Soil Improvement of <i>Pinus yunnanensis</i> Forest at Different Age in Central Yunnan Plateau

Abstract

Took the Pinus yunnanensis forest as the research object, and took planted forest for control, carried on a research in soil physicochemical properties of different forest ages of Pinus yunnanensis. The results show that: For secondary forests at different ages, (1) middle-aged forest has the smallest soil bulk density and largest soil natural water content. Compared with the same age planted forest, secondary forest has smaller soil bulk density and larger soil natural water content.(2) Middle-aged forest has the smallest soil pH value, and the tallest total nitrogen content and soil organic matter in the 0-20cm soil layer. Compared with the same age planted forest, secondary forest has smaller pH value. While its soil organic matter and total nitrogen content are more than planted forest significantly.(3)There is an extremely significant negative correlation among pH value, soil organic carbon and total nitrogen content; while an extremely significant positive correlation between soil organic carbon and total nitrogen content.

Four New Limonoids from the Barks of Toona ciliata

“…The genus Toona , belonging to the family Meliaceae, contains 15 species mainly distributed in the regions of tropical Asia and Africa, of which four species and six varieties grow in China [ 1 ]. Toona ciliata Roem.…”