Abstract

Tree crown volume is a fundamental tree characteristic. It correlates to forest biomass production and most relevant ecosystem and environmental functions, such as carbon sequestration and air pollution reduction. When researching these relationships, it is necessary to clearly define and then quantify tree crown variables in a both accurate and operational manner. In this paper, we review the reported literature on the assessment of tree crown volume. First, we compile the varying definitions of crown volume and other tree crown variables that may be used as inputs to quantify crown volume. Then, we examine the data sources for quantifying these variables, including field measurements, terrestrial photographs, aerial photographs and laser scanning. Furthermore, we compare the published approaches on translating these crown variable measurements into tree crown volume. These approaches include the approximation of simple geometric solids, approaches of computational geometry and voxelization. We also compare the reported accuracies and major challenges of these approaches. From this literature review, the reader may craft a suitable approach for the assessment of crown volume.

中文翻译：

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评估树冠体积—综述

摘要

树冠体积是树木的基本特征。它与森林生物量生产以及最相关的生态系统和环境功能（例如碳固存和减少空气污染）相关。在研究这些关系时，有必要以准确和可操作的方式清楚地定义然后量化树冠变量​​。在本文中，我们回顾了有关树冠体积评估的文献报道。首先，我们汇编树冠体积和其他树冠变量的各种定义，这些变量可用作量化树冠体积的输入。然后，我们检查用于量化这些变量的数据源，包括野外测量，地面照片，航拍照片和激光扫描。此外，我们比较了将这些树冠变量测量值转换为树冠体积的已公开方法。这些方法包括简单几何实体的近似，计算几何和体素化的方法。我们还比较了这些方法的报告准确性和主要挑战。通过该文献综述，读者可以设计出合适的方法来评估牙冠的体积。