重庆永川市土地利用变化及社会驱动力分析

根据1996~2004年重庆永川市土地利用数据,分析其土地利用动态、土地利用程度及土地利用效益的变化情况,并对土地利用变化社会驱动力进行定性分析,指出影响永川市土地利用变化的社会驱动力主要有经济发展、城镇化和工业化以及政治经济政策。然后运用社会经济发展状况有关数据和主成分分析的方法对耕地变化的社会驱动力作定量分析,进一步验证了土地利用变化与主要社会驱动力的相互关系。     

鄱阳湖地区耕地变化及其驱动力研究 II.耕地变化驱动力分析

依据鄱阳湖地区1949～2002年耕地面积和社会经济统计数据,运用主成分分析和多元线性回归模型等统计方法分析该地区耕地面积变化的驱动因素。结果表明,在近53年里人口增加和第三产业发展是该地区耕地面积减少的主要驱动因素,粮食需求则是耕地面积增加的主要驱动因素。     

安徽省油茶生产现状及发展对策

油茶是我国重要的木本食用油料树种,也是世界四大木本油料树种之一.笔者针对安徽省油茶生产现状,分析了当前油茶生产中存在的问题,从加强宣传、合理规划、加大资金投入、提高栽培管理水平、加强示范林和基地建设、开展综合利用研究等方面提出了相应的发展思路与对策,为安徽油茶产业健康发展提供借鉴.     

休闲农业发展探析——基于生态环境的视角

休闲农业与生态环境的联系十分密切。作者尝试从生态环境的视角将休闲农业划分为水域型、山地型及平原型3 类,并从环境驱动力及正外部性2 个角度阐述休闲农业的发展机理,最后从生态环境保护的角度提出促进休闲农业可持续发展的建议。     

Forest productivity and tree diversity relationships depend on ecological context within mid-Atlantic and Appalachian forests (USA)

Factors influencing the relationship between ecosystem productivity and biological diversity form the basis of much ecological theory. An understanding of how productivity-diversity relationships are influenced by scale of observation and unique attributes of ecoregions may provide important insights to aid conservation planning for carbon retention and biodiversity. Here we use publically available datasets to investigate patterns of productivity-diversity and explore potential factors influencing these patterns in forests located in five mid-Atlantic and Appalachian states. We used a geographic information system (GIS) to overlay multiple publically available datasets including remotely sensed estimates of productivity from MODIS and tree diversity estimated from the forest inventory analysis (FIA) database. We evaluated productivity-diversity relationships using two scales of observation (among and within ecoregions). We also determined if productivity-diversity relationships might be related to region-wide patterns in land use, and if the relationships varied by forest type, land management zones, and along gradients of mean productivity and diversity. Productivity-diversity relationships depended on scale and varied among ecoregions, and land use was correlated with both productivity and diversity. Mountainous ecoregions were characterized by positive productivity-diversity relationships, whereas coastal ecoregions were characterized by negative productivity-diversity relationships. Forest types and management zones that were on average less productive and more diverse exhibited positive productivity-diversity relationships across stands (the most productive stands were more diverse). In contrast, ecoregions and forest types that were on average more productive and less diverse exhibited negative productivity-diversity relationships (the most productive stands were less diverse). In conclusion, regional and local ecological and anthropogenic factors likely influence productivity-diversity relationships and these relationships appear to change along gradients of productivity and diversity.     

