A new analysis by Forest Research has examined species diversity of the Public Forest Estate in Britain to help inform the future direction of research on species and provenance. The work was carried out by Dr. Richard Jinks who was until his recent retirement the Project Leader for Tree Species in Forest Research.
To perform an analysis of species diversity of the Public Forest Estate in Britain to help inform the future direction of research on species and provenance.
Findings and Recommendations
There are three reports describing the work and they can be found here. The first two documents are the full report and appendices; the third document is a summary of the work and includes suggested priorities for future research.
There are five main reasons why this work is important:
- Diversifying the species composition of our forests is a pragmatic way to develop the resilience of the forests throughout the United Kingdom.
- This study is the first analysis of species diversity of the Public Forest Estate to be published since the formation of the Forestry Commission in 1919. The analysis focussed on the 20 most common species and, importantly, considered present and future climates.
- The analysis divides the country into four climate regions (cold-wet; cool-wet; cool-humid and warm-dry) and quantifies that species diversity is much lower in the cold-wet and cool-wet regions, which account for 44% of the area.
- The report suggests there are two main ways to increase species diversity: (1) use a substitute species from the 20 considered in the analysis or (2) consider another species, which we know less about (i.e. the Emerging Species*). To give one example, based on climate factors Table 3 (of the summary and main report) can be used as a guide to substitution within each climate region. This shows that in the cold-wet region there are six of the 20 species that could be considered as substitutes for Sitka spruce. Of these six species four currently have restricted use because of pest and disease problems and the list is probably much more restricted if site and soil factors are also considered. A key question for our work is: how many of the Emerging Species* could be considered to increase the available choice?
- The effects of climate change by 2050 will shift much of the Public Forest Estate to the next warmest temperature zone, hence areas in the cold zone move into the cool zone and much of those in the cool zone shift into the warm zone. The present warm zone also shifts into a new zone for Britain, very warm, and by 2050 this could cover 10-33% of the area. This is a real challenge for forestry in the warm-dry region and research on species choice for this novel climate should be a priority.
The report identifies three main priorities for research on species and provenance:
- Identification of species that can be used to diversify forests in the cold-wet and cool-wet regions; specifically, alternatives for Sitka spruce.
- Evaluate new species and provenances for the warmer climates that will be found throughout Britain with the priority focus being sites that will shift into the very warm zone.
- Ensure that pests and disease susceptibilities and limitations are considered for all species as well as their silvicultural deployment.
Forest Research will be taking this work forward using a combination of the following methods:
- Evaluation of experience of using all species present in British forests.
- Monitoring the growth and development of trees in arboreta and other tree collections.
- Revisiting existing species and provenance trials established in the period 1950-1980 when there was active establishment of new experiments.
- Matching future climate zones to current climates elsewhere in the world and identifying potential new species with a focus on drought tolerance.
- Establishing new experiments of the most promising species and provenances in selected climate regions.
*Emerging Species – what are they?
In the analysis described in the report tree species were divided into different categories:
Principal tree species are defined as species that are currently widely used for timber production and will continue to be the dominant species unless affected by a new pest or disease or adversely affected by climate change.
Secondary tree species are trees that have been planted on a much smaller scale than the principal species, but are reasonably well understood and have demonstrated their suitability for forestry in terms of stem form, growth rate and hardiness under current conditions and so have potential for wider use in future.
Plot-stage species are a group of species that have not been planted on any significant scale, but have demonstrated silvicultural characteristics in trial plots and have qualities suitable for forestry objectives to justify further testing and development.
Specimen-stage species are species that have not been trialled for forest potential in experimental plots, but have demonstrated positive traits of good form, growth rate and hardiness as specimens in tree collections to warrant further testing in plots on a limited scale.
Emerging Species is a collective term used to describe the secondary and plot-stage species.