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In the face of a new pest/pathogen outbreak a key choice facing decision makers is whether or not to adopt control. They must weigh up the costs of control measures versus the potential benefits of reduced damage due to the pest/pathogen. Such a decision is complicated by the uncertainty in the future spread of the pest/pathogen as well as the irreversible nature of many control measures, such as the felling of trees.
In our new paper, we use an approach from the investment literature called real options to answer the question: "When should a decision maker adopt control, given that the future spread of the pest/pathogen is uncertain?" Under the traditional net present value approach, control should be adopted as soon as the level of the pest/pathogen is such that the benefits from control outweigh the costs. However, we find that the future uncertainty increases the threshold in the level of the pest/pathogen at which you should adopt control, so essentially you should wait longer before adopting control. The greater the uncertainty in the future or the faster the pest/pathogen is spreading the longer you should wait.
An important novelty of our work is that we use a more realistic way of describing the future uncertainty in the dynamics of the pest/pathogen spread than has previously been used in the literature. We find that this more realistic approach can significantly alter the threshold at which control should be adopted, particularly when there is great uncertainty in the future or the pest/pathogen is spreading quickly.
You can read the full paper online here.
Dangerfield C.E., Whalley, A.E., Hanley, N., and Gilligan, C.A. (2017) What a difference a stochastic process makes: epidemiological-based real options models of optimal treatment of disease Environmental and Resource Economics (DOI:10.1007/s10640-017-0168-x)
The question of whether to plant multiple tree species or a single tree species in a forest is a complex issue. The literature examining the effect of diversification of the tree species composition of forests on timber and non-timber outputs is ever expanding; however, the range of ecological impacts are difficult to disentangle and explicitly define. In a new paper, we create a bioeconomic model to examine how the optimal planting strategy is altered when disease is present.
We assume that the forest manager has the option of two tree species which can be planted in a monoculture (one of the species) or a mixture (both species). Moreover, we assume that the commercially preferred tree species is under threat from a new disease which may arrive within the rotation and reduce the timber benefit. The main question we address is how to different bioeconomic conditions alter the optimal planting strategy (which maximises the economic benefit from the forest).
We find that diversifying the species composition can reduce the economic loss from disease even when the benefit from the resistant species is small. However, this key result is sensitive to a pathogen's characteristics (probability of arrival, time of arrival, rate of spread of infection) and the losses (damage of the disease to the susceptible species and reduced benefit of planting the resistant species).
The full paper is available online here.
Morag F. Macpherson, Adam Kleczkowski, John R. Healey, Christopher P. Quine and Nick Hanley. (2017) The Effects of Invasive Pests and Diseases on Strategies for Forest Diversification Ecological Modelling 350:87-99 (DOI:10.1016/j.ecolmodel.2017.02.003)
In a new paper, we investigate the preferences and willingness to pay of the UK general public for a range of forest disease control measures. To do this we use a choice experiment where respondents are presented with a number of options for new tree diseases' control and are asked to choose which they prefer. These choice options do not refer to actual options that the government has already decided to implement, but simply show the kinds of features which future schemes might incorporate in order to find out the relative attractiveness of each to forest managers. The information generated by this research will help develop an understanding of the consequences of different management options.
A key result from this study is that there is significant public support for part-financing forest disease control policies in the UK, but this is conditional on forest ownership and the type of control measures used. For example, the study showed that disease control programmes within publicly-owned forests and forests owned by charitable trusts are more likely to be supported by the public than equivalent control programmes in privately-owned and/or commercial forests. Furthermore a negative sentiment against some disease control measures, such as clear felling of a forest, and chemical or biocide spraying, was highlighted.
The study also gathered information on the respondents recreational habits and general knowledge of tree disease and disease control measures. Generally respondents were relatively well informed about general tree disease-related issues, but they were less knowledgeable about specific tree diseases. We found that the greater knowledge about tree diseases and more frequent visits to forests are correlated with greater willingness to support publicly-funded tree disease control programmes in forests.
You can read the full paper online here.
Sheremet, O., Healey, J.R., Quine, C.P. and Hanley, N. (2017) Public Preferences and Willingness to Pay for Forest Disease Control in the UK Journal of Agricultural Economics DOI:10.1111/1477-9552.12210
Forests are under threat from tree pests and diseases which alter the flow of ecosystem services that they provide. In a previous paper (The Effects of Disease on Optimal Forest Rotation: A Generalisable Analytical Framework). We built a bioeconomic model which analysed how tree disease effects the time at which to clear-fell a forest which was predominately for timber production.
In our new paper titled "Payment for multiple forest benefits alters the effect of tree disease on optimal forest rotation length", we expand on this study to investigate how tree disease impacts the optimal rotation length of a forest which supplies a range of ecosystem services. This is a really important question since forests supply a wide range of timber and non-timber benefits, like carbon sequestration, conservation of biodiversity and the recreational and aesthetic value we place on them. Thus, we should consider all the benefits provided when making management decisions. A strength of this paper is that the framework we present can be extended to explicitly incorporate multiple ecosystem services and how disease affects their provision.
