Impact of Douglas-fir and Scots pine seedlings on plagioclase weathering under acidic conditions

• Published in: Plant and soil 2004-10, Vol.266 (1-2), p.247-259
• Main Authors: Bakker, M.R, George, E, Turpault, M.P, Zhang, J.L, Zeller, B
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; aluminum; Animal and plant ecology; Animal, plant and microbial ecology; Autoecology; Biological and medical sciences; Biological weathering; calcium; Chemical, physicochemical, biochemical and biological properties; Dissolution; forest ecosystems; forest trees; Fundamental and applied biological sciences. Psychology; leachates; Leaching; Life Sciences; losses from soil; magnesium; Mineral components. Ionic and exchange properties; Minerals; nutrient solutions; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Pine trees; Pinus sylvestris; Plagioclase; plant nutrition; Plant roots; Plants and fungi; Pseudotsuga menziesii; Seedlings; silicon; soil pH; Soil science; soil weathering; soil-plant interactions; Vegetal Biology; Weathering processes
• ISSN: 0032-079X; 1573-5036

The weathering of soil minerals in forest ecosystems increases nutrient availability for the trees. The rate of such weathering and its relative contribution to forest tree nutrition, is a major issue when evaluating present and potential forest stand productivity and sustainability. The current paper examines the weathering rate of plagioclase with and without Douglas-fir or Scots pine seedlings, in a laboratory experiment at pH 3-4 and 25 °C. All nutrients, with the exception of Ca, were supplied in sufficient amounts in a nutrient solution. The objective of the experiment was to evaluate the potential of trees to mobilise Ca from the mineral plagioclase that contained 12% of Ca. Amounts of nutrients supplied in the nutrient solution, amounts accumulated in the living tissue of the seedlings and amounts leached from the experimental vessels, were measured. A weathering balance, accounting for leached + accumulated -supplied amounts, was established. Bio-induced weathering, defined as the weathering increase in the presence of trees, relative to the weathering rate without trees (geochemical weathering; control vessels), under the present experimental conditions, explained on average, 40% of total weathering (biological H-geochemical). These conditions appeared more beneficial to Scots pine (higher relative growth rate, higher Ca incorporation) than to Douglas-fir.