How do you design a nature reserve that most effectively protects biodiversity given limited resources? Complex natural resource management problems can have millions of potential solutions- how do you choose one that meets all of your goals?




Marxan provides decision support to a range of conservation planning problems, including:

  • the design of new reserve systems
  • reporting on the performance of existing reserve systems
  • developing multiple-use zoning plans for natural resource management
  • What makes Marxan the most widely used conservation planning software in the world?

These features provide users with decision support to achieve an efficient allocation of resources across a range of different uses.

What you can do with Marxan:

  • Identify areas that efficiently meet targets for a range of biodiversity features for minimal cost
  • Use the principle of complementarity to select planning units which complement the conservation area network (the whole is more than the sum of its parts);
  • Meet spatial requirements such as compactness of a reserve system;
  • Include data on ecological processes, threats, and condition;
  • Identify tradeoffs between conservation and socio-economic objectives; and
  • Generate a number of very good solutions.

How has Marxan been used?

Marxan is the most widely used conservation planning tool supporting the design of marine and terrestrial reserves worldwide and is used by more than 1300 users in over 100 countries worldwide. Marxan software has contributed to several major conservation projects: it underpinned the rezoning of the Great Barrier Reef Marine Park in Australia and informed the design of marine protected areas for the Channel Islands in California. You can read more examples of Marxan's use HERE.

Marxan can assist with the evaluation of existing reserve systems to identify gaps in biodiversity protection, identify areas to include in new reserve systems, and provide decision support by producing a number of different options that meet both socio-economic and conservation objectives. Marxan has also been used to support multiple-use zoning plans that balance the varied interests of stakeholders. 

Why use systematic conservation planning tools like Marxan?

The practice of conservation planning has generally not been systematic and new reserves have often been located in places that do not contribute to the representation of biodiversity. Decisions about both on- and off- reserve conservation (if they are not to be ad hoc) should be guided by explicit goals, an understanding of current and future threats and priorities, and provide clear choices between alternative forms of management. Marxan incorporates best scientific information and makes the costs and benefits of alternative decisions clear, leading to more informed decision making. In addition, having multiple solutions to choose from helps in stakeholder driven decision making processes.

Is Marxan data hungry?

How much time you choose to invest in acquiring data can be highly variable and will largely depend on whether you are risk adverse to uncertainty or biases in your dataset. Marxan includes or excludes planning units in a conservation network based on information about the distribution of conservation features across your planning region. Marxan does not consider uncertainty in the data so the quality of what you put in is reflected in the results generated.

Marxan is the most widely used conservation planning tool in the world and is used by more than 1300 users in over 100 countries worldwide.  The software has contributed to several major conservation projects; it underpinned the rezoning of the Great Barrier Reef Marine Park in Australia and informed the design of marine protected areas for the Channel Islands in California.

How was Marxan developed?

The software is primarily a product of Ian Ball's PhD thesis (Ball 2000) that was supervised by and funded through Professor Hugh Possingham. In the initial stages, it was called SPEXAN, a combination of the words Spatially Explicit Annealing. At that time, the most substantial funding was from Environment Australia (EA). We owe much to Andrew Taplin for this initial support. An early version of SPEXAN is the site selection algorithm used within the Environment Australia planning software, REST.

The Nature Conservancy (TNC) funded, through UC Santa Barbara, a project where Ian Ball integrated SPEXAN in to ARCVIEW ( Sandy Andelman, Frank Davis and David Stoms wrote a very useful tutorial for this new tool that is now extensively used by TNC. The version of SPEXAN that underpins Sites is now somewhat dated and recent discussions with TNC will hopefully yield an upgraded tool.

Marxan was developed as a modified version of SPEXAN to meet the needs of the Great Barrier Reef Marine Planning Authority (GBRMPA) in their 2003-2004 rezoning plans. GBRMPA provided partial support for the modification. Marxan also was used by Adam Lewis and Suzanne Slegers to provide decision support for the GBR representative areas program. Along with the TNC ecoregional planning processes, these represent some of the largest applications of Marxan/SPEXAN.

The US National Marine Fisheries Service (NMFS) have funded us to advance Marxan further and provide technical advice on its application to Salmon recovery planning. Mary Ruckelshaus heads this project. (

The National Centre for Ecological Analysis and Synthesis (NCEAS) has played host during development and sharing of this software. We are grateful to NCEAS for some funding and substantial inkind support.

Marxan software is FREE

... download or join in the Cloud HERE

Marxan is flexible

... it can be applied to a wide range of problems such as reserve design and natural resource management in terrestrial, freshwater, and marine systems.

Marxan is efficient & repeatable

... providing many good solutions to complex problems and encouraging stakeholder participation.