Successfull Underplanting - Silvicultural Guide
The document focuses on guiding forest managers in Britain on the principles and practices of successful underplanting, which involves establishing young trees beneath an existing canopy to promote forest resilience, diversity, and sustainable management. Its purpose is to provide detailed instructions, case studies, and decision-making frameworks for planning, species selection, operational implementation, and monitoring of underplanting efforts, emphasizing ecological and silvicultural considerations to ensure long-term stand development. The intended audience includes forest managers, silviculturists, and policy makers involved in woodland management and forest conservation seeking practical, research-backed guidance to incorporate underplanting into forest regeneration and improvement strategies.
Summary
Introduction
The guide aims to assist forest managers in executing successful underplanting, which involves planting young trees beneath an existing canopy either for regeneration or to diversify the forest structure. The practice offers silvicultural benefits like microclimate regulation but also presents risks if not properly managed. The policy context in Britain emphasizes improving resilience, diversity, and adapting to climate change through methods including underplanting, which has been adopted in European systems like Germany. The guide defines two primary types: regeneration underplanting, aimed at eventual overstorey replacement, and stand improvement underplanting, intended to supplement and manage existing stands. It highlights the importance of understanding ecological development stages, the influence of canopy presence, and the need for a strategic approach to achieve operational success.
Objectives
This section discusses the management goals that justify underplanting. Regeneration underplanting is suitable for species change, genetic improvement, natural regeneration failure, establishing sensitive or demanding species, or on difficult sites, primarily when the goal is replacement of the stand without natural regeneration. Stand improvement underplanting aims to increase yield, improve timber quality, control ground vegetation, and enhance ecological benefits. It often involves managing two canopy layers within a single stand for ecological and structural diversification, with objectives tailored to economic, environmental, and social values, emphasizing planning for natural regeneration and future harvesting.
Ecological context
The ecological foundation of underplanting is compared to traditional restocking, emphasizing persistent canopy influence on the young stand in terms of growth, species composition, soil, and operations. A developmental model outlines phases like stand initiation, stem exclusion, understorey reinitiation, and uneven-aged growth, which influence optimal timing for underplanting — generally during the understorey reinitiation phase to maximize success. Challenges such as natural regeneration, pest and disease risks, and mammal browsing are discussed, stressing the importance of site-specific ecological understanding and adaptive management strategies for successful underplanting.
Design and planning
Effective underplanting design begins with a long-term vision aligning management objectives with future stand structure and composition. Key considerations include species selection—focused on site adaptation, ecological compatibility, and management goals; stand environment—shade tolerance and stand density; protection measures against mammals; group planting strategies; operational logistics—access and site organization; timing—based on growth rates and stand development; and stand stability—to protect against windthrow. The section emphasizes matching species to site conditions, using decision tools like the Ecological Site Classification, planning planting patterns considering future harvests, and addressing operational logistics such as access routes and rack placement for machinery.
Implementation
This section provides practical guidance on planting operations, highlighting that ground preparation is usually minimal but should address specific issues like weeds or soil disturbance. The importance of planting size, type (transplants, cell-grown stock), and handling during dormancy is stressed to ensure high survival rates. Planting techniques—such as notch, pit, and angle-notch methods—and tools are discussed to optimize root establishment. Spacing strategies should consider future harvesting, operational ease, and ecological needs, with high-density planting often favored for timber production. The section also covers protecting young trees from mammals through fencing or tree shelters, and addressing pests and disease risks, especially fungal infections and insect pests, which are more prevalent in underplanting environments. Finally, it underscores the importance of early monitoring and flexible management to adapt to unforeseen problems.
Protection and maintenance
Protection measures include weed control—either through suppression under the canopy or targeted weed removal—and safeguarding trees from mammal browsing using fences or shelters. Disease management focuses on pest control, including specific pests like aphids affecting spruce and fungal diseases common in moist understorey environments. Respacing involves managing natural regeneration, which can outcompete young plants, through selective removal or chemical control, emphasizing early detection and intervention to maintain stand composition. Overall, ongoing maintenance is crucial to ensure survival and growth, with adaptive strategies recommended based on ongoing assessment.
Monitoring and review
Successful underplanting depends heavily on ongoing monitoring, emphasizing regular site visits to gather data and implement adaptive management. Site assessment methods like FCIN45 help evaluate stand health, growth, and success according to criteria like light availability, growth form, and damage from pests or mammals. The importance of understanding growth responses under canopy influence—such as leader: lateral ratios in conifers or branch growth in broadleaves—is highlighted for early detection of stress or constraints. Feedback from monitoring actions guides future management, helping to adjust operations and improve success rates based on practical experience.
Acknowledgements
The guide acknowledges contributions from experts and reviewers who provided feedback, images, and insights, including forestry professionals, researchers, and institutional support. It notes the increasing trend of underplanting in Britain as part of broader efforts to enhance forest resilience.
References
A comprehensive list of references is provided, citing authoritative sources on forest management, silvicultural techniques, ecological modeling, pest and disease management, and monitoring protocols, ensuring the guide's credibility and grounding in established scientific and practical knowledge.
Appendix: Setting a long-term vision
The appendix emphasizes the importance of establishing a clear, long-term management vision for the stand, aligning with ecological and operational objectives. Two detailed examples illustrate how to plan future stand structures with specific species proportions and arrangements over decades, integrating ecological, economic, and social objectives. These visions help guide decisions on species choice, planting patterns, and stand management, ensuring that underplanting contributes to sustainable and resilient forest estates.
Successfull Underplanting - Silvicultural Guide (en)
Number of pages: 42
Target countries: United Kingdom
Key takeaways
- Underplanting enhances stand resilience and diversity
- The guide emphasizes that well-designed underplanting can build a more resilient, diverse forest estate, reducing risks from pests, pathogens, and climate change, and may be necessary for developing continuous cover or mixed-species stands.
- Species choice must be carefully adapted to site conditions and ecological context
- Selecting site-adapted species based on climatic, soil, and future climate change predictions is fundamental; tools like ESC-DSS assist but local site observations are critical for appropriate species selection.
- Timing of underplanting is crucial and depends on management objectives
- For regeneration, planting is flexible and often aligned with stand rotation stages, while for stand improvement, timing should optimize growth rates without risking competition or canopy interference.
- Protection from mammals and pests is essential for successful establishment
- Effective measures such as fencing or individual tree protection are necessary to prevent browsing damage, which can significantly threaten early survival of underplanted trees.
- Operational planning must consider future harvest and access requirements
- Designing zones for planting and felling, careful rack placement, and adaptable extraction strategies are vital to minimize soil disturbance and facilitate ongoing management operations.
- High planting densities can improve establishment success and reduce weed control costs
- Using increased densities (e.g., 5000–10000 trees per hectare) in underplanting can enhance rapid canopy closure, providing benefits such as natural regeneration and operational efficiencies.
- Monitoring and adaptive management are key to long-term success
- Regular site visits, data collection, and flexibility in management interventions help address issues like natural regeneration, competition, or environmental threats, ensuring the longevity and performance of underplanting schemes.
Sources
- Successfull Underplanting - Silvicultural Guide - 2016-10-11 - https://cdn.forestresearch.gov.uk/2022/02/underplantingguideversion10_11october2016.pdf
