森林资源与生态监测的空间平衡抽样方法研究

Spatially Balanced Sampling for Monitoring Forest Resources and Ecological System

  • 摘要: 以南京紫金山国家森林公园为对象,在介绍空间平衡抽样(SBS)反向随机四分递归栅格算法(RRQRR)基本步骤基础上,通过计算 Voronoi多边形面积方差之比评价不同抽样方法的空间平衡性,分简单随机抽样、系统抽样、空间平衡抽样3种方法,从调查成本、调查精度2方面,对研究地区线状地物(道路)、离散分布的面状地物(湖泊、水库)进行抽样设计和方案评价。结果表明,在100~1000m多个抽样尺度上,空间平衡抽样的空间平衡性能高于简单随机抽样,但低于系统抽样。只有当抽样强度>3000时,空间平衡抽样样本点的均衡分布性能才能体现出来。在对离散分布的线状地物、面状地物进行生态监测时,空间平衡样本点的平均海拔最低(68.72、34.72m)、平均坡度最小(8.20°、2.63°)、距调查对象的平均距离最短(13.33、0.80m),落在调查对象上的样点占总数的百分比最高(96%、89%)、每个调查对象上的平均样点数最多(1.68、2.70)。

     

    Abstract: On the basis of introducing the fundamental work steps of spatially balanced sampling (SBS) and the algorithm of RRQRR (Reversed Randomized Quadrant Recursive Raster), taking Zijin Mount National Forest Park as a case study area, the evaluation of sampling design precision and scheme performance of three sampling methods, namely simple random, systematic sampling and spatially balanced sample (SBS) were conducted for the linear features of road and discrete distributed surface features (lakes, reservoirs) from two aspects of investigation cost and sampling accuracy by means of calculating the ratios of area variance of Voronoi polygon to assess the spatial balance of different sample methods. The studies showed that at the sampling scale from 100m to 1000m, the spatially balanced performance of spatially balanced sampling was superior to the simple random sampling, but inferior to systematic sampling. The property of spatial balance of SBS could be reflected only if the sampling volume was greater than 3000. In ecological monitoring of the discrete liner and surface features, the average elevation of sample points of SBS were lowest (68.72m,34.72m), the average slope were the smallest (8.20°, 2.63°), and the mean distance from sample points to the objects were the shortest (13.33m, 0.80m), the percentage of the sample points on objects to the total number were the highest (96%, 89%), the average points on the sampling objects were the largest (1.68, 2.70).

     

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