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Posts tagged ‘Optimisation’

Jan 20

Fast and accurate MARXAN: the return of the ILP (Integer Linear Programming)

In Beyer et al (Ecological Modelling, 2016), Yann and co-authors propose an efficient integer linear program (ILP)  to solve conservation planning problems for MARXAN and MARXAN with zones.

Because conservation planning problems are not linear, an accurate linearization was required to get an efficient ILP model, i.e. running in a good computing time. Yann’s contribution was to propose an efficient linearization, and to clarify the advantages of using ILP compared to the current heuristic used in MARXAN (simulated annealing). ILP is an exact method so it always provides optimal solutions. Moreover, ILP allows to easily integrate multiple objectives and to deal with unknown instances by using robust approaches.

In conservation, ILP has been avoided for the past decades because of long computational running times. However, recent versions of linear programming software solutions include new algorithms such as new branch-and-cuts / dynamic search processes, reducing the computation time required to solve ILP problems by millions compared to the first versions.

The results are impressive and you should definitely have a look if your conservation planning problem takes too long to solve or you are uncertain about the quality of the solutions! Congratulations Yann and team!

Hawthorne L. Beyer, Yann Dujardin, Matthew E. Watts, Hugh P. Possingham, Solving conservation planning problems with integer linear programming, Ecological Modelling, Volume 328, 24 May 2016, Pages 14-22, ISSN 0304-3800, http://dx.doi.org/10.1016/j.ecolmodel.2016.02.005.

 

Aug 24

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UPDATE: Getting our priority right: 9 publications on Priority Threat Management

Perhaps the most impactful decision support tool we have developed to date, Priority Threat Management (PTM) is a team adventure where a dedicated bunch of interdisciplinary scientists and kick ass facilitator work alongside stakeholders to establish the best strategies to manage threats to biodiversity. Stay tuned as we have grand plans to improve PTM and make it available to the entire world.

I was asked to provide a list of reference on priority threat management, sharing it with you here:

Freely accessible material:

  1. Ponce Reyes, R., Firn, J., Nicol, S., Chadès, I., Stratford, D.S., Martin, T.G., Whitten, S., Carwardine, J. (2016) Priority Threat
    Management for Imperilled Species of the Queensland Brigalow Belt CSIRO, Brisbane. (PDF) (see The Conversation article, CSIRO website)
  2. Firn, J., Maggini, R., Chadès, I., Nicol, S., Walters, B., Reeson, A., Martin, T. G., Possingham, H. P., Pichancourt, J.-B., Ponce-Reyes, R. and Carwardine, J. (2015), Priority threat management of invasive animals to protect biodiversity: Lake Eyre Basin ( see the Conversation article, CSIRO website with PDFs)
  3. Carwardine J., Nicol S., van Leeuwen S.,Walters B., Firn J., Reeson A., Martin T.G., Chades I. (2014) Priority threat management for Pilbara species of conservation significance, CSIRO Ecosystems Sciences, Brisbane. (PDF) (see The Conversation article, blog post, CSIRO website)
  4. Firn, J., Martin, T.G., Walters, B., Hayes, J.,Nicol, S., Chadès, I., and Carwardine, J. (2013) Priority Threat Management of invasive plants species in the Lake Eyre Basin. CSIRO Climate Adaptation Flagship Working Paper No. 17 (QUT and CSIRO) (PDF) (blog post)
  5. Carwardine, J., O’Connor, T., Legge, S., Mackey, B., Possingham, H.P., Martin, T.G. (2011) Priority threat management to protect Kimberley wildlife CSIRO Ecosystem Sciences, Brisbane. (PDF)

CapturePTMLakeEyre (Medium)

Journal paper (PDF available upon request):

  1. Firn, J., Maggini, R., Chadès, I., Nicol, S., Walters, B., Reeson, A., Martin, T. G., Possingham, H. P., Pichancourt, J.-B., Ponce-Reyes, R. and Carwardine, J. (2015), Priority threat management of invasive animals to protect biodiversity under climate change. Global Change Biology. doi: 10.1111/gcb.13034
  2. Firn, J., Martin, T. G., Chadès, I., Walters, B., Hayes, J., Nicol, S., Carwardine, J. (2015), Priority threat management of non-native plants to maintain ecosystem integrity across heterogeneous landscapes. Journal of Applied Ecology. doi: 10.1111/1365-2664.12500
  3. Chadés, I., Nicol, S., van Leeuwen, S., Walters, B., Firn, J., Reeson, A., Martin, T. G.  and Carwardine, J. (2015), Benefits of integrating complementarity into priority threat management. Conservation Biology, 29: 525–536. doi: 10.1111/cobi.12413
  4. Carwardine, J., O’Connor, T., Legge, S., Mackey, B., Possingham, H.P., Martin, T.G. (2012). Prioritizing threat management for biodiversity conservation. Conservation Letters. 5:196–204 doi: 10.1111/j.1755-263X.2012.00228.x
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