The Green Corridor in the lower reaches of the Tarim River is not only a unique natural landscape in desert but also an important passageway. Nowadays, the ecologic environment of the corridor is getting worse and wor...The Green Corridor in the lower reaches of the Tarim River is not only a unique natural landscape in desert but also an important passageway. Nowadays, the ecologic environment of the corridor is getting worse and worse due to man’s economic activities and the lack of knowledge of the importance of the environment, which is one of is the three environment problems in Xinjiang. The corridor is in great need of planning and managing.展开更多
Urbanization research is essential for the sustainable use of regional land resources and ecological environment protection.The expansion process and driving factors of urban construction land at different scales in t...Urbanization research is essential for the sustainable use of regional land resources and ecological environment protection.The expansion process and driving factors of urban construction land at different scales in the middle reaches of the Yellow River(MRYR)have not been comprehensively elucidated.In this study,we explored the distribution pattern of urban construction land on different slope gradients at different scales and analyzed its influencing factors.The main findings were as follows:(1)There has been significant expansion of urban construction land in the MRYR over the past 20 years.Spatial heterogeneity was observed in the regional urban construction land expansion process among different geomorphic regions.(2)The urban construction land in the MRYR was expanded vertically to areas with slopes of>5°,particularly in 2005–2010.Significant slope climbing of urban construction land was observed in the loess hilly-gully and rocky mountain areas.(3)In MRYR,68.45%of the counties were categorized as the slope-climbing types,including 37.38%high-slope-climbing types.(4)The regional population density and economic development level were closely associated with regional urban construction land area variability.(5)The climbing process of regional urban construction can effectively alleviate farmland encroachment and pressure on the regional ecological environment.The urban expansion of the metropolitan distribution areas in the Plain region(such as Xi'an,Taiyuan)had a relatively significant impact on the local carbon storage.展开更多
Ecological experiment was conducted in this paper to study the allometric growth in Squaliobarbus curriculus larvae and juveniles from Zhaoqing Reach of the Pearl River. The results showed that after first feeding, th...Ecological experiment was conducted in this paper to study the allometric growth in Squaliobarbus curriculus larvae and juveniles from Zhaoqing Reach of the Pearl River. The results showed that after first feeding, the organs associated to swimming, feeling and feeding of larvae differentiated rapidly, and exhibited allometric growth. The head length, tail length and head height exhibited positive allometric growth, while trunk length exhibited negative allometric growth before reaching the growth inflexion point 20 d after first feeding, and positive allometric growth after the inflection point. Body height exhibited positive allometric growth both before and after the growth inflexion point at 18 d after first feeding. The inflexion points of snout length, eye diameter and post-eye head length occurred 23, 19 and 16 d after first feeding. For swimming organs, the dorsal fin, pelvic fins and anal fin exhibited positive allometric growth both before and after the inflexion point at 18, 19 and 17 d after first feeding; but the tail fin exhibited positive allometric growth before the inflexion point at 14 d after first feeding, and negative allometric growth after the inflexion point. S. curriculus larvae can possess various abilities soon after first feeding to survive at early stage due to the rapid development of swimming, feeling, feeding and other organs, which has important ecological significance to adapt to the complex external environment.展开更多
倒伏是限制长江流域直播油菜高产稳产的关键因素之一,水稻秸秆还田后,氮肥运筹通过碳氮代谢和茎秆结构影响油菜抗倒性能。本研究采用裂区设计,以华油杂62为材料,基于稻-油轮作定位试验,研究秸秆管理耦合氮肥运筹对高密度直播油菜抗倒性...倒伏是限制长江流域直播油菜高产稳产的关键因素之一,水稻秸秆还田后,氮肥运筹通过碳氮代谢和茎秆结构影响油菜抗倒性能。本研究采用裂区设计,以华油杂62为材料,基于稻-油轮作定位试验,研究秸秆管理耦合氮肥运筹对高密度直播油菜抗倒性的影响。以秸秆还田处理为主区(R0为秸秆不还田, R1为全量还田),以氮肥运筹为副区, CK为240 kg hm^(-2)的常规施氮量及基肥∶苗肥∶薹肥∶花肥=6∶4∶0∶0, N1、N2、N3、N4均为减氮20%,但基肥∶苗肥∶薹肥∶花肥分别为10∶0∶0∶0、6∶4∶0∶0、6∶2∶2∶0和6∶2∶0∶2,研究不同处理对成熟期油菜茎秆细胞壁成分、茎秆硅钙含量及花期茎秆显微结构等指标的影响。结果表明,相较于秸秆不还田,秸秆还田后,油菜成熟期地上部鲜重增加29.1%,茎秆抗折力增加23.3%,茎秆纤维素、总木质素、果胶、硅、钙含量分别显著(P<0.05)增加了26.3%、3.4%、30.6%、45.0%和9.5%,茎秆强度和韧性显著增强,但油菜株高、地上部鲜重的增幅大于茎秆抗折力增幅,导致倒伏指数平均增加了7.9%。合理的氮肥运筹可提高茎秆质量,从而降低倒伏指数。秸秆还田下N3处理使田间实际倒伏角度较常规施氮处理降低2.6%,茎秆抗折力增加15.2%,倒伏指数降低10.2%,优于其他处理。其机理是该处理显著增加了茎秆纤维素、果胶和钙含量及花期茎秆皮层厚度、表皮厚度、维管束长、横截面积、维管束数目以及维管束面积,显微结构排列更加合理,抗倒性显著增强。因此,在长江流域水稻秸秆还田和油菜高密直播条件下,以全生育期施氮192 kg hm^(-2)(基肥∶苗肥∶薹肥=6∶2∶2)为推荐施肥方案,可以减少氮肥投入,增强茎秆的抗倒伏能力,提高机械收获效率,实现高产抗倒协同的目标。展开更多
文摘The Green Corridor in the lower reaches of the Tarim River is not only a unique natural landscape in desert but also an important passageway. Nowadays, the ecologic environment of the corridor is getting worse and worse due to man’s economic activities and the lack of knowledge of the importance of the environment, which is one of is the three environment problems in Xinjiang. The corridor is in great need of planning and managing.
