Bark Inclusions are serious tree defects that are very common, and often lead to breakage under low to medium loads. They occur between two co-dominant stems, as they grow. The bark between the two stems included in the trunk, as the cambuim advances year after year. This acts essentially as a wedge, pushing the stems apart, and thus producing an extremely weak union. Included bark accounts for over 50% of the wind damage that I see.
Co-Dominance is when we have two or more main stems, or a single stem that bifrucates into two or more equally dominant leaders. This architecture is generally detrimental to the organism because it lends itself to breakage.