4,7-diphenyl-],10-phenanthroline （BCP）/Ag） were fabricated with NIR power conversion efficiencies 〉1.3% and peak, zero bias external quantum efficiency of 18% at λ = 1205 nm.
基金The National Basic Research Program of China(973 Program),No.2015CB452702National Natural Science Foundation of China,No.41571098,No.41530749+2 种基金Key Programs of Chinese Academy of Sciences,ZDRW-ZS-2016-6-4-4Major Consulting Project of Strategic Development Institute,Chinese Academy of Sciences,No.Y02015003China Clean Development Mechanism Fund Grant Program(Climate Change Risk and Countermeasures in Xinjiang Region)
文摘The tradeoffs and optimizations of ecosystem services are the key research fields of ecology and geography.It is necessary to maximize the overall benefit of timber production and carbon storage for forest ecological development in China.We selected the Huitong National Research Station of Forest Ecosystem as our study area,and used In VEST model to evaluate timber production and carbon storage quantitatively.The results showed that:(1)While timber production increased with harvesting intensity over the planning horizon,carbon storage decreased.There were tradeoffs between timber production and carbon storage according to the significant negative relationship.(2)While the overall benefit of timber production and carbon storage increased with harvesting intensity,the value of tradeoffs decreased.T1 and T2 scenarios,with harvesting intensity of 10%–20% every 10 years,are the optimum management regimes for the two ecosystem services to gain more benefit and less tradeoffs.(3)The current harvesting intensity in Huitong County was slightly higher than the optimum harvesting intensity.On practical dimension,these findings suggested that obvious objectives are needed to formulate the corresponding countermeasures of tradeoffs,in order to realize the improvement of ecosystem services and the optimization of ecosystem structures.
文摘Considering the uncertainty of kelp-abalone-sea cucumber population, an interval model of carbon sink fisheries with multi-trophic levels is proposed. The equilibria of the model are identified and the corresponding stabilities are discussed. And the existence of bionomic equilibrium of the model is investigated. Next the optimal controller is designed to obtain the optimal harvest using Pontryagin＇s maximum principle. Numerical simulations are carried to prove the results.
