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| Nutrient allocation and cycling pattern in the Robinia pseudoacacia plantation in hilly region of Taihang Mountains |
| Zhao Yong1,Fan Wei2,Wu Mingzuo1,Zhang Jun1,Zhu Yanfeng1 |
| 1.The Environmental Department of Henan Agricultural University,450002;2.The Henan Forestry Academy,450003:Zhengzhou,China |
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Abstract The biomass and nutrient return in the Robinia pseucdoacacia plantation stand in hilly region of Taihang Mountains were investigated by means of the sample tree harvest method.The results indicate as follows: 1) The total biomass of tree layer was 39.87 t/hm2.The descending order of biomass of different organs was stem,root,bark,branch,leaf.2) The concentration of three elements in different organs showed the significant difference.The descending order of contents of three elements in stem,roots and bark was Nitrogen,Phosphors,Calcium, as for that in branch and leaf,Calcium,Nitrogen,Phosphors.3) The descending order of main elements in different organs was stem,leaf,branch,root,bark.Nutrient accumulation of three elements of the stand was 633.20 kg/hm2,The descending order of annual accumulation and retained amount is Calcium,Nitrogen,Phosphors,The accumulation of Calcium in the stands was 368.36 kg/hm2,18.19 kg/hm2 for Phosphors,and 276.65kg/hm2 for Nitrogen.4) The annual returned amount of three nutrient through litter was 286.52 kg/hm2,descending order of which is Calcium,Nitrogen,Phosphors.The annual returned amount of Calcium was 196.48 kg/hm2,that was 2.31 times more than those of Nitrogen and 40.26 times,for Phosphors.5) The descending order of absorption and enrichment coefficients of nutrient elements in the stand is Nitrogen,Phosphors,Calcium,as for utilization and cycling coefficients,Calcium,Nitrogen,Phosphors.The turnover period of Calcium was 1.87 a,which was the shortest among three elements,while the longest one,Phosphors with 3.73 a and the middle one,Nitrogen with 3.25 a.
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Received: 12 December 2008
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