Reduced snow cover and shifting vegetation patterns, both driven by climate change, are having major combined impacts on biodiversity and functioning of ecosystems in the Alps, according to new research.
An international research team, led by the University of Manchester and also involving the UK Centre for Ecology & Hydrology (UKCEH), investigated seasonal changes in plant and soil processes in mountain ecosystems.
Following snowmelt in spring, plants start to grow and compete with soil microbes for nutrients, thereby triggering a shift in the storage of nutrients from soil to plants. This transfer is reversed in autumn, as plants die back and nutrients are returned to the soil within dead leaves and roots.
Meanwhile, snow acts like an insulating blanket that allows soil microbes to continue functioning and store key nutrients, particularly nitrogen, and enables plants to survive cold alpine winters.
However, mountain ranges covering vast areas of the world are warming much faster than surrounding lowland areas. Climate change is predicted to cause an 80-90% loss of snow cover by the end of the century in parts of the European Alps and advance the timing of snowmelt by five to 10 weeks.
Warmer grasslands are expected to result in an expansion of alpine shrub coverage such as heather, which cause increased soil erosion as well as changes in pH and nutrient availability.
By investigating how differences in snow cover, temperature of soils and abundance of shrubs affect the availability of nutrients for plants and microbes, the study showed how climate change affects the seasonal processes.
As part of the study, UKCEH scientists extracted the DNA from sampled alpine soils and sequenced this DNA to look at the differences between seasonal bacterial and fungal communities.
“We found the seasonal species composition and abundance of these communities altered in response to increased alpine shrub cover and to slower nutrient cycling in spring and autumn,” explains UKCEH microbial ecologist Dr Lindsay Newbold, a co-author of the study.
This could diminish the capacity of these globally widespread alpine ecosystems to retain nitrogen and support plant productivity under future climate change.
Interactions between direct and indirect climate change factors, such as snow cover change and as dwarf-shrub expansion, can lead to sudden and unexpected changes in ecosystem functioning. More research is needed to investigate these direct and indirect consequences because impacts are impossible to predict by studying climate change factors in isolation.
The study, published in the journal Global Change Biology, was funded by the Natural Environment Research Council.
Paper information
Broadbent et al. 2024. Climate change disrupts the seasonal coupling of plant and soil microbial nutrient cycling in an alpine ecosystem. Global Change Biology. DOI: 10.1111/gcb.17245. Open access.
The study involved scientists from the University of Manchester, UKCEH, University of Innsbruck and Helmholtz Zentrum München.