Bioturbation by mammals and fire interact to alter ecosystem-level nutrient dynamics in longleaf pine forests

Area of Science:

• Terrestrial ecology
• Ecosystem engineering
• Nutrient cycling

Background:

• Ecosystem engineers significantly influence ecosystem processes.
• Bioturbation, soil disturbance by organisms, is a key ecosystem engineering activity.
• Southeastern pocket gophers (Geomys pinetis) are ecosystem engineers in longleaf pine forests.

Purpose of the Study:

• To investigate how bioturbation by pocket gophers affects forest floor nutrient dynamics.
• To evaluate the interactive effects of litter burial and fire on nutrient cycling.

Main Methods:

• Field measurements of litter decomposition and nutrient (N and P) turnover over four years.
• Simulation of ecosystem-level effects of litter burial and fire on N and P dynamics.

Main Results:

• Buried litter decomposed faster and released N and P more rapidly than surface litter.
• Pocket gopher mound formation (2.3% of forest floor annually) reduced litter mass and N/P content by ~11% over eight years.
• Buried litter was protected from fire, conserving N, especially with longer fire intervals.

Conclusions:

• Bioturbation by pocket gophers accelerates N and P turnover in forest ecosystems.
• Litter burial by pocket gophers conserves nitrogen in fire-prone, nutrient-limited ecosystems.