Impact of climate change on soil nitric oxide and nitrous oxide emissions from typical land uses in Scotland

Abstract

Soil emissions of NO and N _2 O from typical land uses across Lowland and Highland Scotland were simulated under climate change conditions, during a short-term laboratory study. All locations investigated were significant sources of N _2 O (range: 157–277 µ g N _2 O–N m ^−2 h ^−1 ) and low-to-moderate sources of NO emissions (range: 0.4–30.5 µ g NO–N m ^−2 h ^−1 ), with a general tendency to decrease with altitude and increase with fertiliser and atmospheric N inputs. Simulated climate warming and extreme events (drought, intensive rainfall) increased soil NO pulses and N _2 O emissions from both natural and managed ecosystems in the following order: natural Highlands < natural Lowlands < grazed grasslands < natural moorland receiving high NH _3 deposition rates. Largest NO emission rates were observed from natural moorlands exposed to high NH _3 deposition rates. Although soil NO emissions were much smaller (6–660 times) than those of N _2 O, their impact on air quality is likely to increase as combustion sources of NO _x are declining as a result of successful mitigation. This study provides evidence of high N emission rates from natural ecosystems and calls for urgent action to improve existing national and intergovernmental inventories for NO and N _2 O, which at present do not fully account for emissions from natural soils receiving no direct anthropogenic N inputs.

Keywords

• NO
• N2O
• atmospheric N deposition
• climate change
• drought