Aim:

Diversifying our woodlands to create resilience

A lone tree with blue sky behind

Project Description

The UK government supports rapid woodland expansion. Consequently, we need to ensure woodlands are resilient to climate change, pests and diseases. DiversiTree investigated the impacts of diversifying woodlands to increase resilience, working across scales and including microbial communities, biodiversity, stakeholder perspectives and management practices.

Microbial analysis of Scots pine (Pinus sylvestris) and Sitka spruce (Picea sitchensis) illuminated the microbial diversity on pine needles when the two species were together and when they were with more diverse species.

We also assessed if diversification could ensure functional redundancy—meaning that some tree species would maintain ecosystem functions and support similar biodiversity if Sitka spruce declined.

What we discovered...

  • We found that species diversity’s importance in increasing woodland resilience in an uncertain future is evident. However, consideration of which species are used in diversification is essential to maximise the effectiveness of investment in woodland creation.
  • The selection of tree species for diversification is critical. Scots pine hosts many species that depend on it, suggesting that diversifying Scots pine forests may not safeguard biodiversity.
  • In contrast, diversifying Sitka spruce forests could increase resilience, as most species associated with it are generalists that can thrive on other trees.
  • Practical limitations exist in implementing mixed planting strategies. Commercial forestry that includes Sitka spruce may need to consider blocks of species mixes rather than intermate mixed planting, which could reduce diversification’s biodiversity and resilience benefits, depending on the block size.
  • Woodland managers understand the connection between diversity and resilience but face significant barriers, including financial constraints, lack of information and perceived incompatibility between diversification and other management goals.

Project Lead(s)

Dr Ruth Mitchell, The James Hutton Institute

Project Website

https://www.hutton.ac.uk/project/diversitree/