Population structures and dynamics of Abies nephrolepis and Picea koraiensis in the Changbai Mountains of northeastern China

We studied the population structures and dynamics of Abies nephrolepis and Picea koraiensis in the Changbai Mountains of northeastern China to compile the static life table of A. nephrolepis and P. koraiensis populations, and to determine the mortality rate curve, vanishing rate curve , survival rate curve and survival function curve. Based on the population life table and theory of survival analysis and using the age class structure represented by DBH class and smoothing out technique, the population dynamics was analyzed by spectral analysis. There were abundant seedlings and saplings of A. nephrolepis and its DBH class structure followed the typical shape of an inverse J, and the number of individuals decreased with increasing DBH class. While the DBH class of P. koraiensis approximately appeared an inverse J form, and there were more seedlings than others. Two peaks of mortality rate and vanishing rate existed in the A. nephrolepis lifespan: one in the 4th age class periods and the other in the 9th age class. The mortality rate and vanishing rate of P. koraiensis were stable and they were same basically. The survival curves of A. nephrolepis and P. koraiensis populations were Deevey type II. The survival analysis of the two populations showed that the population cumulative mortality rate was increasing all along, while the survival rate was decreasing all the time. Mortality density and hazard rate curve of A. nephrolepis population were same basically, so was P. koraiensis. Spectral analysis of A. nephrolepis and P. koraiensis populations showed that there was a marked periodic fluctuation in the process of natural regeneration, and the effect of fundamental wave of A. nephrolepis was most prominent, but the effect of fundamental wave of P. koraiensis was smaller.