Responding to the coffee crisis: a pilot study of farmers' adaptations in Mexico, Guatemala and Honduras   总被引：6，自引：0，他引：6  

HALLIE EAKIN  CATHERINE TUCKER†  EDWIN CASTELLANOS‡ 《The Geographical journal》2006,172(2):156-171

This article explores the impacts of market shocks and institutional change on smallholder livelihoods, and the challenge of adaptation in Mexico, Guatemala and Honduras. The rapid decline in coffee prices since the dissolution of the International Coffee Agreement in 1989 has had widespread and profound impacts across coffee-producing regions. The data collected in the three case studies of this project confirm the severity of the impact, particularly in the Mexican and Guatemalan communities. They also illustrate the importance of the historical relationship between farmers and public institutions in defining farmers' perception of risk, their awareness of the nature of the changes they face, and thus the flexibility of their responses to present and future uncertainty. The project's findings indicate that the existence and development of local networks among farmers, service providers and information sources may be critical for facilitating adaptation, particularly in the context of economic liberalization and globalized agriculture.  相似文献   

印尼8.9级地震前同一纬度"段"上东西两侧震兆信息讨论     

王泽皋  孙佩卿  乔子云  靳艳萍  马风霞  孙彦雪  常庆湘  张跃刚 《国际地震动态》2006,(8):36-39

根据观测,2004年12月26日印尼苏门答腊附近海域发生8.9级地震前同一纬度“段”上两侧MS≥6.0地震活动是具有时间和空间信息的,二者都可以作出回顾性时、空预测的结果。不仅如此,根据红山地震台的记录仍然可以得到“活动时段”预测的结果。最后强调了我们对大震预测的基本认识:大震前小震活动水平的涨落和分布情况是预测未来大震活动时间和空间的基础资料,而且都是这次大震前的“整体多维活动”。  相似文献   

Spectral Estimation in Space and Time Domain by Nonstationary Minimum Variance Spectral Estimator     

Li Chao 《Mathematical Geology》1998,30(6):675-693

A multidimensional version of the nonstationary minimum variance spectral estimator has been developed. The numerical results have shown that this method has more resolution power than the conventional nonstationary spectral estimation methods based on periodograms. The application of the spectral estimation method to an irregularly sampled multidimensional nonstationary rainfall mode is also investigated. The other advantage of this spectral estimation method is that it does not require window selection.  相似文献   

Distribution of diatoms among intermittent ponds on the Atlantic Coastal Plain: development of a model to preduct drought periodicity from surface-sediment assemblages     

Evelyn E. Gaiser  Thomas E. Philippi  Barbara E. Taylor 《Journal of Paleolimnology》1998,20(1):71-90

Inferences of past climate from the fossil record in lakes rely on the accurate quantification of a relationship of fossilizing organisms to their environment. Whereas the relationship of diatoms to water chemistry parameters has been modeled in many systems, few studies adequately address the relationship of diatoms to physical properties, such as water depth or hydrology, that may be more directly tied to climate. We examined the composition of modern diatoms in surface sediments of 75 isolated ponds (mostly Carolina bays) of the Atlantic Coastal Plain to: (1) assess the influence of physical and chemical variables on the distribution of diatoms among ponds of the region, and (2) develop a model that predicts hydroperiod (a measure of pond permanence) from diatom assemblages. We constructed two hydroperiod calibration models: the first infers hydroperiod from the weighted-average optima and tolerances of taxa along the hydroperiod gradient, the second bases inferences on the hydroperiod estimates of compositionally similar samples. Both approaches incorporate a-priori and post-hoc tests of assumptions often inherent in the construction of transfer functions. Diatom assemblage composition had strong, approximately linear relationships to hydroperiod, water depth, and calcium concentration in non-metric multidimensional ordination space; effects of other variables, including pH, were non-linear or ambiguous. Overall, the assemblages reflected the dilute, acidic chemical characteristics of bays. The assemblages contained differing abundances of euterrestrial, benthic and planktonic taxa, depending on a pond's susceptibility to drying. A weighted-averaging regression model based on taxon-specific hydroperiod optima generated adequate, unbiased hydroperiod inferences from diatom species composition (r² = 0.81). This model may be used to infer past drought episodes from fossil diatom assemblages at appropriate sites on the Atlantic Coastal Plain.  相似文献   

Unilateral ARMA processes on a square net by the herringbone method     

Benjamin F. Turner  W. E. Sharp 《Mathematical Geology》1994,26(5):557-564

Because multidimensional ARMA processes have great potential for the simulation of geological parameters such as aquifer permeability, it was important to resolve which of two proposed alternative methods should be used for determining the two-dimensional weighting parameter, , for a unilateral ARMA (1, 0) process on a square net. Practical simulations demonstrates that the correct formulation is: =₁₀/(1+ ₁₀ ² where _r,s is the correlation between lattice points at lagsr and s. When the simulations are performed with correlations of 0.8 or more a residual bias was detected which was found to be caused by a difference in the variance between the one- and two-dimensional models. This can be rectified by modifying the two- dimensional model as follows: z_ij=(z_{i–1, j} + z_{i, j–1}) + a_ij where ²=1/(1 + ₁₀ ² ).  相似文献   

