High mountain trees: altitudinal records recently broken for eleven different tree species in Britain

Abstract

In 2022 a project was initiated utilising citizen science to document observations of trees growing in Britain above 900 m. This focused recording effort contributed to eleven new altitudinal records for tree species in this country, including Sorbus aucuparia at 1150 m and Picea sitchensis at 1125 m (both East Inverness-shire, v.c.96). Some of these observations involved increases of at least 200 m above previous known altitudinal limits. The new records were a mix of small, stunted plants not expected to reach maturity in these extreme environments, as well as arctic-alpine Salix shrubs adapted to low temperatures and exposed conditions. Although these findings are currently too restricted to draw broad conclusions on the impacts of climate warming and land management on tree colonisation in mountain environments, long-term data collection may allow an analysis of drivers of change in the future. Out of a total of 72 tree records above 900 m collated by the author in 2022, 56% were Picea sitchensis, highlighting the ability of this neophyte to spread into high elevation habitats. The project has been useful for generating public interest in biological recording at and above the altitudinal treeline, and the continuation of such work will assist with mountain woodland restoration projects for a variety of ecologically important taxa and plant communities.