西藏“两江四河”流域生态化造林绿化模式的探讨     

范志浩 《中南林业调查规划》2015,(2)

生态化造林绿化既是一项生态工程,也是一项社会和经济工程,既强调造林绿化对促进区域自然生态系统向良性循环方向演替的功能,也注重造林绿化对地方经社会发展和满足人们生产生活需求的贡献。依据西藏"两江四河"流域的自然条件和生态状况,从生态化的角度,对区域内造林绿化模式进行了探讨。  相似文献   

Anthropogenically disturbed potentially toxic elements in roadside topsoils of a suburban region of Bishkek,Central Asia     

Long Ma  Jilili Abuduwaili  Yaoming Li  Wen Liu 《Soil Use and Management》2019,35(2):283-292

The ecological environment in Central Asia is vulnerable to pressure from human activity due to the physical geography and climatic fragility of this region. A set of indicators suitable for the future assessment of this pressure needs to be proposed. Thirty‐six topsoil samples (0–5 cm) were collected from roadsides in a suburban region of Bishkek, the capital of the Kyrgyz Republic in Central Asia, and a risk assessment of anthropogenically disturbed potentially toxic elements (PTEs) was systematically conducted with classic statistical methods. The results of detrended correspondence analysis and principal component analysis clearly showed that topsoil samples with high contents of PTEs (Pb, Zn and Cu) were strongly affected by traffic within a distance threshold of 200 m and that anthropogenic effects decreased significantly with increasing distance from the highway. The enrichment factor and anthropogenic contribution for Pb were the highest among the three PTEs, with average values of 2.0% and 47.4%, respectively, suggesting enrichment. However, the results of the human health risk assessment also indicated that noncarcinogenic risks did not occur for any of the anthropogenic PTEs. The reported method provides a new systematic pathway to reveal anthropogenic influences on the geochemical composition of soil. The conclusions of this work will be highly valuable as important guidelines for agriculture, and the results of the PTE contents will provide a scientific basis for soil collection in future studies.  相似文献   

基于MaxEnt模型的可可潜在适宜分布研究     

秦晓威  郝朝运  李付鹏  谭乐和  宋应辉  赖剑雄 《热带作物学报》2016,37(5):1022-1029

根据野外采样和文献查阅,系统整理了可可的地理分布记录,并利用MaxEnt生态位模型和ArcGIS软件对可可的潜在适宜分布范围进行预测。结果表明:北美洲南部、中南美洲北部、非洲西部、亚洲东南部以及太平洋美拉尼西亚群岛地区均是可可的潜在适宜分布区域。其中,中国海南、台湾南部、云南西双版纳、广东雷州半岛也属于可可的适生范围。经ROC(Receiver operating characteristic)曲线分析法验证,MaxEnt模型的AUC(Area under curve)值为0.977,表明预测结果具有较高的可信度。各环境变量重要性的Jacknife检验表明,极端最低温度、年降雨量、年温度变化范围、最暖季降雨量对可可的潜在分布影响最大。  相似文献   

农业供应链金融风险的主要特征与风险防范的基本原则     

彭路 《湖南农业大学学报(自然科学版)》2015,(6):20-24

我国农业供应链突出表现为“集体化”、“现代化”和“生态化”，资金的安全性、流动性和信用程度都需要整体协同管控。交易成本和信息不对称决定了我国农业供应链以间接融资为主，其金融风险的特征主要表现为道德风险突出、整体风险难识别、可能引致区域系统性风险和行业系统性风险。因此，应当因地制宜确定农业供应链金融支持项目，并运用系统论原理控制农业供应链金融风险。  相似文献   

Cause and Consequence in Maize Planting Dates in Germany          下载免费PDF全文

P. S. Parker  J. S. Shonkwiler  J. Aurbacher 《Journal of Agronomy and Crop Science》2017,203(3):227-240

An important part of agricultural adaptation is the timing of crop sowing dates, affecting yields and the level of risk incurred during a particular season. Cold stress is especially relevant in maize, Zea mays L., so that the timing of planting in the spring is a tactical response to short‐term weather, but is also subject to strategic planning with regard to longer‐term climate. Both factors compare the potential implications of cold stress to the additional yield obtainable through earlier planting. New cultivars suited to growing conditions in Europe and generally increasing spring temperatures have enabled earlier planting, but it is still dependent on short‐term weather during the planting period. In the context of field‐level decision‐making, a panel regression is used to estimate the relationship between weekly local temperature and precipitation and planting dates at specific sites throughout Germany. Next, localised weather data and planting behaviour are linked to yields at the district (Landkreis) level to show the effects of planting date on yield. Based on these relationships optimal planting dates are explored with some associated costs and benefits. Results show a trend towards earlier planting that follows observed increasing spring temperatures and the availability of more cold‐tolerant cultivars but this advance is buffered by the increasing severity of minimum temperatures during a critical period. Earlier planting potentially increases yield but this is offset by additional management costs and risk. A robust and simple depiction of farmer behaviour in climatic, technological and economic context can help to understand trends in crop management and productivity that effect agricultural landscapes.  相似文献   

