Effects on soil chemistry and nutrient uptake by admixture of birch in Norway spruce stands

In English Spruce stands, pure Norway spruce, pure birch and mixed plots of birch and Norway spruce were established in 1984/1985 at four locations in southern and central Sweden. The soil was sampled down to 30cm soil depth in1984 /1986, 1993 and 2001. We report results on soil chemical changes and changes in base cation stores above and below ground. No significant positive effect on soil chemical status of the birch admixture was found even though the uptake of base cations into the trees was smaller in the mixed stands. All treatments showed a decrease in soil chemical status in the mineral soil over time.