In order to explore the differences in the compressive strength parallel to grain （CSPG） between different clones and individual woods of Populus deltoides Marsh., the CSPGs of 5 15-year-old P. deltoides clones were...In order to explore the differences in the compressive strength parallel to grain （CSPG） between different clones and individual woods of Populus deltoides Marsh., the CSPGs of 5 15-year-old P. deltoides clones were determined and analyzed. The results showed that there were significant differences in CSPG of wood between different clones of P. deltoides . The CSPG of the tested clones reached more than 41 MPa, which was higher than the average compressive strength of P. deltoides （32.94 MPa）. Similar to the changes of stem height, the CSPG of the clones gradually increased with the increase of stem height. However, there were significant differences in CSPG of an individual plant at different tree heights. The CSPG of P. deltoides clones was related with their growth traits, but not significantly. Therefore, it is expected to achieve simultaneous and independent improvement on CSPG and the growth of P. deltoides , so as to get excellent individuals with fast growth and high CSPG.展开更多
Botticelli’s The Birth of Venus continues to serve as an iconographic enigma and remains an enduring subject of scholarly analysis concerning the significance of mythological art and its symbolism during the Italian ...Botticelli’s The Birth of Venus continues to serve as an iconographic enigma and remains an enduring subject of scholarly analysis concerning the significance of mythological art and its symbolism during the Italian Renaissance.Therefore,it is particularly noteworthy to examine further the symbolic elements embedded within the imagery.This essay focuses on a specific component in the landscape of The Birth of Venus-the marsh plant on the riverbank,commonly known as cattail in English,tifa or stiancia in Italian,and Typha latifolia in Latin.Botticelli’s The Birth of Venus,executed between 1485 and 1490,is a tempera on canvas with gesso and gold applications.It was commissioned with specific aesthetic,cultural,and intellectual objectives and was intended to be displayed in a private chamber for personal viewing by members of the Medici family.Situated initially within the Medicean Villa at Castello,it has been exhibited at the Galleria degli Uffizi in Florence since 1815.This mythological painting exemplifies the Italian Renaissance principles of both physical and metaphysical humanism,visualized in a fusion of pagan and Christian iconography and iconology,incorporating symbolism that engages with antiquity and classical mythology.It also incorporates Italian Renaissance Neoplatonic philosophy,reflects Renaissance love poetry,demonstrates inventive patronage,and embodies spirituality directed towards a higher purpose.展开更多
海平面上升引起的淹水高度增加将改变潮汐湿地的碳循环过程。然而,目前的研究主要集中在淹水高度增加对土壤总碳库的影响上,对于其如何影响碳收支的平衡尚未厘清。基于此,该研究在闽江河口潮汐湿地搭建“沼泽管”实验平台,并设置CK(对照...海平面上升引起的淹水高度增加将改变潮汐湿地的碳循环过程。然而,目前的研究主要集中在淹水高度增加对土壤总碳库的影响上,对于其如何影响碳收支的平衡尚未厘清。基于此,该研究在闽江河口潮汐湿地搭建“沼泽管”实验平台,并设置CK(对照)、CK+20 cm、CK+40 cm 3种淹水处理,模拟当前、未来50年和100年的海平面上升情景。通过测定淹水高度增加对短叶茳芏(Cyperus malaccensis)沼泽湿地净生态系统CO_(2)交换量(NEE)、总初级生产力(GPP)、生态系统呼吸(ER)、植物生物量、植物光合特性指标和土壤理化指标的影响,从而明晰海平面上升对潮汐湿地碳收支平衡的影响。研究结果表明:淹水高度增加导致短叶茳芏地上生物量减少,地下生物量增加。与CK相比,CK+20 cm和CK+40 cm处理中,GPP分别降低27%和32%,ER分别增加20%和58%。GPP的减少与淹水高度增加后地上生物量的减少和植物光合特性指标(净光合速率、气孔导度、胞间CO_(2)浓度)的下降有关;而ER的增加与淹水高度增加后土壤氧化还原电位和可溶性有机碳含量的增加相关。在CK、CK+20 cm、CK+40 cm 3种淹水处理下,NEE分别为–539.8、–102.7和185.6 g C·m^(–2)·a^(–1)。上述结果表明,海平面上升情景下短叶茳芏沼泽湿地碳收支平衡被破坏。淹水高度增加20 cm,NEE增加,表明短叶茳芏沼泽湿地碳吸收能力减弱;淹水高度增加40 cm,NEE由负值转变为正值,表明短叶茳芏沼泽湿地生态系统由碳吸收转变为碳排放。该研究为预测和应对未来海平面上升对潮汐湿地碳循环的影响提供了科学依据。展开更多
Scirpus mariqueter Tang et Zhang is a typical pioneer plant colonizing the bare beaches of the Yangtse River estuary. To explore the life history strategy of the species with reference to environmental physical stre...Scirpus mariqueter Tang et Zhang is a typical pioneer plant colonizing the bare beaches of the Yangtse River estuary. To explore the life history strategy of the species with reference to environmental physical stress, the biomass allocations to different plant components and some related morphological parameters were examined along an elevational gradient within a salt marsh. Authors found that S. mariqueter performed best at medium elevation within the marsh, with relatively high density of shoot and individual ramet dry mass. Biomass allocation to corm was the highest at low elevations, and the least at high elevations, suggesting that a conservative strategy was adopted by the species to cope with the harsh physical conditions at the low elevation. The investment in rhizome decreased from low to high elevations, while the proportion of inflorescence mass increased, indicating that during the life history, the species shifts from predominant asexual reproduction to predominant sexual reproduction. This may be favourable for the species to colonize larger area, and to spread and persist at a meta_population level. Correlation analyses showed that sexual reproduction was inversely related to growth and asexual reproduction. However, it is difficult to determine the relationship between asexual reproduction and growth possibly because of the varied function of the corms of the species in different life history stages.展开更多