Our analysis shows a range complex interactions between factors including the rate of spread of infection and the impact of disease on the value of harvested timber and non-timber benefits. A key result from this paper is that whilst disease generally acts to reduce the optimal rotation length, the non-timber benefit will counter this effect and act to increase the optimal rotation length.
All our papers are Open Access, and you can read it here.
Macpherson, M.F., Kleczkowski, A., Healey, J.R. Hanley, N. (2017) Payment for multiple forest benefits alters the effect of tree disease on optimal forest rotation length. Ecological Economics 134: 82-94 doi:10.1016/j.ecolecon.2017.01.008
The project team are delighted to announce the first published paper from our work. The paper is titled "The effects of disease on optimal forest rotation: a generalisable analytical framework" and can be found online in Environmental and Resource Economics. In this paper we develop a novel model to examine how the optimal rotation length of a forest is altered by (1) different types of tree diseases and (2) different economic conditions. We reveal a complex trade-off between waiting for the forest grow for longer, but the infection spreading further.
Macpherson, M.F., Kleczkowski, A., Healey, J.R. Hanley, N. (2016) The Effects of Disease on Optimal Forest Rotation: A Generalisable Analytical Framework Environmental and Resource Economics doi:10.1007/s10640-016-0077-4
The Agricultural Economics Society's 90th Annual Conference was held at the University of Warwick, England, from Monday 4th to Wednesday 6th of April. The FOREMOD team had four members present at the conference and Nick Hanley co-organised a symposium on Plant Biosecurity Economics and Policy with Prof. Rob Fraser from The University of Kent. Morag and Ciara both presented work along with David Cook (Western Australian Department of Agriculutre and University of Western Australia) and Prof Ben While (University of Western Australia). Ciara present work titled "Optimal timing of invasive species control: a real options model", and Morag presented work titled "How does disease change the optimal forest planting strategy? If you'd like a copy of their presentations please get in touch, their working papers will shortly be available.
The project team was very happy to pretest one of the designed choice experiments at the 2nd PROTREE Stakeholder workshop. The workshop was organized by the Centre for Ecology and Hydrology and hosted at the Royal Botanic Garden Edinburgh on December 7, 2015. We are very thankful to Dr. Stephen Cavers for providing us with such a nice opportunity.
The workshop's presentations gave a very interesting overview of the history and current state of tree disease spread across Scotland. In particular, several participants, both from the academia and the forestry, stressed high genetic variability and possible cross-race hybridization of Dothistroma Needle Blight (DNB), and thus a threat of the disease's jumping to other pine species.
Choice experiments are based on the assumption that by presenting a respondent with a sequence of multi-variant choice situations and collecting her answers, the researcher can estimate the respondent's attitudes and preferences about the problem described by choice situations. For example, we are interested in understanding preferences of forest owners and managers with respect to tree disease control measures and their financing by the government. So we created a set of hypothetical choice situations, framed as contracts with forest and woodland owners under a new government-financed grant scheme for disease control. These contracts are characterized by several attributes, such as contract length, frequency of inspection visits, annual payments from the government etc. The results of this pilot choice experiment are quite informative and will be used to adjust the choice situations we used to elicit forest owners' preferences.
The project team were delighted to have the opportunity to be shown round Tenstmuir forest by Matt Young, the Planning Manager (Forest Enterprise Scotland). Tenstmuir is situated north of St Andrews in Fife, and is largely a pine forest owned by the Forestry Commission Scotland. Matt was kind enough to spend a day with us explaining the management strategies that are used at Tenstmuir. This was hugely informative as it showed some of the management strategies we have considered in practice. It also emphasised how the forest management is driven by the forest objective. For example Tenstmuir is a public forest attracting thousands of visitors each year, therefore thinning and disruptive management strategies normally occur out of peak season.
This was also a great opportunity to talk about management of forest diseases as some parts of the forest are infected with Dothistroma Needle Blight (DNB). It is common practice to manage DNB by thinning and Matt was kind enough to talk about the plans for Tentsmuir. Whilst we were there we saw DNB thinning in operation (see photo below). In addition to spending a Friday in a forest, this was a great experience and very valuable for the team. Thanks to Matt for being a superb host! We hope to continue links for future work.
Thinning on a DNB infected site at Tentsmuir forest.
The project are delighted to be involved in the Special UNEP (United Nations Environment Programme) Session on Infectious Diseases at the 2015 BIOECON conference. Ciara Dangerfield will be presenting work titled "An Epidemiological-based Model for Disease Spread within the Real Options Framework: The impact on the Optimal Timing of Treatment" and Morag Macpherson will be presenting "The Optimal Rotation Length of a Production Forest in the Presence of Disease". Other speakers in this session are Charles Sims (The University of Tennessee), David Finoff (University of Wyoming) and Eli Fenichel (Yale University). Nick Hanley and Adam Kleczowski will also be presenting work at BIOECON. The conference takes place at Kings College Cambridge on the 13th to the 15th of September. The final programme can be found here.