Distribution and seasonal variation of macro-nutrients, starch and radio-nuclides in short rotation Salix plantationsvon Fircks, Yuehua
The present work consists of two main parts. The first part includes studies of distribution and seasonal variation of macro-nutrients and starch in Salix plants. The second part deals with the uptake and distribution of radio-nuclides 137Cs and 90Sr in Salix plants grown in contaminated soil.
In the first part, the experiments were carried out in growth chambers and under outdoor conditions, using cutting-propagated Salix viminalis L. and Salix dasyclados Wimm. plants. Nutrients were supplied using steady-state nutrient techniques with two nutrient levels. The studies showed that plants cultured under high availability of nutrients had: i) higher concentrations of all macro-nutrients, ii) a delay of leaf senescence and dormancy, iii) an earlier growth start, and iv) contained less starch compared with plants grown under low nutrient availability plants. Between 40-50% of N and about 60% of P was withdrawn from the leaves prior to abscission and stored mainly in the aboveground perennial organs. Starch proved to be an abundant nutrient, particularly in roots, which had larger amounts of starch than aboveground plant parts during most of the seasons. The root starch in coppiced plants decreased more rapidly than in intact plants, indicating that starch reserves are important for early phases of growth and that coppicing creates a strong sink for internal carbohydrate reserves.
In the second part, an experiment was carried out in lysimeters contaminated artificially with 137Cs and 90Sr, and a field trial was established on agricultural soil in an area contaminated with radio-caesium from the Chernobyl accident. These studies showed that the 137Cs concentration in leaves decreased from summer to autumn while the 90Sr concentration in leaves increased during the same time. The fine roots had the highest 137Cs concentration, whereas the 90Sr concentration was highest in leaves. The low transfer rate of 137Cs from the soil to the plants resulted in low levels of 137Cs in the wood ashes. It was therefore concluded that fast-growing Salix coppicing systems exhibit promising features for a possible economic utilisation of contaminated agricultural soils.
Keywordsaccumulation; ash recycling; Chernobyl accident; contamination; coppice systems; nutrient cycling
Published inActa Universitatis Agriculturae Sueciae. Silvestria
2000, number: 171
Publisher: Department of Short Rotation Forestry, Swedish University of Agricultural Sciences
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