Potential of Minor Conifer Species

Investigating the range of conifer species available for commercial forestry on marginal agricultural land in Ireland

Background

This research project was led by Dr Niall Farrelly and assisted by PhD Walsh Fellow Richard Walsh examining forestry options on marginal agricultural land.

Forestry options have been reduced in recent years, with the reduction in species choice for farmers due to the impact of novel pests and diseases (i.e. Hymenoscyphus fraxineus in ash, Phytophthora ramorum in larch and Dothistroma septosporum in pine). As a result, species choice has become more limited. In order to provide more information on the potential of minor species that may afford silvicultural options on certain sites and provide for increased diversity in the forest estate, the potential of a range of minor conifer species were evaluated. While there is a perceived lack of information about more minor species, information on the performance of tree species exists in arboreta, research plots and forest stands that could be utilised to assist in assessing their performance in Ireland. Species such as Scots pine, Douglas fir could be utilized on drier sites and western red cedar for wetter sites and are all currently eligible for grant aid. The performance of a range of species across different soil types is lacking, especially on marginal soils that may be more readily available for forestry. This information is essential to offer a wider range of species choice that may have commercial potential for farmers to facilitate a viable forest enterprise and the achievement of forestry targets.

Species

While over 200 species of conifer species exist, the species deemed to have potential are limited to perhaps 20. While Sitka spruce, Lodgepole pine, Norway spruce and Japanese larch are well represented, making up approximately 95% of the coniferous species, other species could be considered of minor importance but may be worth examining.

Species such as Douglas fir, Scots pine, Noble fir, Grand fir, Corsican pine, European silver fir, Pacific silver fir, western red cedar, western hemlock, Japanese red cedar and coast redwood may provide potential on better/poorer quality soils, fulfil ecological niches and be adapted for climate change.

Furthermore, the potential of these species over a range of soils needs to be available before recommendations could be made regarding their suitability, including their suitability on marginal agricultural soils. For example,

Douglas fir shows potential on drier sites in the east of the country and may be a suitable option for sites subject to drought under current climate change predictions.
Western red cedar may provide options for wetter sites or alkaline sites, the latter where species choice is extremely limited or be suitable in mixture with Sitka spruce.
Western hemlock also shows some potential: it offers compatibility with our current major species, our climate and in mixture and produces timber that has desirable strength properties, similar to Sitka spruce.

Objectives

This research provided critical information on the suitability of these species, on land deemed marginal for economic agriculture. Specific objectives of the study were as follows:

Examine the growth potential of minor conifer species
What species can perform in mixture with Sitka spruce
Do mixed species stands show increased or decreased productivity
What species are suitable for sites where Sitka spruce is unsuitable (e.g. high elevation, drought risk, very wet sites, high pH, low nutrients)
Do mixtures spread risk of potential biotic damage
Are there new market opportunities, engineered timber products, durable products, biomass that certain species may be able to fill

For further information, contact Dr Niall Farrelly, Teagasc.