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Historical Stand Dynamics And Disturbance History Of An Evergreen Broadleaved Forest Dominated By Schima Superba And Castanopsis Carlesii, On Mt. Tiantong, East China

Posted on:2008-04-15Degree:MasterType:Thesis
Country:ChinaCandidate:K SongFull Text:PDF
GTID:2120360212491057Subject:Ecology
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Historical dynamics reconstruction is an important method for researching forest dynamics, which can help us to understand the species composition and community structure in today's forest, and find out the drives of dynamics and community maintaining mechanisms. Reconstructing historical dynamics for evergreen broadleaved forest (EBLF) can find out the nature drives of stand dynamics and the impact of human disturbance, which helpful to restore and reconstruct destroyed EBLF in academic. In this research, Castanopsis carlesii-Schima superba forest in Tiantong National Forest Park is chosen to reconstruct its stand dynamics in the later 50years of last century. The age structure and growth pattern of three dominant species: Castanopsis carlesii, Schima superba, Lithocarpus glaber are discussed. Meanwhile, historical disturbances are reconstructed across temporal and spatial. All of these are based on tree-ring analysis. The results indicate that:(1) Castanopsis carlesii and Lithocarpus glaber have the inverse-J type age-structure with a gap in the middle age interval. Schima superba has the bimodal type age-structure. There is a regeneration peak in1950s to 1960s for three species. The age-structure is similar with the DBH-class distribution and high-class distribution for three species.(2) Castanopsis carlesii has the fastest diameter growth rate and height growth rate in three species. The diameter growth rates have a little difference among different DBH class for Castanopsis carlesii and Lithocarpus glaber. But the diameter growth in small DBH class is slower than big DBH class for Schima superba. The height growth gets slower with the increasing of height for three species. With the DBH increasing, releasing events happened in three species and suppression events happened in Schima superba gradually get fewer. But suppression events happened in Castanopsis carlesii and Lithocarpus glaber have two peak in small class and big class, respectively.(3) Six canopy accession types are divided basing on the number of releasing events and suppression events happened in canopy accession process. The average growth rates are contracted between different canopy accession types and species. The individuals experienced only one releasing event and one suppression event have the fastest growth rate. More releasing events and suppression events experienced, the growth rate is slower. Individuals always in suppression have the slowest growth rate. Schima superba experienced more releasing events and suppression events than Castanopsis carlesii, which expanding the difference of canopy accession speed between them.(4) Castanopsis carlesii has bigger growth potential, stable growth rate. Its seedling/sampling can adjust the diameter-height growth rate extremely, having more sprouting. So Castanopsis carlesii has strong competitiveness, can quickly accessing canopy. Schima superba has strong growth plasticitye and shade-tolerance, which can help it to take more chances to access the canopy after long time enduring. Because of these differences in growth characteristic, Castanopsis carlesii and Castanopsis carlesii have different growth patterns: the former takes its own way without mind to habitat, the latter changes with the habitat. It is the reason why Castanopsis carlesii experienced fewer releasing and suppression events than Schima superba. Also, it made Castanopsis carlesii easily to die in middle size and form a gap in age-structure. The differentiation of growth pattern promotes theirs coexistence.(5) There are five disturbances in the second half of last century, almost one time per 10 years. Man-felling and typhoon are the main disturbance. The first two disturbances happened about the 1950 and 1960 are seriously, which decided the canopy species composition and form the community with Schima superba as the first dominant species. The others disturbance formed some gaps, not only helpful to evergreen broadleaved tree's regeneration and growth, but also offering regeneration chance for light-demanding deciduous species, such as Lindera glauca, Alniphyllum axililiavis, Sassafras tzumu, which increasd the species diversity. Temporal and spatial patterns of disturbances determined the regeneration peak and establishing pattern, also doing effect on the canopy structure.(6) Frequent typhoons are not only helpful for middle size individuals of Castanopsis carlesii to grow into canopy, but also offer chances for Schima superba to germination and regeneration. So, although due to the age-structure and growth characteristic, Castanopsis carlesii will take the place of Schima superba to be the first dominant species, but Schima superba will stay in community for a long term. Maybe this is an important reason why Schima superba can often occur at the late succession stage in research area.
Keywords/Search Tags:historical dynamics reconstruction, age-structure, growth pattern, tree-ring analysis, historical disturbances, Castanopsis carlesii-Schima superba forest
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