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1.
[目的]研究气候变暖背景下黄土高原地区干湿区界线动态变化过程。[方法]利用1960—2013年黄土高原地区的76个气象站点逐日平均气温、平均最低气温、平均最高气温、降水、平均风速、日照时数、相对湿度数据,采用Penman Monteith模型计算了黄土高原地区的潜在蒸散量,进而计算干燥度指数。运用线性趋势法、Mann Kendall趋势检验法对黄土高原地区的干燥度趋势进行了分析,运用反距离加权差值(IDW)研究了干燥度界线的动态变化格局。[结果]近54年黄土高原地区干燥度指数呈微弱增加趋势,四季变化中春季呈上升趋势,冬季为减小趋势,夏、秋季变化不明显,空间上兰州以西,银川—太原一线北干燥度指数呈减小趋势; (2)干旱与半干旱区界线在1075°E, 375°N以东表现为经向变化,以西为纬向变化,近54年干旱区范围变化不明显; (3)半干旱与半湿润区界线南北方向波动变化明显, 20世纪90年代向南扩张到华家岭—六盘山—平凉—庆阳—延安—三门峡—长治一线以南,半干旱区面积达到最大,比20世纪60年代的半干旱区范围扩大14%,比2000—2009年大5%左右。[结论]近54年黄土高原总体上地区呈干旱化趋势,半干旱区面积扩大,半干旱与半湿润区界线年代际南北波动频繁,变化范围大,半干旱区是黄土高原地区气候变化的敏感区。  相似文献   

2.
[目的]以湖南省油菜春季涝渍灾害为例,创建基于涝渍过程的逐日灾变等级指标、灾害影响量化评价与灾损量化评估模型,探索区域农作物涝渍灾变动态监测评估的天气学方法。[方法]基于湖南省油菜春季涝渍灾变过程解析,以过程灾变判别指标为基础,采用基于假设的滚动模拟寻优、实际灾情验证与个例分析等方法,厘定轻度涝渍与重度涝渍灾变的最佳阈值,构建油菜春季涝渍过程逐日灾变等级指标; 利用多元回归等方法,构建对应的灾害影响量化评价模型和减产率量化评估模型; 基于个例分析,验证指标及模型结果与历史灾情记录的吻合情况。[结果]湖南省轻度与重度涝渍灾变的最佳阈值为144; 不同县涝渍灾变等级阈值存在一定差异,平均受灾频率越低,洪涝脆弱性越低,防灾减灾能力越强,阈值越高; 基于受灾天数和重灾天数的灾害影响指数都表现为结荚期涝渍对油菜减产率影响更大,且两者的空间分布形势都与各县年平均减产率的空间分布形势基本一致; 个例中,基于指标的全省重灾站数百分比的时间演变与实际灾情记录一致,减产率量化评估模型的结果也与实际灾损相匹配。[结论]油菜涝渍灾变等级指标、灾害影响指数及减产率量化评估模型,实现了对涝渍灾变过程等级的动态监测、影响与灾损的量化评估,为基于天气学方法开展区域油菜涝渍灾变等级的动态监测提供了理论支持和方法支撑,同时为历史灾情资料的补充和量化及灾情记录的再分析提供了可行的思路。  相似文献   

3.
[目的]文章研究2007—2016年10年山东德州的耕作层平均地温的变化趋势和近50年来的气候突变情况。[方法]根据2007—2016年山东德州地区10个县、市、区,1967—2016年德州市德城区夏玉米生长季(6—9月)耕作层5cm、10cm、15cm、20cm平均地温,及同期月平均气温资料,采用气候倾向率、累积距平、信噪比等气候诊断方法。[结果](1)近10年德州地区各县市夏玉米生长季耕作层平均地温、各月平均地温大部分呈上升趋势,临邑、夏津两县各土层均呈下降趋势。各层上升幅度最大值均出现在齐河,为233~280℃/10年。(2)同时段的地温高于气温,地气温差均为正值,5~20cm温差范围分别为11~20℃、10~17℃、08~15℃、06~13℃,各层地气温差最大的是庆云、宁津,最小的是武城。浅层地温与气温的变化存在明显的正相关关系。(3)近50年来,各月平均地温都出现了一次显著的波动。6月份5cm、10cm平均地温在2004年发生了气候突变,7月份10cm平均地温在2005年发生了气候突变,8月份5cm至20cm平均地温在1981年均发生了气候突变。[结论]以上各月浅层地温气候突变前为相对偏冷期,突变后为相对偏暖期。该地区夏玉米生长季期间耕作层地温的上升,有利于夏玉米根系生长和充分吸收深层养分、水分,增加玉米干物质积累,有利于夏玉米提高产量,降低生长季后期其他气象因素带来的不利影响。  相似文献   

