东北东部天然次生林的景观类型空间连接与分布规律--以黑龙江省帽儿山林场为例

帽儿山地区是东北东部山区较典型的天然次生林区。本文利用ARC／INFO软件，对帽儿山林场景观类型最小距离指数和景观连接度指数进行分析，进而对帽儿山林场各景观类型的空间分布规律进行了探讨。结果表明：有林地与无林地的景观连接度有明显差异，无林地的景观连接度普遍大于有林地；天然林的景观连接度都接近于O，景观破碎化程度较高。人工林的最小距离指数低于天然林和非林地；人工林中，人工针叶混交林的距离指数最小，格局接近于团聚分布；天然林的景观格局近于随机分布；非林地中，采伐迹地的距离指数最小，接近于团聚分布。图2参15。     

基于改进随机Hough变换的椭圆形农产品大小分级

针对椭圆形农产品的分级问题,采用最近邻分类算法和随机Hough变换理论,对哈密瓜这类椭圆形农产品的大小分级方法进行研究。结果表明:1)哈密瓜边缘轮廓近似椭圆形,所测出的长短轴半径,可以作为椭圆形哈密瓜大小分级的新标准;2)通过试验测定,对于白色背景的哈密瓜,最近邻分类算法可以提取出较为完整的边缘轮廓;3)随机Hough变换可以在边缘轮廓不完整且有随机噪声干扰的情况下,检测出任意曲率的哈密瓜边缘轮廓的近似椭圆;4)与椭圆形哈密瓜的半径的真实值相比,本改进算法识别值的相对误差小于6%;5)当哈密瓜处在不同倾斜状态时,如0°、45°、90°、135°,本改进算法仍可以准确测得其长短轴半径。本改进算法还可以推广到其他椭圆形和类椭圆形农产品的大小分级中。     

山东省乡村旅游景点空间结构及影响因素研究

乡村旅游已成为农村实现产业融合的新型产业形态,为探求其开发和发展的空间结构,以山东省193个乡村旅游景点为研究样本,运用最近邻指数、多距离空间聚类分析和核密度分析等GIS空间分析和计量地理方法,对山东省乡村旅游景点的空间结构及影响因素进行定量研究,旨在为山东省乡村旅游的发展规划提出决策参考。结果显示:1)山东省乡村旅游景点的最近邻指数(R)为0.74,在空间分布上表现为典型的集聚型分布,主要分布于青岛、济南、临沂及枣庄4座城市周围。2)山东省乡村旅游景点热点区和冷点区空间差异明显,在省域尺度下表现出明显的"块状"分布特征。3)山东省乡村旅游景点受交通、区位、社会经济、资源禀赋、地形地貌等多种因素综合作用的影响。基于此,结合山东省乡村旅游发展现状提出两点建议:1)加强鲁东、鲁西、鲁北、鲁中4大片区合作,构建多个"核心—边缘"乡村旅游发展区。2)完善旅游交通网,实现景点之间的有机链接。     

多源降水融合分析产品在重庆复杂地形下的精度评价

利用2020-2021年两套多源降水融合分析产品FAST和FRT产品、经过质量控制后的重庆地区35个国家气象站逐小时降水量资料,结合各站点地形因子对两套产品进行相关性和误差检验,为复杂地形下的水文气象研究提供数据支撑。结果表明：（1）FAST、FRT产品与观测值的相关性较好,呈正相关,误差较小,产品整体比观测值偏低,两者略有差别。（2）在月、季时间尺度上,春季的精度最好,汛期5-9月的误差和离散程度最大。（3）随着降水等级增大,产品的误差、相关性以及TS等级评分的分布越离散,误差绝对值逐渐增大,TS等级评分逐渐降低,相关性则先降低后增大,其中降水等级0.1～1.9mm、≥20mm的相关性较好。（4）在地形因子上,产品精度略有差别,其中斜坡上产品的精度最优,其余依次为平坡、陡坡以上和缓坡;起伏度大于70m产品的精度最优;随着海拔增加,产品精度先降低,当海拔大于700m时,产品精度提升;坡向为西南、东的产品精度更优,其中西南坡向最优。FAST和FRT降水产品在重庆地区具有较高的精度,可以为自动站点稀少地区的降水数据提供有效补充。     

