Background： Currently, the common and feasible way to estimate the most accurate forest biomass requires ground measurements and allometric models.Previous studies have been conducted on allometric equations developm...Background： Currently, the common and feasible way to estimate the most accurate forest biomass requires ground measurements and allometric models.Previous studies have been conducted on allometric equations development for estimating tree aboveground biomass（AGB） of tropical dipterocarp forests（TDFs） in Kalimantan（Indonesian Borneo）.However, before the use of existing equations, a validation for the selection of the best allometric equation is required to assess the model bias and precision.This study aims at evaluating the validity of local and pantropical equations; developing new allometric equations for estimating tree AGB in TDFs of Kalimantan; and validating the new equations using independent datasets.Methods： We used 108 tree samples from destructive sampling to develop the allometric equations, with maximum tree diameter of 175 cm and another 109 samples from previous studies for validating our equations.We performed ordinary least squares linear regression to explore the relationship between the AGB and the predictor variables in the natural logarithmic form.Results： This study found that most of the existing local equations tended to be biased and imprecise, with mean relative error and mean absolute relative error more than 0.1 and 0.3, respectively.We developed new allometric equations for tree AGB estimation in the TDFs of Kalimantan.Through a validation using an independent dataset,we found that our equations were reliable in estimating tree AGB in TDF.The pantropical equation, which includes tree diameter, wood density and total height as predictor variables performed only slightly worse than our new models.Conclusions： Our equations improve the precision and reduce the bias of AGB estimates of TDFs.Local models developed from small samples tend to systematically bias.A validation of existing AGB models is essential before the use of the models.展开更多
Angiogenesis is the proliferation of new blood vessels that enable the normal embryonic development and may also induce growth of numerous pathologies like tumor growth and cancer metastasis.The assays were used for b...Angiogenesis is the proliferation of new blood vessels that enable the normal embryonic development and may also induce growth of numerous pathologies like tumor growth and cancer metastasis.The assays were used for both pro and anti-angiogenic agents.This study evaluated the angiosuppressive activity of Pleurotus florida on the developing chick embryo using chorioallantoic membrane(CAM)assay and used destructive sampling into four different treatment concentrations and a control.The result revealed a decrease in the number of blood vessels branch points formed after 24,48,and 72 hours at higher treatment concentrations(0.50%and 1%).Statistical analysis showed that 24 hours and 48 hours of exposure to various concentrations have no significant difference.Nevertheless,after 72 hours of exposure,the mean blood vessel branch points formed showed a significant difference among the treatment means between the highest concentration of P.florida(1%)and the control treatment(sterile water).In terms of the percentage of angiosuppressive activity of P.florida with the greatest angiogenic effect,which was the 1%P.florida treatment concentration possesses 35.69%and 36.85%angiosuppressive rate after 48 and 72 hours of exposure respectively.Thus,this study showed that P.florida lyophilized hot water extract exhibits angiosuppressive activity on the developing chick embryo using chorioallantoic membrane assay and is concentration and time exposure dependent.展开更多
Most studies do not consider the potential variation in carbon concentration among the different tree components of the same species in regional scale. This study examined the carbon concentrations of the compo- nents...Most studies do not consider the potential variation in carbon concentration among the different tree components of the same species in regional scale. This study examined the carbon concentrations of the compo- nents （i.e., foliage, branch, stem, and root） in a 10-year-old poplar species （Populus davidiana Dode） from the Desertification Combating Program of Northern China. The highest and lowest carbon concentrations were found in the stem and foliage, respectively. There was a significant difference in carbon concentrations among the different tree components. All of the observed carbon concentrations of tree components were lower than those predicted using the conversion factor of 0.5 applied to component biomass. Stem carbon made up 59.7% of the total tree biomass carbon. The power equation estimating proportion of tree biomass carbon against the independent variable of diameter at breast height explained more than 90% of the variability in allocation of carbon among tree components. Tree height, as a second independent variable is also discussed. Our results suggest that the difference in organic carbon concentration among tree components should be incorporated into accurately develop forest carbon budget. Moreover, further investigations on how the diameter at breast height equation developed in the present study performs across broader scales are required.展开更多