4.
[目的]根据区域景观差异性进行土地利用景观分区,以期为土地利用分区和土地利用政策制定提供理论依据。[方法]文章以重庆市永川区为研究对象,以2005年和2015年的遥感影像为基础数据源,借助RS和GIS技术对2期的影像进行解译,得到永川区2期土地利用类型图; 利用景观指数法与Shannon 多样性t值检验法进行全区土地利用景观格局变化的数量结构和各乡镇土地利用景观变化显著性分区研究。[结果](1)从类别层级分析, 2005—2015年间,建设用地、林地表现为增加趋势,耕地、草地、未利用地表现为减小趋势。耕地为永川区的优势景观类型(2005年和2015年各占土地总面积5446%、4976%),耕地、建设用地、林地受人为干扰强烈且趋于规则化。(2)从景观层级分析,蔓延度指数增大,Shannon多样性指数、Shannon均匀度指数、散布与并列指数、景观形状指数均减小。(3)利用Shannon多样性t检验法对永川区进行土地利用景观格局分区。景观变化极显著区,主要位于主城区及其周围地区,城市化现象显著,人为活动影响大; 景观变化显著区,该区土地利用程度较弱, 2005—2015年林地和水域面积增大,耕地面积减小; 景观变化不明显区,该区主要分布在远离中心城区,经济欠发达,景观格局变化不明显,人为活动干扰不明显。[结论]永川区各乡镇的土地利用景观格局变化差异性,表明在自然因素稳定的条件下,今后应因地制宜地加强人为因素的调控,保证各乡镇土地利用景观格局稳定协调发展。  相似文献   

5.
[目的]研究“镰刀弯”政策影响下全国玉米变化规律,对优化农业种植结构至关重要。[方法]采用综合考虑植被物候和叶片水分变化的玉米制图方法,结合海拔、坡度、积温和降雨等不同环境因子分析“镰刀弯”地区玉米的时空变化特征。[结果]通过2 767个调研点位验证,总体精度达9082%,Kappa系数为086。[结论]2015—2018年全国玉米种植面积持续下降,减少约27948万hm2,比例下降64%,其中80%以上减少玉米集中在“镰刀弯”地区。4年来“镰刀弯”地区玉米减小面积近90%发生在东北冷凉区与北方农牧交错区。东北冷凉区玉米面积先减小后微弱增加,面积整体下降约117%,玉米减少主要发生在玉米种植面积大且较为密集的地区,而在海拔较高、积温低和降雨少等自然环境较差区域玉米相对减少比例更大,更易受政策影响。北方农牧交错区玉米种植面积持续下降,面积减少约135%,与其他环境因素相比,降雨不足对玉米种植变化的影响更大。综合考虑实地的自然环境因素,对“镰刀弯”政策的实施会更加有效。  相似文献   

6.
[目的]蒸散发是影响陆地和大气系统能量交换过程的关键因素,也是评价陆地生态系统的重要指标。文章运用中分辨率成像光谱仪(MODIS MOD16A2和MOD13A1)产品数据,并结合中国气象数据共享网的气象数据,估算了2008—2017年呼伦贝尔植被的蒸散发量,并在年度和季节两个时间尺度开展了植被蒸散发时空变化分析。[方法]运用变异系数(CV)和突变检验法(Mann Kendall),研究2008—2017年呼伦贝尔地区年际和季节蒸散发时空变化趋势。使用Pearson相关分析法,对呼伦贝尔地区季节尺度的蒸散发与归一化植被指数(NDVI)、各气象要素进行相关分析。[结果]2008—2017年呼伦贝尔地区蒸散发呈上升趋势,蒸散发值较大的月份为3月、8月和11月,蒸散发主要集中在5—10月份。变异系数的空间分布较均匀,平均变异系数为038,变异系数变化幅度较大的区域主要集中在呼伦贝尔北部,CV值均在1~265。CV变化幅度较小的区域主要分布在呼伦贝尔中部和南部,CV值在041~084。从年际变化趋势来看, 2013年为一个蒸散发突变年; 根据呼伦贝尔月份变异系数的计算,从1—12月变异系数幅度变化较大,说明呼伦贝尔ET变异剧烈。呼伦贝尔月份平均CV值是1,草原区的CV平均值是096,森林区的CV平均值是104,农区的CV平均值097。植被蒸散发与气象要素关系分析表明:蒸散发与气温、水汽压、NDVI、降水、日照时数呈显著正相关关系。[结论]2008—2017年呼伦贝尔地区蒸散发总体呈上升趋势,从整个季节变化来看,蒸散发起伏变化趋势明显,波动变化较大。从空间分布上来看,总体表现为呼伦贝尔南部的蒸散发大于北部。蒸散发主要集中在4—10月份,多年的低值出现在5月。不同区划类型平均蒸散发量由大到小依次为草原区>农区>森林区,全区的蒸散发变化趋势与农区变化趋势较为一致。正相关性强度依次为气温>日照时数>NDVI>水汽压>降水>风速。  相似文献   

