关键词: 油松, 林窗, 幼苗根系, 土壤理化性质

Abstract:

The effects of gap size created by thinning on the root growth of seedlings and physical and chemical properties of the soil in Pinus tabulaeformis plantation were studied by investigation of typical sample plots. Results showed that on shady slope, the seedling root grew better with increasing gap size, and the facilitating effect increased with the age of seedlings; On sunny slope, the seedling root grew better in small gaps than in big gaps. As gap size increased in both shady and sunny gaps, the dry weights of litter and humus increased, while the soil bulk in 0-10 cm soil layers decreased. On shady slope, the soil water content increased with increasing gap size in the same soil layer, whereas on sunny slope the soil water content decreased. The contents of available phosphorus, ammonium nitrogen and nitrate nitrogen in the same soil layer were higher in small gaps than big gaps in both shady and sunny gaps. The analysis of step-wise regression suggested that the root growth of seedlings was mainly influenced by the ammonium nitrogen content. In the management of P. tabulaeformis plantation, high intense thinning should not be carried out on sunny slope, due to strong light level; whereas high intense thinning can be implemented on shady slope, which could provide favorable conditions for regeneration of P. tabulaeformis plantation.

Key words: Pinus tabulaeformis, gap size, root of seedlings, physical and chemical characteristics of soil