| The effects of planting density on growth,timber stem form,biomass,root distribution, leaf area and leaf nutrition content of Fraxinus mandshurica plantation were analyzed by using the data obtained during 10 years from the experiment stand(including 1m×1m(A),1.5m×1.5 m(B),2m×2m(C).3m×1.5(D) 4 density levels) which was located in Mt.Mao'er.The result showed that:(1) It had obvious effect on stand growth in varied density stand of Fraxinus mandshurica plantation.With the decrease of planting density,diameter at breast height(DBH),single tree volume,crown diameter,increased significantly,but growing stock increased significantly. Timber's DBH,single tree volume,crown diameter,were 9.4%,20.7%and 37.7%(P＜0.05); 9%,66%and 77%(P＜0.05);20%,46.7%and 80%(P＜0.05) greater in stands B,C and D than that in stand A,respectively;growing stock were 8.1%,21.8%and 31.5%(P＜0.05) lower in stands of density level B,C and D than that in stand of density level A,respectively.Planting density had no significant effect on height growth.(2) It had obvious effect on and timber stem form quality in varied density stand of Fraxinus mandshurica plantation.With the decrease of planting density,forking rate and ratio of crown length to tree height increased significantly,but tree height/DBH and forking height decreased significantly.Forking ratio,ratio of crown length to tree height were 92%,195%and 323%(P＜0.05);26.4%,35.8%and 52.8%(P＜0.05) greater in stands B,C and D than that in stand A,respectively;forking height and tree height/DBH were 15%,16%and 41%(P＜0.05); 8.1%,21.8%and 31.5%(P＜0.05) lower in stands of density level B,C and D than that in stand of density level A,respectively.(3) Planting density had obvious effect on individual stem biomass and stand biomass in Fraxinus mandshurica plantation.With the decreased of the planting density the biomass of individual stem increased and the biomass of stand decreased significantly.Biomass of individual stem were 30%,86%and 148%greater in B,C and D stand than in A stand respectively(P＜0.05);stand biomass were 15%,20%and 30%lower in B,C and D stand than in A stand respectively(P＜0.05).Biomass allocation exhibited a pattern of stem＞root＞branch＞leaf.With the increased of planting density the ratio of stem biomass increased from 46%to 58%,gradually;but ratio of branch and leaf decreased gradually from 18%to 12%and 10%to 3%,respectively.(4) Planting density had obvious effect on biomass of root system in Fraxinus mandshurica plantation.With the decrease of planting density,biomass of the individual root system increased,but the root biomass of the population decreased significantly.Biomass of individual root system was 34%,83%and 140%greater in B,C and D stand than in A stand respectively(P＜0.05);but root biomass of the population was 13%,21%and 42%lower in B,C and D stand than in A stand respectively(P＜0.05).Planting density had obvious effect on root spread range,it was 38%,93%and 129%greater in B,C and D stand than in A stand respectively(P＜0.05);there was very less ratio of root biomass in depth soil,with the increase of planting density,the ratio of root biomass in depth soil increased from 13%to 30%, gradually;fine root biomass ratio increase from 7%to 30%,gradually.(5) It had obvious effect on individual leaf area in varied density stand of Fraxinus mandshurica plantation.With the increase of density,individual leaf area was 92%,228%and 323%more in B,C and D stand than in A stand respectively(P＜0.05).Planting density had no obvious effect on leaf area index,leaf nitrogen contents and leaf chlorophyll contents.(6) Based on growth,timber stem form quality,stand volume production and biomass of Fraxinus mandshurica plantation,we regard the density level C is the most reasonable planting density in the four density levels.
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