New study reveals 23 tree species needed to support more than 40% of biodiversity associated with Scots pine
A new study led by The James Hutton Institute has highlighted the importance of protecting the UK’s Scots pine woodland by showing that 23 separate tree species would be needed to support even 41% of the biodiversity which is supported by Scots pine.
The study, which brought together experts from the Hutton, the RSPB, the Royal Botanic Garden Edinburgh, and the Woodland Trust, assessed whether increased tree species diversity would improve the resilience of biodiversity and ecosystem functioning in Scots pine forests.
Scots pine is the most widespread and commercially important of the UK’s three native conifers, providing a keystone for biodiversity and a softwood timber which is widely used in construction and joinery. However, diseases and the changes brought by climate change present a threat to this invaluable species and the woodlands it creates.
To discover if any other trees could provide increased resilience for the biodiversity associated with Scots pine, and to better understand how any diversification would impact their ecosystems, researchers created a first-of-its kind list cataloguing every species which is supported by Scots pine.
They found that 1,589 species within the UK use Scots pine for either living or feeding on – 17 birds, 130 bryophytes, 539 fungi, 420 invertebrates, 468 lichens and 15 mammals. Of these, 199 fungi, 16 invertebrates and 12 lichens are obligates, meaning they depend exclusively on Scots pine for survival. The researchers then compared the list of non-obligate species against 47 other tree species to see what percentage of the Scots pine-associated biodiversity they could support.
Their findings showed that the most promising alternative species were sessile/pedunculate oak, European beech, and silver/downy birch which all supported 15% of Scots pine-associated biodiversity. Meanwhile, 11% of the species supported by Scots pine could survive on only one of the 47 alternative tree species assessed, and a total of 23 alternative species would be needed to support even 41% of Scots pine-associated biodiversity.
Researchers also found that diversifying with native broad-leaved trees could speed up nutrient cycling in Scot’s pine woodlands, while diversifying with other conifers would maintain a similar rate.
The study demonstrates that tree species diversification will only provide improved resilience for a fraction of the biodiversity associated with the UK’s Scots pine forests and underlines the importance of protecting this vital species and the ecosystems it supports.
Dr Ruth Mitchell, a woodland ecologist at the Hutton and the study’s lead author, said, “We generally think of trees as good for biodiversity, but not all trees are equal and not all tree associated biodiversity can use every tree.
“Generally, we are trying to promote tree species diversification of our forests to increase resilience. This study shows that if the aim is to provide resilience for tree associated biodiversity we need to think carefully about which trees we establish.
The full study, titled Pining for diversity: Does greater tree species diversity enhance the resilience of associated biodiversity and ecosystem functioning in Pinus sylvestris forests?, can be accessed on ScienceDirect.
