Numeric dynamics of natural populations of <I>Paeonia delavayi</I> (Paeoniaceae)

Abstract

Aims Paeonia delavayi (Paeoniaceae) is an endangered plant restricted to southwestern China. Our objective was to study the numerical population dynamics of the largest and most concentrated natural population in Shangri-La, Yunnan Province, China. Methods The distribution area of P. delavayi was investigated from 2009 to 2011. We studied the numerical dy- namics of the population using static life table, survivorship and mortality curves, fecundity schedule and Leslie matrix model. Important findings P. delavayi underwent strong environmental screening at ages three to six years. The physio- logical life span was about 15 years, and generation span was eight years. The net reproductive rate (R0 = 0.985 7), intrinsic rate of increase (rm = -0.001 7) and finite rate of increase (λ = 0.998 3) were relatively low, indicating that the population was decreasing. The Leslie matrix model showed that plant numbers from seedlings and sprouts declined about 50% during the past 30 years. The survival rate exhibited a steep curve (B1 type). The mortality rate of individuals was different at every stage, and the killing power (Kx) was high at the ages of six and 12 years. The present population is maintained mainly by sprouts and seedlings. Likely key threats to the species are the