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METAPHOR

METAPHOR is a tool for Spatial Population Analysis.

It answers these types of questions:

  • What is the survival probability of a certain species in a given area?
  • Which parameters have the strongest effect on population viability (e.g. mortality, reproduction, landscape parameters)?
  • What is the most effective way to improve the population viability (comparison of different scenarios)?

The main processes in spatial population dynamics are reproduction, mortality and dispersal. METAPHOR simulates these processes over time in order to estimate long term viability of a fragmented population (a metapopulation). METAPHOR can calculate effects on metapopulation processes due to changes in landscape patterns caused by habitat redesign or management. A few examples are:

  • mortality caused by traffic or hunting,
  • reproductive failure due to loss of habitat quality or disturbance,
  • comparing sustainability of scenarios with different mortality or habitat quality patterns.

METAPHOR – Ecology

Metaphor is an individual-based, spatial explicit model. Each individual is modelled separately in space, time and individual traits. It can be used to make predictions on population dynamics, estimate survival probabilities and gain a deeper understanding of ecological systems.

METAPHOR input

Typical METAPHOR input consists of:

  • habitat suitability map.
  • estimates of life history parameters (birth rate, mortality rate, dispersal characteristics)
  • estimates of carrying capacity (or average potential density) of habitat units.

METAPHOR results

The main result of METAPHOR analysis is the viability of a metapopulation, as a probability of surviving a certain period of time (e.g. 100 years). More interesting results are obtained by comparing outcomes of several METAPHOR simulations. Sensitivity analysis is performed by variation of life history parameters. In scenario studies the landscape changes. Sensitivity analysis can reveal the most important parameter for managing population processes. Scenario studies can determine the effects of enlarging and connecting habitat patches or enhancing habitat quality.

Due to the very flexible programming structure, Metaphor can easily be adapted to different species with a different ecology. At the moment it is a single-species-model, but it’s possible to extend it to a multi-species-model on one or more trophic levels. The model can work in landscapes with simple circle-shaped patches as well as in real landscapes (ArcView files). Two versions for different species are:

METAPHOR bear

The individual brown bears live in subpopulations (continuous patches of suitable habitat). Dispersing bears connect single subpopulations. Most dispersing bears are males in the age of 2 or 3 years. If dispersing bears find a suitable subpopulation, they settle down. Female bears produce a litter of 2 to 3 cubs every 2 years. The spatially explicit movements of the dispersing bears are modelled by Smallsteps. The model is used for the brown bear population in the Abruzzo region in Central Italy to make predictions for the future population trend and evaluate different management scenarios.

METAPHOR plant

The plant version is designed for plant species in Dutch grassland like Succisa pratensis or Centaurea jacea. The total lifecycle of all individual plants is modelled spatially explicit, including seed dispersal. Seed dispersal follows a given dispersal kernel, which can be modified. Plants can have an individual genotype, which is related to dispersal traits. Also cloning plants like Cirsium dissectum can be modelled spatially explicit. The model is used in research projects on the effect of inbreeding and evolution on plant dispersal in fragmented landscapes.

Examples

Sensitivity analysis

Sensitivity analysis determines the size a population should have to reduce extinction probability to a standard, for example less than 5% in 100 year. Such populations are called MVP's: minimum viable populations. To find the number of individuals needed to meet this norm, the population dynamics is computed over 100 years and the survival is estimated. The sustainability norm for the bittern is 60 individuals or 30 pair, in a situation without immigration.

METAPHOR

Scenario study

A METAPHOR-analysis of several scenarios of opening areas for recreational use. The colours are occupation probabilities of habitat patches. Scenario A is the current situation. In scenario B recreation is limited to less vulnerable patches. In Scenario C the total area is closed for recreational use.

METAPHOR

Literature

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