Biomass characteristics of understory vegetation in pure and mixed pinus massoniana forests

In this paper, we studied the biomass characteristics of understory vegetation in pure pinus massoniana forest and mixed forest of pinus massoniana and broad-leaved trees in Dashan Forest Center, Zongyang county. The results were as follows. The biomass proportions of shrub layer in pure forest and mixed forest were91.61% and 74.80%, respectively. The biomass proportions of the allocation to different parts of shrub layer in two different pinus massoniana stands were rootsstemsleaves. The aboveground biomass of the herbaceous layer in different stands was much less than that from the underground part. Compared with pure pinus massoniana forest, the soil bulk density in mixed forest was lower, but the soil water content, 0.25 mm water-stable aggregate content, organic matter, total N, hydrolysable N, available P and available k in mixed forest were higher than those in pure pinus massoniana forest. The correlation analysis showed that there were significantly negative relationships between the underground biomass and the soil bulk density and the soil water content, but the relationships between the underground biomass and the organic matter, total N and available P were significantly positive.