Persistent decadal differences in plant communities assembled under contrasting climate conditions

Area of Science:

• Ecology
• Environmental Science
• Restoration Ecology

Background:

• Plant community assembly can be influenced by the year of establishment due to environmental variations.
• The long-term persistence of these 'year effects' on a decadal timescale remains poorly understood.

Purpose of the Study:

• To investigate short-term (5-year) and persistent (decadal) effects of establishment year climate on plant community assembly outcomes.
• To determine if initial climate conditions lead to transient or stable community states over time.

Main Methods:

• Restored four prairie sites using identical methods in different years (2010, 2012, 2014, 2016) to capture varied initial climate conditions.
• Monitored species composition for 5 years in all sites, and 9-11 years in the two oldest sites.
• Analyzed the relationship between establishment year precipitation (June-July) and community metrics.

Main Results:

• Significant differences in community composition were observed in the first year, persisting for 5 years.
• Establishment year precipitation influenced species richness and grass/forb cover, with wet years favoring grasses and dry years favoring forbs.
• Differences in community composition, richness, and cover persisted for 9-11 years, indicating stable, distinct states.

Conclusions:

• Establishment year climate effects, driven by stochastic weather variations, can create persistent, decadal-scale differences in plant community assembly.
• Restored prairies exhibit long-term ecological memory, with initial conditions shaping community trajectories over extended periods.