The objective of the research was to analyze the relationship between diameter and merchantable height in Tetrastylidium peruvianum Sleumer, commonly known as "huacapú negro," within a natural forest, using different sampling methods. The study evaluated trees of the species with a diameter at breast height (DBH) equal to or greater than 10 cm. Various sampling techniques were applied, including Sample 1 (M1), which grouped individuals into diameter classes with a 3 cm amplitude; Sample 2 (M2), with individuals distributed in diameter classes with a 2 cm amplitude; and Sample 3 (M3), which was a representative sample without diameter class stratification, meaning the data distribution was random. The results show that, for the relationship between diameter and merchantable height in Tetrastylidium peruvianum Sleumer in natural forest conditions, the cubic allometric model provided the b...