The effects of harvesting on the long-term mass balances of calcium (Ca), magnesium (Mg) and potassium (K) were evaluated on a regional level in Sweden. A new high-resolution weathering database was used together with estimates of total deposition, losses through harvest and leaching. Estimates were made for pine and spruce separately and for two harvesting intensity scenarios: stem harvesting and whole-tree harvesting. The mass balance calculations showed net losses of Ca and Mg in almost the whole country for both scenarios. The losses were smaller for pine than for spruce. The K balances were mainly positive for pine but negative for spruce. Leaching was a main factor in the mass balances, especially for Ca and Mg. Whole-tree harvesting in spruce forests led to substantially higher net losses of K and Ca than stem harvesting, according to the calculations. In the whole-tree harvesting scenario in spruce forests the estimated yearly net losses of Ca, Mg and K corresponded to at least 5%, 8% and 3% of the pools of exchangeable base cations, respectively, at 25% of the analysed sites. If losses of this magnitude continue the depletion of the pools of Ca, Mg and K may lead to very low base saturation of the soils, possibly accompanied by negative effects on soil fertility, runoff water quality, tree vitality and tree growth within a forest rotation in parts of Sweden. Avoiding whole-tree harvesting can improve the situation substantially for K, but the losses of Ca and Mg will still be significant.
|Number of pages||10|
|Journal||Water, Air, and Soil Pollution: Focus|
|Publication status||Published - Mar 2007|
Bibliographical noteFunding Information:
Acknowledgements This study is the result of cooperation between two Swedish research programs, ASTA and SUFOR. The ASTA program is funded by MISTRA (the Foundation for Strategic Environmental Research), the Swedish Energy Agency, the National Board of Forestry in Sweden and the Swedish Environmental Protection Agency. The SUFOR program (Sustainable Forestry in Southern Sweden) is funded by MISTRA. The forest data were made available by the Swedish National Survey of Forest Soils and Vegetation, performed by the Department of Forest Soils, Swedish University of Agricultural Sciences (SLU), Uppsala. The authors are solely responsible for the interpretation of data.
- Base cations
- Forest soils