Plant preference for ammonium versus nitrate: a neglected determinant of ecosystem functioning?

Area of Science:

• Ecology
• Ecosystem Science
• Plant Biology

Background:

• Nitrogen (N) availability is crucial for ecosystem properties.
• The ecological role of plant preference for ammonium versus nitrate (β) in ecosystem functioning and community structure is understudied.

Purpose of the Study:

• To model the impact of plant preference for ammonium versus nitrate (β) on ecosystem properties and community structure in two contrasting ecosystems.
• To investigate how β influences biomass, productivity, and nitrogen (N) losses.
• To explore the role of contrasting β values and nitrification control in plant species coexistence.

Main Methods:

• Ecological modeling was employed to simulate plant preference for ammonium versus nitrate (β).
• The models were applied to two distinct ecosystem types.
• Species replacement dynamics were analyzed in relation to ecosystem functioning.

Main Results:

• Plant preference for ammonium versus nitrate (β) significantly affects ecosystem properties including biomass, productivity, and N losses.
• An intermediate β value was found to maximize primary productivity and minimize mineral N losses.
• Contrasting β values between plant types facilitate coexistence, with nitrification control further modifying these dynamics.
• Species replacement dynamics did not lead to optimal N pool minimization or productivity maximization, challenging Tilman's R* rule.

Conclusions:

• Plant preference for ammonium versus nitrate (β) has significant consequences for ecosystem functioning and plant community structure in diverse ecosystems.
• The findings highlight the importance of considering plant N uptake preferences in ecological research and management.
• The study suggests that plant N preference is a key factor shaping ecosystem dynamics beyond traditional resource competition theories.