After the Wenchuan earthquake on May 12, 2008 and the rainstorm and debris flow on August 14, 2010, the vegetation in Hongchun Gully, Yingxiu town is gradually recovering naturally, and the plant community is graduall...After the Wenchuan earthquake on May 12, 2008 and the rainstorm and debris flow on August 14, 2010, the vegetation in Hongchun Gully, Yingxiu town is gradually recovering naturally, and the plant community is gradually undergoing community succession. Based on the field vegetation survey data of 46 quadrats in 5 field plots, this study comprehensively analyzed the plant community, species number changes and vegetation characteristics of Hongchun Gully in Yingxiu town at different stages of vegetation succession after the earthquake by using the unified method. The results show that: 1) There are 61 families, 96 genera and 110 species of plants on the Hongchun Gully landslide. Among them, Cunninghamia lanceolata is the most widely distributed, and together with Cryptomeria japonica, it constitutes the main dominant species in the tree layer;The dominant species in shrub layer are Rubussp., Hydrangea strigosa, Rubus tephrodes, etc. The dominant species in herb layer are Artemisia argyi, Stellaria media and Senecio scandens. 2) The vegetation restoration in Hongchun Gully is relatively good, with herbs as the main species in the early stage of succession, shrubs and herbs as the main species in the middle stage of succession and trees as the main species in the late stage of succession;And the longer the succession time, the better the vegetation restoration and the richer the species. 3) Vegetation succession is related to the succession time, and the succession is always in the direction of strong adaptability. The study provides important data reference for further discussing the natural restoration and succession process and mechanism of plant communities on the damaged landslide formed after the earthquake, and provides theoretical basis for vegetation restoration and ecological reconstruction in the hardest hit areas in southwest China after the earthquake.展开更多
Objective： To explore the relationships between the daily total intake of fluoride, dental fluorosis and dental caries. Methods： An epidemiological method was used to investigate the daily total intake of fluoride, ...Objective： To explore the relationships between the daily total intake of fluoride, dental fluorosis and dental caries. Methods： An epidemiological method was used to investigate the daily total intake of fluoride, dental fluorosis, and dental caries among 236 and 290 children aged 8-13 years in a severe endemic area and in a non-fluorosis control area, respectively. The children were divided into eight subgroups according to each child＇ s estimated daily total intake of fluoride. The prevalence of dental fluorosis and dental caries in each group was calculated. Results： As expected, elevated levels of fluoride intake were significantly associated with a higher prevalence of dental fluorosis and an increasing amount of more severe defect dental fluorosis. When the daily total F intake was 2.78 mg/child/day, the prevalence of dental fluorosis was nearly 100%, with the prevalence of defect dental fluorosis increasing with increasing fluoride intake. There was also a significant negative（inverse） dose-response relationship between the daily total intake of fluoride and the overall prevalence of dental caries, the prevalence of which decreased when the daily total intake of fluoride increased up to 3.32 mg/child/day. However, at higher levels of daily total intake of fluoride the prevalence of dental caries increased, giving rise to a U-shaped dose-response relationship curve. Conclusion： It is important to monitor total fluoride exposure and protect children from excessive fluoride intake, especially during the years of tooth development.展开更多
文摘After the Wenchuan earthquake on May 12, 2008 and the rainstorm and debris flow on August 14, 2010, the vegetation in Hongchun Gully, Yingxiu town is gradually recovering naturally, and the plant community is gradually undergoing community succession. Based on the field vegetation survey data of 46 quadrats in 5 field plots, this study comprehensively analyzed the plant community, species number changes and vegetation characteristics of Hongchun Gully in Yingxiu town at different stages of vegetation succession after the earthquake by using the unified method. The results show that: 1) There are 61 families, 96 genera and 110 species of plants on the Hongchun Gully landslide. Among them, Cunninghamia lanceolata is the most widely distributed, and together with Cryptomeria japonica, it constitutes the main dominant species in the tree layer;The dominant species in shrub layer are Rubussp., Hydrangea strigosa, Rubus tephrodes, etc. The dominant species in herb layer are Artemisia argyi, Stellaria media and Senecio scandens. 2) The vegetation restoration in Hongchun Gully is relatively good, with herbs as the main species in the early stage of succession, shrubs and herbs as the main species in the middle stage of succession and trees as the main species in the late stage of succession;And the longer the succession time, the better the vegetation restoration and the richer the species. 3) Vegetation succession is related to the succession time, and the succession is always in the direction of strong adaptability. The study provides important data reference for further discussing the natural restoration and succession process and mechanism of plant communities on the damaged landslide formed after the earthquake, and provides theoretical basis for vegetation restoration and ecological reconstruction in the hardest hit areas in southwest China after the earthquake.
基金supported by Jiangsu Provincial Foundation of Prevention Medicine(Y200621)
文摘Objective： To explore the relationships between the daily total intake of fluoride, dental fluorosis and dental caries. Methods： An epidemiological method was used to investigate the daily total intake of fluoride, dental fluorosis, and dental caries among 236 and 290 children aged 8-13 years in a severe endemic area and in a non-fluorosis control area, respectively. The children were divided into eight subgroups according to each child＇ s estimated daily total intake of fluoride. The prevalence of dental fluorosis and dental caries in each group was calculated. Results： As expected, elevated levels of fluoride intake were significantly associated with a higher prevalence of dental fluorosis and an increasing amount of more severe defect dental fluorosis. When the daily total F intake was 2.78 mg/child/day, the prevalence of dental fluorosis was nearly 100%, with the prevalence of defect dental fluorosis increasing with increasing fluoride intake. There was also a significant negative（inverse） dose-response relationship between the daily total intake of fluoride and the overall prevalence of dental caries, the prevalence of which decreased when the daily total intake of fluoride increased up to 3.32 mg/child/day. However, at higher levels of daily total intake of fluoride the prevalence of dental caries increased, giving rise to a U-shaped dose-response relationship curve. Conclusion： It is important to monitor total fluoride exposure and protect children from excessive fluoride intake, especially during the years of tooth development.
