Improved understanding of the spatial dynamics of invasive plant species is critical for effective land management and control of future invasion. The Yancheng National Nature Reserve (YNNR), an internationally import...Improved understanding of the spatial dynamics of invasive plant species is critical for effective land management and control of future invasion. The Yancheng National Nature Reserve (YNNR), an internationally important wetland, has the largest distribution of alien Spartina alterniflora in China. This alien plant was intentionally introduced for erosion prevention and dike protection in China. However, it became an aggressive competitor with native salt marsh plants in the coastal regions in China. High resolution imagery, SPOT-5, was used to map plant communities including invasive species in the south core zone of YNNR with the natural ecosystem of salt marshes in 2003, 2005 and 2008. The fuzzy set assessment method significantly improved the classification accuracies over the conventional error matrix, i.e., from 73.8%, 73.5% and 81.4% to 91.5%, 91.6% and 93.4% in 2003, 2005 and 2008, respectively. It shows a great potential for mapping invasive plant species. Phragmites australis and S. alterniflora were the most accurately mapped classes, and sparse and dense Suaeda glauca were the least accurately mapped. From 2003 to 2008, S. alterniflora increased 28.8% from 1664.1 to 2142.6 ha in area size, and more than 2.5 times from 742 to 2608 patches. The highest increase in patch number occurred within the interval between 2001 and 3000 m from the eastern baseline. This increase was dominated by small patches with area less than 200 m<sup>2</sup>. During the study period, the mean spread width was 405 ± 80.7 m in the original large patch of area over 200 ha. The eastward/seaward spread was distinctively larger than the westward/landward. The results enhance the understanding of alien plant’s invasion patterns and help improve conservation efforts.展开更多
A multi-scale approach is essential to assess the factors that limit avian habitat use. Numerous studies have examined habitat use by the red-crowned crane, but integrated multi-scale habitat use information is lackin...A multi-scale approach is essential to assess the factors that limit avian habitat use. Numerous studies have examined habitat use by the red-crowned crane, but integrated multi-scale habitat use information is lacking. We evaluated the effects of several habitat variables quantified across many spatial scales on crane use and abundance in two periods （2000 and 2009） at Yancheng National Nature Reserve, China. The natural wetlands decreased in area by 30,601 ha （-6.9%） from 2000 to 2009, pre- dominantly as a result of conversion to aquaculture ponds and farmland, and the remaining was under degradation due to expan- sion of the exotic smooth cordgrass. The cranes are focusing in on either larger patches or those that are in close proximity to each other in both years, but occupied patches had smaller size, less proximity and more regular boundaries in 2009. At landscape scales, the area percentage of common seepweed, reed ponds and paddy fields had a greater positive impact on crane presence than the area percentage of aquaculture ponds. The cranes were more abundant in patches that had a greater percent area of common seepweed and reed ponds, while the percent area of paddy fields was inversely related to crane abundance in 2009 due to changing agricultural practices. In 2009, cranes tended to use less fragmented plots in natural wetlands and more fragmented plots in anthropogenic paddy fields, which were largely associated with the huge loss and degradation of natural habitats between the two years. Management should focus on restoration of large patches of natural wetlands, and formation of a relatively stable area of large paddy field and reed pond to mitigate the loss of natural wetlands [Current Zoology 59 （5）： 604-617, 2013].展开更多
Objective: To isolate bioactive compounds from the endophytic fungus Fusarium sporotrichioides isolated from Rauwolfia yunnanensis, and investigate their pharmacological activities.Methods: The chemical constituents w...Objective: To isolate bioactive compounds from the endophytic fungus Fusarium sporotrichioides isolated from Rauwolfia yunnanensis, and investigate their pharmacological activities.Methods: The chemical constituents were isolated and purified by combining with ODS column chromatography, silica gel column chromatography and by performing semipreparative HPLC. Their structures were established on the basis of 1D NMR(1H-NMR and13C-NMR) and 2D NMR(1H–1H COSY,HSQC, HMBC and NOESY), as well as HRESIMS and comparison with literature data. In addition, the