Post-fire spatial patterns of soil nitrogen mineralization and microbial abundance

Area of Science:

• Forest ecology
• Soil science
• Microbial ecology

Background:

• Stand-replacing fires significantly alter soil nitrogen availability and microbial communities.
• Fires create spatial heterogeneity, leading to inconsistent post-fire ecological dynamics.
• Understanding these dynamics is crucial for predicting ecosystem function and nutrient cycling.

Purpose of the Study:

• To quantify the spatial structure of microbial communities in recently fire-affected forest stands.
• To determine if microbial variables can predict in situ net nitrogen mineralization rates.
• To investigate post-fire ecological dynamics in Greater Yellowstone's lodgepole pine and spruce/fir forests.

Main Methods:

• Utilized a fully probabilistic spatial process model and Bayesian kriging.
• Analyzed microbial lipid abundance and fungi-to-bacteria ratios.
• Conducted stepwise regression to model net nitrogen mineralization rates.

Main Results:

• Microbial lipid abundance and fungi-to-bacteria ratios exhibited spatial structure within plots two years post-fire.
• Spatial patterns of microbial variables, nitrogen mineralization, and cover variables showed congruence.
• Models predicting net nitrogen mineralization included fungal and bacterial abundance, but with low explained variance (R²<0.29).

Conclusions:

• Soil microbial communities display spatial structure following stand-replacing fires.
• Microbial variables offer some predictive power for nitrogen mineralization, though relationships are complex.
• Further research is needed to fully understand microbial regulation of post-fire nutrient cycling in fire-prone regions like Greater Yellowstone.