Vertical Distribution Characteristics Of Carbon Stable Isotope Of Organic Matter In Successtional Stages In Tiantong National Forest Park

In order to realize the response relationship between stable carbon isotope of soil organic matter in vertical gradient and vegetation successions in Tiantong national forest park. The study research the characteristics of vegetation successions and selection the representative community in succession that early shrub community, succession of schima superba community and in the middle of the climax katus community as the research community. The study form November of2011to December of2011, the study rigorous collection and dispose the samples among the leaves of dominant species plants in the community, the undergrowth withered leaves layer, the soil samples of soil profile of different depths. This research mainly measure the main physical and chemical factors of soil, the content of soil organic matter, the ratio of nitrogen and carbon in soil organic matter, the characteristic of stable isotopes δ13C value in the vertical distribution in the community, the trend of soil organic matter particles and enrichment in different particle size and the stable isotopes δ13C value distribution characteristics. Preliminary study the organic matter stable carbon isotopic distribution in Tiantong national forest park. The main findings are as follows:1Physical and chemical factors of soilThe soil water content in different depths of katus community are overall higher than other communities, numerical lower than schima superba community is in the50～70cm soil layer (28.49%). The highest water content in the0～5cm soil layer of katus community (50.98%), the lowest numerical is in the50～70cm layer of shrub community. The soil water content sequence in different successtional stages is that katus community> schima superb community>shrub community, the numerical in the same community decrease with the soil depth increase.Soil pH value in different successtional stages is approaches, the minimum value is3.94, appear in the0～5cm layer of schima supereba community; the maximum value is4.73, appeared in the50～70cm layer of katus community. The pH value fluctuating range Shrub community is4.51～4.58, The wave of numerical in schima superba community is the largest, a range of3.94～4.40.2Soil organic matterThe sequence numerical of soil organic matter in different communities is katus community>schima superb community>shrub community.the maximum value is61.36mg/g, which appeared in the0～5cm soil layer of katus community, the minimum value is31.70mg/g, appeared in40～50cm soil layer in schima superba community. There is a significant positive correlation between Soil organic matter and soil depth, the highest numerical of the three communities all in the0～5cm soil layer, and the lowest all in the40～70cm layer.The range of Soil organic matter in different communities is that: shrub community for32.87～41.49g/mg. schima superba community for31.70～40.08g/mg, katus community for34.13～61.36g/mg.3The ratio between N、P in soilThe maximum value of N/P in soil of different communities all appeared in the0～5cm soil layer, the maximum value of shrub community is45.92,which in schima superba community is41.79, and in the katus community the value is41.79. The minimum value of N/P in different communities have some certain differences, the value in the50～70cm layer in shrub communities and schima superb, and which in the5～10cm layer of katus community.The range of N/P in three communities is that shrub community for18.48～45.92, schima superba community for18.52～67.81, katus community for24.85～41.79.4The vertical distribution characteristics of δ13C of organic matterThe δ13C of organic matter show a characteristic of gradually enrichment through the gradient of the leaves of dominant plant species-leaf-withered layer-surface soil. The minimum value of δ13C all appeared in the leaves of dominant plant species, the values are closed and show the dominant plant species are the C3plant, the value is that shrub community for-30.05‰, schima superba community for-31.02‰, katus community for-31.01‰. The maximum value all appeared in the10～20cm soil layer,the value is that shrub community for-25.48‰, schima superba community for-25.77‰, katus community for-26.46‰.The value show that the organic matter of earlier successtinal stage could decomposition and enrichment easier in soil.The vertical distribution characteristics of organic matter δ13C in different communities all show the significant trend that the value first increase and then decrease, the maximum value in the10～20cm layer of shrub community is-25.47%o, in the10～20cm layer of schima superba community is-25.73%o, in the30～40cm layer of katus community is-26.01‰. The miniimum value in the0～5cm layer of shrub community is-25.73‰, in the0～5cm layer of schima superba community is-26.17‰, in the0～5cm layer of katus community is-27.08‰. The difference value between maximum and minimum is that katus community>schima superba community> shrub community, show that the fractionation effect of soil organic matter in katus community is strongest.The value of δ13C of soil organic matter and soil water content show the relationship between tow stages:the first stage show a negative correlation between them and the second stage show a positive correlation between them, and the relationship is closed the decomposition of organic matter in the soil layer.There is a positive correlation between soil pH value and soil organic matters δ13C value in katus community and shrub community, and not a significant correlation of it in schima superb community. Which show that the degree of acid and alkali could effect the soil organic matter δ13C value, and the significant negative correlation between organic matter δ13C value and soil water content, show that the soil water content is a limiting factor with the organic carbon isotope fractionation.5The vertical distribution characteristics of soil particle componentsThe content distribution of sand composition (2000～50μm) in different soil vertical gradient of different communities are minimum, numerical range in the shrub community for7.18～28.02%, schima superba community for7.08～13.72%, katus community for11.30～24.77%. Particle (50～2μm) is the the research community are maximum, numerical range from47.67to55.47%in shrub community, from54.50to59.47%in schima superba community, from53.81to55.62%in katus community and the value of viscous grain components (<2μm) is average. The sand content of lower middle soil layer is less than upper soil layer, the value of powder in the soil layer distribution is uniformity, the ratio of viscous grain in the communities show a trend that with soil depth increase the value increased.6The characteristics of distribution and enrichment of different particle componentThe distribution of organic matter in sand component is all the minimum in different succession communities, the range of shrub community is1.88～25.38%. schima superba community is3.04～17.57%and which in katus community of8.02～28.39%. the genera distribution of organic matter in particle component in shrub community and the range is34.03～63.38%. and the distribution of organic matter in particle component and viscous grain component both enrichment in vertical soil layer. The ratio maximum value is78.54%which appeared in40～50cm soil layer and minimum value is1.88which appeared in40～50cm soli layer.The enrichment coefficient of organic matter in particle component of research community is<1,show that the particle component is total losses organic matter. Sand components are losses organic matter and the minimum value is0.10which appeared in40～50cm soil layer in shrub community, the organic matter enrich in particle component only appeared in30～40cm,40～50cm soil layer in schima superba community, the value is1.13and1.26. the organic matter enrich in viscous grain component are all appeared in research community which is1.12in50～70cm of shrub community.1.04in0-5cm layer and1.01in50～70cm layer of schima superba community and1.33in20～30cm layer of katus community.7The vertical characteristics of organic matter δ13C in different componentsThere is a clear thend of the vertical distribution of organic matte δ13C in shrub community, and the numerical wave in schima superba community and katus community is aarger extent. The organic matte δ13C value in three succession community general show a significant positive correlation, the organic matte δ13C of particle component show a positive correlation with whole soil organic matter δ13C value. The wave of organic matte δ13C is become more intense belong the depth increase, the organic matte δ13C value of sand component show a negative correlation with whole soil.