Effects Of Forest Thinning On The Plant Diversity In Oak-pine Mixed Forest In The Qinling Mountains

Species diversity, one of the most direct and most easily observed indexes in biodiversity,reveals the relationship between the communities and the environment.The structure andfunction of the soil seed bank, indicating the trends of the vegetation in the future, influencethe ability and direction of natural regeneration of forest vegetation, which are anindispensable part in the biodiversity research. Ecological stoichiometry provides a strongsupport for further study of ecology by putting bio-ecological characteristics of various levels,all areas of biological research community and all kinds of research areas together. Thinningis one of the main anthropogenic interference ways in forest ecosystems. Impact on plantspecies diversity of thinning under different intensity and residue removal on forest ecologicalsystem, has important significance on the sustainable management of forest ecosystems.Inthis study, the effects on forest plant species under different thinning intensity and residueremoval can be studied from diversity, soil seed bank and ecological stoichiometry of plantspecies diversity in the oak-pine mixed forest in the Qinling Mountains. The main conclusionsare as follows:1. Litsea cubeba, Symplocos paniculata and Lespedeza bicolor are dominant in theunderstory shrubs, Carex lanceolata, Astil bechinensis and Deyeuxia sylvatica of theunderstory herbs occupy dominant positions in a oak-pine mixed forest in the QinlingMountains;2. There are44species in the soil seed bank of oak-pine mixed forest, belonging to17families22genera.The number of herb, shrub and tree species diversity of soil seed bank is expressed as0~5cm soil> litter layer>5~10cm soil, and the herb is dominant in the soil seed bank. Theseed density (296Granule·m-2) are expressed as0~5cm soil> litter layer>5~10cm soil.Thinning intensity of15%and residue removed intensity of50%own the best speciessimilarity between the soil seed bank and aboveground plants.3. The richness of understory plants species increased under thinning in oak-pine mixedforest in the Qinling Mountains. Different thinning treatments had different influence on species diversity and evenness of understory plants. Before and after tending, species richness,species diversity and species evenness showed shrub layer is greater than the herb layer.4. As the season change, the nitrogen and phosphorus content in leaves of Litsea cubebaand Symplocos paniculata firstly increased and then decreased, on contrary, Lespedezabicolor showed the opposite trend. The leaf N:P ration of Litsea cubeba as the seasons changeis not regular, The leaf N:P ration of Symplocos paniculata firstly decreased and thenincreased and the leaf N:P ration of Lespedeza bicolor firstly increased and then decreased.The leaf nitrogen and phosphorus content of Carex lanceolata as the seasons changeincreased, the leaf nitrogen and phosphorus content of Astil bechinensis and Deyeuxiasylvatica firstly decreased and then increased. They leaf N:P ration are all inregular.5. Thinning intensity is a major factor on species diversity of understory plants in theoak-pine mixed forest in the Qinling Mountains. The research derived the highest speciesdiversity under the thinning intensity of11.97%~14.03%and residue removed intensity of34.83%~41.17%.