THE VALUE OF MERISTEM STATES, AS ESTIMATED BY A DISCRETE-TIME MARKOV-CHAIN

Modelled the dynamics of meristem states of mountain white birch Betula cordifolia at their elevational limit. Meristems could enter different states from summer to summer (summer dormancy, short-shoot production, long-shoot production, death), according to sets of transition probabilities. A Markov chain was used to estimate the life-expectancy of each meristem state and to compute the life-time rewards (number of meristems produced) brought to the host plant by each meristem state. Summer-dormant buds ultimately made a greater contribution to growth than other states because of the increased longevity of summer-dormant meristems combined with their ability to change state. Summer-dormant were crucial for repairs after damage caused by unfavourable climatic episodes at the tree line. By accumulating summer-dormant meristems, tundra birches could thus survive periodic crown destruction and "wait' for climatic improvements that would allow them to reach the threshold height needed for sexual reproduction. -from Author