[Biomass of Quercus fabri population under different ecological restoration regimes in subtropical China].

In this paper, the tissue-specific biomass and above-ground biomass of Quercus fabri under different ecological restoration regimes in subtropical China were analyzed by establishing allometric models with different parameters. The best-fitted equations were adopted for estimating the biomass and its annual growth, and the below-ground biomass and its increment were estimated on the basis of its linear relationship with above-ground biomass. The results showed that the biomass of the branches and of the total above-ground tissues was best described by power-function models, and the best fitted independent variables were d2l and D2H, respectively. The tissue-specific biomass and total biomass of Q. fabri population were all greater in secondary forest than in Pinus elliottii plantation. The above-ground biomass and below-ground biomass of Q. fabri population in secondary forest were 3.592 and 1.723 t x hm(-2), respectively, in which, different tissue components were ranked in the order of stem > branch > leaf; while those in P. elliottii plantation were 0.666 and 0.462 t x hm(-2), respectively, in which, different tissue components were ranked in the order of stem > leaf > branch. From 2004 to 2006, the annual increments of above-ground, below-ground, and total biomass increased with time, and the increment of above-ground biomass had an ascent tendency, which was from 54.35% to 62.20% in P. elliottii plantation and from 67.27% to 68.94% in secondary forest. In comparing with that in secondary forest, the biomass increment of Q. fabri population in P. elliottii plantation was small, despite its relatively high growth rate.

[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.