7.
[目的]开展连片特困区脆弱生态环境和贫困耦合关系的演变及预测模拟研究,为研究区统筹扶贫开发与生态环境保护提供政策依据。[方法]通过构建生态环境和贫困评价体系,运用系统耦合模型和GM(1,1)预测模型,对1995年、2000年、2005年、2010年、2015年研究区脆弱生态环境与贫困耦合关系演变进行了分析,并对2020年、2025年、2030年、2035年、2040年研究区两系统耦合关系进行了预测模拟。[结果](1)1995年、2000年、2005年、2010年、2015年河北连片特困区贫困度指数呈下降趋势,由0902下降到0761,生态环境脆弱性指数略有下降,由0438下降到0412。(2)1995年、2000年、2005年、2010年、2015年河北连片特困区贫困和生态环境耦合类型由拮抗时期过渡到磨合阶段,协调类型由轻度失调型转变为濒临衰退型。低水平耦合县主要分布集中在太行山北部山区,耦合协调度呈现“两头高、中间低”的分布特征,北部燕山山区和南部太行山山区各县耦合协调度普遍较高。(3)2020年、2025年、2030年、2035年、2040年研究区域生态环境脆弱性指数和贫困度指数都在降低,两者的耦合度在不断提高,耦合类型处于磨合阶段,接近于高水平耦合,耦合协调度在不断降低,协调类型由濒临衰退型过渡到勉强协调型。[结论]快速提高片区经济发展水平是片区生态环境与经济协调发展的关键。  相似文献   

8.
[目的]研究第二次土地利用现状调查以来山东省生态用地变化特点及驱动因素,评价各类驱动因素对生态用地的影响程度,为科学编制区域空间规划,保护和合理利用生态用地提供参考。[方法]文章构建了全省生态用地转移矩阵,归纳了影响生态因素变化的主要驱动因素,提出了驱动力指数计算方法,定量分析和比对了各驱动因素对生态用地的影响。[结果]2009—2017年生态用地共计转出2048万hm2,占生态用地总面积的472%; 转入316万hm2,占生态用地总面积的072%。8年来全省生态用地净减少1732万hm2,占2009年生态用地总面积的400%。生态用地的流向以耕地最多,向城镇村及工矿用地流出次之,向设施农用地的流出也有较大面积。[结论](1)在影响生态用地变化的六大驱动因素中,耕地开发和城镇村工矿占用的驱动力指数最高,非耕农业占用对生态用地的变化有一定影响。(2)六大因素中城镇村工矿占用对当地生态环境的破坏力最强。  相似文献   

9.
[目的]通过对个性化的江西省乡村旅游区的空间分布进行研究,并对个性化的红色旅游资源进行评价,以期对乡村旅游的发展提供新的思考路径,建立具有个性化的乡村旅游体系。[方法]运用GIS102操作平台对江西省119个红色乡村旅游区的空间分布情况进行研究,通过计算最临近点指数、地理集中指数和核密度计算分析其空间分布特征。以资源要素价值、开发价值和社会效益组成评价层,下分14个指标,对江西省红色旅游资源进行评价研究。[结果](1)江西省红色旅游区分布类型为集聚型,分布不均衡; (2)在评价准则层中,旅游资源要素价值权重最大,为0647 9,其次为社会效应,权重为0229 9,开发条件权重最低,为0122 2; (3)指标层权重排名前三位的依次为资源完整性、教育性和组织管理,权重值分别为0162 0,0116 5和0111 7。[结论]江西省乡村红色旅游区数量较多,但整体呈集聚型分布特点; 旅游资源要素价值权重最高,且整体资源禀赋较强,社会带动效应明显,具有极强的开发价值。  相似文献   