absolute configuration of compound 1 was determined by calculated ECD data.Results: One previously undescribed tetracyclic triterpenoid derivative, named as integracide L(1), 12aacetoxy-4,4-dimethyl-24-methylene-5a-cholesta-8,14-diene-2a,3β,11β-triol(2), 12a-acetoxy-4,4-dime thyl-24-methylene-5a-cholesta-8-momoene-2a,3β,11β-triol(3), 12a-acetoxy-4,4-dimethyl-24-methy lene-5a-cholesta-8,14-diene-3β,11β-triol(4), and 12a-acetoxy-4,4-dimethyl-24-methylene-5acholesta-8-momoene-3β,11β-triol(5) were isolated from F. sporotrichioide. Moreover, compound 1 was rare tetracyclic triterpenoid with single methyl replacement at C-4 position.Conclusion: Compound 1 was a new tetracyclic triterpenoid isolated from the endophytic fungus F.sporotrichioides. In addition, compound 2 could inhibit the growth of three different human cancer cells significantly. Compounds 3 and 5 were found to possess better cytotoxic activities on Hep G-2 cells than the other compounds, with IC50values of(2.8 ± 0.1) and(6.3 ± 0.3) μmol/L respectively.展开更多
Soil loss by water erosion is one of the main threats to soil health and food production in intensively used agricultural areas.To assess its significance to overall sediment production,we applied the Water and Tillag...Soil loss by water erosion is one of the main threats to soil health and food production in intensively used agricultural areas.To assess its significance to overall sediment production,we applied the Water and Tillage Erosion Model/Sediment Delivery model(WaTEM/SEDEM)to the Luoyugou catchment,a sub-catchment of the Yellow River Basin within the Chinese Loess Plateau.WaTEM/SEDEM considers rill and interrill erosion and deposition rates to calculate the sediment yield rates leaving the catchment.Ter-races were established in the 1990s to reduce soil loss in this area,but no soil erosion modeling has been published regarding the effect of this mitigation measure.Therefore,we applied 1000 Monte Carlo simulations of the WaTEM/SEDEM,and the modeled average soil loss by rill and interrill erosion for 2020 was 12.2±0.5 t ha^(-1)yr^(-1),with a sediment yield at the outlet of 53,207.8±11,244.1 t yr^(-1).The results indicated that the terracing reduced gross soil loss rates(from 51.8t ha^(-1)yr^(-1)in 1986 to 12.2±0.5 t ha^(-1)yr^(-1)in 2020),while land cover changes,mainly the conversion of forests and grassland,partly coun-teracted the mitigation(combined effect:76%reduction).Modeled sediment loads by rill and interrill erosion accounted for 22.8%of the total long-term sediment production recorded by flow discharge measurements.Other processes not considered by the model,such as landslides,gully erosion,riverbank erosion,and sediment production by construction,seem to predominantly influence the overall sedi-ment yield.Considering years with baseline sediment production only,the measured and modeled sediment yields compared favorably,indicating that the latter processes primarily contribute during extreme events.展开更多
文摘Improved understanding of the spatial dynamics of invasive plant species is critical for effective land management and control of future invasion. The Yancheng National Nature Reserve (YNNR), an internationally important wetland, has the largest distribution of alien Spartina alterniflora in China. This alien plant was intentionally introduced for erosion prevention and dike protection in China. However, it became an aggressive competitor with native salt marsh plants in the coastal regions in China. High resolution imagery, SPOT-5, was used to map plant communities including invasive species in the south core zone of YNNR with the natural ecosystem of salt marshes in 2003, 2005 and 2008. The fuzzy set assessment method significantly improved the classification accuracies over the conventional error matrix, i.e., from 73.8%, 73.5% and 81.4% to 91.5%, 91.6% and 93.4% in 2003, 2005 and 2008, respectively. It shows a great potential for mapping invasive plant species. Phragmites australis and S. alterniflora were the most accurately mapped classes, and sparse and dense Suaeda glauca were the least accurately mapped. From 2003 to 2008, S. alterniflora increased 28.8% from 1664.1 to 2142.6 ha in area size, and more than 2.5 times from 742 to 2608 patches. The highest increase in patch number occurred within the interval between 2001 and 3000 m from the eastern baseline. This increase was dominated by small patches with area less than 200 m<sup>2</sup>. During the study period, the mean spread width was 405 ± 80.7 m in the original large patch of area over 200 ha. The eastward/seaward spread was distinctively larger than the westward/landward. The results enhance the understanding of alien plant’s invasion patterns and help improve conservation efforts.
