Study On Regeneration And Succession Of Schima Superba Mixed Forest On Qingshigang State-owned Forest Farm

This paper belongs to the forestry public industry scientific research " Forest thinning and efficient use technology research on southern collective secondary forest (Project number:201004032)".In this article, nine typical Schima superba mixed forests on state-owned forest farm of Qingshigang, Yanling County, Hunan province were studied. Regeneration statues of seedlings in the regeneration layer were analyzed by building the evaluation index system; In order to identify the important impact factors on the regeneration layer of Schima superba seedlings, the relationship between possible environmental and soil chemical properties impact factors and seedlings regeneration was studied; The succession trend of Schima superba mixed forests was analyzed; So that we can provide certain theoretical basis for artificial aids to natural regeneration and sustainable forest management. Results are as follows:1.Based on previous literatures, combined with the actual situation of Schima superba mixed forests on state-owned forest farm of Qingshigang, five indicators:Number of per unit area, frequency, average height, average ground diameter and big seedling percentage, were selected in this study from three aspects of distribution, growth and age structure.2.This article first proposed the concept of regeneration index, whose values was between0and0.5. According to the values of regeneration index, the order of regeneration status of nine samples from good to bad was:sample1> sample2> sample7> sample3> sample4> sample6> sample8> sample5> sample9.3.Correlation analysis was done between five evaluation indexes and nine environmental factors, results showed that:Amount of growing stock of Schima superba proportion and seedlings number of per unit area of Schima superba was significantly positively correlated, which meant that seed tree’s fruiting ability and seed quality had a decisive effect on the seedlings number of per unit area of Schima superba. Litter thickness and seedlings number of per unit area of Schima superba was significantly negatively correlated, which meant that litters hindered Schima superba seedling germination. Large shrub coverage hindered forest regeneration process, so that seedlings and young trees must break the shrub vegetation to grow into a tree.4.Correlation analysis was done between five evaluation indicators and five soil factors, results showed that:The pH value and average height of Schima superba seedlings was significantly positively correlated while in pH value was in [4.13,4.75], pH value was more conducive to the growth of seedling height, and this study identified pH=4.75was to achieve natural regeneration requirements. The content of soil organic matter and Schima superba seedlings had obvious negative correlation while it was in [1.83,6.30](g/kg). Due to the limited data, it cannot be determined when the content of soil organic matter (namely threshold) began to have a negative effect on plant growth. We could temporarily believe that it’s more favorable to germination and seedling growth when soil organic matter content was1.83g/kg. The total N content of soil had significantly negative correlation with the average height of Schima superba seedlings, and had negative correlation with the average ground diameter and big seedling percentage while its value was in [0.06,0.25](g/kg), which meant soil total N content played an inhibition role on indicators of growth of Schima superba seedlings. According to existing data, the growth of Schima superba seedlings maight be the most appropriate when the N content was about0.1g/kg. The soil total K content and average height of Schima superba seedling showed significant positive correlation while its value was in [13.63,26.48](mg/kg), which meant that it played a clear role in promoting the longitudinal growth. Based on existing data, Schima superba seedlings growth maight be the most appropriate when the soil total K content was24mg/kg.5.The succession trend of each stand was studied and results showed that:The stand in sample plot7would transfer into evergreen and deciduous coniferous and broad-leaved mixed forest, Castanopsis eyrei (Evergreen broadleaf hardwood) was the dominant species, Quercus fabri (deciduous broadleaf hardwood), Schima superba (Evergreen broadleaf hardwood) and Cunninghamia lanceolata (Evergreen coniferous) were accompanying species. The rest stands would transfer into evergreen broadleaf (or coniferous and broad-leaved) mixed forest, Schima superba (Evergreen broadleaf hardwood) was the dominant species, the subdominant species and associated species were slightly different. As the number of trees in the succession layer was not enough in in sample plot8and9, so the prerequisite for successful succession was seedlings in regeneration layer could enter the succession layer at large number.