The To Ruoergai Vlangalii (phrynocephalus Vlangalii) Population Ecology

Mark-recapture, counting entrances to lizard holes and measuring depth of lizard holes were used to collect data on population ecology of Phrynocephalus vlangalii, distributed in Zuoergaigrassland, Northwest Sichuan, in 2001 and 2002. The data include: 1) the time of mark-recapture, and body length, body mass and tail length, 2) position of lizards captured, 3) the number of lizard holes and position, 4) depth of holes. The data were analyzed by cluster analyses and one-way ANOVA, Mest and regression analyses.The results suggest that 1) Body length is a more reasonable criterion to classify ages of lizards. The body length of 3 age groups is ranging, respectively, 26 mm - 36 mm, 37 mm - 50 mm and 51 mm - 65 mm. The age structure of P. vlangalii tends to be of pyramid, but the number of the individual in Group II is a little less. The sex ratios (female : male) of three age groups are, respectively, 7.7:1, 32:1 and 1:2.1, but the sex ratio of the population is 1.76:1. The sexual dimorphism of body size of P. vlangalii shows opposite patterns before and after sexual mature.Growth rates of both the male and female lizards are the same before June of the second year of hatching. But growth rate of males is greater than that of femals after mature. Growth duration of femals is longer than that of males. Growth of both males and females show approximately logistic. The relationship between body mass (w) and body length (x) is w=1 .4258-0.1465 x +0.00466x2(df= 1. n =552, p =.000), and body mass and tail (/) length is W=0.1604 X e ?0636/ (df= 1, n =552 , p =.000)oPopulation densities of P. vlangalii in September of 2002 year is , respective, 149ind./1000 m2, 250 ind./ 1000m2 and 220 ind./ 1000m2. Population density peaks in September and is the lowest in July. The population density in 2002 year was higher than that in 2001. The most fitable environmental capacity is about 170 ind./ 1000m2.Mean densities of lizard holes varies while vegetation covers change. Relationship between the number of lizard holes and vegetation covers showsnegative. The mean depth of holes, where no lizards live and depth of holes is less than 73 cm, is 42 ± 5cm. The mean depth of holes, where lizards live and depth of holes is greater than 73 cm, is 42±5cm.