Simulation of Cotton Production for Precision Farming

Most crop simulation models do not directly consider the spatial variability of inputs nor do they produce outputs that show the expected spatial variability of yield across a field. If such models were available for precision farming, then researchers could much better evaluate the effects of soil sampling densities to determine the number of samples necessary to adequately model a particular field. The objectives of this study were: (1) to design and implement a spatial simulation methodology for examining details of precision farming and (2) use this to evaluate the effects of different soil sampling resolutions on predicted yield and residual nitrates through spatially variable nitrogen applications. The GOSSYM/COMAX cotton growth model/expert system and the GRASS geographic information system were used to develop a spatial simulation that produces spatially variable outputs. Inputs to the model were collected from a 3.9-ha cotton field. Soil nitrate, a primary driver in fertilizer recommendations, was sampled on a 15.2-m regular grid for depths to 15 cm and on a 30.5-m regular grid at six 15-cm depth intervals (down to 90 cm). COMAX was used to determine spatially variable fertilizer recommendations. GOSSYM was used to simulate perfect application of these recommendations and predicted spatially variable yield and residual nitrates. Reductions in sampling density or resolution were simulated by systematically reducing the amount of data available to COMAX for calculating spatially variable fertilizer recommendations. GOSSYM subsequently used these recommendations (based upon less and less knowledge of soil nitrates) to simulate the effects of differing sampling resolutions on predicted yield and residual nitrates. For recommendations based upon a 15.2-m grid of inputs, 41.4 kg/ha of nitrate fertilizer produced 801.7 kg/ha of cotton and left an average of 9.4 ppm of nitrate in the soil profile. For a 30.5-m grid, 42.8 kg/ha of nitrate fertilizer resulted in a yield of 811.2 kg/ha and residual soil nitrate of 8.3 ppm. For 45.7-m and 61.0-m grids, the results were 43.3 kg/ha and 41.2 kg/ha of nitrate fertilizer, 755.3 kg/ha and 794.3 kg/ha of cotton, and 11.5 ppm and 8.1 ppm of residual soil nitrate, respectively. This study concluded that crop simulations and geographic information systems are a valuable combination for modeling the effects of precision farming and planning variable rate treatments. Simulation results indicate that excessive fertilization, while potentially damaging to the environment, may also have a negative impact on yield.     

吉林西部环境质量空间模糊综合评价

在建立吉林省西部环境质量评价指标体系的基础上,运用空间模糊综合评价方法,对研究区环境质量空间总体状况进行了综合评价,并深入研究和实践了区域环境质量评价中遇到的隶属度的空间化、权向量的确定等具体问题.评价结果显示,研究区环境质量总体处在中、差等级水平,空间上呈东西分布,环境恶化趋势从西南部逐渐向北部和东部蔓延.     

Loess erosion in relation to land-use changes in the ganspoel catchment,central Belgium

This paper examines the changes of land uses and landscape patterns in the Ganspoel Catchment, central Belgium, using aerial photography interpretation (photographs taken in 1947, 1969 and 1986). The comparison of land cover areal changes and a transition matrix were used to assess land-use changes in time and space. The size, fractal dimension and elongation index of patches were quantified for landscape pattern analysis. Grassland increased and farmland decreased in the study area from the 1940s to the 1980s. Forest increased from 1947 to 1969 and decreased from 1969 to 1986. About 49 per cent of the study area experienced changes of land use between 1947 and 1969, and about 36 per cent between 1969 and 1986. The landscape of the study area is more fragmented than it was in the 1940s. Patches have generally increased in number and decreased in size, although the landscape was most fragmented in 1969; fractal dimension of patches are lower, indicating less complex shapes. From 1969 to 1986, 59 per cent of the area of change was on 0–3 degree slopes, and from 1969 to 1986 6.7 per cent was on >8 degree slopes. Changing land uses and landscape patterns may have important ecological implications.     

