Biomass production and mineral element content of Swietenia macrophylla King in the juvenile phase under plantation conditions in Central Amazonia
Schmidt, P. | Liebere, R. | Bauch, J. | L. Gasparotto
The experimental study was carried out in order to evaluate in which way a sustainable growth of mixed plantation systems under the prevailing site conditions is possible. For this reason, the biomass production and the mineral element supply of six 2«-year-old plants of the high-quality wood species Swietenia macrophylla King including roots were determined. Up to twelve fractions (leaves, wood, bark, etc.) were separated and the element content (Ca, Mg, K, P, S, Fe, Al) of the different tissues was determined by Optical Emission Spectrometry (ICP-OES). The fractions allowed a high differentiation of the element content and can reveal physiological sinks within the plants. Parallel to this, the availability of nutrient elements in the soil was analyzed. As potassium is continuously transported from old to young leaves, this mineral element is "internally recycled". However, Ca accumulates in the old leaves and will, therefore, follow an "external recycling". The elements Al and Fe can be blocked in the cortex of the fine roots. The high demand for Ca, K, and P in the plant underlines that in the long run, a specific fertilization will be an urgent need, in order to guarantee a sustainable growth for high-qualitytimber trees. The low alkaline saturation of the soil and the low concentration of nutrient elements in the soil, which can only be improved immediately after burning for some months, reflect this insufficient nutrient supply.
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