The effects of invasive pests and pathogens on strategies for forest diversification

Morag F Macpherson,Adam Kleczkowski,John R Healey,Christopher P Quine,Nick Hanley

doi:10.1016/j.ecolmodel.2017.02.003

Morag F Macpherson, Adam Kleczkowski + Show 3 more

Open Access

https://doi.org/10.1016/j.ecolmodel.2017.02.003

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Abstract

Diversification of the tree species composition of production forests is a frequently advocated strategy to increase resilience to pests and pathogens; however, there is a lack of a general framework to analyse the impact of economic and biological conditions on the optimal planting strategy in the presence of tree disease. To meet this need we use a novel bioeconomic model to quantitatively assess the effect of tree disease on the optimal planting proportion of two tree species. 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). This study provides an exemplar framework which can be used to help understand the effect of a pathogen on forest management strategies.

Highlights

Tree pest and pathogen outbreaks can have negative economic and environmental impacts, especially when large areas of forest are affected (Pimentel et al, 2005; Ayres and Lombardero, 2000)
The two research questions that this paper addresses are: (1) what is the optimal planting strategy when species A returns a higher timber benefit than species B, but species A is susceptible to a new disease, whereas species B is not, and (2) how do different bioeconomic conditions alter the optimal planting strategy? Examining these questions for a range of bioeconomic parameter sets facilitates a better understanding of the qualitative effects that pathogen characteristics can have on the optimal planting strategy, since our model is not based on a specific host–pathogen system
Once the primary and/or the secondary infection rate is large enough for the infection to spread throughout the whole plot by the end of the rotation (IA(T, 0) = L), the optimal planting strategy is predominantly determined by the probability of arrival, P, and the timber value of species B relative to that of species A, relative to species A (RP)

Summary

Introduction

Tree pest and pathogen outbreaks can have negative economic and environmental impacts, especially when large areas of forest are affected (Pimentel et al, 2005; Ayres and Lombardero, 2000). M.F. Macpherson et al / Ecological Modelling 350 (2017) 87–99 gus Cryphonectria cubensis (Wingfield, 2003), is beginning to have a negative affect (Wingfield et al, 2008). Macpherson et al / Ecological Modelling 350 (2017) 87–99 gus Cryphonectria cubensis (Wingfield, 2003), is beginning to have a negative affect (Wingfield et al, 2008) Another example is Ips typographus that has been shown to have a greater effect on stands with higher proportions of spruce trees (Wermelinger, 2004). Due to the high proportion of Picea sitchensis monocultures in the UK, a contingency plan (Forestry Commission, 2015) has been created in case the beetle is found

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