A 5-year mid-mountain subtropical evergreen broadleaved forest study in Baishanzu，east China

Key words: 
• forest ecology /
• evergreen broadleaved forest /
• mortality rate /
• recruitment rate /
• fitness /
• growth form /
• species composition

Abstract: Population dynamics of primary forest species are important for a stable community structure and function. To explore mortalities，recruitments，fitness and changes of population size of the primary forest species in a mid-mountain，subtropical evergreen broadleaved forest in a short term，how do these parameters differ with species life form, and finally the community dynamics of the forest，a 5 hm2 plot （250 m200 m） was established in 2002 on the north slope of Baishanzu Peak in Fengyangshan-Baishanzu National Nature Reserve, east China. In 2003，all 30 092 woody plants alive with a DBH （diameter at breast height） 1 cm were tagged，mapped，measured，and identified by species. In 2008，all these woody plants were measured， their living states were examined，and other individuals reached 1 cm DBH during the 5-year term were tagged，mapped，measured，and identified by species. Based on two datasets from censuses in 2003 and 2008，living，dead and recruited plants were grouped into canopy，mid-story，understory tree and shrub （4 functional groups），and analyzed to estimate annual mortality，recruitment rates and fitness of 30 tree species， and the species composition dynamics of the community were determined with non-metric multidimensional scaling （NMS）. Results showed that （1） compared to plants living in 2003，over five years a total of 2 343 stems （7.79%） belonging to 96 species had died，and 1 131 stems（3.93%） comprising 65 species （36.72%） reached 1 cm DBH. （2） Of all species in the plot，the average annual mortality rate was 1.45%，and the average annual recruitment rate was 0.62%. The annual mortality rates of 4 functional groups were 1.19%， 1.95%, 1.30%，and 2.59% respectively，while the annual recruitment rates of them were 0.67%， 0.92%，0.68% and 0.92%. （3）For the 30 major species，the average annual mortality was 1.55%，the average annual recruitment rate was 0.78%，and the annual mortality as well as the recruitment rate and fitness，which were all unrelated to abundance of species. （4）The change of species composition of the community during the 5 years was mild，comparing to the difference in species composition caused by spatial heterogeneity of the plot. Thus，the mid-mountain, subtropical evergreen broadleaved forest had difficulty regenerating itself and independent of functional group and abundance, while the structure of the community was relatively stable during the 5 years.［Ch，2 fig. 2 tab. 31 ref.］