We used sequences of mitochondrial control region （807bp） in 75 samples from three breeding colonies and one wintering population to investigate the genetic diversity and population structure of Marsh Grassbird （Lo...We used sequences of mitochondrial control region （807bp） in 75 samples from three breeding colonies and one wintering population to investigate the genetic diversity and population structure of Marsh Grassbird （Locustella pryeri sinensis） in different regions of China. Marsh Grassbird retained a moderate amount of haplotype （0.759 ± 0.056） and nucleotide diversity （0.002）. The results of FST among 3 phy-logeographic units and ФST between breeding and wintering sites revealed little evidence of genetic distinction between different colonies. Neither UPGMA tree structure analysis nor Network picture analysis showed obvious divergence between populations at different locations. Analysis of molecular variance also showed a lack of regional subdivision within Locustella pryeri sinesis, 98.5% of source of variation within populations and only 1.5% among populations. The neutrality test showed negative Fu’s FS value, which, in combination with detection of the mismatch distribution, suggested that population expansion occurred in the evolu-tionary history of this species. This hypothesis was further supported by Tajima’s D test and Fu’s test （D = -1.80, p = 0.02; Fs = -22.11, p = 0.001）, this expansion was estimated to occur about 28,700 years ago.展开更多
基金Supported by the Major Science and Technology Program of Hunan Province(2017NK1010)the Research on High Efficient Cultivation of Populus deltoids Industrial Resources in Dongting Lake Area,the Special Found for the Development and Efficient Utilization Technology Innovation of Forestry Resources during the"13th Five-Year Plan"(2016YFD0600402-2)the Research and Demonstration of Populus Engineering Structural Materials Directional Cultivation and Value-Added Key Technologies,the Science and Technology Planning Project for Forestry of Hunan Province(XLK201506)
文摘In order to explore the differences in the compressive strength parallel to grain （CSPG） between different clones and individual woods of Populus deltoides Marsh., the CSPGs of 5 15-year-old P. deltoides clones were determined and analyzed. The results showed that there were significant differences in CSPG of wood between different clones of P. deltoides . The CSPG of the tested clones reached more than 41 MPa, which was higher than the average compressive strength of P. deltoides （32.94 MPa）. Similar to the changes of stem height, the CSPG of the clones gradually increased with the increase of stem height. However, there were significant differences in CSPG of an individual plant at different tree heights. The CSPG of P. deltoides clones was related with their growth traits, but not significantly. Therefore, it is expected to achieve simultaneous and independent improvement on CSPG and the growth of P. deltoides , so as to get excellent individuals with fast growth and high CSPG.
文摘Botticelli’s The Birth of Venus continues to serve as an iconographic enigma and remains an enduring subject of scholarly analysis concerning the significance of mythological art and its symbolism during the Italian Renaissance.Therefore,it is particularly noteworthy to examine further the symbolic elements embedded within the imagery.This essay focuses on a specific component in the landscape of The Birth of Venus-the marsh plant on the riverbank,commonly known as cattail in English,tifa or stiancia in Italian,and Typha latifolia in Latin.Botticelli’s The Birth of Venus,executed between 1485 and 1490,is a tempera on canvas with gesso and gold applications.It was commissioned with specific aesthetic,cultural,and intellectual objectives and was intended to be displayed in a private chamber for personal viewing by members of the Medici family.Situated initially within the Medicean Villa at Castello,it has been exhibited at the Galleria degli Uffizi in Florence since 1815.This mythological painting exemplifies the Italian Renaissance principles of both physical and metaphysical humanism,visualized in a fusion of pagan and Christian iconography and iconology,incorporating symbolism that engages with antiquity and classical mythology.It also incorporates Italian Renaissance Neoplatonic philosophy,reflects Renaissance love poetry,demonstrates inventive patronage,and embodies spirituality directed towards a higher purpose.
