关键词: 油松人工林, 林分密度, 树冠生长, 植物多样性

Abstract: This paper studied the changes in stand growth,understory plant diversity,forest biomass and crown growth of Pinus tabulaeformis plantation (40 years old or so) under the different conditions of stand density at low hill shade slope.Results showed that:DBH,tree height,crown width decreased with stand density increase,when stand density increases to 1500 individuals per hectare,the reduced tendency was to stabilize.The average amount of branch length growth,year after year volume growth increased with age increase and then decreased afterwards.With stand density>1500 individuals per hectare,the average amount of branch length growth decreased significantly.Branch volume increment also increases with stand density that shows inhibition of response,and the amount of branch length variation of a similar growth.As stand density increases,the understory shrubs,herbaceous species evenness index Jsw,Simpson diversity index and Shannon-Wiener diversity index decreased.With stand density decreases,the herb layer biomass increased gradually,shrub layer biomass increased and slightly reduced.The biomass of shrubs was maximum when stand density was 1000-1200 individuals per hectare.For Beijing low hill shade slope Pinus tabulaeformis plantation (40 years old or so),the management density is between 1000-1500 individuals per hectare.

Key words: Pinus tabulaeformis plantation, stand density, tree crown growth, plant diversity