Which of the following is used to measure the diameter of a tree?

The diameter tape is specifically designed to measure the diameter of a tree at a standardized height, typically 4.5 feet above the ground, commonly known as breast height. This tape is marked in units that allow users to read the diameter directly without needing to perform any calculations. The diameter of a tree is a crucial metric in forestry, ecology, and conservation science, as it can provide valuable information regarding the health, age, and biomass of the tree.

Other tools listed have different functions; for instance, an increment borer is used to extract a core sample from a tree to study its growth rings, while a basal area calculator calculates the area of tree stems at breast height, primarily for assessing forest density. A tree height gauge measures the height of a tree, which is another important factor but not related to determining its diameter.