Genetic variation within a dominant shrub structures green and brown community assemblages

Area of Science:

• Ecology
• Genetics
• Ecosystem Science

Background:

• Understanding linkages between above- and belowground ecosystems is a key ecological challenge.
• Connecting genetic variation to ecological consequences is an emerging research area.
• Intraspecific variation in plant traits can influence ecosystem structure and function.

Purpose of the Study:

• To investigate how genetic variation in a dominant shrub species (Baccharis pilularis) affects above- and belowground communities and ecosystem processes.
• To explore the relationship between plant architecture (erect vs. prostrate morphs) and associated ecological outcomes.
• To integrate genetic and ecological perspectives in a coastal dune ecosystem.

Main Methods:

• Long-term common-garden experiment with Baccharis pilularis morphotypes.
• Comparison of green (foliage) and brown (detritus) community assemblages.
• Assessment of local ecosystem processes and understory microclimate.
• Analysis of arthropod and soil bacterial communities.

Main Results:

• Prostrate morphs supported richer and more distinct foliage arthropod, litter microarthropod, and soil bacterial communities compared to erect morphs.
• Community compositional differences persisted from foliage to litter to soil.
• Shrub biomass primarily explained green assemblage variation, while understory abiotic conditions explained brown assemblage variation.
• Prostrate morphs, with greater biomass and litter, fostered more humid understories, leading to higher decomposition rates despite lower litter quality.

Conclusions:

• Intraspecific genetic variation in primary producers significantly mediates above- and belowground ecological linkages.
• Integrating genetic and ecological perspectives provides novel insights into terrestrial community-ecosystem connections.
• Plant architectural variation influences community composition, microclimate, and ecosystem processes, highlighting the role of genetic diversity in ecosystem stability.