Time is involved with each of these, but all too often we tend to envision the environment as static rather than dynamic. This is perhaps more so for vegetation than anything else. Factors influencing growth.
Most people think that trees add a ring for every year of growth.
To a great extent this is true, but there is more. Coniferous trees have proven to be the best and easiest, but not the only, trees with which to work. Trees also add one ring for each rainy season within a year. If the climate of a particular region is wet year-round, as in the tropics, rings tend to be very thick and almost indistinguishable. If the climate of an area has two distinct rainy seasons separated by periods of no rain, trees will add two rings per year .