Abstract: By using an automatic onset HOBO mini-weather station,the air temperature and the air relative humidity were monitored for one year(2013)at Changjiang,Renhua,Guangdong where the national Grade II key protected plant species Cephalotaxus oliveri grows.The soil physic-chemical characteristics,the leaf surface light intensity,some eco-physiological indexes and the population structures of C.oliveri were also measured during the year in order to provide basic data for protecting and enhancing the plant population.Results showed that the mean annual air temperature was 13.854 ℃,the mean annual air relative humidity was 96.317% at the field site.Soil pH was 5.49 with a relative high effect K content of 742.50 mg/kg.The light intension on leaf surface of inner forest was 15% less than that of open outside of the forest.The leaf SPAD values was about 60,the net photosynthesis rate and transpiration rate of C.oliveri leaf were 2.85~3.53 μmol/(m²·s)(calculated by CO₂)and 0.36~1.43 mmol/(m²·s)(calculated by H₂O),respectively.The net photosynthesis rate and transpiration rate determined in July,2013 were significantly lower than that of the same genus species of C.fortune.The results of size class,height class and age class structures suggested that the population had an increasing tendency at present,but no seedlings below four years of age,which was probably caused by the icy disaster in early 2008 in the Nanling Mount region.It was predicted that the population would decrease after about 40 years.The ex-situ and in-site conservation measures of the key protected plant should be taken.

Key words: Cephalotaxus oliveri, population, habitat, characteristics, eco-physiology, Renhua, Guangdong