基于矿质元素的苦荞产地判别研究

 【目的】分析不同省份苦荞矿质元素的特点,筛选判别苦荞产地的有效指标,同时探索苦荞产地溯源和判别的方法。【方法】对苦荞主产区山西、甘肃、青海、四川和云南省的39个苦荞品种中的7种矿质元素Cu、Zn、Fe、Mn、Ca、P和Se的含量进行统计分析,在对7种矿质元素进行逐步筛选的基础上,应用非参数判别的K最近邻法进行判别分析。【结果】不同省份苦荞品种的矿质元素含量存在不同程度的差异,云南苦荞Cu、P含量最高;山西苦荞Se含量最高;青海苦荞Zn、Fe、Ca含量最高;四川苦荞Cu、Zn、Fe、Ca、P含量均最低,Mn和Se含量也较低;甘肃苦荞Mn含量最低。Se、Mn、Zn、Ca和P对苦荞分类有极显著影响,Fe和Cu对苦荞判别影响不显著;判别结果回判正确率和交互验证正确率均为97.4%。【结论】矿质元素含量和现代统计技术相结合的判别方法,用于苦荞产地溯源和判别是有效、可行的。     

面向对象的土地利用遥感分类方法研究

以重庆市忠县为研究区,以LANDSAT-5 TM影像为数据源,利用TM及其衍生指数、DEM及其衍生数据,借助ENVI4.8、ArcGIS10.0以及eCognition软件,进行土地利用遥感信息提取方法研究,通过综合利用基于知识的决策树分类和基于样本的最近邻分类,对研究区进行土地利用遥感信息提取,并与监督分类和非监督分类方法相比进行精度评价。研究结果表明,与传统分类方法相比较,面向对象分类方法精度更高。     

Estimating forest carbon fluxes for large regions based on process-based modelling, NFI data and Landsat satellite images

The aim of this study was to develop and evaluate a new approach for estimating forest carbon fluxes for large regions based on climate-sensitive process-based model, national forest inventory (NFI) data and satellite images. The approach was tested for Central Finland and Lapland with NFI field data and daily weather data from 2004 to 2008.The approach combines (1) a light use efficiency (LUE) model, (2) a process-based summary model for estimating gross primary production (GPP) and net primary production (NPP), and (3) the Yasso07 soil carbon model, which together allow the estimation of net ecosystem exchange (NEE). Landsat TM 5 satellite images were utilized to generalize the carbon fluxes obtained for field sample plots for all forested areas using the k-NN imputation method. The accuracy of the imputations was examined by leave-one-out cross validation and by comparing the imputed and simulated values with Eddy covariance (EC) measurements.RMSE of the k-NN imputations was slightly better in Central Finland than in Lapland, the bias staying at a similar level. Based on the EC comparisons, the approach seemed to work rather well with GPP estimates in both areas, but in the north the NEE estimates were remarkably biased. The main advantages of the approach include its applicability to basic NFI data and a high output resolution (30 m).The method proved to be a promising way to produce carbon flux estimates based on large-scale forest inventory data and could therefore be easily applied to the whole of Northern Europe. However, there are still drawbacks to the approach, such as lacking parameters for peat lands. One of the future goals is to integrate the approach with an interactive mapping framework, which could thereafter be utilized, for example, in climate change research.     

