ABSTRACT

Many forestry practitioners need information on the amount of dead wood for various purposes, often at the level of individual stands. Our aim was to compare four simple dead-wood inventory methods of which systematic circular plot inventory is a well-known method, while relascope plot inventory (using the ordinary horizontal angle relascope also for downed trees), diameter class counting and total inventory are new methods. Seven surveyors tested the methods in four stands in southern Finland. All the methods produced rather accurate volume estimates. Mean percent error was the smallest (−5.7%) in total inventory and the largest (−12.4%) in diameter class counting. Precision differed significantly between the methods. Variation among individual measurements, expressed as percentage SD, was 15.9% in total inventory, 24.8% in diameter counting, 36.6% in relascope inventory and 43.0% in circular plot inventory. Diameter counting was by far the fastest method. Relascope inventory and circular plot inventory took about twice as much time, and total inventory over three times as much time as diameter counting. In conclusion, diameter class counting is a cost-effective dead-wood assessment method, if the purpose is to get an estimate of the total volume of dead wood within a forest stand with a reasonable precision.

摘要

许多林业从业者需要有关各种用途的死木数量的信息，通常是单个林分的信息。我们的目的是比较四种简单的死木清查方法，其中系统圆形小区清查是一种众所周知的方法，而 relascope 小区清查（也使用普通水平角 relascope 来处理倒下的树木）、直径等级计数和总清查是新方法方法。七名测量员在芬兰南部的四个站测试了这些方法。所有方法都产生了相当准确的体积估计。总库存中的平均百分比误差最小（-5.7%），直径等级计数中的平均百分比误差最大（-12.4%）。两种方法之间的精确度存在显着差异。各个测量值之间的变异（以百分比 SD 表示）为总库存的 15.9%，直径计数为 24.8%，36。6% 为 relascope 库存，43.0% 为圆形地块库存。直径计数是迄今为止最快的方法。Relascope 盘点和圆形图盘点所花费的时间大约是直径计数的两倍，总盘点时间是直径盘点的三倍多。总之，如果目的是以合理的精度估算林分内死木的总体积，则直径等级计数是一种具有成本效益的死木评估方法。