基于点评估方法的两广地区番木瓜中农药残留膳食暴露风险研究     

郭宏斌  刘福现  林玲  叶剑芝  杨春亮 《热带作物学报》2020,41(12):2548-2554

为评估两广地区番木瓜中主要农药的残留情况及其产生的风险,采集了广东、广西地区40个生产基地的番木瓜样品进行测试分析,研究其生产过程中使用的杀虫剂、杀菌剂、杀螨剂和植物生长调节剂等各种农药残留情况,并对我国不同人群的膳食暴露风险进行了评估。结果显示,40批次番木瓜中检出农药残留32批次;在检出的32份番木瓜样品中,检出率超过10%的有咪鲜胺、吡虫啉、多菌灵、啶虫脒和苯醚甲环唑5种农药,检出率分别为51.1%、21.5%、13.3%、11.1%、10.9%。采用点评估方法,选择检出率在10%以上的咪鲜胺、吡虫啉、多菌灵、啶虫脒和苯醚甲环唑,进行农药残留慢性膳食摄入风险（%ADI）评估、急性膳食摄入风险（%ARfD）评估,并进行不同消费人群暴露点评估。结果显示：检出的5种农药%ADI均低于100.00%,为0.00023%~0.0059%;%ARfD远低于100%,为0.50%~28.3%,5种农药的急性和慢性摄入风险均为儿童高于成年人,绝大多数女性的摄入风险高于男性;5种农药急性摄入风险均高于慢性摄入风险,风险水平由高到低为咪鲜胺>啶虫脒>苯醚甲环唑>多菌灵>吡虫啉,但点评估结果均远低于100%,说明通过食用番木瓜摄入的农药残留极其微量,不会对人体产生急性或慢性风险。  相似文献   

乡村生态文明建设与乡村旅游协调发展路径研究——以海口周边乡村地域为例     

陈海鹰  曾小红  黄崇利  康由发 《热带作物学报》2016,36(2):96-101

乡村生态文明建设与乡村旅游发展具有互存互促关系。以海口周边生态文明村建设与乡村旅游互动发展现状及乡村旅游发展条件为依据，探讨该地域乡村生态文明建设与乡村旅游协调发展路径，提出应以生态文明村建设成果为基础，注重乡村旅游的经济发展、文化促进和民生服务等多重功能发挥，通过提高居民主体意识、制定乡村旅游整体规划、加强乡村基础设施建设、提升旅游服务和管理质量、保护乡村文化与生态环境以及实施乡村旅游生态补偿、加强乡村旅游产品宣传等，实现乡村旅游与乡村生态文明建设的互动发展。  相似文献   

国内乡村生态旅游研究综述          下载免费PDF全文

王小芳 《北京农业职业学院学报》2020,(5):39-45

乡村生态旅游作为推动乡村经济发展的新形式已经成为乡村发展研究的新热点。以近 20年内发表于SCI、CSSCI和核心期刊的 225篇文献为研究对象发现，国内乡村生态旅游相关研究划分为基础性研究和宏观性研究两大类。分别对其相关概念、理论基础、影响因素和发展模式做出基础性阐释，对其开发管理、可持续发展、利益相关者和相关评价体系进行理论性研究发现，现阶段的研究在研究领域、研究范围、研究方法方面得到发展，但在研究内容和案例选址方面仍存在缺陷，需平衡各个研究领域，不断完善相关研究，精细挑选案例地址，推动中国乡村生态旅游研究。  相似文献   

大凌河流域生态综合治理项目效益分析     

王彪东 《国际沙棘研究与开发》2016,(4)

葫芦岛市建昌县2014年国家农业综合开发大凌河流域生态综合治理项目分布在建昌县新开岭乡新开岭村、贺杖子乡碾房村、素珠营子乡梁杖子村.通过该项目治理后,生态环境得到明显改善,经济效益十分显著,社会效益巨大,促进了区域经济社会发展.同时工程建设也起到了科技示范作用,为推动生态环境建设奠定了坚实基础保障.  相似文献   

Turbidity‐induced changes in emergent effects of multiple predators with different foraging strategies     

Matthew M. VanLandeghem  David H. Wahl 《Ecology of Freshwater Fish》2011,20(2):279-286

Abstract – In natural systems, prey frequently interact with multiple predators and the outcome often cannot be predicted by summing the effects of individual predator species. Multiple predator interactions can create emergent effects for prey, but how those change across environmental gradients is poorly understood. Turbidity is an environmental factor in aquatic systems that may influence multiple predator effects on prey. Interactions between a cruising predator (largemouth bass Micropterus salmoides) and an ambush predator (muskellunge Esox masquinongy) and their combination foraging on a shared prey (bluegill Lepomis macrochirus) were examined across a turbidity gradient. Turbidity modified multiple predator effects on prey. In clear water, combined predators consumed in total more prey than expected from individual predator treatments, suggesting risk enhancement for prey. In moderately turbid water, the predators consumed fewer prey together than expected, suggesting a risk reduction for prey. At high turbidity, there were no apparent emergent effects; however, the cruising predator consumed more prey than the ambush predator, suggesting an advantage for this predator. Understanding multiple predator traits across a gradient of turbidity increases our understanding of how complex natural systems function.  相似文献