[Objective] The aim was to build an optimal leaf area measurement model of E. urophylla and E. grandis×E.urophylla. [Method] The correlation between leaf area and leaf＇s eigenvalue of E. urophylla and E. grandis×E.urophylla were studied. [Result] There was certain difference in leaf characteristics values between the 2 species. The leaf areas of E. urophylla and E. grandis×E.urophylla both had significant correlation with leaf length,leaf width,leaf perimeter,leaf length × leaf width,the ratio of leaf length to leaf width,shape factor,etc.,so the factors could be constructed into a regression model with leaf area. Among them,the best 2 models for leaf area calculation which were built by leaf length × leaf width of E. urophylla and E. grandis×E.urophylla both had relatively high accuracy and practical applications. [Conclusion] The research provides a simple and effective leaf area measurement method for studies on the 2 tree species.
[Objective] The aim was to provide a reference for studying the resistant ability of subtropical forest to freeze disaster and detecting the recovery and evolution of Huodendron biaristatum species after freeze disaster.[Method] Effects of the damage caused by the southern ice storm in early 2008 on Huodendron biaristatum,dominant species of evergreen broad-leaved forest on the Damingshan,were studied in the aspect of population ecology.[Result] Among the 1 090 Huodendron biaristatum individuals （DBH ≥ 1 cm）,697 individuals were victims,accounting for 63.9%.The largest part of the victims was crown breakdown,which took up 37.6%.13.0% of the victims were bent,and 10.2% of the victims were trunk broken.The least part of the victims were uprooted,accounting for only 3.1%.Different types and extent of forestry damage had remarkable differences in diameter class,tree height,crown and taper.Rates of damage and crown breakdown increased with the increase of DBH,while bent rate decreased.Rates of damage,bent and trunk broken declined slowly with the increase of tree height,while crown breakdown rate followed the normal distribution.As the crown level increased,rates of damage and crown breakdown increased,while the rate of trunk broken decreased.Individuals with high taper were more susceptible to crown damage,bending,breaking and uprooted.[Conclusion] The resistant ability of Huodendron biaristatum species to freeze disaster is affected by many factors like DBH,tree height,crown,taper,etc..Huodendron biaristatum species in Damingshan affected by those factors show various kinds of damaged types dominant by mechanical damage,but there is few individual to die.
