The recent heatwave and drought could be having a deeper, more negative effect on soil than we first realised say scientists.

This could have widespread implications for plants and other vegetation which, in turn, may impact on the wider entire ecosystem.

The new study, involving scientists at Lancaster University and led by researchers at The University of Manchester, which has been published in Nature Communications, provides new insight into how a drought alters soil at microbial level. It shows that expected changes in climate will affect UK soil and that soil is not as tough as previously thought.

Due to climate change, disturbances such as drought are increasing in intensity and frequency. These extreme weather conditions change vegetation composition and soil moisture, which in turn impact underlying microbial networks.

By studying how microbes react to severe drought, the study provides a better understanding of how underground soil networks respond to such environmental disturbances.

Lead author, Dr Franciska de Vries, from Manchester’s School of Earth and Environmental Sciences, explains: “Soils harbour highly diverse microbial communities that are crucial for soil to function as it should.

“A major challenge is to understand how these complex microbial communities respond to and recover from disturbances, such as climate extremes, which are predicted to increase in frequency and intensity with climate change.

“These microbial communities within the soil play a crucial role in any ecosystem. But it wasn’t known how soil networks respond to disturbances, such as climate extremes, until now.”

Science conducted as part of Lancaster University’s Hazelrigg grassland experiment was key to the findings.

Professor Nick Ostle from the Lancaster Environment Centre said: “Our hot and dry summer this year is a ‘wake up’ to prepare for future weather stresses. We have just had the hottest ten years in UK history. This work shows that continued summer droughts will change soil biology. This matters as we plan for ensuring food security that depends on healthy soil.”

Researchers from across the UK, Italy, Sweden, and France compared the effects of drought on bacterial and fungal communities in soil. The team found that bacterial networks may not be as resilient to extreme climate as previously thought.

The research team tested the effects of summer drought on plant communities consisting of four common grassland species. They found that drought increased the abundance of a certain fast-growing, drought-tolerant grass. With greater aboveground vegetation comes an increased rate of evapotranspiration, or cycling of water from plants to the atmosphere, lowering the overall soil moisture.

Bacteria, but not fungi, were directly affected by this newfound abundance of grass. Due to the interactions between plant and microbial systems, this change in plant community composition could cause long-term consequences on bacterial communities. The team therefore unearthed the effects of how both aboveground and belowground communities withstand disturbances. These impacts on bacteria were also longer lasting than they were on fungi.

Unlike past research, this study considered the multitude of direct and indirect interactions occurring between different microbial organisms in soil. Rather than focusing on select attributes of bacteria and fungi, this research takes a comprehensive approach to studying soil ecosystems.

Dr de Vries: “This study allows soil ecologists to estimate the current and future impacts of drought on belowground organisms, helping to understand the complex interactions of species due to climate change.”

DOI 10.1038/s41467-018-05516-7