Work Package 3 – Rehabilitation of poorly performing established broadleaf plantations
Poor stem quality is a common problem within broadleaved plantations. Whilst this problem is inherent in first rotation, green field silviculture, questionable provenance and species choice may have exacerbated the situation. The best site / provenance matches are often not considered, requested or indeed available – a fundamental problem with regard to the legacy of our first rotation broadleaved forests. Species choice may sometimes be overly optimistic with regard to site conditions, or more fundamentally misguided by the current GPC hierarchy. However, while forest policy should seek to direct the fundamentals of broadleaved plantation establishment, there remains the need to apply best (innovative) silvicultural practice to already established broadleaved plantations where stem quality is generally poor.
From observation in the field during COFORD field-tours and reports from the industry, it is apparent that there is a substantial area of broadleaf plantations, particularly ash, that for whatever reasons are under-performing and/or are of poor quality. The vast majority of broadleaf plantations are privately owned and their owners require an income from the plantations. Currently it is unclear how such poorly growing plantations should be managed although some options have been put forward internationally e.g. see Figure below.
A range of treatments may be possible, e.g. coppice with standards, underplanting, free growth, etc, which may form the basis of silvicultural trials and which could present an opportunity to begin the early diversification of first rotation broadleaved woodlands. This early intervention may therefore be seen as a positive step toward the integration of certain features which allow such woodlands to better fulfil a range of functions:
- Coppicing, underplanting and a general (early) diversity of structure will better serve ecological and landscape functions
- An early move toward Continuous Cover Forestry again supports ecological and landscape continuity and also begins to ensure greater continuity of supply (with regard to small lots of specialist hardwood timber – in support of local markets)
Indeed a general move toward species, age class and structural diversity within plantation woodlands may help secure certain desirable features of longer established broadleaved forests, therefore enhancing the most disadvantaged of our broadleaved plantations.
Figure 1. Silvicultural options for treating poor quality broadleaf stands. Redrawn from Evans (1984)
- To establish a minimum of three pilot studies on methods of bringing poorly growing broadleaf plantations into productive use.
- To produce, where possible, a set of guidelines/protocols for the rehabilitation of poorly performing established broadleaf plantations.
WP3a – State-of-the-Art
- A comprehensive literature review was conducted, making use of the internet and available abstracts databases. The British library Document Supply service and inter-library loans was extensively used to obtain hardcopies of the literature.
- All literature collected was entered into a database (EndNote) and filed.
- A review of unpublished work undertaken in Ireland was carried out
- NATFOREX database was interrogated to source any existing national trials to visit
WP3b – Establish trial sites
- Source a minimum of 3 suitable sites
- With regard to information gained from WP3a, establish plots (months 6 – 42)
- Possible treatments may include free growth, thinning and underplanting, coppice with standards
- Endeavour to use recognised experimental designs where possible to facilitate long-term research in conjunction with demonstration
- Measure and monitor plots to end of project
- Survival; Stem diameter; Stem height; Stem form
- Manage the trial sites to end of project
WP3c – Protocols
Using preliminary results from WP3, a draft set of guidelines/protocols was produced.
- Short, I., Hawe, J., Campion, J. and Byrne, R. (2015). A review of stumping back and case study of its use in the rehabilitation of poorly performing pole-stage sycamore. Irish Forestry 72: 58-77.
- Short, I. and Campion, J. (2015) How remedial silviculture can improve poorly performing pole-stage broadleaves. Forestry & Energy Review 5(2): 14-16.
- Short, I. and Campion, J. (2014) Coppice-with-standards: An old silvicultural system with new potential? Forestry & Energy Review 4(1): 42-44.
- Short, I. (2013) The potential for using a free-growth system in the rehabilitation of poorly performing pole-stage broadleaf stands. Irish Forestry 70: 157-171.
- Hawe, J. and Short, I. (2012) A review of the causes of poor performance in broadleaf plantations and possible remedial silvicultural systems. Irish Forestry 69 (1&2): 126-147.
- Short, I. and Hawe, J. (2012) Possible silvicultural systems for use in the rehabilitation of poorly performing broadleaf stands – Coppice-with-standards. Irish Forestry 69 (1&2): 148-166.
- Short, I. (2011). Tending and thinning of broadleaves: A simple guide to selecting quality trees. Forestry & Energy Review 1(2): 34-36.