With the accelerating urbanization, ecological environment of the city has attracted increasing attention, so the resulting problems have become key research focuses in all countries. Against this background, urban ag...With the accelerating urbanization, ecological environment of the city has attracted increasing attention, so the resulting problems have become key research focuses in all countries. Against this background, urban agriculture has been applied as one of the effective approaches for relieving urbanization. From the perspective of industrial form of urban agriculture, planning models of urban agriculture were explored, industrial form and planning model of Chengdu urban agriculture were analyzed to forecast its development prospects. Multi-dimensional development, and sustainable development measures were given to guarantee the sustainable development of urban agriculture.展开更多
The integrated planting and breeding of paddy fields is a kind of eco-planting and breeding mode which makes rice and aquatic animals benefit from each other,greatly reducing the harm of rice pests and diseases,using ...The integrated planting and breeding of paddy fields is a kind of eco-planting and breeding mode which makes rice and aquatic animals benefit from each other,greatly reducing the harm of rice pests and diseases,using less or even no fertilizers or pesticides,greatly reducing the agricultural non-point source pollution,thus achieving the " multiple use of water,multiple harvests in one field,grain and fishing winwin,ecological and high efficient use. " In this paper,the high yield and efficient cultivation techniques of rice under the rice-fish intergrowth model in Chengdu was introduced from the aspects of selecting good paddy fields for fishing,using appropriate rice varieties,soaking disinfection,timely sowing and nurturing strong seedlings,reasonable close planting,reasonable fertilization,scientific water management,scientific pest control and rice harvests.展开更多
【目的】成都平原是中华文明的重要发源地之一,深入重建该地区中—晚全新世环境演变历史,对理解长江上游史前文明发展的环境背景及探讨全球气候变化与人类社会可持续发展的关系具有重要意义。目前学界对成都平原中—晚全新世气候演变特...【目的】成都平原是中华文明的重要发源地之一,深入重建该地区中—晚全新世环境演变历史,对理解长江上游史前文明发展的环境背景及探讨全球气候变化与人类社会可持续发展的关系具有重要意义。目前学界对成都平原中—晚全新世气候演变特征及其是否响应“4.2 ka”气候突变事件仍存在争议。【方法】基于RS-1岩心的AMS 14C测年构建年代框架,采用粒度端元模型分析,结合磁化率和色度指标,重建成都平原中—晚全新世的沉积环境演变过程。【结果】粒度数据分解出5个端元组分,分别反映不同水动力条件下的沉积特征,其中EM1代表弱水动力条件下由河流远源悬浮物形成的稳定沉积;EM2和EM3反映较强水动力条件下沉积的组分,EM3对应更强的搬运动力;EM4和EM5则代表洪水期间的粗颗粒跃移沉积组分。【结论】成都平原中—晚全新世的环境演变可划分为四个阶段:4.7~4.4 cal ka B.P.期间气候湿润,干湿波动显著;4.4~4.2 cal ka B.P.气候出现轻微冷干化趋势;4.2~3.7 cal ka B.P.为气候极端不稳定期,洪水事件频发;3.7 cal ka B.P.以后气候逐渐干旱,这种“干—湿—干”的气候变化模式反映了该区域对“4.2 ka事件”的显著响应,区域水文气候的响应大约始于4.4 cal ka B.P.,并持续至约3.7 cal ka B.P.。展开更多
文摘With the accelerating urbanization, ecological environment of the city has attracted increasing attention, so the resulting problems have become key research focuses in all countries. Against this background, urban agriculture has been applied as one of the effective approaches for relieving urbanization. From the perspective of industrial form of urban agriculture, planning models of urban agriculture were explored, industrial form and planning model of Chengdu urban agriculture were analyzed to forecast its development prospects. Multi-dimensional development, and sustainable development measures were given to guarantee the sustainable development of urban agriculture.
文摘The integrated planting and breeding of paddy fields is a kind of eco-planting and breeding mode which makes rice and aquatic animals benefit from each other,greatly reducing the harm of rice pests and diseases,using less or even no fertilizers or pesticides,greatly reducing the agricultural non-point source pollution,thus achieving the " multiple use of water,multiple harvests in one field,grain and fishing winwin,ecological and high efficient use. " In this paper,the high yield and efficient cultivation techniques of rice under the rice-fish intergrowth model in Chengdu was introduced from the aspects of selecting good paddy fields for fishing,using appropriate rice varieties,soaking disinfection,timely sowing and nurturing strong seedlings,reasonable close planting,reasonable fertilization,scientific water management,scientific pest control and rice harvests.
文摘【目的】成都平原是中华文明的重要发源地之一,深入重建该地区中—晚全新世环境演变历史,对理解长江上游史前文明发展的环境背景及探讨全球气候变化与人类社会可持续发展的关系具有重要意义。目前学界对成都平原中—晚全新世气候演变特征及其是否响应“4.2 ka”气候突变事件仍存在争议。【方法】基于RS-1岩心的AMS 14C测年构建年代框架,采用粒度端元模型分析,结合磁化率和色度指标,重建成都平原中—晚全新世的沉积环境演变过程。【结果】粒度数据分解出5个端元组分,分别反映不同水动力条件下的沉积特征,其中EM1代表弱水动力条件下由河流远源悬浮物形成的稳定沉积;EM2和EM3反映较强水动力条件下沉积的组分,EM3对应更强的搬运动力;EM4和EM5则代表洪水期间的粗颗粒跃移沉积组分。【结论】成都平原中—晚全新世的环境演变可划分为四个阶段:4.7~4.4 cal ka B.P.期间气候湿润,干湿波动显著;4.4~4.2 cal ka B.P.气候出现轻微冷干化趋势;4.2~3.7 cal ka B.P.为气候极端不稳定期,洪水事件频发;3.7 cal ka B.P.以后气候逐渐干旱,这种“干—湿—干”的气候变化模式反映了该区域对“4.2 ka事件”的显著响应,区域水文气候的响应大约始于4.4 cal ka B.P.,并持续至约3.7 cal ka B.P.。
