Abstract:

Plot survey and stem analysis were conducted in a 10-year-old manchurian ash(Fraxinus mandshurica) plantation with different initial planting density to learn the influence of initial spacing on the biomass accumulation and root growth pattern. 1)single tree biomass increased dramatically with the decrease of initial density(P<0.05), with 30.3%, 85.6% and 146.7% increase for intermediate(I1, I2)and lowest(W)density stands, respectively; in comparison with highest density(N)stand. 2)There were significant differences in stand level biomass among the stands with different initial density, and the total tree biomass production in I1, I2 and W stand was 84.8%, 80.5% and 60.5% , respectively, of that in N stand. The stand level biomass structures were also impacted by initial stand density. 3) The mean single tree root biomass increased with the decrease of initial density, with 34.3%, 83.2% and 139.7% increases in I1, I2 and W stands(P<0.05)in comparison to the N stand, whereas the stand level root biomass production had a drastic decrease with the initial density, accounted for 87.4%, 79.4% and 58.5% of that in the N stand, respectively(P<0.05). 4)The horizontal distribution range of lateral root increased with the decrease of initial density(P<0.05), whereas the taproot rooting depth tended to decrease. In terms of a combination of stand level biomass accumulation, stem biomass ratio and root distribution pattern, we suggest a relatively greater initial planting density for manchurian ash plantation establishment.

Key words: Fraxinus mandshurica, plantation forest, planting density, biomass, root