10.
[目的]研究新疆农业生产效率地区差异及影响因素。[方法]文章基于新疆2004—2015年的面板数据,使用非期望产出的Super SBM测算新疆各地区的农业生产效率,随后使用Theil指数分解和GMS邓氏关联模型对新疆农业生产效率的地区差异和外部影响因素进行研究。[结果]北疆、东疆、南疆的效率得分均值分别为0943、1059、0854; 新疆农业生产效率Theil指数呈上升趋势; Theil指数区域贡献率中区域内差异逐年下降,区域间差异逐年上升,区域内差异中北疆Theil指数区域贡献率最大; GMS邓氏关联模型得出的外部影响因素排序为城市化水平差异、人口密度差异、财政支出分权差异、产业结构差异、教育水平差异。[结论]调整农业财政分配比重,积极引进高新生产技术; 增强区域内外互动,挖掘区域潜力,高效率地区进行辐射带动,扩大农业产业目标市场; 加快城市化建设,优化农业布局,提高农业从业人员素质。  相似文献   

11.
The theory of demand and supply implies a positive relationship, or “price transmission” between the prices of products at different stages of manufacturing. This relationship was investigated with quarterly prices of softwood stumpage in the US South, and national prices of forest products, from 1977 to 2002. All prices, net of inflation, were found to be nonstationary and there was no evidence of co-integration between prices. Vector autogressive models, augmented by Granger causality tests and multiplier analysis showed that there was a one-to-one permanent positive response of the southern sawtimber stumpage price to a permanent change in the national lumber price. There was also a one-third permanent positive response of the national paper price to a permanent change in the national pulp price. There was no relation between regional pulpwood prices and national pulp or paper prices. When price transmission was significant, the full adjustment took about 2 years.  相似文献   

12.
Owners, local residents, government, and conservation organisations can express divergent preferences in the development and management of local woodlands. The perceptions of these four groups were examined, in the context of three community woodlands in Eastern England, using an ecosystem function framework. In a pilot study, residents were able to allocate a relative importance to woodland ecosystem services which were then related to “regulation”, “habitat”, and “production” or “information” functions. However residents also placed importance on negative services or “dis-services” associated with the woodland ecosystem. Therefore a fifth category of “dis-services” was included in the main survey which included 84 local residents, three woodland owners, three government institutions, and six representatives from conservation groups. Each of the four groups placed greatest importance on services associated with habitat (16–39% of the total importance) and information (30–50%) functions suggesting, in this example, mutual interest in the use of woodlands as a habitat or recreational resource. By contrast a potential area of difference was the particularly high importance placed by one owner on dis-services such as fly tipping. In addition the woodland owners placed higher importance (10–20%), than local residents and conservation groups (7–9%), on the productive services of the wood. This suggests a need for communication when production-related operations affect recreation. The ecosystem function framework appears to be a useful approach for highlighting potential tensions and areas of mutual interest in the management of semi-natural ecosystems.  相似文献   

13.
China is one of the largest wine importing countries in the world and is poised for continued import growth in the future. Increased wine purchases throughout China have given rise to persistent fraud where fake wines are packaged and sold with counterfeit contents and labels. For exporting countries like France, counterfeit wines displace market share, damage foreign brand reputation, and cause distrust in consumers who are aware of counterfeiting problems throughout the country. We examine the impact of fraudulent wine events (as measured by negative media reports) on Chinese wine demand differentiated by supplying country. We employ the Rotterdam demand system and a switching regression procedure to estimate import demand and compare results across different media variable specifications. Results consistently show that negative reports disproportionately affect French wine regardless of how the media variable is specified. This is not surprising because most fraudulent events involve French wine counterfeits.  相似文献   

14.
In recent years earthquakes and their secondary hazards have claimed the largest number of lives of all large natural disasters. Some of the world’s most earthquake-prone zones are also areas of high population density. The impact is magnified by vulnerability factors including non-enforcement of building codes, knowledge gaps, urban poverty and poor governance capacity to manage and reduce earthquake risks. Poor security of land tenure and property rights increases the vulnerability of people and affects their ability to respond to natural disasters.Earthquake recovery and reconstruction provides very significant challenges for land agencies, with these challenges differing from one country to the next due to differences in the local context. Drawing on contrasting case studies in Haiti, Nepal and New Zealand this paper identifies the common post-earthquake land administration functions and challenges that may apply to many contexts. These lessons provide land agencies and other key stakeholders with a summary of the challenges an earthquake poses for land administration at different post-disaster stages. We also discuss the policy and regulatory, institutional, operational and preparedness lessons for land administration. From these lessons we propose a framework for evaluating the earthquake-responsiveness of a land administration system. This framework can be used by a land agency in an earthquake prone region, or where an earthquake has recently occurred, to assess what challenges to land administration might occur in the event of an earthquake, and the preparedness of their land administration system.  相似文献   