文摘A multi-scale approach is essential to assess the factors that limit avian habitat use. Numerous studies have examined habitat use by the red-crowned crane, but integrated multi-scale habitat use information is lacking. We evaluated the effects of several habitat variables quantified across many spatial scales on crane use and abundance in two periods （2000 and 2009） at Yancheng National Nature Reserve, China. The natural wetlands decreased in area by 30,601 ha （-6.9%） from 2000 to 2009, pre- dominantly as a result of conversion to aquaculture ponds and farmland, and the remaining was under degradation due to expan- sion of the exotic smooth cordgrass. The cranes are focusing in on either larger patches or those that are in close proximity to each other in both years, but occupied patches had smaller size, less proximity and more regular boundaries in 2009. At landscape scales, the area percentage of common seepweed, reed ponds and paddy fields had a greater positive impact on crane presence than the area percentage of aquaculture ponds. The cranes were more abundant in patches that had a greater percent area of common seepweed and reed ponds, while the percent area of paddy fields was inversely related to crane abundance in 2009 due to changing agricultural practices. In 2009, cranes tended to use less fragmented plots in natural wetlands and more fragmented plots in anthropogenic paddy fields, which were largely associated with the huge loss and degradation of natural habitats between the two years. Management should focus on restoration of large patches of natural wetlands, and formation of a relatively stable area of large paddy field and reed pond to mitigate the loss of natural wetlands [Current Zoology 59 （5）： 604-617, 2013].
基金funded by Outstanding Youth Foundation of Heilongjiang province(NO.YQ2021H009).
文摘Objective: To isolate bioactive compounds from the endophytic fungus Fusarium sporotrichioides isolated from Rauwolfia yunnanensis, and investigate their pharmacological activities.Methods: The chemical constituents were isolated and purified by combining with ODS column chromatography, silica gel column chromatography and by performing semipreparative HPLC. Their structures were established on the basis of 1D NMR(1H-NMR and13C-NMR) and 2D NMR(1H–1H COSY,HSQC, HMBC and NOESY), as well as HRESIMS and comparison with literature data. In addition, the absolute configuration of compound 1 was determined by calculated ECD data.Results: One previously undescribed tetracyclic triterpenoid derivative, named as integracide L(1), 12aacetoxy-4,4-dimethyl-24-methylene-5a-cholesta-8,14-diene-2a,3β,11β-triol(2), 12a-acetoxy-4,4-dime thyl-24-methylene-5a-cholesta-8-momoene-2a,3β,11β-triol(3), 12a-acetoxy-4,4-dimethyl-24-methy lene-5a-cholesta-8,14-diene-3β,11β-triol(4), and 12a-acetoxy-4,4-dimethyl-24-methylene-5acholesta-8-momoene-3β,11β-triol(5) were isolated from F. sporotrichioide. Moreover, compound 1 was rare tetracyclic triterpenoid with single methyl replacement at C-4 position.Conclusion: Compound 1 was a new tetracyclic triterpenoid isolated from the endophytic fungus F.sporotrichioides. In addition, compound 2 could inhibit the growth of three different human cancer cells significantly. Compounds 3 and 5 were found to possess better cytotoxic activities on Hep G-2 cells than the other compounds, with IC50values of(2.8 ± 0.1) and(6.3 ± 0.3) μmol/L respectively.
文摘Soil loss by water erosion is one of the main threats to soil health and food production in intensively used agricultural areas.To assess its significance to overall sediment production,we applied the Water and Tillage Erosion Model/Sediment Delivery model(WaTEM/SEDEM)to the Luoyugou catchment,a sub-catchment of the Yellow River Basin within the Chinese Loess Plateau.WaTEM/SEDEM considers rill and interrill erosion and deposition rates to calculate the sediment yield rates leaving the catchment.Ter-races were established in the 1990s to reduce soil loss in this area,but no soil erosion modeling has been published regarding the effect of this mitigation measure.Therefore,we applied 1000 Monte Carlo simulations of the WaTEM/SEDEM,and the modeled average soil loss by rill and interrill erosion for 2020 was 12.2±0.5 t ha^(-1)yr^(-1),with a sediment yield at the outlet of 53,207.8±11,244.1 t yr^(-1).The results indicated that the terracing reduced gross soil loss rates(from 51.8t ha^(-1)yr^(-1)in 1986 to 12.2±0.5 t ha^(-1)yr^(-1)in 2020),while land cover changes,mainly the conversion of forests and grassland,partly coun-teracted the mitigation(combined effect:76%reduction).Modeled sediment loads by rill and interrill erosion accounted for 22.8%of the total long-term sediment production recorded by flow discharge measurements.Other processes not considered by the model,such as landslides,gully erosion,riverbank erosion,and sediment production by construction,seem to predominantly influence the overall sedi-ment yield.Considering years with baseline sediment production only,the measured and modeled sediment yields compared favorably,indicating that the latter processes primarily contribute during extreme events.
