Effects of aluminium and mineral nutrition on growth and chemical composition of hydroponically grown seedlings of five different forest tree species

Abstract

Forest die-back and impaired tree vitality have frequently been ascribed to Al-toxicity and Al-induced nutritional disorders due to increased acidification of forest soils. Therefore, in this experiment effects of A1 were studied on growth and nutrient uptake with seedlings of five different forest tree species. During growth in culture solutions with and without AI all five species proved to be very Al-tolerant, despite high accumulation of AI in roots. In the coniferous evergreens Douglas-fir and Scots pine shoot as well as root A1 concentrations were significantly higher than in the deciduous broad-leaved species oak and birch. Larch showed intermediate AI levels.In none of the five species did AI reduce nutrient concentrations or the Ca/A1 ratio to values below the critical level. Besides differences in AI accumulation, coniferous and broad-leaved species also differed with respect to uptake and assimilation of nitrogen. Due to extra NH~ uptake, oak and birch showed a much higher N uptake and higher NH~ preference than the coniferous species. Especially with oak this high NH4 + preference in combination with a low specific root surface area resulted in a high root proton efflux density. In comparison to both broad-leaved trees and Scots pine the NO3 reduction capacity of larch and Douglas-fir was extremely low. This may have important consequences for both species if grown in NO;--rich soils.

Effects of water and nutrient applications in a Scots pine stand to tree growth and nutrient cycling

“…Exchange of applied base cations, predominantly K, with solved AI and H persisted during all the years, causing a lower pH of the soil solution and high concentrations of dissolved AI. This may have deleterious effects on roots (Keltjens and Van Loenen, 1989). A similar exchange with A1 and H was observed after application of K salts on acid soil (Matzner et al, 1983;Tamm, 1991).…”

“…Yet after two years growth started to decrease slightly and declined below control levels in the fifth treatment year. Keltjens and Van Loenen (1989) showed Scots pine to be very tolerant of A1, so growth decrease might not be related to the observed high AI concentrations (upto 70 mg L -1). However A1 could have induced P stress by formation of A1PO4 precipitates in roots (Cumming et al, 1986).…”

“…This is due to nitrification of NH4 (Van Breemen et al, 1982) or to proton excretion by roots when NH4 uptake dominates over NO3 (Arnold, 1993;De Visser and Keltjens, 1993). The increased proton production has led to high concentrations of H and free AI, that were shown harmful to roots of tree seedlings (Eldhuset et al, 1987;Keltjens and Van Loenen, 1989).…”

Effects of aluminium and pH on growth and potassium uptake by three ectomycorrhizal fungi in liquid culture

“…A beneficial growth effect of low A1 concentrations has also been reported in plant species (Foy et al, 1978), including Douglas-fir (Kamminga-Van Wijk. 1991; Keltjens and Van Loenen, 1989). Aluminium is not considered as a nutrient for growth.…”

Calculating critical loads for acidity with the simple mass balance method

“…For forest soil ecosystems, there is a most substantial uncertainty in the available data on A1 toxicity to trees (Abrahamsen, 1984;Asher, 1987;Berd6n et al, 1987;Boxman et al, 1988;Bossel et al, 1985;Ryan et al, 1986a, b;McCormac and Steiner, 1978;Steiner et al, 1978, Joslin and Wolfe, 1988, 1989Keltjens and van Loenen, 1989;Schulze et al, 1985;Smit et al, 1987;Sverdrup and Warfvinge, 1993;Ulrich et al, 1984;Huetterman and Ulrich, 1984). The general consensus is that a (Ca + Mg + K)/A1 molar ratio less than 1.0 may inhibit plant growth.…”