15.
This paper analyses poverty and calorific undernourishment in the Indian state of Gujarat, where high and market‐led industrial growth has resulted in rapid economic improvement. The study is carried out through a combination of secondary and survey‐based data. We conclude that the neoliberal agenda of uncontrolled, outward‐looking growth has not resulted in significant reduction of poverty or malnourishment in rural areas. Furthermore, while land ownership is officially used as a proxy for wealth distribution, class position appears a better predictor of poverty status in the rural areas than landownership per se. At the policy level, there is a need to revive the agrarian economy and create new non‐agricultural assets, and the primary focus in the state must shift to the distribution of created assets rather than a single‐minded focus on growth.  相似文献   

16.
This paper tests the ‘systems of innovation’ hypothesis for a selection of crops in Ghana and Burkina Faso that have shown significant growth in production over an approximately 20-year period. The question is whether such growth can only occur if supported by a system of innovation. Using two indicators (a common understanding on objectives and priorities, and a high level of interactivity), we find little evidence for the existence of anything that might be considered a high functioning system of innovation.  相似文献   

17.
The values ascribed to industrial tree plantations are often controversial. Hence knowledge of their perceived impacts is important for improving their integration in rural landscapes. In 2016 we conducted household surveys with 606 respondents living in villages adjacent to acacia, teak and pine plantations across three islands in Indonesia (Java, Borneo, Sumatra). Results show that perceptions toward pine and teak plantations tend to differ from those toward acacia pulpwood plantations in several ways. Pine and teak plantations are perceived to have a higher number and variety of benefits and services, a higher number of positive impacts, a better environmental record, and to present more opportunities to local people for use of plantation land and products for improving rural livelihoods. In addition, we find that villagers around acacia pulpwood plantations tend to seek economic development and infrastructure to open up remote areas, yet their expectations were often only partially met. Recommendations from our analysis include: the role of the State in plantations must be clarified and potentially reinforced; the role of institutions as intermediaries is fundamental; and contributions by communities to design of management plans should be accommodated.  相似文献   

18.
Large‐scale tree plantations in high rainfall upstream areas can reduce fresh water inflows to river systems, thereby imposing external costs on downstream irrigation, stock and domestic water users and wetland interests. We take the novel approach of expressing all benefits and costs of establishing plantations in terms of $ per gigalitre (GL) of water removed annually from river flows, setting upstream demands on the same basis as downstream demands. For the Macquarie Valley, a New South Wales sub‐catchment of Australia’s Murray‐Darling Basin, we project changes in land and water use and changes in economic surpluses under two policy settings: without and with a policy requiring permanent water entitlements to be purchased from downstream parties, before plantation establishment. Without the policy, and given a high stumpage value for trees ($70/m3), upstream gains in economic surplus projected from expanding plantations are $639 million; balanced against $233 million in economic losses by downstream irrigators and stock and domestic water users for a net gain of $406 million, but 345 GL lower mean annual environmental flows. With the policy, smaller gains in upstream economic surplus from trees ($192 million), added to net downstream gains ($138 million) from sale of water, result in gains of $330 million with no reduction in environmental flows. Sustaining the 345 GL flow for a $76 million (406–330) reduction in gains to economic surplus may be seen to cost only $0.22 million/GL; but this is much lower than the market value of the first units of that water to agriculture and forestry.  相似文献   

19.
Fieldwork shows that many Sierra Leonean producers do not receive the official producer price for their coffee and cocoa, due to the concentration of buying stations, credit relations, the small quantities offered for sale, and the lack of marketing knowledge of the numerous and unorganized farmers. To the traders underpayment may seem economically justifiable to a certain extent, but to the farmers it means poverty and debt. A new village marketing centre project aims at remedying this situation and has already led to higher prices. Although no longer allowed to take their "just" share from the producers, traders are still willing to deal with the new centres.  相似文献   

20.
The cost of accessing healthcare can be a major determinant of disease prevalence, which in turn has short‐ and long‐term welfare implications on poor households. In response, governments in developing countries often resort to subsidizing the cost of drugs, which, while perhaps easier to administer, may not always be the most effective way of addressing healthcare cost. In this regard, we analyze the impact of different types of household level health expenses on disease incidence and agricultural production efficiency. We use data from the 2006 Uganda National Household Survey, which covered approximately 7,400 households. The results suggest that a 10% increase in consultation, medicine, and hospitalization expenses would reduce malaria incidence respectively by 35.6%, 20.5%, and 21.3 %, which translates into a 1.1%, 0.6%, and 0.6 % decrease in agricultural inefficiency, respectively. The results indicate that helping poor households meet expenses for consultation through subsidies or eliminating consultation fees has a larger impact on malaria incidence and agricultural productivity among poor rural households than subsidizing the cost of medical drugs, the most common avenue chosen by developing country governments in the fight against the disease.  相似文献   

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