Study On The Productivity And Wood Mechanical Properties Of Eucalyptus Grandiflorum In Zhangzhou, Fujian

Eucalyptus cloeziana F.Muell.is one of the main fast-growing tree species introduced and cultivated in southern China.It has excellent properties such as straight stem form,less branches,high wood quality and straight wood texture.In this study,main soil properties,tree growth,biomass,productivity,wood mechanical properties and stem taper equation of a 12-year-old E.cloeziana plantation in Zhangzhou City,Fujian province,were studied for scientific management and rational wood utilization.The research findings are as follows:(1)Soil fertility of the E.cloeziana plantation belonged to lower-middle level.The concentrations of soil total carbon ranged from 3.30 to 12.93 g·kg-1,soil total nitrogen ranged from 0.80 to 1.60 g·kg-1.Soil available potassium,exchangeable calcium,exchangeable magnesium,available phosphorus,ammonium nitrogen and nitrate nitrogen in different soil layers ranged from 39.0 to 72.0 g·kg-1,1.3 to 10.3 g·kg-1,0.9 to 5.3 g·kg-1,1.6 to 17.3 g·kg-1,28.1 to 75.2 g·kg-1 and 6.0 to 32.1 g·kg-1.The highest and the lowest concentrations were all distributed in 0?10 cm soil layer for available potassium,exchangeable calcium,exchangeable magnesium and nitrate nitrogen.The highest and lowest contents of ammonium nitrogen were all in the 10-20 cm soil layer.The concentrations of soil total carbon,total nitrogen and available phosphorus decreased with the deepening of the soil layer,the law is obvious.(2)Mean annual increment of tree volume did not decline during the 12years period indicating that the E.cloeziana trees did not reach age of quantitative maturity of tree volume.(3)Stand volume of the 12-year-old E.cloeziana plantation was 396.00 m3·hm-2,slightly higher than the neighboring 23-year-old M.macclurei plantation(393.97 m3·hm-2)with nearly same site conditions.Stand volume mean annual increment of the E.cloeziana plantation(33.00 m3·hm-2·a-1)was 1.93 times as much as in the M.macclurei plantation.Above ground tree layer biomass of the E.cloeziana plantation(289.35 t·hm-2)was 1.18 times as much as in the M.macclurei plantation,and its mean annual increment(24.11 t·hm-2·a-1)was 2.26 times as much as in the M.macclurei plantation(10.69 t·hm-2·a-1).(4)Air-dry density of the E.cloeziana wood was 0.78 g·cm-3,it belonged to IV class(0.751-0.95 g·cm-3),indicating that E.cloeziana wood was high in hardness and density.Swelling of air-dry and water absorption of E.cloeziana wood were low indicating that is has stable size and did not change shape easily.Its compressive strength parallel to grain and bending strength were middle-higher,and its composite strength was middle-higher(203.7 MPa).(5)Six stem taper equation were developed for E.cloeziana,and taper model by Kozak(1988)was the most precise model with determination coefficient(R2)0.9927.