[Responses of Manglietia glauca growth to soil nutrients and climatic factors].

Tree height and diameter of breast height (DBH) as growth characteristics of Manglietia glauca introduced from Vietnam were measured at many sites in south China and responses of M. glauca growth to soil nutrients and climatic factors were analyzed in this study. Annual average increments of tree height and DBH among different planted sites had significant differences. Annual average increments of tree height and DBH had significant positive correlation with soil total N and P, available N and P, but no significant correlation with soil organic matter, total K, available K, indicating that soil N and P contents could be the main affecting factors for the growth of M. glauca. Annual average increment of tree height had significant difference, but annual average increment of DBH had no significant difference at different altitudes. Annual average increment of tree height increased with the altitude from 150 to 550 m, the maximum was at the altitude of 550 m, and then it decreased. It indicated that the most appropriate altitude for M. glauca introduction is 550 m. Annual average increments of tree height and DBH had significant negative correlation with annual average temperature and > or = 10 degrees C accumulated temperature, and significant positive correlation with annual average precipitation, suggesting that annual mean temperature, > or = 10 degrees C accumulated temperature and annual average precipitation could be the main climatic factors influencing the growth of M. glauca.

[Soil physical and chemical characteristics under different vegetation restoration patterns in China south subtropical area].

This paper studied the change of soil physical and chemical properties under eleven vegetation restoration patterns (1 kind of secondary forest, 2 kinds of pure coniferous plantations, 5 kinds of evergreen broad-leaved plantations, 2 kinds of conifer and broad-leaved mixed plantations, and 1 kind of shrub) typical in Daqingshan of Guangxi. Obvious differences were observed in the soil physical and chemical properties under different vegetation restoration patterns. The soil physical properties were better in secondary forest but poorer in pure conifer plantations. Conifer and broad-leaved mixed plantations had lower soil bulk density, and their soil total porosity and water-holding capacity were higher than those in pure plantations. There were no significant differences in the soil porosity among the 5 evergreen broad-leaved plantations. Except that of soil total K, the contents of soil nutrients in secondary forest were higher than those in plantations, and the soil C/N ratio and pH value were relatively lower. Comparing with shrub, the 9 plantations had an obvious change in their soil nutrient contents, e. g. , the increase of soil total N and available K. The 2 pure coniferous plantations had lower soil nutrient contents, but after mixed planted with evergreen broad-leaved trees, their soil nutrient contents increased markedly, and the soil C/N ratio decreased.