Pyric herbivory decreases soil denitrification despite increased nitrate availability in a temperate grassland

Area of Science:

• Ecology
• Soil Science
• Rangeland Management

Background:

• Pyric herbivory (controlled burning + grazing) restores shrub-encroached rangelands.
• This practice may affect soil nitrogen pools and increase nitrogen losses.
• Understanding impacts on nitrification and denitrification is crucial for ecosystem functioning.

Purpose of the Study:

• Investigate pyric herbivory effects on soil nitrification and denitrification potentials.
• Assess mineral nitrogen content in a temperate rangeland.
• Determine impacts six months post-burning.

Main Methods:

• Compared high-severity burn + grazing, low-severity burn + grazing, and control treatments.
• Measured net and gross nitrification/denitrification potentials.
• Quantified mineral nitrogen, microbial biomass, soil properties, and bacterial abundance.

Main Results:

• Nitrification potential remained unaffected and highly variable across treatments.
• Gross denitrification potential and nitrous oxide reduction decreased in high-severity burned areas.
• Denitrification correlated with microbial biomass nitrogen, soil organic carbon, and water content.

Conclusions:

• Pyric herbivory shows minimal mid-term impact on nitrification in temperate ecosystems.
• Intense burning within pyric herbivory may decrease denitrification rates.
• Assessing land management impacts on soil nutrient cycling is vital.