Biomass allocation and estimation model at different planting ages ofwine grape forest in east Helan Mountain

The biomass and morphological indexes of different planting ages of wine grape forest (1~12 years) were investigated by analyzing biomass distributions in different organs of varying-age stands and the relationships of biomass with component factors in east Helan Mountain. The study then established biomass prediction models for wine grape forests in the region. The results showed that plant height (H), stem height (SH), young shoot height (YSH), branch number (BN) and stem diameter (D) gradually increased with increasing planting age. Also different aboveground organs biomass increased with increasing forest age. The distribution of aboveground biomass showed an order of leaf > young shoot > stem for forest of ages 1~4 years. Although leaf formed a principal component of aboveground biomass, stem biomass was greater than young shoot biomass which was in turn greater than leaf biomass for forest of ages 4~12 years. Aboveground biomass gradually transformed into stem and young shoot. Belowground and aboveground biomasses significantly increased for ages 1~12 years. Biomass allocation was in the order as follows: aboveground biomass > belowground biomass for forest ages of 2~12 years. The pattern of relationship between biomasses of different plant organs and D²H was uniform with age structures. The optimal biomass models were the power function models of the form W=a×(D²H)^b. The relationship between leaf biomass and D²H fitted the form W=12.909×(D²H)^{0.825 9} (R²=0.849 9, P=0.000); that between shoot biomass and D²H fitted the form W=3.963 4×(D²H)^{1.344 9} (R²=0.938 1, P=0.000); also that between young shoot biomass and D²H fitted the form W=6.190 6×(D²H)^{1.051 7} (R²=0.804 7, P=0.000); next that between aboveground biomass and D²H fitted the form W=23.017×(D²H)^{1.076 6} (R²=0.938 5, P=0.000); and the relationship between belowground biomass and D²H fitted the form W=27.126×(D²H)^0.689 (R²=0.892 4, P=0.000). The optimal wine grape biomass models at different planting ages showed a certain degree of generality of high accuracy.