Land Cover and Road Network Map for the Monarch Butterfly Biosphere Reserve in Mexico, 2003

Abstract

To preserve the monarch butterfly (Danaus plexippus L.) overwintering sites in Mexico, the fir forests used for the main colonies have been protected by three presidential decrees, in 1980, 1986 and 2000. The territory of the current Monarch Butterfly Biosphere Reserve (MBBR) belongs mainly to communal properties (ejidos and indigenous communities). Contrary to expectation, this protected area is still facing severe disturbance and loss of forest cover, because of intensive illegal and legal logging, and subsistence farming activities. Roads are landscape elements well known as a cause of disturbance and deforestation. Therefore, the aim of this map is to illustrate the road network and land cover relationship in the MBBR, taking into account the land tenure. The roads vector layer was obtained by photointerpretation of one meter resolution digital aerial photograph mosaics from March 2003, and one meter resolution Ikonos pansharpened images from March 2004, as well as field work, using GPS georeferenced tracks. Land cover polygons were constructed by visual interpretation of January 2003 Landsat ETM+ color composites, simultaneously verified with the aerial photograph mosaics. The final 1:75000 map shows very high human pressures over the reserve forests. This is expressed by a high density road network, composed mainly of tertiary roads opened to wood extraction, in many cases illegally, and incompatible with the protection category of these forests.