The cost of apical dominance in white pine (Pinus strobus L.) : Growth in multi-stemmed versus single-stemmed trees

CHAMBERLIN, E. A. AND L. W AARSSEN. (Department of Biology, Queen's University, Kingston, ON, Canada K7L 3N6). The cost of apical dominance in white pine (Pinus strobus L.): Growth in multi-stemmed versus single-stemmed trees. Bull. Torrey Bot. Club 123: 268-272. 1996-White pine (Pinus strobus L.) normally has a single main stem extending the full height of the tree. Multi-stemmed trees however are occassionally formed following destruction of the terminal shoot, usually by stem-boring insects, which releases lateral shoots from apical dominance. With resources being channelled into more than one main 'sink,' multi-stemmed trees may be able to display greater photosynthetic surface area. Thus, we tested whether or not multi-stemmed trees had overcompensated for terminal shoot damage. Based on a survey of mature pine forest in eastern Ontario, Canada, multi-stemmed trees of a given age had shorter heights but greater trunk diameters and greater stem volumes than single-stemmed trees. Hence, multi-stemmed trees appear to be capable of overcompensating for terminal shoot damage, suggesting that there is a potential fitness cost of apical dominance (in terms of biomass production).