Forestry in the Project Area
Forestry covers 6% of the Caragh catchment and 14% of the Blackwater catchment. Commercial forests were established in the catchments by the State in the 1960/70s and by private forest planting from the mid-1980s onwards. The ratio of public to private forestry is 64:36 in the Caragh and 46:54% in the Blackwater.
Commercial forest plantations in the catchment occur typically on peat and peaty podzol soils and on steep slopes, often in close proximity to aquatic zones and freshwater pearl mussel populations. Principal conifer species include Sitka Spruce (Picea sitchensis), Lodgepole Pine (Pinus contorta) and Japanese Larch (Larix kaempferi), with small areas of other conifer species and assorted broadleaves (typically native broadleaves in semi-natural woodland). The conifer forest lifecycle or rotation is typically 40 years. Establishment and management of conifer forests generally involve ground preparation, drainage, fertiliser application, road construction, thinning, clearfelling and replanting.
Many of these operations can act as a significant potential source of both silt and/or nutrient input into aquatic zones. Erosion risk is especially high during forestry operations such as road construction, crop establishment and clearfelling, during which soils are exposed or damaged. Periodic, piecemeal clearfelling in both catchments can work in combination to cause episodic nutrient and sediment spikes and a gradual deterioration in water quality.
A number of small, fragmented, semi-natural broadleaf woodland are also found throughout the project area, most of which are located along riparian corridors. Although limited in scale, these play a largely beneficial role in mitigating negative impacts to freshwater pearl mussel populations, especially where they act as fully functional buffers with respect to hydrological integrity. These semi-natural remnants are typical of ‘ancient’ riparian woodland, occurring along aquatic corridors. They generally comprise of Birch (Betula pubescens), Willow (Salix spp.), Alder (Alnus glutinosa) and other native trees and shrubs typical of riparian woodland communities. Elsewhere on free draining slopes small pockets of acidophillous oak-woodland occur, which are dominated by Sessile Oak (Quercus petraea) and Holly (Ilex aquifolium).
The KerryLIFE project is working closely with forest owners and managers in the project area to collaborate in development of sustainable forestry for freshwater pearl mussel conservation. There are at least eight-publicly owned forests and two privately-owned forest expected to participate in the project covering over 500 ha. Various methods of sustainable forest practices are currently being developed within these forests.
The KerryLIFE project aims to restructure 175 ha of conifer forests currently managed under the clearfell system into permanent protective woodland. This will result in the creation of mixed-age broadleaf or conifer dominated woodland, which will be managed for the protection of water-quality and freshwater pearl mussels, as well as for wider biodiversity purposes. A wide range of sensitive forestry operations will be demonstrated over the course of the project and the impact of these concrete conservation actions will be monitored and evaluated.
Forestry Conservation measures
Clearfelling and other operations, such as ground preparation and road construction, that form part of the current silvicultural system, carry risks of compaction and other soil disturbances that can lead to significant losses of sediment to water. Fertilisation of the crop during the first rotation, as well as the decomposition of needles and branches remaining on site following clearfelling, can lead to significant losses of dissolved and particulate nutrients. In high risk settings, the cumulative negative impacts of harvesting and re-establishment on a 40-year cycle will not be effectively mitigated by measures such as sediment trapping and buffer zone creation. Removing all or parts of high risk plantations from commercial production is the only alternative. The establishment of permanent, long-term retention woodland in critical source areas will significantly reduce the risk of on-going and future sediment and nutrient loss. Long-term retention woodland will subsequently develop as mixed (native broadleaves and conifers), uneven-aged forests managed for biodiversity and the protection of water quality. This less intensive land-use will ensure that future impacts on pearl mussel populations will be minimised, principally through the avoidance of the clearfell/ replanting cycle.
The KerryLIFE project is trialling a number of targeted freshwater pearl mussel conservation actions in forestry including:
- Various methods for restructuring commercial plantations to long-term retention woodland
- The transformation of conventional clearfell-managed commercial forests to continuous cover forestry
- Alternative methods of firebreak management
- Sustainable management of forestry drains