[Estimation models of understory shrub biomass and their applications in red soil hilly region].

With 16 familiar species of understory shrub at Qianyezhou ecological experimental station in red soil hilly region under Chinese Academy of Sciences as test objects, crown area (A(c)) and projected volume (V(c)) were used as the variables for building quadratic and power allometric equations, respectively, to estimate the biomass of individual populations, and mixed-model was used to estimate the biomass of the 16 species. The best-fit models were applied to estimate the biomass of understory shrub in different forest types. The results showed that the biomass of shrub layer varied significantly among different stand types. With species-specific models, the biomass in deciduous, secondary, and coniferous forests was estimated as 4 773, 3 175 and 733 kg x hm(-2), respectively; while with mixed model, the estimation result was a little lower, being 3 946, 2 772 and 840 kg x hm(-2), respectively. Under the conditions of species-specific models being not established, mixed model was more convenient and practical in estimating the biomass of understory shrub.