Task Force Population Dynamics

Why study population dynamics?

Ambrosia life cycle

Ambrosia life cycle

The new, sustainable strategies that SMARTER develops to control common ragweed in Europe should reduce the population growth in the long term (e.g. decades). To be able to assess, and compare, the potential of different management options for such long-term control under local conditions, a better understanding of the population dynamics of common ragweed is required. Currently, this knowledge is lacking.

How to assess population dynamics? A modelling approach

Measuring plants in the field

Measuring plants in the field

The Task Force will collect empirical data from field populations of common ragweed in different habitats, regions and climates throughout Europe, over several years. We measure essential vital rates such as seedling establishment, seedling survival, plant growth, reproduction, and seed survival, and study how they relate to plant density and individual size. We will then use these data as ‘building blocks’ to construct a population dynamics model that describes the natural spatio-temporal variation in the demography of ragweed in Europe.

What will this model bring?

Population growth rates

Population growth rates

The population dynamics model will project the growth of ragweed populations under different European conditions. By then integrating empirical data from experiments on ragweed management, the model can be used to compare how the growth of populations will be changed by different management regimes. This innovative tool will thus help to develop region- and habitat-specific best practice manuals for the integrated management of ragweed, one of the main aims of SMARTER.

Research questions

picture vital rates common ragweedHow does the demography of common ragweed populations vary naturally across European climates and habitats?

  1. Which vital rates contribute most to population growth?
  2. Which environmental factors cause most variation in population growth?


  1. Conduct a field survey to collect data on the spatio-temporal variation in the demography of natural, unmanaged common ragweed populations across Europe.
  2. Use these data to develop an integrated projection model of the population dynamics of common ragweed in Europe.

About 20 researchers from over 15 countries participate in this population dynamics survey, that runs from 2014 to 2016. The map shows the populations being monitored. The participants exchange experiences through a forum. A team of demographic modellers processes the data.

pop dyn overview pops May 2014


???????????????????????????????Suzanne Lommen, coordinator
University of Fribourg, Switzerland

Personal webpage at University of Fribourg

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