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首页> 外文会议>Statistics, mathematics and computers : Caring for the forest: research in a changing world >How Locally Reliable Are Forestry Data? An Examination of Spatial Distributions of Trees for Forest Inventory
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How Locally Reliable Are Forestry Data? An Examination of Spatial Distributions of Trees for Forest Inventory

机译：林业数据在当地有多可靠？森林资源调查用树木的空间分布调查

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摘要

It is shown that the coefficient of variation due to sample location for commonly used sizes of point (2.0 BAF) and plot (0.04 ha) samples can be 69% and 43%, respectively, for point and plot sampling for sparsely stocked stands, 26% and 8% for fully stocked stands, and may drop to 24% and 4% for over stocked stands. This was determined by generating spatial locations for trees for two 1 ha stands of each stocking level and locating seven sample plots in each stand within a maximum distance of 6 m from stand centre. Two new alternative forest sampling units were also examined - modified triangle based probability polygons (MTBPP) and triangular tessellation (TT). The latter two consider the spatial arrangement of trees in defining a sample unit. They appear to have a clear advantage over point and plot sampling in accuracy and precision of basal area for under stocked stands and, as stand density increases, continue to provide basal area estimates comparable to plot sampling. They also may require less field work for a given level of sample precision although more work is required on this subject.
机译：结果表明，对于稀疏林分的点样和样点采样，对于常用点样（2.0 BAF）和样点（0.04 ha）样品，由于样点位置而引起的变异系数分别为69％和43％，26完全存放的看台的百分比为8％和8％，过度存放的看台的百分比可能为24％和4％。通过为每个放养水平的两个1公顷林分生成树木的空间位置，并在距林分中心最大6 m的距离内的每个林分中定位七个样本地块，来确定这一点。还检查了两个新的替代森林采样单位-修改后的基于三角形的概率多边形（MTBPP）和三角形镶嵌（TT）。后两者在定义样本单位时考虑了树木的空间排列。对于储备不足的林分，它们似乎在点积和基点采样方面具有明显的优势，其基础面积的准确度和精度更高，并且随着林分密度的增加，它们继续提供可与基点采样相比的基础面积估计。对于给定的样品精度水平，他们可能还需要较少的现场工作，尽管在此主题上需要进行更多的工作。

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