Effect of canopy closure on the growth and mineral nutrition of Ormosia hosiei seedlings under Cryptomeria japonica plantation
To investigate the silvicultural effect of Ormosia hosiei under different canopy closure levels,and to de-termine the optimal canopy closure level for understory regeneration of O.hosiei,three canopy closure levels,i.e.,L1(0.6),L2(0.5)and L3(0.4)were set in the existing Cryptomeria japonica plantation,2-year-old O.hosiei seed-lings were planted in the understory,and their growth indexes(height,root collar diameter,biomass)and leaf mineral nutrient contents(nitrogen,phosphorus,potassium)were measured.A comprehensive evaluation was carried out by using the membership function.The results showed that the difference in height and root collar diameter of O.hosiei seedlings was not significant(P>0.05)among different treatments.0.5 canopy closure level had the highest height index,which was 19.27%and 11.52%higher than 0.6 canopy closure level and 0.4 canopy closure level,respec-tively;0.5 canopy closure level had the highest root collar diameter index,which was 0.06%higher than 0.4 cano-py closure level.The root,stem,leaf and total biomass of O.hosiei seedlings differed significantly(P<0.05)among different treatments.The root,leaf and total biomass performed best at 0.5 canopy closure level.The nitrogen,phos-phorus and potassium contents of O.hosiei leaves differed significantly(P<0.05)among different treatments,with the highest content at 0.5 canopy closure level.The comprehensive analysis of the membership function showed that the growth of O.hosiei under different canopy closure levels was L2>L1>L3.It is concluded that the suitable canopy closure level for 2-year-old O.hosiei seedlings planted under C.japonica plantation is 0.5.
NETL
NSTL
万方数据
