Effect of droughts and climate change on future soil weathering rates in Sweden
In a future warmer climate, extremely dry, warm summers might become more common. Soil weathering is affected by temperature and precipitation, and climate change and droughts can therefore affect soil chemistry and plant nutrition. In this study, climate change and drought effects on soil weatherin...
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Veröffentlicht in: | Biogeosciences 2023-05, Vol.20 (10), p.1879-1899 |
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Zusammenfassung: | In a future warmer climate, extremely dry, warm summers
might become more common. Soil weathering is affected by temperature and
precipitation, and climate change and droughts can therefore affect
soil chemistry and plant nutrition. In this study, climate change and
drought effects on soil weathering rates and release of Ca, Mg, K and Na
were studied on seven forest sites across different climates in Sweden,
using the dynamical model ForSAFE. Two climate scenarios were run, one
medium severity climate change scenario from IPCC (A1B) and one scenario
where a future drought period of 5 years was added, while everything else
was equal to the first scenario. The model results show a large geographical
variation of weathering rates for the sites, without any geographical
gradient, despite the strong dependence of temperature on weathering and
the strong gradient in temperature in Sweden. This is because soil texture
and mineralogy have strong effects on weathering. The weathering rates have
a pronounced seasonal dynamic. Weathering rates are low during winters and
generally high, but variable, during summers, depending on soil moisture and
temperature. According to the model runs, the future yearly average
weathering rates will increase by 5 %–17 % per degree of warming. The
relative increase is largest in the two southeastern sites, with low total
weathering rates. At sites in southern Sweden, future weathering increase
occurs throughout the year according to the modelling. In the north, the
increase in weathering during winters is almost negligible, despite larger
temperature increases than in other regions or seasons (5.9 ∘C
increase in winter in Högbränna; the yearly average temperature
increase for all sites is 3.7 ∘C), as the winter temperatures
still will mostly be below zero. The drought scenario has the strongest
effect in southern Sweden, where weathering during the later parts of the
drought summers decreases to typical winter weathering rates. Soil texture
and amount of gravel also influence how fast the weathering decreases during
drought and how fast the soil rewets and reaches normal weathering rates
after the drought. The coarsest of the modelled soils dries out and rewets
quicker than the less coarse of the modelled soils. In the north, the soils
do not dry out as much as in the south, despite the low precipitation, due to
lower evapotranspiration, and in the northernmost site, weathering is not
much affected. Yearly weathering during the droug |
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ISSN: | 1726-4189 1726-4170 1726-4189 |
DOI: | 10.5194/bg-20-1879-2023 |