The ups and downs of forest management on low-nutrient soils were well illustrated during a recent field trip to Curraghmore West, 7km south of Tralee, on the western foothills on the Slieve Mish Mountains in Kerry.

The 127ha forest was established in 1987 on cutaway raised bog and for a number of years went into check due to poor soil fertility.

William Merivale, who now manages the forest for Adrian Brink, said that the discoloured slow-growing trees that went into check during the early 1990s made a remarkable recovery after canopy closure. Today, the yield class (YC) varies from 12 to 20m3/ha/annum on 97ha of the forest.

The remaining area, covering 30ha, struggled to close canopy and in 2010 received a reconstitution grant to cover the cost of re-fertilisation with ground mineral phosphate and inter-planting with lodgepole pine. The area is responding well as a mixed age forest is now emerging, comprising:

  • Harvested area of 2.5ha after windblow which will be reforested during the 2018-2019 planting season.
  • Mature areas, which will be clearfelled on a phased basis when a felling licence application is approved.
  • Reconstitution area, while responding well will require a few more years growth before a production plan is finalised.
  • Windblow

    Storm Darwin blew down 2.5ha of Sitka spruce in February 2014 which was harvested in early 2017. While the blown area needed at least a further four years to achieve maximum yield, it still produced 682 tonnes of logs comprising 170t of sawlog, 332t of pallet or boxwood and 180t of pulp as outlined by Kevin Kennelly, who purchased the clearfell on behalf of GP Wood.

    Reforestation, which once was a relatively simple operation of clearing the site and planting with the best commercial crop, is now a more complex operation. William Merivale outlined some of the requirements for second-rotation crops to satisfy certification and Forest Service guidelines. These include:

  • Leaving deadwood.
  • Species selection. Reducing Sitka spruce cover to 65% of the total reforested site.
  • The Forest Service requires at least 5m3/ha of deadwood to be left on the site after clearfell. This includes mainly lop and top.

    In recent years, some of this material has been used for wood energy. Leaving deadwood has soil amelioration and biodiversity benefits.

    Some of the participants at the field day, organised by the ITGA, acknowledged these benefits on poor-nutrient soils but felt it was unnecessary on better-quality sites as the continuous breakdown of litter over the years should provide sufficient nutrients.

    Species selection

    Species selection is providing a major reforestation challenge in Curraghmore West. Limiting Sitka spruce to 65% of the reforested area created much debate as the remaining area is likely to comprise 10% open space and 25% diverse conifers and broadleaves.

    Broadleaves such as birch and alder are options, while conifers might include western red cedar, lodgepole pine, western hemlock and Scots pine. Whatever the species mix, the production and commercial potential of the second rotation will be reduced considerably.

    While the desirability of mixed species on afforestation and reforestation sites was largely welcome on rich nutrient sites, many in the group questioned the wisdom of a 65:35 Sitka-diverse species mix on low-nutrient exposed sites.

    Species diversity in the second rotation will continue to be an issue over the coming years in Curraghmore West as most of the productive forest is now at or approaching the clearfell stage. Some of the crops here with YC 18-20 would normally be allowed a further three growing seasons but the damage caused by Storm Darwin in 2014 is an influencing factor in deciding to clearfell these blocks this year.

    Some of these stands have a standing volume of up to 720m3/ha so clearfelling is the option as the top height is 18m. The average tree volume is 0.5m3 and stocking is between 1,200 and 1,400 trees/ ha.

    The temptation in crops with a 12-18YC range and a standing volume of 320m3/ha is to wait for four or five more years when the volume should exceed 400m3/ha.

    However, as the top height is now at 15m, these stands are becoming more vulnerable to windblow with each passing year.

    In other crops which have a 50:50 mix of Sitka spruce and lodgepole pine, the yields and quality are mixed. The pine in particular is heavily branched and should be removed but this could create instability so it is likely that the management decision will be to allow both species to grow on.

    Felling licences

    A major talking point at the Kerry field day was the felling licence approval system. A felling licence application had been submitted last March to the Forest Service which was forwarded to the National Parks and Wildlife Service. Ideally, a time period of four to six weeks between application and approval is acceptable but the felling licence for Curraghmore West had yet to be approved six months after application.

    Many at the field day maintained that forest owners need to be able to respond quickly to market trends when selling timber and when a prospective buyer offers a price, it is in the belief that the crop can be harvested within a reasonable time.

    The current delay is regarded as unacceptable, especially as the Forestry Act 2014 allows for a flexible decision on a felling licence application “within four months of receipt by the Forest Service of a complete application; or failing that, notification of an expected date for a decision”.

    On a positive note, the Act allows for felling licences to last for a period up to 10 years with the “facility for the Forest Service to extend that validity for an additional five years”.