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Large-scale tree planting for environmental benefits

Home research Assessment of large-scale plant biosecurity risks to Scotland Large-scale tree planting for environmental benefits

Findings and Recommendations

  • This study features five case studies on the potential biosecurity risks from large-scale tree planting schemes which aim to deliver environmental benefits within Scotland. We conducted 18 interviews with key players involved at different stages of the project and reviewed key documents.
  • Existing pests and diseases within the region were of greatest concern, while emerging threats present in other parts of the country or overseas (such as emerald ash borerXylella fastidiosa or acute oak decline) were infrequently mentioned. 
  • Despite awareness and experience with a number of pests and diseases, there is a feeling that some – particularly those dispersing by wind – are difficult if not impossible to prevent. Lack of awareness about how best to manage for some threats (due to the complexities of applying guidance to real word situations) may contribute to an acceptance of risk.
  • Managers regularly attempted use of local provenances and locally collected seed, and to specify plants suited to the site conditions. This is thought to reduce the risk of introducing pests and diseases to the site, and to ensure optimal health of the trees and thereby their resilience to pests and diseases. However, sometimes supply issues may necessitate use of stock from further afield or of different provenances.
  • Complications may arise due to the large volumes of trees needed for these projects, and the number of actors involved. This may include prolonged periods of storage which can act as a quarantining period but can also pose health risks to the trees through stress, infection or cross-contamination.
  • It was recognised that good biosecurity practices are needed to prevent introduction and spread of pests and diseases on clothes, vehicles and equipment. However, this can be difficult to enforce in large-scale planting projects across open-access areas with multiple actors.
  • Delivery of planting stock on site was recognised as a potential pest and disease pathway. Often more than one nursery is required to source the specified stock, which makes the supply chain more complicated with more potential pathways for pest and disease introductions. Ultimately, managers of such schemes rely on trusted nurseries to supply biosecure stock.

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