20170609
Author :
Thornton, B.Martin, G.
Procee, M.
Miller, D. R.
Coull, M.
Yao, H.
Chapman, S. J.
Hudson, G.
Midwood, A. J.
Year :
2015
Title :
Distributions of carbon and nitrogen isotopes in Scotland's topsoil: a national-scale study
Distributions of carbon and nitrogen isotopes in Scotland's topsoil: a national-scale study
Journal :
European Journal of Soil Science
Comment :
This paper describes for the first time the spatial distribution of these isotopes in the topsoil of
Scotland. They applied linear modelling to assess the extent to which land use and climate can control the observed distributions.
Topsoil 𝛿13C values were tightly constrained about the mean, and possibly because of this we were able to explain only 23.6% of the variance even after considering the potential effects of a wide range of abiotic factors and land uses. Precipitation and land use explained the greatest variance in topsoil 𝛿13C, but individually this was only 10.4 and 9.9%, respectively.
For topsoil 𝛿15N, all explanatory variables together explained 55.7% of the variance, with land use alone explaining 45.4%. Soil under arable land and improved grassland, the more fertile sites, had the most enriched 𝛿15N values, whereas woodland and bogs had the most depleted values. A positive relationship between topsoil 𝛿15N and potential rate of nitrification suggested that this was due, at least in part, to greater losses of nitrate under arable land and improved grassland.
Under Scottish conditions of exclusively C3 vegetation and relatively large MAP values, climate has a weak effect on soil 𝛿13C values. Climate change would not be expected to alter the current
pattern of soil 𝛿13C values unless either the ingress of C4 plants occurred or transpiration stress increased to levels where discrimination against 13C was reduced.
Land use showed little control over soil 𝛿13C and hence its change would have little effect currently on the spatial distribution of soil 𝛿13C.
Climate showed little control over soil 𝛿15N; any change would not be expected to cause a great difference to the distribution of soil 𝛿15N. In contrast, land use showed relatively strong control over
soil 𝛿15N values; a pattern of increased soil 𝛿15N would follow any increase in arable land and improved grassland, and the converse would also be true.
European Journal of Soil Science
Comment :
This paper describes for the first time the spatial distribution of these isotopes in the topsoil of
Scotland. They applied linear modelling to assess the extent to which land use and climate can control the observed distributions.
Topsoil 𝛿13C values were tightly constrained about the mean, and possibly because of this we were able to explain only 23.6% of the variance even after considering the potential effects of a wide range of abiotic factors and land uses. Precipitation and land use explained the greatest variance in topsoil 𝛿13C, but individually this was only 10.4 and 9.9%, respectively.
For topsoil 𝛿15N, all explanatory variables together explained 55.7% of the variance, with land use alone explaining 45.4%. Soil under arable land and improved grassland, the more fertile sites, had the most enriched 𝛿15N values, whereas woodland and bogs had the most depleted values. A positive relationship between topsoil 𝛿15N and potential rate of nitrification suggested that this was due, at least in part, to greater losses of nitrate under arable land and improved grassland.
Under Scottish conditions of exclusively C3 vegetation and relatively large MAP values, climate has a weak effect on soil 𝛿13C values. Climate change would not be expected to alter the current
pattern of soil 𝛿13C values unless either the ingress of C4 plants occurred or transpiration stress increased to levels where discrimination against 13C was reduced.
Land use showed little control over soil 𝛿13C and hence its change would have little effect currently on the spatial distribution of soil 𝛿13C.
Climate showed little control over soil 𝛿15N; any change would not be expected to cause a great difference to the distribution of soil 𝛿15N. In contrast, land use showed relatively strong control over
soil 𝛿15N values; a pattern of increased soil 𝛿15N would follow any increase in arable land and improved grassland, and the converse would also be true.
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