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| Titel |
The effect of harvest intensity on long-term calcium dynamics in soil and soil solution at three coniferous sites in Sweden |
| VerfasserIn |
Therese Zetterberg, Bengt Olsson, Stefan Löfgren, Claudia von Brömssen, Per-Olov Brandtberg |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250075721
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| Zusammenfassung |
| Bioenergy from forests is a mean to reduce fossil fuel related carbon dioxide (CO2)
emissions. The potential to replace fossil fuel with logging residues is large in countries with
extensive forest resources such as Sweden where the supply of bioenergy to district heating
plants has quintupled since the 1990’s, now accounting for 46% of the total energy supply.
However, the loss of nutrients and other elements in biomass is higher following harvest for
bioenergy purposes (whole-tree harvest, WTH) compared with traditional clear-cutting
(conventional harvest, CH).
Calcium (Ca2+) is an important base cation, which buffer soils and surface water against
acidification. The loss of Ca2+ and other base cations via harvest for bioenergy could
therefore result in soil acidification and there is a growing concern in Sweden that the
depletion in base cation pools would also lead to surface water acidification associated with
lower base cation concentrations in runoff (Swedish Environmental Protection Agency,
2007). Furthermore, WTH may also prevent or delay a recovery from acidification in areas
such as the southwestern parts of Sweden, where the pools of exchangeable cations
have been substantially depleted as a result of historically high sulfate (SO42-)
deposition.
In this paper, long-term treatment differences in soil exchangeable Ca2+ pools (down to
20 cm) and soil solution Ca2+ concentrations at 50 cm soil depth were examined at three
coniferous sites in Sweden following CH and WTH in 1974-76.
The results showed that soil water concentrations of Ca2+were -17 μeq l-1 (or 40%)
lower in WTH plots compared with CH plots, 27-30 years after harvest. The main treatment
differences had largely disappeared 32 to 35 years after harvest although site specific
treatment differences (ΔWTH-CH: -24 μeq l-1) were still measurable at the well-buffered
site in northern Sweden.
These results are in agreement with soil data showing that previously found treatment
differences in Ca2+ pools had diminished in the forest floor but remained in deeper soil
layers
(-0.29, -0.37 and -0.24 kmolc ha-1 in the 5-10, 10-15 and 15-20 cm soil layer, respectively).
The effects on soil Ca2+ pools appeared to be most pronounced at the well-buffered northern
site.
These results indicate that the effect of WTH on soil and soil solution concentrations is
temporary but site specific. Contrary to common beliefs, the greatest effects were
observed at the well-buffered site where the loss of Ca2+ during WTH is less likely
to lead to acidification effects. The treatment effects on soil solution at the more
acidic sites in southern Sweden were much smaller and probably not large enough
to fully counterbalance the general recovery from acidification during the study
period.
References
Swedish Environmental Protection Agency, 2007. Bara naturlig försurning. Bilagor till
underlagsrapport till fördjupad utvärdering av miljömålen. Rapport 5780. 208 pp. In
Swedish. |
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