基金the GIZ-Forclime project, a bilateral project between Indonesia and German governments, for funding the field measurements
文摘Background： Currently, the common and feasible way to estimate the most accurate forest biomass requires ground measurements and allometric models.Previous studies have been conducted on allometric equations development for estimating tree aboveground biomass（AGB） of tropical dipterocarp forests（TDFs） in Kalimantan（Indonesian Borneo）.However, before the use of existing equations, a validation for the selection of the best allometric equation is required to assess the model bias and precision.This study aims at evaluating the validity of local and pantropical equations; developing new allometric equations for estimating tree AGB in TDFs of Kalimantan; and validating the new equations using independent datasets.Methods： We used 108 tree samples from destructive sampling to develop the allometric equations, with maximum tree diameter of 175 cm and another 109 samples from previous studies for validating our equations.We performed ordinary least squares linear regression to explore the relationship between the AGB and the predictor variables in the natural logarithmic form.Results： This study found that most of the existing local equations tended to be biased and imprecise, with mean relative error and mean absolute relative error more than 0.1 and 0.3, respectively.We developed new allometric equations for tree AGB estimation in the TDFs of Kalimantan.Through a validation using an independent dataset,we found that our equations were reliable in estimating tree AGB in TDF.The pantropical equation, which includes tree diameter, wood density and total height as predictor variables performed only slightly worse than our new models.Conclusions： Our equations improve the precision and reduce the bias of AGB estimates of TDFs.Local models developed from small samples tend to systematically bias.A validation of existing AGB models is essential before the use of the models.
文摘Angiogenesis is the proliferation of new blood vessels that enable the normal embryonic development and may also induce growth of numerous pathologies like tumor growth and cancer metastasis.The assays were used for both pro and anti-angiogenic agents.This study evaluated the angiosuppressive activity of Pleurotus florida on the developing chick embryo using chorioallantoic membrane(CAM)assay and used destructive sampling into four different treatment concentrations and a control.The result revealed a decrease in the number of blood vessels branch points formed after 24,48,and 72 hours at higher treatment concentrations(0.50%and 1%).Statistical analysis showed that 24 hours and 48 hours of exposure to various concentrations have no significant difference.Nevertheless,after 72 hours of exposure,the mean blood vessel branch points formed showed a significant difference among the treatment means between the highest concentration of P.florida(1%)and the control treatment(sterile water).In terms of the percentage of angiosuppressive activity of P.florida with the greatest angiogenic effect,which was the 1%P.florida treatment concentration possesses 35.69%and 36.85%angiosuppressive rate after 48 and 72 hours of exposure respectively.Thus,this study showed that P.florida lyophilized hot water extract exhibits angiosuppressive activity on the developing chick embryo using chorioallantoic membrane assay and is concentration and time exposure dependent.
基金Acknowledgements We thank Xinqiang Zhang, Xinhua Zeng, and Xin Zhao for their assistance in the field survey and laboratory analysis. This work was funded jointly by the Strategic Priority Research Program of the Chinese Academy of Sciences （No. XDA05060600）, the Natural Science Foundation of Hebei Province （No. C2015503008）, and the Doctoral Initial Fund Project of Hebei Academy of Sciences （No. 20150503LR62-1）. We would also like to thank Christine Verhille at the University of British Columbia for her assistance with the English language and grammatical editing of the manuscript.
文摘Most studies do not consider the potential variation in carbon concentration among the different tree components of the same species in regional scale. This study examined the carbon concentrations of the compo- nents （i.e., foliage, branch, stem, and root） in a 10-year-old poplar species （Populus davidiana Dode） from the Desertification Combating Program of Northern China. The highest and lowest carbon concentrations were found in the stem and foliage, respectively. There was a significant difference in carbon concentrations among the different tree components. All of the observed carbon concentrations of tree components were lower than those predicted using the conversion factor of 0.5 applied to component biomass. Stem carbon made up 59.7% of the total tree biomass carbon. The power equation estimating proportion of tree biomass carbon against the independent variable of diameter at breast height explained more than 90% of the variability in allocation of carbon among tree components. Tree height, as a second independent variable is also discussed. Our results suggest that the difference in organic carbon concentration among tree components should be incorporated into accurately develop forest carbon budget. Moreover, further investigations on how the diameter at breast height equation developed in the present study performs across broader scales are required.
