Population dynamics of Zea diploperennis, an endangered perennial herb:: effect of slash and burn practice

1 Zea diploperennis is a wild relative of maize that is endemic to the Sierra de Manantlan Biosphere Reserve in Mexico. Because this species is a priority for conservation in the reserve, the effects on its populations of the most common types of anthropogenic disturbance - slash-and-burn, and slash without subsequent burning - were investigated in three populations for 5 years. 2 The patterns of establishment and mortality were similar in all populations studied. Numbers of ears and fruits produced were significantly higher when disturbances were applied. 3 Because permanence is the most important stage in contributing to lambda, the results suggest that the first genets to become established have an advantage over newly recruited plants. 4 When the two disturbance types were applied, lambda was close to 1 or > 1. After the first disturbance, lambda increased by almost 100%. In almost all situations, with or without disturbance, the persistence loops of Z. diploperennis are the most important life history pathways in the relative contribution to lambda. In general, when lambda increases, sexual growth loops also increase in importance, and persistence loops decrease. Changes in lambda are not related to changes in vegetative growth loops. 5 If populations of Z. diploperennis are not disturbed at least once every 5 years, then species will go locally extinct in the wild.