«The Economic and Social Aspects of Biodiversity Benefits and Costs of Biodiversity in Ireland REPORT PREPARED BY: CRAIG BULLOCK, OPTIMIZE CONSULTANTS ...»
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4.1 T H E R E LAT I ON S H I P B E T W E E N F O R E S T RY A N D B I O D I V E R S I T YForests provide a range of ecosystem services including the direct benefits of forest products and amenity, and the indirect benefits of carbon sequestration and the retention and filtering of water.
In countries with large areas of forest, both temperate and tropical, these benefits have been argued to far exceed those from timber or conversion to agriculture (NFPA, 2006).
The situation for Ireland is rather different in that forest represents such a small proportion of the land area. While the area under forestry has increased from just over 1% to 9.8% of the land area (Fahy & Foley, 2004), almost all this increase has been represented by commercial forestry based on exotic conifers. As trees grow quickly in Ireland’s climate, the wood is fibrous and so is used mostly for pulp and board. This leads to a tendency for short-rotations whereas longer rotations would be more ideal for biodiversity.
The Forest Service has set a national target of increasing forest coverage by 20,000 hectares per year to 2035. Conifers will constitute the greater proportion of this planting, but the Native Woodland Scheme and elements of the Woodland Improvement Sub-Measure now encourage the planting of native broadleafs too. This is a positive move in that broad-leaf woodland contains a high diversity of plant and animal species that cannot readily adapt to commercial forestry. Furthermore, the inclusion of objectives for broad-leaf woodland is especially important for biodiversity in that surviving examples of old woodland sites are rare. In 2002, such forests represented only 6.3% of Coillte’s estate.
The benefits of native broad-leaf woodland arise from the mix of tree, shrub and ground-cover plants, the varying age profile of the trees, and the presence of natural clearings represented by alternative micro-habitats. The rich biodiversity is demonstrated by an abundance of invertebrates which survive on dead or decaying wood or hole-nesting birds. The scarcity of such woodland in Ireland means that many of these species are now absent or rare, although the mixture of pasture, conifers and scattering of broad-leafs does mean that Ireland has an estimated 40% of the European population of badgers (Hayden, 1995).
Plantation forestry typically contains many of the same limited range of non-native species (Carey, 2003). Trees are usually grown as a densely-planted monoculture. Alternative planting regimes which are more supportive of biodiversity are likely to be less economic. They can be supported through appropriate grants, although potentially an enhanced market exists for hardwoods, e.g. for house construction or flooring, and this could yet encourage more broad-leaf planting. Short-lived biomass plantations, although typically another monoculture, could also have some biodiversity benefits where not clear-felled or planted on ecologically valuable land.
( 1 ) S u s t ai n ab i l i t y an d E x t e r n a l C o s t s Much of Ireland’s plantation forest has been planted on poor quality grazing land in uplands. By adding diversity into a largely grassland landscape, plantation forestry can provide some ecological benefits in its early years before canopy closure. Young plantations support good populations of songbirds, small mammals and associated predators such as hen harriers and merlin (Hickie, 1990, Good et al, 1991). Alternatively, if allowed to fully mature, trees can provide for large invertebrate populations, hole-nesting birds and for other species feeding off dead-wood.
Unfortunately, much of the planting prior to the mid-1990s occurred on old demesnes and marginal land, sometimes replacing previous areas of broad-leaf. Where this has occurred, the benefits have often been out-weighed by the destruction of valuable semi-natural or peatland habitats. If planted on poorly buffered soils, conifer plantations can contribute to the aluminium toxicity and the acidification of water-courses leading to a loss of aquatic biodiversity and external costs for anglers due to reduced fish populations. In addition, a sizeable external cost arises from the aesthetic impact of blocks of densely packed conifers which have been planted with little consideration for the surrounding landscape, a familiar site in many upland areas.
