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Research On The Carbon Process Of Forest Ecosysterms In Changbai Mountains

Posted on:2004-08-26Degree:MasterType:Thesis
Country:ChinaCandidate:X F LiFull Text:PDF
GTID:2133360095455567Subject:Ecology
Abstract/Summary:PDF Full Text Request
Litter is an important part of forest carbon pool, and its decomposition is a major process of nutrient cycling in forest ecosystem. Furthermore litter is also related to the global change caused by the increasing of CO2 concentration in the air. Through studying the litter-fall of typical ecosystems in Northeast of China, the decomposing rate of 5 different kinds of twigs and leaf and the changing of C concentration, N concentration ,P concentration ,C:N ratio and C:P ratio in these tree's leaves, the process of carbon cycle of forest ecosystem can be understood more clearly. By investigating many forest types in 4 different areas, we found that there are great differences in litter-fall in these areas which are influenced by geographical locations and forest types. In the same area the production of the largest litter-fall is 2 to 2.5 times bigger than that of the smallest .The study on the same kind of forest type distributing in different regions showed that the litter-fall in low latitude is always larger than that in higher latitude. The composition of litter-fall is leaves 48%-88%, branches 6%-22%, flowers and other mixed-matter 2%-22%.There exists notable variety of litter-fall composition among different forest types.The study on the variance analysis of the decomposition of twigs and leaves in 5 types of broad-leaved forests reflected litter decomposition is controlled greatly by time .Forest types also have notable influence on the decomposition of twigs and leaves placing on the surface and twigs 5cm below the surface ,but have no notable effects on leaves lying 5cm below the surface .There are mark able distinctions of decomposing rate among five types of litter in different periods. In the same types of forest the decomposing rate of litter on the surface is slower than that 5cm below the surface.The analysis of the changing of C concentration, N concentration, P concentration, C:N ratio and C:P ratio in the leaves of five types of forest showed C concentration is not influenced by time and location ,and there do not exist notable differences among them. But forest type and time have great effects on change trend of N concentration, P concentration, C:N ratio and C:P ratio in the leaves. During the degradation of 14 months, N concentration increased continuously. In the last 2 months it increased slowly or began to decrease. P concentration declined in the former 10 months and raised in the next 4 months. C:N ratio reduced rapidly in the former 12 months and decreased slowly in the next 2 months. C:P ratio increased rapidly in the former 10 months and increased slowly or decreased in the next 2 months .In the last 2 months it decreased sharply. There are notable differences of N concentration ,P concentration ,C:N ratio and C:P ratio between leaves on the surface and those 5cm below the surface .The simulative experiment testified that elevated CO2 atmospheric concentration and precipitation change have great effects on the N concentration, P concentration, C:N ratio and C:P ratio in the leaves of Fraxinus mandshurica.
Keywords/Search Tags:litter, decomposing rate, litter-fall, forest type, dynamics of decomposition
PDF Full Text Request
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