A Review 1.Preliminary investigations in China's forest ecosystems and the establishment of institutions In the1950s,Chinese Academy of Sciences(CAS) and several relevant institutes organized a series of large-sca...A Review 1.Preliminary investigations in China's forest ecosystems and the establishment of institutions In the1950s,Chinese Academy of Sciences(CAS) and several relevant institutes organized a series of large-scale comprehensive surveys on the flora and展开更多
Phylobetadiversity incorporates phylogenetic information and beta diversity,and can account for the ecological similarities between communities with a phylogenetic perspective.Although different phylobetadiversity ind...Phylobetadiversity incorporates phylogenetic information and beta diversity,and can account for the ecological similarities between communities with a phylogenetic perspective.Although different phylobetadiversity indices reflect differences in different characteristics between communities,the results of different phylobetadiversity indices are not comparable.In this study we examined phylobetadiversity indices for a 24-hm 2 plot in the Gutianshan National Nature Reserve.It was found the abundanceweighted D pw was almost identical to Rao's D of Rao's quadratic entropy.PhyloSor had a similar ecological meaning and algorithm to UniFrac.Although Dnn was different in definition from UniFrac and PhyloSor,they were all strongly correlated.The effect of species abundance on phylobetadiversity was not significant when scales were relatively small,but was significant at larger scales.These contrasts likely resulted from reductions in evenness in communities as scales increased.P ST and Rao's H better reflected the distance-decay changes caused by spatial and habitat variation than other indices at larger scales,whereas AW-D nn and D nn better reflected these changes at small scales.展开更多
Measurements were taken of Bt protein expressed in the leaves of transgenic cotton (Gos- sypium hirsutum) transformed with a synthesized Bt (Bacillus thuringiensis) cry1A gene and its persistent level in larval bodies...Measurements were taken of Bt protein expressed in the leaves of transgenic cotton (Gos- sypium hirsutum) transformed with a synthesized Bt (Bacillus thuringiensis) cry1A gene and its persistent level in larval bodies and faeces of a non-targeted insect pest, beet armyworm (Spodoptera exigua). We performed enzyme linked immunosorbent assays (ELISA) and bioassays using neonate larvae of cot- ton bollworm (Helicoverpa armigera) to detect the insecticidal activity of residual Bt protein at the sec- ond trophic level. The results showed that Bt protein content in functional leaves was different at various developmental stages and was different among plants at the same stage. Even though Bt protein concentration in the larval bodies and faeces de- creased 97.5%―99% compared to that found in cotton leaves subsequently fed to beet armyworm larvae, it still had a lethal effect on neonate cotton bollworm larvae. Therefore, Bt protein present at the second trophic level had insecticidal activity. This result is important in understanding and predicting the effect of transgenic plants on nontarget organisms.展开更多
With the full survey data for a 24-ha subtropical evergreen broad-leaved forest dynamics plot,we evaluated spatial variation in forest structure characteristics(basal area and aboveground biomass),and calculated the m...With the full survey data for a 24-ha subtropical evergreen broad-leaved forest dynamics plot,we evaluated spatial variation in forest structure characteristics(basal area and aboveground biomass),and calculated the minimal sample size and total sampling area necessary to estimate the forest structure characteristics within 20%(±10%) of the observed values with 95% probability for particular quadrat sizes by using a computer program that is designed to simulate the sampling process by allowing different sized quadrats to be randomly located within the sampling region.We found that(1) based on the 600 20 m×20 m subplots,basal area and aboveground biomass displayed a high degree of variation,with respective coefficients of variation of 27% and 31%;(2) based on the computer simulation analysis,the variability of basal area and aboveground biomass decreased with increasing quadrat size.The number of quadrats required to achieve the specified degree of precision dropped sharply with the increase of quadrat size.However,the total sampling area increased with increasing quadrat size,suggesting that using several small quadrats across the sampling area is more efficient than using fewer larger quadrats.Results of this study are valuable for evaluating the reliability of previous research and may assist researchers in designing effective sampling strategies for future field surveys,particularly in subtropical evergreen broad-leaved forests in China.展开更多
