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对湘南低山丘岗区密度为 90 0 ,112 5 ,15 0 0株·hm- 2的 6年生巨尾桉 Eucalyptusgrandis× urophglla丰产林营养元素进行了测定分析 .研究结果表明 :各不同组分的营养元素含量差异较大 ,以树叶营养元素含量最高 ,树干最低 .各组分中大量元素 K和 N的含量最高 ,P的含量最低 .微量元素中 Mn和 Fe的含量最高 ,Cu最低 .单株林木营养元素积累量随林分密度的增加而减小 ,低密度林分是高密度林分的 1.44倍 ,不同组分营养元素积累量的高低不受林分密度制约 ,单株林木各种营养元素积累量依次为 :Ca>K>N>Mg>P>Mn>Fe>Zn>Cu;林分营养元素积累量随林分密度的增加而增加 ;乔木层营养元素积累量占整个林分养分总积累量的 75 .3 %以上 .各种不同密度林分均以 N素积累量最高 ,K和 Ca较高 ,Cu的积累量最低 .年净积累量随林分密度的增加而提高 .3种密度林分年净积累量分别达到 2 3 9.45 48,2 64 .1148,2 70 .2 64 8kg· hm- 2 a- 1 ,大量元素占总量的 95 .2 0 %以上 .各种元素的年净积累量以 Ca为最大 ,占 41.0 8%～ 41.42 %;Cu的年净积累量最小 ,仅占 0 .66%.林分大量元素的吸收量达 3 5 1.1961～ 3 73 .7767kg· hm- 2 a- 1 ;微量元素的吸收量达 15 .95 49～ 18.9697kg· hm- 2 a- 1 .以中等密度林分为高 .各种元素吸收
The nutrient elements of 6-year-old Eucalyptus grandis × urophglla high density forests with density of 90 0, 112 5 and 150 000 hm-2 in the hilly area of southern Hunan were measured and analyzed. The results showed that: The contents of nutrient elements were quite different, with the highest content of nutrient elements and the lowest of trunk.The content of K and N and the content of P were the lowest in all components.The content of Mn and Fe in trace elements was the highest and Cu was the lowest. The accumulation of nutrient elements in forest decreased with the increase of stand density. The low-density stands were 1.44 times that of high-density stands. The accumulation of nutrients in different components was not affected by stand density, The order of element accumulation was Ca> K> N> Mg> P> Mn> Fe> Zn> Cu. The nutrient accumulation in stand increased with the increase of stand density. The nutrient accumulation in stand The total accumulation of more than 75.3% .All kinds of different density of the forest were the highest accumulation of N, K and Ca is higher, the lowest accumulation of Cu. Annual net accumulation increased with the increase of stand density.3 The net annual accumulation of species density stands is 2 3 9.45 48,2 64 .1148,2 respectively 70.264 8 kg · hm-2 a-1, with the major elements accounting for more than 95.2% of the total, with the annual net accumulation of various elements accounting for 41.0 8% -41.42% The net accumulation was the smallest, accounting for only 0.66%. The uptake of the major elements in the stand reached 35.11961 ~ 373.77767kg · hm-2 a-1 and the trace element absorption reached 15.9595-18.9697kg · hm- 2 a- 1 to medium-density forest is high. Various elements of absorption