Temperature effects on N₂O production pathways in temperate forest soils.

Area of Science:

• Environmental Science
• Soil Science
• Biogeochemistry

Background:

• Nitrous oxide (N₂O) is a potent greenhouse gas and stratospheric ozone-depleting substance.
• Increasing global temperatures are expected to influence soil N₂O production, but pathway-specific responses remain unclear.

Purpose of the Study:

• To investigate the influence of temperature on individual N₂O production pathways (denitrification, autotrophic nitrification, heterotrophic nitrification) in forest soils.
• To compare laboratory and field experimental results for estimating in situ N₂O production.

Main Methods:

• Laboratory ¹⁵N isotope tracing experiments with a temperature gradient (5°C to 35°C) in Korean pine and Redwood coniferous forest soils.
• Field ¹⁵N isotope tracing experiments across different seasons and years (2015-2017) in the same forest types.
• Analysis of N₂O production rates and pathway contributions under varying temperature conditions.

Main Results:

• Denitrification's contribution to N₂O varied with temperature, increasing with it in Korean pine forests but decreasing in Redwood forests.
• Autotrophic nitrification rates increased with temperature in both forest types, while its contribution varied.
• Heterotrophic nitrification rates increased with temperature, but its contribution showed complex relationships with temperature and gross nitrification rates.

Conclusions:

• Temperature exerts differential control over N₂O production pathways in temperate forest soils.
• The developed in situ ¹⁵N tracing technique is suitable for estimating and predicting soil N₂O production.
• Further validation of the methodology in diverse ecosystems is recommended.