文摘A Review 1.Preliminary investigations in China's forest ecosystems and the establishment of institutions In the1950s,Chinese Academy of Sciences(CAS) and several relevant institutes organized a series of large-scale comprehensive surveys on the flora and
基金supported by Key Innovation Project of Chinese Academy of Sciences (KZCX2-EW-Z-5)National Natural Science Foundation of China (31170401)
文摘Phylobetadiversity incorporates phylogenetic information and beta diversity,and can account for the ecological similarities between communities with a phylogenetic perspective.Although different phylobetadiversity indices reflect differences in different characteristics between communities,the results of different phylobetadiversity indices are not comparable.In this study we examined phylobetadiversity indices for a 24-hm 2 plot in the Gutianshan National Nature Reserve.It was found the abundanceweighted D pw was almost identical to Rao's D of Rao's quadratic entropy.PhyloSor had a similar ecological meaning and algorithm to UniFrac.Although Dnn was different in definition from UniFrac and PhyloSor,they were all strongly correlated.The effect of species abundance on phylobetadiversity was not significant when scales were relatively small,but was significant at larger scales.These contrasts likely resulted from reductions in evenness in communities as scales increased.P ST and Rao's H better reflected the distance-decay changes caused by spatial and habitat variation than other indices at larger scales,whereas AW-D nn and D nn better reflected these changes at small scales.
基金supported by part of a 973 Project(Grant No.2001CB109004)National Natural Science Foundation of China(Grant No.30270228)a grant of the President Foundation of CAS,China,to Wei Wei.
文摘Measurements were taken of Bt protein expressed in the leaves of transgenic cotton (Gos- sypium hirsutum) transformed with a synthesized Bt (Bacillus thuringiensis) cry1A gene and its persistent level in larval bodies and faeces of a non-targeted insect pest, beet armyworm (Spodoptera exigua). We performed enzyme linked immunosorbent assays (ELISA) and bioassays using neonate larvae of cot- ton bollworm (Helicoverpa armigera) to detect the insecticidal activity of residual Bt protein at the sec- ond trophic level. The results showed that Bt protein content in functional leaves was different at various developmental stages and was different among plants at the same stage. Even though Bt protein concentration in the larval bodies and faeces de- creased 97.5%―99% compared to that found in cotton leaves subsequently fed to beet armyworm larvae, it still had a lethal effect on neonate cotton bollworm larvae. Therefore, Bt protein present at the second trophic level had insecticidal activity. This result is important in understanding and predicting the effect of transgenic plants on nontarget organisms.
基金supported by Key Innovation Project of Chinese Academy of Sciences (KZCX2-YW-430)the Strategic Priority Research Program of Chinese Academy of Sciences (XDA05050204)
文摘With the full survey data for a 24-ha subtropical evergreen broad-leaved forest dynamics plot,we evaluated spatial variation in forest structure characteristics(basal area and aboveground biomass),and calculated the minimal sample size and total sampling area necessary to estimate the forest structure characteristics within 20%(±10%) of the observed values with 95% probability for particular quadrat sizes by using a computer program that is designed to simulate the sampling process by allowing different sized quadrats to be randomly located within the sampling region.We found that(1) based on the 600 20 m×20 m subplots,basal area and aboveground biomass displayed a high degree of variation,with respective coefficients of variation of 27% and 31%;(2) based on the computer simulation analysis,the variability of basal area and aboveground biomass decreased with increasing quadrat size.The number of quadrats required to achieve the specified degree of precision dropped sharply with the increase of quadrat size.However,the total sampling area increased with increasing quadrat size,suggesting that using several small quadrats across the sampling area is more efficient than using fewer larger quadrats.Results of this study are valuable for evaluating the reliability of previous research and may assist researchers in designing effective sampling strategies for future field surveys,particularly in subtropical evergreen broad-leaved forests in China.
