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ANNEX C: DATA SOURCES AND ASSUMPTIONS USED IN QUANTIFYING IMPACTS
i. Cost of government inspections: figures have been provided by Scottish Government Rural Payments and Inspections Directorate, who carry out plant health inspections. Costs are based on current hourly staff costs, including pay and overheads, and the average visit time for different types of premises. These are then multiplied by the number of visits required under each option, plus additional visits to premises where infection is found. The number of outbreaks is estimated based on the percentage of premises visited at which infection has been detected in past years.
ii. Diagnostic costs: SASA provides diagnostic services and scientific advice on agricultural issues for the Scottish Government. The number of samples to be tested has been estimated based on the number of inspection visits required under each option. This figure has then been combined with the current costs of carrying out tests for P. ramorum and P. kernoviae to arrive at an overall cost for diagnostic services.
iii. Costs to nursery and garden centre industry: There are a range of impacts which disease spread and control activities may have on the nursery and garden centre trades. These are:
a. Destruction of plants when a nursery or garden centre infection is identified: Official controls require destruction of plants within a 2m radius of any infected plants, and further monitoring of host plants within 10m. The number of infected plants found will vary with disease spread. Based on experience with past outbreaks in Scottish nurseries and garden centres, it has been estimated that the average value of plants which have to be destroyed is £2521 per premises. Plants held in quarantine in a ten metre radius around an infected plant may miss their market and be sold at a discount or destroyed. For the purposes of this calculation it has been estimated that on average 5% of the value of plants in the 10 metre quarantine zone will be lost. The figures given are average costs based on conservative estimates, it is recognised that losses to individual businesses may be greater or lower than the averages used.
b. Staff costs: nursery or garden centre managers will need to use staff time to manage diseases. For these two diseases which are controlled by official inspection nursery and garden centre staff will need to spend additional time preparing for and dealing with the inspectors. The assumption is that on average nursery and garden centre staff are present or involved for 50% of the inspector's on site time.
c. Loss of export market: if third countries lose confidence in Great Britain's measures to control the spread of any disease they can restrict exports of susceptible plants from Great Britain to their country. The estimated value of exports from Scotland of susceptible species by the principal exporters is £11,200 per annum. However, it has been assumed that some of the plants would be sold to the domestic and EU market and that over time bilateral trading arrangements would be agreed with plant health authorities in third countries, lessening the impact of any loss in export market.
d. Domestic trade impact: Information from the Horticultural Trades Association indicates that growers may choose not to produce susceptible host plants if disease levels reach a certain point, reducing the risk of disease spread and the costs of nursery disease management. Landscape architects are, however, prone to continue to specify susceptible plants, and the demand is likely to be met from non GB suppliers. Due to lack of information on how and when such a transition might take place, this aspect has not been included in the quantification of the costs.
e. Administrative burden: the total cost of the administrative burden falling on industry as a result of existing measures against P. ramorum and P. kernoviae has been estimated at around £57 per year. This covers, for example, the need to maintain records to demonstrate that susceptible materials imported into the UK from the USA are accompanied by a phytosanitary certificate. These requirements are not expected to change under current proposals, therefore this issue has not been included in the quantification of impacts.
iv. Costs to historic and public gardens:
a. Historic and public gardens at which P. ramorum or P. kernoviae is identified are likely to see an impact on visitor numbers, since either infection or clearance work may make the garden unsightly and may require closure of part or all of the garden for a time. There are also costs of replanting with less susceptible plants. However, it is unclear how visitor numbers would change with each option, therefore this aspect has not been quantified.
b. From existing case studies of sites in England and Wales, the average cost of clearing infected plants has been estimated at £15k per garden.
v. Rhododendron clearance costs: calculations are based on a figure of £3,500 per hectare, the level at which rhododendron clearance may be funded through the Scotland Rural Development Programme.
vi. Loss of social and environmental benefits of woodlands: A range of tree species in Great Britain are susceptible to P. ramorum and P. kernoviae. The most susceptible tree in British woodlands is beech. For the cost benefit analysis areas of beech woodland in high risk climatic areas have been mapped against acid soils (acid soils have been used as a proxy for the presence of R. ponticum, since mapping of the presence of R. ponticum is not sufficiently accurate at present). This has identified an area of 9000ha of highly susceptible woodland in Scotland, which has been used in the calculations. It is possible that if the diseases spread or inoculum levels increase sufficiently other susceptible woodland areas may become infected. The annual value of the non-market social
and environmental benefits of Scottish woodland has been estimated at £104 million 1 [Kenneth G Willis et al 2003], based on its recreational, landscape, biodiversity and carbon sequestration benefits. It should be noted that the aggregate landscape value in the study is likely to be an underestimate.
When woodlands become infected with P. ramorum and P. kernoviae, ecosystem service benefits will be reduced but not all will be lost. Estimates from the Forestry Commission suggest that severely damaged beech woodland would lose between 50 and 70% of their annual biodiversity and recreational benefits. However, when woodlands are first infected, the losses will be much smaller and it will take some time before the beech woodland will be severely damaged. For recreational benefits, there is also the possibility that people will simply move to non-infected woodlands instead. These factors would suggest on average a lower proportion than 50 to 70% would be lost. For this exercise, a value of 25% was used as the best estimate. For landscape and carbon sequestration benefits, the best estimate is that 10% of annual landscape and carbon sequestration benefits will be lost when woodlands are infected.
Based on current information it is estimated that, once infection takes hold in an area, the area of woodland infected would increase by 31 per cent per year.
No account has been taken of the costs of felling diseased trees for safety, which may range from tens of pounds to several thousand depending on operational circumstances.
vii. Loss of ecosystems services of heathland: Scotland has 19,000ha of lowland heath and 623,000ha of upland heath, which represents around 50% of the world's total resource of this habitat. Vaccinium myrtillus (bilberry / blaeberry) is native to heaths, moors and acidic woodlands and forms an integral component of native heathland. It is commonly found throughout the British Isles and can become locally dominant in England towards the southeast. V. myrtillus was identified as a susceptible species for both pathogens in laboratory experiments by the Central Science Laboratory in 2006. Other heathland species have also been shown to be highly susceptible ( Vaccinium vitis-idaea and Arctostaphylos uva-ursi to P. kernoviae with Calluna vulgaris being highly susceptible to P. ramorum). In December 2007 V. myrtillus was found infected with P. kernoviae in woodland in Cornwall, and in February 2008 in open heathland. P. ramorum has not been found affecting heathland species to date. Spread of the diseases to native heathland could have significant impacts on heathland areas and biodiversity of heathland sites. For the purposes of this cost benefit analysis the values used in the recent study by Eftec (2007) on valuing ecosystem services, for both woodland and heathland (lowland heath) have been used. These are:
Low £500/ha
Mid £2000/ha
High £6000/ha
viii. Biodiversity benefit of rhododendron clearance: For this impact assessment it has been assumed that the value of the increase in biodiversity is equivalent to 70% of the cost of clearance. The woodland areas which would need to be cleared for disease control may not offer the best sites for clearance for biodiversity purposes, therefore it was assumed that the costs exceed the benefits as a conservative estimate.
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