台湾地区9.21及3.31地震的地下水位异常统计与介入分析     

林淑真  李宗仰  陈 《地震研究》2003,26(4):321-327

探讨了9．21及3．31两次强震所引起的地下水位异常形态，由许多地下水位震例资料获得的异常形态是复杂多样的，但同一井水位异常形态也有其再现性。将地下水位在两次地震中的异常进行统计，选取有代表性进行介入模式的量化计算，得知阶变与涌冲两种异常形态可取得特定的介入模式，该成果可作为对地下水位异常现象进行识别时参考。  相似文献   

基于Web的空间OLAP研究   总被引：1，自引：0，他引：1  

徐铭杰  李慧典  王淑彬 《地域研究与开发》2002,21(3):89-92

OLAP（在线分析处理）是空间信息集成，查询与分析的重要领域和手段，基于Web的OLAP需要解决体系结构，空间数据仓库构建，多维数据模型，WebGIS，数据挖掘等诸多理论和工程问题，体系结构规定了系统开发和应用的模式，多维数据模型中定义了基于数据仓库的度量和维度结构，是OLAP和某些数据挖掘模型的基础，是数据仓库应用的重要手段，传统的体系架构，多维数据模型和OLAP技术在处理穸间数据过程中具有较大的局限性，文章尝试探讨在Internet环境下，在传统多维数据模型中引入空间维度，度量中指向空间聚合结构的空间数据索引及其空间算子集合，从而构造出空间多维数据模型，并在模型物理实现的基础上，试验了空间立方体的Web OLAP操作，可以预测，空间OLAP研究将成为GIS研究的热点，具有极大的应用价值。  相似文献   

场所叙事视角下乡愁的多维解构与影响机理——基于新民谣歌词与评论的分析   总被引：1，自引：0，他引：1  

洪学婷  黄震方  陈晓艳  徐冬 《地理科学》2021,41(1):55-63

乡愁主题的新民谣具有场所叙事特征,通过NVivo10质性分析和自然语言处理方法分析新民谣歌词与评论,探讨场所叙事理论视角下乡愁呈现的维度特征与生产机理。研究结果表明:乡愁呈现空间、时间、记忆及情感维度。乡愁中的空间维度包括家、地方和区域不同的尺度空间,以家为核心意象的乡愁是最广泛的实践;时间维度中具有日、月、年嵌套的时间层次,体现了循环和线性时间下乡愁的表征;乡愁的积极情感与消极情感交融;记忆维度表现了场景、人物和事件。乡愁是主体人与客体地方在影响因素的综合作用下形成的情感。  相似文献   

Identification and alleviation pathways of multidimensional poverty and relative poverty in counties of China   总被引：1，自引：1，他引：0  

XU Lidan  DENG Xiangzheng  JIANG Qun'ou  MA Fengkui 《地理学报(英文版)》2021,31(12):1715-1736

To realize efficient and sustainable poverty alleviation,this study firstly investigated the identification of multidimensional poverty and relative poverty,and then explored relevant poverty alleviation pathways.Poverty levels in 31 provinces including the autonomous re-gions and municipalities of China were identified at the county level using the average nighttime light index (ANLI),county multidimensional development index (CMDI),and a method combining multidimensional poverty index and relative poverty standards.Poverty alleviation pathways for poverty-stricken counties were explored from the aspects of industry,education,tourism and agriculture.The results revealed that nearly 60％ of counties in China were primarily under relative poverty,most of which were corresponded to light relative pov-erty.In terms of ANLI and CMDI,63％ and 79％ of the national poverty-stricken counties,as of 2018,could be identified,suggesting that CMDI had a higher performance for identifying poverty at the county level.In terms of poverty alleviation pathways,414,172,442,and 298 poverty-stricken counties were receptive to industry poverty alleviation,education poverty alleviation,tourism poverty alleviation,and agriculture poverty alleviation,and 61％ of coun-ties had more poverty-causing factors,implying that multidimensional poverty alleviation is suitable in most of the counties.  相似文献   

The Evaluation of Food and Livelihood Security in a Globally Important Agricultural Heritage Systems (GIAHS) Site     

YANG Lun  YANG Jianhui  JIAO Wenjun  LIU Moucheng  LI Wenhua 《资源与生态学报(英文版)》2021,12(4):480-488

Based on the basic selection criteria of Globally Important Agricultural Heritage Systems (GIAHS) and food and livelihood security research trends, this paper established an evaluation framework and indicator system for food and livelihood security in GIAHS and selected the first GIAHS site in the Qinghai-Tibet Plateau as a case for empirical evaluation. The results demonstrate that the food and livelihood security of farmers at this site was at a medium level, with an average evaluation value of 2.91, which still lagged behind the level of better food and livelihood security. Specifically, the average values of farmers’ evaluation of food security and livelihood security were 1.43 and 1.48, respectively, which show that farmers’ food security in the study area was at a medium level and that of livelihood security was relatively good. Simultaneously, the more simple a farmers’ economic activities (i.e., agriculture-oriented economic activities or non-agriculture-oriented economic activities), the worse their food and livelihood security; while the more diversified the economic activities (i.e., engaged in part-time economic activities), the better the food and livelihood security.  相似文献