Abstract: Biodiversity and biomass of plantation community in three different types of Larix princicpis-rupprechtii Mayr.in Yanshan Mountainous Region were studied in this paper.The results showed: (1) The number of plant species of both mixed stand of Larix princicpis-rupprechtii Mayr.and Betula platyphylla Suk.and that of Larix princicpis-rupprechtii Mayr.and Populus davidiana Dode.was higher than the one of Larix princicpis-rupprechtii Mayr.forest.The dominant species were significantly different in three types of plant communities; (2) The order of α biodiversity index of three types of plant communities from high to low was herb layer,shurb layer and tree layer,and α biodiversity index in mixed stand was higher than that of pure stand.(3) In Larix princicpis-rupprechtii Mayr.stand,the propotion of biomass of tree layer was 99.33%,which was higest among three types of plant communities. The order whose allocation of different organ biomass was trunk> branches> root> bark> leaves,and the propotion of each organ in the whole biomass was different.

Key words: Larix princicpis-rupprechtii Mayr, biodiversity, biomass