Stochastic and deterministic processes shape bioenergy crop microbiomes along a vertical soil niche

Area of Science:

• Microbiology
• Ecology
• Agronomy

Background:

• Sustainable biofuel cropping systems are vital for climate change mitigation and energy demands.
• Understanding soil and plant-associated microbial community responses is essential for agricultural sustainability and ecosystem function.
• Long-term field experiments provide critical insights into these complex interactions.

Purpose of the Study:

• To investigate how different biofuel cropping systems (poplar, restored prairie, switchgrass) affect soil and root microbial communities.
• To analyze microbial community shifts across a soil-depth gradient.
• To determine the influence of ecological niche, soil depth, and crop type on microbial community structure and function.

Main Methods:

• Utilized a long-term biofuel cropping system field experiment.
• Employed high-throughput amplicon sequencing of the fungal internal transcribed spacer (ITS) and prokaryotic 16S DNA regions.
• Analyzed soil and root samples across various soil depths.

Main Results:

• Microbial richness decreased and evenness increased with soil depth for both root and soil communities.
• Ecological niche (root vs. soil) was the primary driver of community structure, followed by depth and then crop type.
• Stochastic processes influenced fungal communities in deeper soils, while surface soil microbes showed greater co-occurrence and plant enrichment.
• Prokaryotic communities exhibited dispersal limitation at deeper depths.
• Microbial networks in deeper soils displayed increased density, connectedness, and module size.
• Fungal-fungal interactions decreased, while bacteria-bacteria interactions increased with depth, especially in root microbiomes.

Conclusions:

• Soil depth and ecological niche are critical factors shaping microbial communities in biofuel cropping systems.
• Different biofuel crops influence microbial community structure and function in distinct ways.
• Understanding these microbial dynamics is key to optimizing sustainable agriculture and ecosystem health.