A population model of chaparral vegetation response to frequent wildfires.

摘要: The recent increase in wildfire frequency the Santa Monica Mountains (SMM) may substantially impact plant community structure. Species of Chaparral shrubs represent dominant vegetation type SMM. These species can be divided into three life history types according to their response wildfires. Nonsprouting are completely killed by fire and reproduce seeds that germinate a cue, obligate sprouting survive resprouting from dormant buds root crown because destroyed fire, facultative recover after both resprouts. Based on these assumptions, we developed set nonlinear difference equations model each type. models used predict survivorship under varying return intervals. For example, frequent fires lead localized extinction nonsprouting such as Ceanothus megacarpus while several spinosus Malosma (Rhus) laurina will persist documented longitudinal study biological preserve We estimated appropriate parameter values for chaparral using 25 years data explored relationships equilibrium populations. conclude looking at survival strategies intervals changes structure short return. In particular, our predicts an average interval greater than 12 years is required 50 % initial population 25 % survive. contrast, have 90 % least 6 years.