Key message Truncating the angle count sampling plots leads to a higher stock estimate because fewer trees are missed. It also causes a higher uncertainty of the estimates. Context The Austrian National Forest Inventory changed its plot design to angle count sampling plots that are limited to circles of 300 m 2 . A fixed plot size is beneficial for multistage inventory systems. Aims This study aims to quantify the ensuing effects on the national forest inventory on the plot and the national level regarding stock estimates and their uncertainty along with effects on as well as of upper diameter models. Methods Fully surveyed large-scale plots with simulated angle count samples were used to gauge the increase of variability. The full NFI 2007/09 data set was employed to simulate truncations at different distances as well as to parameterise eight alternatives for upper diameter models and to analyse the effects on the stock estimates. Results There is an increase in the stock estimate because the probability of missing sample trees is reduced. The change in upper diameter models had little effect. Conclusion The truncation removes a source of bias, facilitates field work, and is a favourable way forward.

中文翻译：

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截断角度计数抽样方法对奥地利国家森林清单的影响

关键信息 截断角度计数抽样图会导致更高的存量估计值，因为遗漏的树木更少。它还导致估计的更高不确定性。背景 奥地利国家森林清单将其样地设计更改为角度计数抽样样地，该样地仅限于 300 m 2 的圆圈。固定的地块大小有利于多级库存系统。目的 本研究旨在量化随后对国家森林清单对地块和国家层面的关于库存估计及其不确定性的影响，以及对上径模型的影响。方法 使用模拟角度计数样本进行全面调查的大规模地块来衡量变异性的增加。完整的 NFI 2007/09 数据集被用来模拟不同距离的截断，以及参数化上直径模型的八个替代方案，并分析对库存估计的影响。结果 存量估计值增加，因为丢失样本树的概率降低。上部直径模型的变化几乎没有影响。结论 截断消除了偏见的来源，促进了现场工作，是一种有利的前进方式。