Cladoptosis: An interesting phenomenon

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Cladoptosis is a process in which trees shed their branches or “self-prune” as part of their normal physiology or in response to stress through the formation of an abcission layer at the branch base. Sources of stress which may contribute to this shedding include drought, soil and root compaction, or presence of disease. In the case of certain tree species, however, none of these factors need be present in order for Cladoptosis to occur. For some tree species, including larches, pines, poplars, willows, maples, walnut, ashes, bald cypress, and oaks, shedding of branches is normal, often occurring annually in the fall, similar to the shedding of leaves from deciduous trees. Additionally, as trees get older, the number of branches which will be “self-pruned” often increases. Research aimed at gaining an understanding of the advantage to the tree that this process would offer has yielded a wide range of results which suggest that it depends greatly upon the tree species. There is evidence that cladoptosis may occur due to a need to remove less vigorous foliage or foliage which is disadvantaged in its resource availability, and these issues are likely more prominent in mature, older trees and in trees under stress. In other cases, cladoptosis may have a reproductive benefit or promote a more advantageous growth habit. The size of branches which are dropped varies widely but the point from which the branch is separated from the rest of the tree will generally be smooth, and may be somewhat rounded (see image below). Cladoptosis is typically not a cause for concern, though it is always recommended that tree stress be minimized through the implementation of a regular watering and fertilization regime.


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