Species Diversity Of Woody Plant And Updatae Dynamics Research Of Dominant Populations In 24ha Sample Plot At Gutian Mountain National Reserve

Biodiversity is the material basis of the survive and development of human, maintaining basic environment balance and ecological stability as well. Species diversity is an important hierarchy in the study of biodiversity, contributing to the study of community composition, change and development. Changes of community structure are the performance characteristics of forest succession, the update dynamics of dominant populations decide the direction of forest succession largely. The update dynamics research of dominant populations reveals the role that species coexistence mechanisms play in the species diversity maintaining furtherly. It also provides scientific basis for seizing the community dynamic rules and the conservation of subtropical evergreen broad-leaved forest better. Based on the Gutian mountain subtropical evergreen broad-leaved forest 24ha sample plot, this paper used the investigation data of 2005 and 2010 to analysis species diversity dynamic characteristics of woody plants and update dynamic characteristics of 12 dominant populations in different levels, the main results were as follows:(1)In 2010, there were 121635 woody plants whose DBH>lcm, belong to 159 species,48 families,105 generas. In 2005, there were 140701 woody plants whose DBH>lcm, belong to 159 species,49 families,104 generas. Namely, the plant species remained invariable between 2005 and 2010, but the numbers of woody plants in 2010 are reduced by 19066. Shannon-Wiener index and Pielou index increased, but the ecological dominance index decreased. The top 29 dominant woody plants ranked by important value were invariable from 2005 to 2010. The top 4 dominant species in canopy layer, sub-tree layer and shrub layer remained invariable respectively between 2005 and 2010, just the important value ordering of several species changed.(2)For the top four dominant species respectively distributing in canopy layer, sub-tree layer and shrub layer, the mean stem DBH of Schima superba decreased by 0.094cm, the others’were increasing from 2005 to 2010. The 2008 ice atorm caused the death of abundant individuals in different layers. For the mean basal area(m2·ha-1), except Neolitsea aurata var. Chekiangensis and Camellia chekiang-oleosa whose mean basal area decreased by 0.794m2 and 0.315m2 respectly, the mean basal areas of dominant species were decreasing from 2005 to 2010 as a whole.(3)From 2005 to 2010, the individual numbers of each layer decreased obviously, and the mortality rate was significantly greater than recruitment rate. Compared with the natural regeneration condition, the mortality rate increased greatly as well. The mortality rate of Pinns massoniana was the most grestest(9.08%) and the recruitment rate was remaining low all the time, showing the negative growth tendency and rapid changes, and the rate of change was 8.93%. other species with more rapid changes were as followings:Castanopsis eyrei(4.91%), Quercus glandulifera var. brevipetiolata(3.98%), Chimonanthus salicifolius(3.70%) and Eurya rubiginosa var. Attenuata(4.41%), etc.(4)DBH size classed structure of all dominant species were mainly remaining stable, showing reverse J-shaped pattern. Individual numbers of all dominant species at all DBH stages were decreasing, and the number of die individuals at the smaller DBH were much more, meanwhile, the number of recruitment individuals were not enough to offset the loss induced by death and upgrate. The number of die individuals at different DBH were different, the number of die individuals showed a decreasing trend with the increasing of DBH. The Pinus massoniana population showed a involution form, the number of individuals with greater DBH were more than the individuals with smaller DBH, and death took place at all ages.(5)As with the spatial distribution pattern of dead individuals, Castanopsis eyrei, Schima superba and Pinus massoniana populations and their die individuals at different ages had a clustered distribution across 0-100m scales. The die individuals of Daphniphyllum oldhamii population were close to random distribution, die individuals of adults showed a random distribution at the 74-100m scales. The die individuals of Rhododendron ovatum and Rhaphiolepis indica showed a much smaller cluster degree. The population, adults and juveniles of Rhododendron ovatum’s die individuals had shown a random distribution across a larger scales. Meanwhile, saplings and juveniles’s die individuals of Rhaphiolepis indica had shown a random distribution across a larger scales as well.(6)Overall, the mortality rate of Pinus massoniana population was higher in the high altitude, the die individuals of other 11 dominant populations mainfy distributed in low altitude and mid-slop areas. And die individual and mortality rate were far higher in the habitat types that these dominant populations mainly distributed in. As with the relation between density and mortality rate, several results showed the positive correlation, such as Daphniphyllum oldhamii, Neolitsea aurata var. Chekiangensis, Chimonanthus salicifolius, Rhododendron simsii and Eurya rubiginosa var. Attenuata; several results showed the negative correlation, such as Castanopsis eyrei, Schima superba, Camellia chekiang-oleosa and Quercus glandulifera var. brevipetiolata; several ressults showed no correlation, such as Pinus massoniana, Rhododendron ovatum and Rhaphiolepis indica.