Now, here's a problem to consider. Clearly, dendrochronology isn't as easy and clearcut as it might seem at first glance. Problems affecting growth. Complicating the interpretation of tree rings are other factors, three of the most common of which are burning, sloping terrain, and multiple trunks. Forest fires can burn off the bark and outer rings on one side of a tree and thereby affect the tree's growth, and hence ring formation, in following years.
Slopes can affect the centricity of tree ring formation.
It is not at all unusual to find trees with thicker rings on one side of the tree than on the other. In those cases were trees are growing on stable slopes, the rings tend to be thick on the downslope side. On unstable slopes, where landslides have disturbed vegetation, rings tend to be thicker on the upslope side. Trees with multiple trunks , junipers, for example, pose special problems. Growth patterns above points of bifurcation are usually different from that below the fork although the ages of the two segments might well be the same.