Dynamic Changes Of Nutrient Elements In Typical Plantations Of Toona Sinensis And Masson Pine

In order to clarify the differences of ecological stoichiometric characteristics in different vegetation areas and different types of plantation ecosystems,In this paper,the ecosystem of deciduous broad-leaf tree species Toona sinensis and evergreen conifer species Pinus massoniana plantation in Luzhai County(Karst geomorphology)and Rongshui County(non-Karst)in Guangxi.The basic characteristics of carbon(C),nitrogen(N),phosphorus(P)content and stoichiometric ratio in Arbor layer(leaf,branch,trunk,root),litter layer and soil layer of Toona sinensis and Pinus massoniana plantations were compared and analyzed.The seasonal and interannual variation of stoichiometric characteristics of each component was studied.At the same time,the relationship between ecological stoichiometric characteristics of plant leaves,litter and soil was further discussed,and the interaction between C,N and P elements and the relationship of nutrient cycle were revealed.It is used to enrich the study of nutrient coupling cycle mechanism of ecosystem in Guangxi,and to provide theoretical basis for rational planning,planting and vegetation restoration of Toona sinensis and Pinus massoniana plantations in Guangxi.The main findings are as follows:(1)There are significant differences in the contents of C,N,P and their ratios in the ecosystems of Toona sinensis and Pinus massoniana plantation.The C content of the organs of Pinus massoniana in the two study areas is significantly larger than that of the camphor,but N.and P content was significantly smaller than that of the camphor;C:N and C:P ratios of the components of the camphor were significantly smaller than those of Pinus massoniana,and N:P ratio was significantly higher than that of Pinus massoniana,and the growth of the camphor was mainly restricted by P,ponytail.Pinusmasso.Pinus growth is mainly limited by N.For different vegetation belts,the C content,the scent of Pinus massoniana,the content of N in Pinus massoniana,the content of C and N in litter of Lusong County were lower than those in Rongshui County,but only P content and branches of Pinus massoniana leaves.The content of N was larger than that of Rongshui County,and the elements of other organs did not show significant differences.The contents of C and N in the soils of T.chinensis and P.massonianawere decreased with the increase of soil depth,and P content remained basically unchanged.The elements and ratios of different tree species and different regions showed some differences.Correlation analysis between leaf,litter and soil eco-stoichiometry of Toona sinensis and Pinus massoniana plantation showed that litter was used as an important link between plant and soil nutrient cycling,causing leaves and litter,litter and soil The middle elements show a strong correlation.(2)The seasonal variation of C,N,P content and its measurement ratio of various organs and litter of arbor and Pinus massoniana were not the same,and the ecological stoichiometry characteristics of different tree species showed significant differences.For example,the content of C in the leaves of Toona sinensis remained at a high level in June,and then decreased first and then increased.The N and P contents showed a downward trend and reached the lowest value in October.The C content of Pinus massoniana leaves remained stable at the early stage of the growing season and increased significantly after August,while the N and P contents showed a trend of decreasing first and then increasing.The ecological stoichiometry of the nutrients of various components of plants under different vegetation belts showed similar seasonal changes.The seasonal variation of C,N,P content and its measurement ratio in most soil layers of Toona sinensis and Pinus massoniana were not significant,but the seasonal variation trend was obvious,especially the seasonal variation trend of soil surface showed obvious volatility..The nutrient content and its measurement ratio of soil under different vegetations showed different changes.In addition,the analysis of the variation sources of plant leaves in Luzhai County and Rongshui County showed that the tree species factors were the main source of the variation,and the interaction between the sampling month and the sampling month and the tree species also significantly changed the N and P content variations.The enffects of different nutrient contents on plant leaves under different vegetation zones indicate that the difference of vegetation zones is also one of the factors affecting the source of plant leaf variation.(3)The contents of C,N,P and their ratios ofoona sinensis and Pinus massoniana showed different interannual variations.The contents of C,such as leaves,branches and litter of camphor and Pinus massoniana in Luzhai County and Rongshui County decreased with the increase of the year;the contents of N and P in the organs of the two species showed inconsistent fluctuations with the increase of the year.The ratios of C:N and C:P in leaves,branches,stems and litter of Luzhai County did not show significant interannual changes,while organs such as camphor root and Pinus massoniana,stem and root C:N,C:P The ratio increases with the year;this indicates that the nutrient variation varies among different tree species and different organs.In addition,the C and N contents of the soils in the two study areas did not show significant interannual changes,and only the surface C content of the soil changed significantly;P content of Luzhai soil did not show significant interannual changes,while the melted soil P content increases with the increase of the year.The ratio of C:N and C:P in Luzhai County increased with the increase of the year,while the ratio of C:N,C:P and N:P in Rongshui County showed a relatively stable trend and did not show significant interannual variation.