文摘海平面上升引起的淹水高度增加将改变潮汐湿地的碳循环过程。然而,目前的研究主要集中在淹水高度增加对土壤总碳库的影响上,对于其如何影响碳收支的平衡尚未厘清。基于此,该研究在闽江河口潮汐湿地搭建“沼泽管”实验平台,并设置CK(对照)、CK+20 cm、CK+40 cm 3种淹水处理,模拟当前、未来50年和100年的海平面上升情景。通过测定淹水高度增加对短叶茳芏(Cyperus malaccensis)沼泽湿地净生态系统CO_(2)交换量(NEE)、总初级生产力(GPP)、生态系统呼吸(ER)、植物生物量、植物光合特性指标和土壤理化指标的影响,从而明晰海平面上升对潮汐湿地碳收支平衡的影响。研究结果表明:淹水高度增加导致短叶茳芏地上生物量减少,地下生物量增加。与CK相比,CK+20 cm和CK+40 cm处理中,GPP分别降低27%和32%,ER分别增加20%和58%。GPP的减少与淹水高度增加后地上生物量的减少和植物光合特性指标(净光合速率、气孔导度、胞间CO_(2)浓度)的下降有关;而ER的增加与淹水高度增加后土壤氧化还原电位和可溶性有机碳含量的增加相关。在CK、CK+20 cm、CK+40 cm 3种淹水处理下,NEE分别为–539.8、–102.7和185.6 g C·m^(–2)·a^(–1)。上述结果表明,海平面上升情景下短叶茳芏沼泽湿地碳收支平衡被破坏。淹水高度增加20 cm,NEE增加,表明短叶茳芏沼泽湿地碳吸收能力减弱;淹水高度增加40 cm,NEE由负值转变为正值,表明短叶茳芏沼泽湿地生态系统由碳吸收转变为碳排放。该研究为预测和应对未来海平面上升对潮汐湿地碳循环的影响提供了科学依据。
文摘Scirpus mariqueter Tang et Zhang is a typical pioneer plant colonizing the bare beaches of the Yangtse River estuary. To explore the life history strategy of the species with reference to environmental physical stress, the biomass allocations to different plant components and some related morphological parameters were examined along an elevational gradient within a salt marsh. Authors found that S. mariqueter performed best at medium elevation within the marsh, with relatively high density of shoot and individual ramet dry mass. Biomass allocation to corm was the highest at low elevations, and the least at high elevations, suggesting that a conservative strategy was adopted by the species to cope with the harsh physical conditions at the low elevation. The investment in rhizome decreased from low to high elevations, while the proportion of inflorescence mass increased, indicating that during the life history, the species shifts from predominant asexual reproduction to predominant sexual reproduction. This may be favourable for the species to colonize larger area, and to spread and persist at a meta_population level. Correlation analyses showed that sexual reproduction was inversely related to growth and asexual reproduction. However, it is difficult to determine the relationship between asexual reproduction and growth possibly because of the varied function of the corms of the species in different life history stages.
基金supported by National Natural Science Foundation of China (No. 130370221 and No. 30770309)
文摘We used sequences of mitochondrial control region （807bp） in 75 samples from three breeding colonies and one wintering population to investigate the genetic diversity and population structure of Marsh Grassbird （Locustella pryeri sinensis） in different regions of China. Marsh Grassbird retained a moderate amount of haplotype （0.759 ± 0.056） and nucleotide diversity （0.002）. The results of FST among 3 phy-logeographic units and ФST between breeding and wintering sites revealed little evidence of genetic distinction between different colonies. Neither UPGMA tree structure analysis nor Network picture analysis showed obvious divergence between populations at different locations. Analysis of molecular variance also showed a lack of regional subdivision within Locustella pryeri sinesis, 98.5% of source of variation within populations and only 1.5% among populations. The neutrality test showed negative Fu’s FS value, which, in combination with detection of the mismatch distribution, suggested that population expansion occurred in the evolu-tionary history of this species. This hypothesis was further supported by Tajima’s D test and Fu’s test （D = -1.80, p = 0.02; Fs = -22.11, p = 0.001）, this expansion was estimated to occur about 28,700 years ago.
