Canopy Biomass of Young and Middle-age Dalbergia odorifera Forest
The study of the distribution characteristics of crown biomass of Dalbergia odorifera plantation can provide theoretical basis for reasonable evaluation of stand biomass and adjustment of crown structure.In this paper,D.odorif-era plantation aged 10-12 a in Dongfang,Hainan,China was taken as the research object.Two sample plots(S1 and S2)with different site conditions were set up,and the crown of the sample trees over 4.5 m was cut off.The biomass of each organ in the canopy was obtained by layered cutting method and total weighing method,and the optimal biomass fitting equation of each organ was established.(1)The order of biomass in each organ was bare branch>branch bark>leaf.The total biomass of bare branches,branch bark and canopy was S1>S2,while the leaf biomass was S1<S2.(2)With the in-crease of canopy class,the biomass of bare branches and branch bark of S1 and S2 showed a wave-like change,in which S1 increased first and then decreased,while S2 was the opposite.As a whole,the leaf biomass increased first and then decreased,in which S1 was mainly distributed in the middle and upper layers of the crown,while S2 was mainly distrib-uted in the lower layers.The upper layer of the canopy of S1 was more competitive than that of S2,there has been seri-ous natural thinning of canopy,the leaf biomass gradually shifted from the lower layer to the middle and upper layers.(3)The optimal fitting model of biomass was power function,which was the total biomass of crown[y=3.904(D²H)1.247],canopy bare branches[y=1.901(D²H)1.28],canopy branch bark[y=0.734(D²H)1.276],and canopy leaves(y=3.86D2.791).
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