Quantifying spatio-temporal dispersion of bark beetle infestations in epidemic and non-epidemic conditions

Spatio-temporal dispersal of pest species such as bark beetles plays a key role in their population ecology and outbreak dynamics. Understanding the underlying patterns is crucial for applying appropriate management strategies.In contrast to most existing studies which focus on dispersing beetles, we analysed patches of killed trees resulting from bark beetle infestation. The study was based on a 22-year time series of annually captured colour-infrared (CIR) images of the Bavarian Forest National Park (Germany), where Ips typographus L. (Coleoptera, Curculionidae, Scolytinae) propagates undisturbed by human activity. Newly infested patches comprising at least 5 spruce trees were identified in every time step. This investigation of spatio-temporal spread of infestations primarily focused on (i) parameterizing the size and shape of infestation patches, (ii) modelling an infestation gradient and (iii) evaluating the risk of subsequent infestations on landscape scale. We developed a GIS-based distance ring approach to quantify the distance relation of subsequent infestations, including the distribution of potential hosts.Infestation spread was revealed to be strongly distance dependent, following an inverse power law function: on average 65% of new infestations occurred within a 100 m radius of the previous year’s infestations, and 95% within 500 m. ‘Distance’ proved to be a major determinant of I. typographus dispersal on the landscape scale in each time step of the 22-year series we investigated. Infestation distance thus describes the outcome of beetle dispersal very accurately. The time series showed two alternating periods of epidemic and non-epidemic infestation. These gradation stages did not affect the size and shape of infested patches, but epidemics correlated significantly with a higher percentage of infestations within short distances. Additionally, the resulting infestation risk is highly sensitive to the gradation stage, particularly within the first 100 m around source spots where it increases up to 30%.Our study therefore contributes to a better understanding of the outbreak dynamics of I. typographus and suggests concentrating efficient bark beetle management on areas in the close vicinity of previous years’ infestations.     

三种重采样方法对冲沟坡度坡长因子的影响

为探索不同重采样方法对形态差异明显的冲沟坡度坡长(Slope length and slope steepness,LS)因子的影响,以元谋县干热河谷1∶5 000比例尺的等高线矢量数据为基础,在Arc GIS平台下构建六条典型冲沟2 m分辨率的数字高程模型(Digital elevation model,DEM),采用最邻近(Nearest,Near)、双线性(Bilinear,Bil)、三次卷积(Cubic,Cub)重采样的DEM计算LS,通过相对差系数、LS因子分级面积比例、XY散点图对比分析三种重采样方法计算冲沟LS的差异性。结果表明:Near重采样计算的LS值与Bil、Cub重采样计算的LS值差异较大,相关程度低,Bil与Cub重采样计算的LS值差异较小,相关程度高;冲沟刚发育时,Cub重采样要优于Near和Bil,冲沟侵蚀强烈时,Near重采样要优于Bil和Cub,冲沟形态稳定时,Bil重采样要优于Cub和Near。     

Spatial associations among tree species in a temperate forest community in North-western Spain

Analyzing spatial patterns in plant communities may provide insights in the importance of different processes for community assembly and dynamics. We applied techniques of spatial point pattern analysis to data from a fully mapped plot of a temperate forest community (Corylus avellana, Crataegus monogyna, Fagus sylvatica, Ilex aquifolium and Taxus baccata) in North-western Spain to conduct a community wide assessment of the type and frequency of intra and interspecific spatial association patterns. We first explored the overall intra and interspecific patterning, and then classified the types of association patterns at various neighbourhoods. By conditioning on the larger scale pattern we then explored small-scale (0–15 m) intraspecific and interspecific patterns. Association patterns varied from strong positive association at small scales to, as a by-product, repulsion at intermediate scales. Surprisingly, there were no negative associations at small scales, but trees were arranged in multi-species clumps, up to 2.5 m in diameter and comprising a few individuals. Ilex and Corylus, the understorey species, were frequently involved in the clumps, showing positive small-scale association with the other tree species. Our analyses highlighted that animal mediated seed dispersal, interspecific facilitation and perturbation processes may operate successively to shape tree distributional patterns, although their relative importance vary among species. Given the complexity of the patterns described and the current threats to some of the species studied, directed experiments in the field are needed to further elucidate some of the hypotheses derived.