OLD-GROWTH MANGROVE FORESTS IN THE UNITED-STATES

Criteria used to identify old-growth forests in the Pacific Northwest have not been proven applicable in other ecological life zones. For ex ample, Pacific Northwest criteria are not suitable for the identificat ion of old-growth mangrove forests. To identify old-growth mangroves o ne has to take into account differences in stand structure and functio n due to geomorphology, within-site environmental gradients, and regio nal disturbance regimes. A flexible and holistic approach is needed. S tand age, defined in terms of Pacific Northwest forests, is not necess arily the best criterion for identifying for conservation mangrove for ests or any forest outside the Pacific Northwest. No single stand will have all old-growth characteristics and even if they are present in a stand, these characteristics do not necessarily assure that the stand is old growth. Whether a mangrove stand reaches old-growth stage depe nds on the dynamics of coastal conditions under which it grows. Moreov er, it is necessary, to differentiate between the age of trees in a st and and the age of the mangrove system, which includes the substrate. Old-growth mangrove stands are improbable states for this ecosystem ty pe, and they can revert to younger stages. Mangroves offer a challenge to the concept of the old-growth forest, and through our analysis of this system we show that when ecosystem functions and states are evalu ated it is necessary to avoid geographic biases based on particular ec ological conditions.