What is a hypsometer used for?

A hypsometer is specifically designed for measuring the height of trees. This tool is essential in forestry because knowing the height of a tree can provide vital information about its growth stage, volume, and biomass. By using trigonometric principles, a hypsometer allows users to determine a tree's height from a distance without the need to physically measure the tree.

Other options, while related to forestry and environmental science, do not pertain to the function of a hypsometer. Measuring tree diameter involves different tools such as calipers or diameter tapes, measuring soil pH requires a pH meter or soil test kits, and rainfall measurement is conducted with rain gauges or similar instruments. Thus, while these are all important aspects of forestry management, they are outside the specific function of a hypsometer.