Experimental warming outside the growing season and exclusion of grazing has a mild effect on upland grassland plant communities in the short term

ABSTRACT

Background

Winters are expected to warm more than summers in central and northern Europe, with largely unknown effects on grassland plant communities.

Aims

By studying the interactions between winter warming and summer grazing, we aimed to disentangle their effects and give recommendations for future grassland management.

Methods

Our study area Upper Teesdale, England has winter temperatures close to 0°C and a well-studied vegetation, known for its arctic-alpine species growing at their climatic warm range limits. We set up a winter warming experiment using open top chambers (ca. +0.5°C) from mid-September until mid-May 2019 to 2022 and excluded sheep grazing during summer in a fully factorial design.

Results

Graminoid biomass increased, and bryophyte biomass decreased with winter warming. There was little to no evidence that winter warming affected any of the other plant response variables we measured, neither did grazing nor the interaction between winter warming and grazing.

Conclusions

Our experiment was relatively short in duration and treatments were realistic in magnitude, therefore the plant communities responded only slightly. Nevertheless, our data suggest a change towards more dominant vascular species and less bryophytes with winter warming, which might lead to lasting changes in the plant communities in the longer-term if not buffered by suitable grazing management.

KEYWORDS:

• British Uplands
• grasslands
• grazing
• open top chambers
• plant biomass
• plant communities
• sesleria caerulea
• winter warming

Acknowledgments

We thank Dr. Margaret Bradshaw for her unbelievable knowledge of the local flora and great enthusiasm for our project, Natural England for their practical and logistical help, and Raby and Strathmore Estates for giving us access to their land. This project formed part of SAOC’s fellowship at the Institute for Advance Studies at Durham University.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/17550874.2023.2286229

Additional information

Funding

The work was supported by the Bolin Centre for Climate Research Stiftelsen Carl Mannerfelts Fond .