不同代数杉木林养分积累和分布的比较研究

在全国杉木中心产区，选择不同栽植代数（１、２、３代）、不同年龄阶段（５、１０、１５、２０）不同立地（１４、１６、１８地位指数）的杉木人工林，进行不同栽植代数杉木木养分积累和分布的比较研究，结果表明，栽值代数对杉木林养分积累和分布有较大影响。随栽植代数增加，杉木林乔木层养分积累及养分利用效率均呈逐代递减趋势，表现为３代〈２代〈１代，而林下植被养分积累呈逐代增加趋势，２、３代杉木层养分积累分别比１代下

A comparative study on nutrient accumulation and distribution of different generations of Chinese fir plantations

The nutrient accumulations and distribution of different generation of Chinese fir plantations in central production areas of China were studied through the investigation of plantation with different generation(first,second and third),ages(5,10,15,20 years old)and sites(site index 14,16 and 18).The nutrient accumulations and distribution of Chinese fir plantations were greatly influenced by the number of planting generation.Nutrient accumulation and utlization efficiency in tree layer of Chinese fir plantations declined with the increasing planting generation number,with the first generation>the second>the third;while the nutrient accumulation of understory vegetation was increased with the increasing of planting generation number.Compared with the first generation plantations,nutrient accumulation of tree layer of the second and the third generations decreased by 17.56% and 36.24% respectively,and the third generation platation decreased by 22.65% than the second generation.Meanwhile,successive planting resulted in a decreasing nutrient utilization efficiency of Chinese fir plantation,and an increasing nutrient necessary for dry matter production per unit,which is disadvantageous to the maintaining of soil fertility,but beneficial to the nutrient accumulation of understory vegetation.