© 1988 by Institute of Chartered Foresters
Phosphorus Uptake by Birch from Various Depths in the Soil
*Institute of Terrestrial Ecology, Merlewood Research Station, Grange-over-Sands, Cumbria. England LA11 6JU
Institute of Terrestrial Ecology Hill of Brathens, Banchory, Scotland AB3 4BY
Potential phosphorus (P) uptake from various depths by trees in a 30-year-old birch stand located at Brathens, Banchory, Scotland, on a brown podzolic soil, was studied using 32P injected at 0, 10, 25 and 50 cm depth at 40 points within a 0.5 m radius of each tree. Two experiments were carried out, the first using 8 trees, the second using 16 trees. The ground vegetation had been hand weeded within a 3 m radius of each tree to remove competition for 32P uptake.
Considerable variation was found in the amount of 32P in leaf samples within and between replicate trees. Because of this, no statistically significant differences in 32P uptake were detected at the 5% level in the first experiment. In the second larger experiment, in which a significant (P <lt; 0. 001) depth effect was detected, the results show that 32P was mainly taken up from the 0–10 cm depth, with less than 1% of uptake coming from the 50 cm depth.
These results are discussed in relation to the findings from other studies that the total phosphorus content of surface soils increases under developing birch stands. It is concluded that these increases are unlikely to result from recycling of P derived from lower soil horizons, but instead from a raising of soil bulk density due to higher rates of organic matter decomposition induced by birch.