常山胡柚新品种选育初报

通过对常山县全县范围内各种有价值的胡柚变异单株进行筛选,选出23个预选母株,经对母株观察评价,选出品质较好的10个初选单株进行高接换种并进行观察鉴定,经果品大小、可溶性固形物、可食率、酸度、口味等指标的综合评价,最终选出7个单株5个性状优良的胡柚初选新品种,并建立了子代鉴定圃。     

Using digital repeat photography and eddy covariance data to model grassland phenology and photosynthetic CO2 uptake

The continuous and automated monitoring of canopy phenology is of increasing scientific interest for the multiple implications of vegetation dynamics on ecosystem carbon and energy fluxes. For this purpose we evaluated the applicability of digital camera imagery for monitoring and modeling phenology and physiology of a subalpine grassland over the 2009 and 2010 growing seasons.We tested the relationships between color indices (i.e. the algebraic combinations of RGB brightness levels) tracking canopy greenness extracted from repeated digital images against field measurements of green and total biomass, leaf area index (LAI), greenness visual estimation, vegetation indices computed from continuous spectroradiometric measurements and CO₂ fluxes observed with the eddy covariance technique. A strong relationship was found between canopy greenness and (i) structural parameters (i.e., LAI) and (ii) canopy photosynthesis (i.e. Gross Primary Production; GPP). Color indices were also well correlated with vegetation indices typically used for monitoring landscape phenology from satellite, suggesting that digital repeat photography provides high-quality ground data for evaluation of satellite phenology products.We demonstrate that by using canopy greenness we can refine phenological models (Growing Season Index, GSI) by describing canopy development and considering the role of ecological factors (e.g., snow, temperature and photoperiod) controlling grassland phenology. Moreover, we show that canopy greenness combined with radiation use efficiency (RUE) obtained from spectral indices related to photochemistry (i.e., scaled Photochemical Reflectance Index) or meteorology (i.e., MOD17 RUE) can be used to predict daily GPP.Building on previous work that has demonstrated that seasonal variation in the structure and function of plant canopies can be quantified using digital camera imagery, we have highlighted the potential use of these data for the development and parameterization of phenological and RUE models, and thus point toward an extension of the proposed methodologies to the dataset collected within PhenoCam Network.     

同仁地区中小学信息技术教育的现状与思考

近几年,随着信息技术的飞速发展和国家对教育事业的不断投入,青海省在中小学信息技术教育方面有了长足的进步和发展,但与发达地区相比,仍存在很大差距,还有许多工作要做。就青海省黄南藏族自治州同仁地区中小学信息技术教育的现状进行了调查研究,分析了存在的问题,并结合藏区的教育实际,提出了切实可行的具体措施。     

振动力场作用下高分子熔体第一法向应力差的计算

基于连续介质力学、高分子微观结构动力学和流变测量学的基础理论，推导出了平行叠加振动条件下高分子熔体第一法向应力差的计算公式；相应地，建立了在自行研制的恒速型毛细管动态流变装置上计算高分子熔体第一法向应力差的步骤和方法．以低密度聚乙烯(LDPE)为原材料，实验测量一定频率和振幅下毛细管的瞬态挤出胀大值、毛细管瞬时入口压力、活塞杆瞬时振动位移、瞬时入口压力与振动位移的相位差等参数值，将这些参数值代入上述计算公式即可求得LDPE熔体在毛细管壁处的第一法向应力差．     

日照白毫乌龙茶初制过程主要生化成分的变化

以日照白毫乌龙茶为研究对象,研究其初制过程中主要生化成分如茶多酚、儿茶素总量、游离氨基酸、咖啡碱以及儿茶素组分(EGC、C、EGCG、EC、ECG),儿茶素氧化产物(茶黄素、茶红素、茶褐素)含量的变化。结果表明,水浸出物含量高于国家标准;茶多酚、儿茶素总量明显下降;游离氨基酸含量在整个初制过程中总体呈上升趋势;咖啡碱与可溶性糖含量在整个初制过程中总体呈下降趋势;儿茶素组分以酯型儿茶素EGCG和ECG变化剧烈;儿茶素氧化产物TF、TR和TB含量呈上升趋势,毛茶的TR/TF比值约为12.10。此外,还对日照白毫乌龙茶与红茶、闽台乌龙茶主要生化成分进行了比较分析,以研究日照白毫乌龙茶的特点。