why are annual rings comparatively well marked in plants growing in hilly areas than those in coastal areas?
The climatic conditions in the coastal regions are almost uniform all throughout the year; thereby, the activity of the cambium is almost uniform. Due to this, their is no differentiation of secondary wood into autumn and spring wood whereas in hilly areas, the activity of cambium varies with the season. The cambium produces autumn wood (darker in colour) in the autumn season and spring wood (lighter in colour) during spring season. Hence, plants growing in hilly areas have well marked annual rings than the plants growing in coastal areas due to difference in the cambial activity.