[Marxan] Liberia Conservation Prioritization

Jessica Junker jessica_junker at eva.mpg.de
Wed Dec 11 01:27:05 EST 2013

Dear all Marxan users

I am new to the group and have a few conceptual questions regarding Marxan.

I would like to prioritize areas for future conservation across Liberia. My
planning units are 1.8*1.8 square km pixels, of which Liberia includes
approximately 29000. Rather than using individual species-distributions, I have
for each pixel modelled nationwide data on chimpanzee abundance, large mammal
species richness and tree species richness (all based on transect data from a
nationwide survey), which I would like to include as conservation feature types.
For each of these I was going to set minimum targets of 30% of the total of all
pixels in Liberia. If the algorithm is able to meet these targets under the
conditions I specify, including some amount of spatial clumping and management
costs, I will try and maximize these targets within the predefined spatial
limits ( i.e. the local authority in Liberia is willing to protect 30% of
Liberia's remaining forest cover).

Additionally, I would like to include positive costs into my conservation
features, namely altutude and slope. Here, I argue that high altitude areas,
which have more slope, are more difficult to logg and thus cheaper to purchase
for conservation purposes. Here my target would be all areas above 500 meters
have low cost and those below 500m have high cost. So my conservation target
would be >500. How can I specify this in my file?

As costs, if have three different categories, which, if I understand the program
correctly, I need to combine as one somehow. These are my costs:
1) snare abundance - a proxy for hunting (unit=number of snares per pixel/
planning unit)
2) empty gunshell abundance - a proxy for hunting (unit=number of empty
gunshells per pixel/ planning unit)
The above two costs are easy to combine as they are measured in the same units
3) Locations of mineral deposits ranked 0-3 (0=no mineral deposit, 1-3=
occurrence of least to most precious mineral deposit). I include this as a
measure of potential future threat, as precious minerals attract illegal miners.

I also include all observations of threatened mammal species (GPS locations)
buffered by their mean home range size into the conservation area network (i.e.
I include all existing protected areas into the conservation area network (i.e.
I exclude all main roads buffered by 2 km on each side from the conservation
area network (i.e. status=3).

My questions are:
1) Seeing that I don't have the usual conservation feature types, such as
individual species distributions or habitat types, do you think Marxan is the
appropriate program to use?

2) Can I try and maximize my conservation feature targets by experimentation as
described in my first paragraph? Is this legitimate?

3) I would like to make my map pixels for which I have values for chimp
abundance, species richness, etc. my planning units. These exist in a raster
format only and I do not know how to convert these into a shapefile format so
that each pixel constitutes one polygon (this doesn't seem to be possible in
ArcMap). And if I am not mistaken, for the planning unit file, I need my units
in the shapefile format?!

4) How can I combine my cost layers and what values should I give them?

5) What will the program do if I have areas that have both status 2 and 3 (e.g.
areas within the home range of threatenend species of which we have observation
records, which are at the same time within the 2km buffer of a road)? Would it
be better then to include roads and surrounds in the cost layer as well? If yes,
how would I be able to combine this information with the other cost layers?

6) In addition to the above mentioned rules, I would also like to prioritize
pixels that are close to protected areas in neighboring countries. Do I need to
pre-select potential pixels close to these areas and include them in the
boundary length file somehow? The conservation areas in the neighboring
countries are actually outside my target area (i.e. they are not part of my
planning units!). Is there any way I can do this?

Sorry for all these questions - I would be grateful for your input and ideas on
Thank you so much for the advice.


Jessica Junker
jessica_junker at eva.mpg.de
PhD candidate
Max-Planck Institute for Evolutionary Anthropology
Department Primatology
Deutscher Platz 6
04103 Leipzig, Germany
Phone: +49 (0)341 3550 805
Cell: +49 (0)160 905 94996

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