Core Measuring and Processing Tree cores are extracted with an increment borer. Notice how the extractor holds the core as it is removed from inside the hollow center of the bit. The bit should be perpendicular to the tree trunk and at a height of about 30 cm from the base of the tree. Annual growth rings of trees are visible in cross-section.
Most trees add one new ring for each year of growth.
The width of each annual ring may be a reflection of forest stand dynamics, natural disturbance regimes, temperature or precipitation. Dendrochronology, the study of annual growth rings, has become prominent in ecology, climatology and geography. The annual growth of the tree is measured by placing the core on a movable stage. The distance the stages moves is recorded automatically. To measure the width of an annual ring, the stage is moved the from one annual ring to the next.