The Population Viability Analysis For Nipponia Nippon

Population viability analysis is is an important content of Conservation Biology. Vortex model, as a computer simulation tool for wildlife population viability assessment, has been used extensively on many endangered species management and conservation. Crested Ibis is one of the most endangered birds in the world. It is listed in the first class of key protected wildlife species in China. In this page, we chose Vortex9.99to simulate the dynamics of this species. But first we need to test the veracity of VORTEX. We collected the population data of Crested Ibis from1981to2000and we divided the data into two part one is the first20years the other is the after10years. We used the first20years population data to set the parameters of VORTEX and used the after10years population data to test the veracity of VORTEX. According to T test (P=0.465>0.05, df=18) and Chi-square test(X2=9.942P=0.355>0.05df=9),we find that the simulation results was not significant compared with the real value.This article used VORTEX to simulate the population dynamics of Crested Ibis in the next50years. The results show that the population of Crested Ibis will not extinct in the next50years and trend to stable growth and it will keep a steady state after20years.after50years the population of Crested Ibis will reach to1654(SD=424),the population expectations heterozygosity will decrease from0.994to0.982.The actual observation heterozygosity will decrease from1to0.017.We simulate the population dynamics of Crested Ibis with and without inbreeding depression.The result shows that there is no difference in both cases.We simulate the influnce of carrying capacity.The result shows that carrying capacity has significant effects on the population dynamics of Crested Ibis.The smaller of carrying capacity the shorter the time required to reach carrying capacity, the final number of Crested Ibis is smaller.We simulate the influnce of density dependence.The result shows that density dependence has little influnce on the population of Crested Ibis.We simulate the influnce of sex ratio.The result shows that sex ratio has great impact on the population of Crested Ibis.The proportion of male accounting for fifty percent, the growth rate of population is fastest.The proportion of male above or below50%,the growth rate will be decline.The proportion of male too high or too low,it will bring about population declines. We simulate the influnce of probability of occurrence of catastrophe. The result shows that the probability of occurrence of disasters inrease to the twice time of before, the time to reach environmental carrying capacity is longer than before.The number of population will maintain at low levels.We simulate the influnce of mortality rate.The result shows that when the mortality rate dcrease the final number of population will increase and the time to reach environmental carrying capacity is shorter.When the mortality rate increase to a certain degree the population of Crested Ibis will be extinct.At the same time we also simulate the influnce of different mortality rate with Chicks, subadult, adult.Sensitivity analysis formulas is Sx=(ΔX/X)/(ΔP/P).After calculation we find that the Sx of carrying capacity is0.94,the Sx of sex ratio is1.30, the Sx of the frequency of catastrophe is0.06,the Sx of mortality rate is0.53.So that the population of Crested Ibis is most sensitive to sex ratio.Different age have different mortality rates and have different impact on Crested Ibis, accroding to sensitivity analysis,the Sx of the mortality of adult is0.24,the Sx of the mortality of subadult is0.07,the Sx of the mortality of chicks is0.14. We can see that the mortality of adult has greatest impact on the population of Crested Ibis.In conclusion,the current conservation efforts is to ramain the sex ratio of Crested Ibis stable,increase the suitable habitats and reduce the mortality rates.