Which method is NOT one of the four methods for determining Tree Protection Zones (TPZ)?

The Tree Protection Zone (TPZ) is an area around a tree that is critical for the tree's health and longevity during construction and development activities. The standard methods for determining TPZs are grounded in principles that consider the tree's growth patterns and root structures.

The drip line method is based on the area beneath the outer perimeter of the tree's branches, as this area often encompasses much of the tree's critical root area. The tree height method involves calculating the TPZ as a function of the tree's height, which provides a proportional area for root protection. The trunk diameter method determines the TPZ size based on the diameter of the tree trunk at breast height, usually providing a reasonable approximation of the root spread.

The root collar method, however, is not commonly recognized as a standard method for TPZ determination. While root collar assessments can provide information on tree health and the condition of the root system, they do not define an area around the tree that preserves its critical root structures for protection during development. Thus, it is not included among the accepted methods for establishing TPZs. Understanding these established methods helps ensure that trees are adequately protected during construction activities, promoting healthier urban forestry.