基于GIS和生态敏感性分析的城乡公园地块规划研究

以湖北红安县马蹄山郊野公园为研究对象,对其地形地质、气候水系、植被覆盖特征进行分析,提出影响其环保生态的三大主要因子为自然本底、生态资源和人类活动,开展影响程度分级、权重因子计算和综合评价方案建立。借助MapGIS地理信息系统平台开展研究区生态敏感性量化分区,将研究地块分为低、轻度、中度、高度和极高敏感5个不同等级区域,并对每个不同等级敏感区域的分布面积、分布范围和规划方向进行研究,得到马蹄山郊野公园的生态改造布局成果,为该地块的生态规划建设提供了科学依据和建设指导。     

基于GIS的三门峡市公园可达性分析

基于GIS技术,以三门峡市中心城区城市公园为例,利用网络分析法定量评价步行、非机动车、机动车3种交通方式下的公园可达性,并结合可达面积与人口分析比较研究区、各行政区、各行政街道间的差异。结果表明,研究区内公园分布不均,湖滨区公园多、陕州区公园少;研究区公园绿地非机动车和机动车方式下的可达性较好;步行方式下的可达性较差,只有不到36.11%居民可步行30 min内到达相近公园;湖滨区公园绿地可达性要好于陕州区;前进街道、涧河街道、湖滨街道公园的可达性最佳,会兴街道、张湾乡公园的可达性最差。     

三屯河灌区水利信息化的应用研究

以昌吉三屯河灌区为研究区域, 利用ArcGIS的水文分析模块对GDEMV3 30M 分辨率数字高程数据进行河网水系的提取, 从而得出水流方向、汇流累计量、分级河网、子流域边界等河网信息,利用AIearth深度学习算法对Sentinel-1 SAR GRD遥感影像进行水体分类提取;不同于用ENVI遥感影像处理软件对研究区影像进行地物识别分类的传统操作,本研究更倾向于通过AIearth使用监督分类算法对Sentinel-2 L2A影像数据进行地物分类,进而绘制出渠系一张图,清晰生动的展现研究区域复杂的水系结构,对GDEMV3 30M 分辨率数字高程数据、野外采样点数据、天地图所选区域0.862m/像素,672瓦片数量的17级Tiff数据进行处理制作采样点的渠系地形三维图,从立体的角度深入探索了水系地貌的特征,为研究提供更全面的视角,并探讨在实验过程中遇到的难点及解决办法。     

信息系统在林业中的应用现状与发展对策

近年来各类信息系统在林业上的应用日益广泛,极大地促进了林业的发展.本文论述了管理信息系统、地理信息系统、决策支持系统、专家系统在国内外林业中应用的现状,并提出了信息系统在林业中应用的发展趋势和我国目前存在的主要问题及发展对策.     

怒江自然保护区的功能区规划设计

怒江自然保护区是我国生物多样性最丰富,模式标本最富集的产地之一,几乎是横断山区的一个缩影,在我国有极其重要的研究价值.该研究在对2004年TM影像判读的基础上,利用植被分布现状图,依据自然保护区景观资源空间结构与生态功能特征,重新对怒江自然保护区福贡片区进行了细致的功能区规划设计.     

基于RUSLE的沂沭泗河流域水土流失强度研究

基于RUSLE对沂沭泗河流域的土壤侵蚀进行定量研究,确定土壤侵蚀风险区域。研究结果表明:该流域土壤59.297%为微弱侵蚀,15.65%为中度侵蚀,主要分布于沂沭泗河流域土壤侵蚀的重点风险区域和重点治理区沂蒙山区;人类合理的活动在减少土壤侵蚀中发挥重要的作用。研究结果为该区域控制水土流失提供了基础数据。     

RS与GIS在土地利用/土地覆盖变化中的应用研究(英文)

综述了在土地利用/土地覆盖变化(LUCC)的研究中遥感(RS)和地理信息系统(GIS)的集成及其应用,LUCC研究中的RS与GIS集成的方式与技术途径、以及土地利用/土地覆盖动态变化监测研究、驱动力研究、模拟研究中RS与GIS集成应用实例。并讨论了RS与GIS在LUCC中应用、集成的问题和LUCC研究的技术发展方向。