Improving prediction and management of range expansions by combining analytical and individual‐based modelling approaches

Abstract

Summary1. Improving the understanding, prediction and management of range expansions is a key challenge for ecology. Over recent years, there has been a rapid increase in modelling effort focussed on range expansions and a shift from predominantly theoretical developments towards application. This is especially the case in the field of invasion biology and also in relation to reintroductions and species' responses to climate change. 2. While earlier models were exclusively analytical, individual-based models (IBMs) are now increasingly widely used. We argue that instead of being viewed as competing methodologies, analytical and individual-based methods can valuably be used in conjunction. 3. We use a mechanistic wind dispersal model to generate age-specific dispersal kernels for the invasive shrub, Rhododendron ponticum. To demonstrate the utility of employing both modelling approaches, this information along with demographic parameters is incorporated into an IBM and an analytical, integrodifference model. From both models, the equilibrium rate of spread is calculated. 4. Estimates of wavespeeds were similar for the two models, although slower rates of spread were consistently projected by the IBM. Further, our results demonstrate the wavespeed to be sensitive to the characterisation of age structure in the model; when few age classes are used, much higher rates of spread are projected. 5. The analytical model is extremely efficient at providing elasticity analysis of the wavespeed, which can provide helpful information for management. We gain qualitatively similar results using the IBM but obtaining the results is time-consuming and, because the model is stochastic, they are noisy and harder to interpret. We argue that analytically derived transient elasticity analyses are needed for the many cases where success of control is measured on a relatively short time horizon. 6. To demonstrate the flexibility of the IBM approach, we run it on a real landscape comprising different habitat types. The comparison of two different control scenarios is an example of the utility of this approach for more tactical applications. 7. As a general conclusion of the study, we emphasise that analytical and individual-based approaches offer different, but complementary, advantages and suggest how their joint use can facilitate the improvement in biodiversity management at a range of spatial scales.

Are Anomalous Invasion Speeds Robust to Demographic Stochasticity?

“…[20] have also highlighted the value of using both deterministic and stochastic modelling approaches when predicting invasion speeds. They found that though both models produced similar trends, their analytical model predicted significantly higher speeds than their stochastic IBM [20].…”

The critical domain size of stochastic population models

“…Travis et al. (2011) have argued have argued for, and explored the advantages of, using both analytical IDEs and individual-based approaches in the context of climate driven range expansions.…”

Inventory and review of quantitative models for spread of plant pests for use in pest risk assessment for the EU territory

“…While it may be possible to develop control measures against plant pests once they are widespread, it is much more effective in terms of time, cost and ultimate success to take action before a pest becomes widespread (Wadsworth et al, 2000; Johnson and Turner, 2010; Kapustka, 2010;Travis et al, 2011). Therefore, risk assessment at an early stage in plant pest invasion forms a valuable weapon against their damaging impacts.…”

“…As globalisation of trade in commodities able to harbour plant pests continues it seems inevitable that many more novel pest introductions to Europe will occur in the future (Meyerson and Mooney, 2007; Hulme, 2009). Furthermore, changing climatic and other environmental conditions may lead to a greater propensity for introduced pests to establish, spread and cause impact than has been observed historically (Walther et al, 2009).While it may be possible to develop control measures against plant pests once they are widespread, it is much more effective in terms of time, cost and ultimate success to take action before a pest becomes widespread (Wadsworth et al, 2000; Johnson and Turner, 2010; Kapustka, 2010;Travis et al, 2011). Therefore, risk assessment at an early stage in plant pest invasion forms a valuable weapon against their damaging impacts.…”