Despite these shortcomings, Clinch (1999) reported that the public have a generally positive view of the Government’s afforestation targets even though these marginally failed to pass a cost-benefit test using Department of Finance criteria. He noted that there is some potential to realise external benefits in terms of carbon sequestration, but that the biodiversity benefits of proposed expansion may be limited. On the assumption that planting would occur on poor grazing land, Clinch believed that this would involve the replacement of one low diversity system with another.
The Forest Service has acted to ensure that all forestry is now subject to Sustainable Forest Management. Planting guidelines now take ecological and landscape factors into consideration. This has involved retention of areas of broad-leaf and of ecologically valuable glades of open space.
Eligibility for grant aid also requires that planting occurs on yield class 14 or above which effectively excludes marginal land and peatland.
4.2 R E L E VA N T S P E C I E S A N D F U N C T I ON SThe threat of deforestation of tropical forests has meant that they have been the subject of much research activity which has demonstrated their benefits in terms of climate, water retention, erosion prevention, pollination and pharmaceutical products. However, ecosystem services within temperate European forestry have received rather less attention, particularly for plantation forests.
In terms of the positive contribution of biodiversity to tree growth or quality, much of the same ecosystem services provided by biodiversity in agriculture also apply to commercial forestry. For example, the natural recycling of organic matter and mineralization of nitrogen is as relevant to forestry as agriculture and sufficient to avoid the need to apply artificial fertilizer. However, phosphates are regularly applied in the early years.
Forest managers are more conscious of biodiversity from the perspective of meeting government policy requirements which, themselves, stem from a perception that biodiversity has social value.
Wood is no longer the sole output of forestry, particularly for a semi-state organization such as Coillte. Increasingly, forest managers are being required to take account of biodiversity and sustainability to meet government environmental criteria or to qualify for product certification. The absence of an obvious feedback in terms of ecosystem services, means that foresters have less incentive than farmers to respect biodiversity as a route to qualifying for government environmental payments at least economic cost. Nevertheless, managing for biodiversity does not necessarily imply significant net costs in that a more diverse age or species stand can provide some direct benefits as described below.
From the perspective of the Forest Service, biodiversity objectives do help to justify support to the sector in the context of increasing the nation’s forest cover. Hence, indicators have been developed by the COFORD BIOFOREST project (http://bioforest.ucc.ie) as a means of demonstrating biodiversity outputs. These include structural indicators of biodiversity (e.g. area, connectivity, dead wood), compositional indicators (species numbers and diversity) and functional indicators (frequency or intensity of natural or human activities).
The principal social benefit of forest biodiversity in Ireland has been realised through recreation. As biodiversity and landscape variety are contributory factors to recreation activity, native woodlands would provide the highest benefits. Nevertheless, a good number of forest estates, although dominated by conifers, are popular destinations for tourism due to their open access and aesthetic value.
The hen harrier
Coillte have been active in the establishment of Biodiversity Action Plans for various threatened species. One of these is the hen harrier, a striking pale grey Bird of prey which breeds in scattered upland areas of Ireland. The hen harrier population has a love-hate relationship with forestry. On the one hand, it favours young conifer forest as nesting habitat, but it also needs undisturbed moorland for hunting. While its numbers had been increasing into the seventies, it has since declined due to the maturity of much forest and the loss of other areas to land reclamation. Persecution has also played a part, while the impact of windfarms is, as yet, unclear.
Agreement has recently been reached between the National Parks and Wildlife Service and the Forest Service to coordinate forestry plantings in Special Protection Areas so as to provide the ideal habitat mix by protecting existing blanket bog and ensuring a continual forest age stand.
4.3 E CO S YS T E M S E RV I C E S
S o i l fa u n a The soil biota performs important ecosystem services in terms of nutrient recycling and nitrogen mineralisation. Some organisms form partnerships with tree roots to extract nutrients, others are important for breaking down organic matter. Just as earthworms remove dead vegetation from surface soil layers, they also perform the same function with leaf litter. Earthworm populations are highest in broadleaf forest where they can contribute to the removal of the annual leaf fall within months.
