Structure and biomass of understory vegetation in masson pine and broad-leaved tree mixed forests.

Based on the proportion of masson pine,5 kinds of 20-year-old masson pine and broad-leaved mixedwoods were tested.The results of the structure and biomass of the understory vegetation showed that richness in shrub layer increased from 0 to 60%,decreased from 60% to 100%.But richness in herb layer had nearly no change and it was lower compared with the shrub.With the increase of the proportion of masson pine,height of shrub layer fluctuated and height of herb declined slowly.And with the increase of the proportion of masson pine,coverage of the shrub tended to decline and coverage of herb did not change significantly;In all the tested mixedwood with different mixed proportions,biomass of the shrub represented the major part of the total biomass of the understory vegetation,biomass of the herb was the minority,the total biomass of the understory vegetation first increased gradually and then decreased gradually with the increase of the proportion of masson pine.