基金supported by Fundamental Research Program of Shanxi Province[Grant No.202303021221154]the Project of Shanxi Province Graduate Education and Teaching Reform[2022YJJG48]。
文摘Urbanization research is essential for the sustainable use of regional land resources and ecological environment protection.The expansion process and driving factors of urban construction land at different scales in the middle reaches of the Yellow River(MRYR)have not been comprehensively elucidated.In this study,we explored the distribution pattern of urban construction land on different slope gradients at different scales and analyzed its influencing factors.The main findings were as follows:(1)There has been significant expansion of urban construction land in the MRYR over the past 20 years.Spatial heterogeneity was observed in the regional urban construction land expansion process among different geomorphic regions.(2)The urban construction land in the MRYR was expanded vertically to areas with slopes of>5°,particularly in 2005–2010.Significant slope climbing of urban construction land was observed in the loess hilly-gully and rocky mountain areas.(3)In MRYR,68.45%of the counties were categorized as the slope-climbing types,including 37.38%high-slope-climbing types.(4)The regional population density and economic development level were closely associated with regional urban construction land area variability.(5)The climbing process of regional urban construction can effectively alleviate farmland encroachment and pressure on the regional ecological environment.The urban expansion of the metropolitan distribution areas in the Plain region(such as Xi'an,Taiyuan)had a relatively significant impact on the local carbon storage.
基金Supported by Special Fund for Agro-scientific Research in the Public Interest(201303048)Major Program of Natural Science Foundation of Guangxi(013GXNSFEA053003)
文摘Ecological experiment was conducted in this paper to study the allometric growth in Squaliobarbus curriculus larvae and juveniles from Zhaoqing Reach of the Pearl River. The results showed that after first feeding, the organs associated to swimming, feeling and feeding of larvae differentiated rapidly, and exhibited allometric growth. The head length, tail length and head height exhibited positive allometric growth, while trunk length exhibited negative allometric growth before reaching the growth inflexion point 20 d after first feeding, and positive allometric growth after the inflection point. Body height exhibited positive allometric growth both before and after the growth inflexion point at 18 d after first feeding. The inflexion points of snout length, eye diameter and post-eye head length occurred 23, 19 and 16 d after first feeding. For swimming organs, the dorsal fin, pelvic fins and anal fin exhibited positive allometric growth both before and after the inflexion point at 18, 19 and 17 d after first feeding; but the tail fin exhibited positive allometric growth before the inflexion point at 14 d after first feeding, and negative allometric growth after the inflexion point. S. curriculus larvae can possess various abilities soon after first feeding to survive at early stage due to the rapid development of swimming, feeling, feeding and other organs, which has important ecological significance to adapt to the complex external environment.
文摘倒伏是限制长江流域直播油菜高产稳产的关键因素之一,水稻秸秆还田后,氮肥运筹通过碳氮代谢和茎秆结构影响油菜抗倒性能。本研究采用裂区设计,以华油杂62为材料,基于稻-油轮作定位试验,研究秸秆管理耦合氮肥运筹对高密度直播油菜抗倒性的影响。以秸秆还田处理为主区(R0为秸秆不还田, R1为全量还田),以氮肥运筹为副区, CK为240 kg hm^(-2)的常规施氮量及基肥∶苗肥∶薹肥∶花肥=6∶4∶0∶0, N1、N2、N3、N4均为减氮20%,但基肥∶苗肥∶薹肥∶花肥分别为10∶0∶0∶0、6∶4∶0∶0、6∶2∶2∶0和6∶2∶0∶2,研究不同处理对成熟期油菜茎秆细胞壁成分、茎秆硅钙含量及花期茎秆显微结构等指标的影响。结果表明,相较于秸秆不还田,秸秆还田后,油菜成熟期地上部鲜重增加29.1%,茎秆抗折力增加23.3%,茎秆纤维素、总木质素、果胶、硅、钙含量分别显著(P<0.05)增加了26.3%、3.4%、30.6%、45.0%和9.5%,茎秆强度和韧性显著增强,但油菜株高、地上部鲜重的增幅大于茎秆抗折力增幅,导致倒伏指数平均增加了7.9%。合理的氮肥运筹可提高茎秆质量,从而降低倒伏指数。秸秆还田下N3处理使田间实际倒伏角度较常规施氮处理降低2.6%,茎秆抗折力增加15.2%,倒伏指数降低10.2%,优于其他处理。其机理是该处理显著增加了茎秆纤维素、果胶和钙含量及花期茎秆皮层厚度、表皮厚度、维管束长、横截面积、维管束数目以及维管束面积,显微结构排列更加合理,抗倒性显著增强。因此,在长江流域水稻秸秆还田和油菜高密直播条件下,以全生育期施氮192 kg hm^(-2)(基肥∶苗肥∶薹肥=6∶2∶2)为推荐施肥方案,可以减少氮肥投入,增强茎秆的抗倒伏能力,提高机械收获效率,实现高产抗倒协同的目标。
