Temporal trends in spider communities at the UK Environmental Change Network Cairngorm field station, 2007-2019: data analysis report

This report details the trends in spider abundance at the Environmental Change Network (ECN) Cairngorms site over 13 years (2007-2019). Spiders were collected from pitfall traps in three habitats (pine woodland, wind-clipped heath, bog) in the Allt a’Mharcaidh catchment near Feshiebridge in the Western regions of the Cairngorms National Park, Scotland. Data was collected using standard ECN protocol, and all collected spider specimens were identified by the same expert araneologist for consistency. The spider communities were diverse, but typical of upland sites in the region, whilst a number of species present were either nationally rare, scarce, or amber listed due to nationwide declines. Over the relatively short period of monitoring none of the 96 species recorded at the site were found to be declining in abundance, whilst 16 species increased. The woodland community had the highest richness of species, consistent with this habitat being the most ecologically accessible to generalist species. Overall, however, abundances were similar across spider communities occupying the woodland, bog and heath habitats. The woodland community also appears to be becoming increasingly stable over time, relative to the heath and bog communities, both of which appeared to show extensive community change in 2013, which lasted for five years. This is likely a response to environmental extremes that occurred during the autumn of 2012 and spring / summer of 2013, but further exploratory research is required.