Enhanced precipitation variability decreases grass- and increases shrub-productivity

Area of Science:

• Ecology
• Climate Change Science
• Plant Ecology

Background:

• Climate change studies often overlook precipitation variability's ecosystem impacts, focusing instead on precipitation amount.
• Interannual precipitation variability is projected to increase, yet its ecological consequences remain understudied.

Purpose of the Study:

• To investigate the effects of increased interannual precipitation variability on ecosystem primary production.
• To understand the differential responses of dominant plant functional types to precipitation variability.

Main Methods:

• A 6-year field experiment manipulating precipitation sequences (wet and dry years) to alter variability.
• Measuring ecosystem primary production and plant functional type productivity (perennial grasses and shrubs).
• Utilizing structural equation analysis to explore root distributions and competitive interactions.

Main Results:

• Increased precipitation variability significantly reduced overall ecosystem primary production.
• Perennial grass productivity decreased by 81%, while shrub productivity increased by 67%.
• Differential nonlinear responses to precipitation and contrasting root distributions explained these shifts, with effects amplifying over time.

Conclusions:

• Interannual precipitation variability has profound, underappreciated impacts on ecosystem structure and function.
• Shifts towards shrub dominance may occur under increased precipitation variability, altering ecosystem services.
• Understanding plant responses to precipitation variability is crucial for predicting climate change impacts on ecosystems.