Comparing deciduous plots with and without earthworms in North America, Groffman et al. (2006) report removal of 28% of carbon in the top 12 cm of the forest surface. The pine needles of a typical commercial forest are less digestible and tend to accumulate for longer, trapping nitrogen.
Therefore, while regular recycling of nutrients may be less important than for crops, there is a dependence on a rather narrow range of species that can digest this litter. Without this service, the forest surface would soon be smothered by material which would, in turn, provide a habitat for pests and pathogens. Retention of biodiversity also helps in the disposal of post-harvest litter and chipped debris. However, this benefit does not appear to have been quantified.
P e s t m an ag e m e n t Irish forests are relatively healthy compared with much of the rest of Europe. The principal problems are caused by fungal root rot (fomes and honey fungus) with some additional damage being caused by green spruce aphid and pine weevil as well as grey squirrel and deer. The spread of the pine weevil (Hylobius abietis) has been encouraged by the quantity of stumps left behind following clear cutting (Battles, 2007).
Purser et al (2006) remark on Ireland’s vulnerability to alien pest species such as the great spruce bark beetle, particularly in the context of climate change which could present more favourable conditions for these pests. An indicator of the potential damage is provided from Britain where a North American beetle was responsible for the virtual removal of elms from the countryside during the seventies.
Nevertheless, there is little information on the role of biodiversity in keeping pest species in check (Watt, 1992). A predator wasp, Bracon hylobii, helps to keep down numbers of weevils, but not enough to stop Coillte artificially introducing parasitic nematodes or using insecticides. It is generally agreed that monocultures would be more susceptible to pests (Lugo, 1997). There is some evidence from abroad that mixed species forests do have a lower incidence of pests, e.g.
spruce budworm in North America (Stiell & Berry, 1985; Hartley, 2006).
4.4 E CON O M I C A N D S O C I A L VA LU E S Around 2.5 million cubic metres of timber is produced in Ireland each year which, once processed, has a gross value added of 395 million. Typical rotations last for 40-50 years and, given that more than half the forest estate is less than 25 years old, this implies that production will increase in the future. In terms of jobs, the sector employs, directly or indirectly, 16,000 people.
As the soil biota is not under imminent threat of extinction and the benefits of pest control are unproven, the case for valuing the direct biodiversity benefits to forestry production is weak.
Insecticide use during tree establishment costs over 100 per hectare and may need to be repeated for up to four years in some circumstances, including an absence of natural predators.
The stronger argument for protecting biodiversity rests on the social benefits. Various international estimates have been provided over the years of the non-market benefits of forestry, principally recreation, but also biodiversity and carbon sequestration. Forestry, as a topic, is regularly visited by environmental economic studies. In Ireland, the CAMAR study indicated an average willingness-topay per visit of between 1.02 and 2.73 (2003 values) (ni Dhubhain et al, 1994). A more recent report (Coillte/Irish Sports Council, 2005) put this value at 5.42, equivalent to 97 million per annum, but with up to an additional 268 million being spent on food and accommodation associated with visits. Both figures are based on forest use rather than biodiversity specifically.
Clinch (1999) included non-use values in his estimate of 21.27 million per annum, noting also that this is a net figure allowing for people who dislike forestry. More recently, Bacon and Associates (2004) estimate that the current non-market benefits of forestry (recreation, carbon storage and biodiversity) are worth 88.4 million per annum, but that the poor treatment of biodiversity within the existing estate means that its contribution amounts to only 5.6 million per annum over that of the alternative land use (assumed to be REPS). On the basis of an assumption that 13% of the afforested area is set aside for biodiversity, Bacon and Associates calculate the proposed 20,000 hectare expansion would enhance this value by 1.6 million per year (a discounted NPV of 23m).