Decreased temperature variance associated with biotic composition enhances coastal shrub encroachment

Area of Science:

• Ecology
• Environmental Science
• Climate Change Research

Background:

• Global shifts from grassland to shrub-dominated landscapes are occurring due to land-use changes and climate change.
• Warming winter temperatures are a primary driver for the expansion of Morella cerifera shrubs in coastal regions.
• Shrub establishment significantly alters local microclimates, but seasonal variations and microclimate variance remain understudied.

Purpose of the Study:

• To assess the influence of Morella cerifera shrubs on microclimate variance, community composition, and physiological functioning.
• To understand the mechanisms driving shrub encroachment in coastal grassland ecosystems.
• To analyze seasonal differences in microclimate variance influenced by shrub expansion.

Main Methods:

• Time-series analysis was applied to interpret microclimatic variance modification.
• Microclimate data, community composition, and physiological functioning were assessed across grass, transitional, and shrub vegetation zones.
• The study was conducted at the Virginia Coast Reserve, a Long-Term Ecological Research site.

Main Results:

• Shrub thickets led to reduced species diversity and increased transpiration and annual productivity.
• Morella cerifera significantly reduced temperature variance (maximum air, minimum air, maximum ground temperature).
• Microclimatic temperature moderation by shrubs reduced extreme summer temperatures even in transitional zones.

Conclusions:

• Morella cerifera encroachment on Virginia barrier islands is driven by reduced cold exposure and enhanced by microclimatic and physiological factors.
• The shift from grassland to shrub thickets alters coastal island productivity and natural resilience.
• Understanding these shifts is crucial for managing coastal ecosystems under climate change.