THE HUMAN FOOTPRINT AND THE LAST OF THE WILD 
Thus begins (and not a precedent the Biblical quotation) article entitled "The Human Footprint and the Last of the Wild" (
Sanderson et al. 2002). According to this post (I'd like to see the faces of the referees) good (and bad news) is that we have been successful, very successful, taking us home to Earth. Every house, every culture, every road, every "thing" to build or play is a part of the human footprint on the planet. But not all those "things" have the same intensity. That intensity can be measured as an area of \u200b\u200binfluence (noise impact distance of a motorway) as a degree of reversibility (ability to regenerate the natural habitat terminated the life of the "thing"), or as a degree of naturalization (not is the same as a wood stocked a natural forest).
Following this idea, the authors of this article
worldwide have mapped the human footprint on the territory , as shown in the following image (black and red = high value trace; oranges and yellow = lowest value of trace).
is a simple but powerful concept, designed to measure the degree of human impact in the territory with a single map, and also to calculate operations are simple, but require a lot of information, it is sometimes difficult to achieve. Sanderson
et al. four types of data used to generate this map: population density, type of land use, accessibility and energy infrastructure.
to population density, these authors assume that the human footprint increases linearly from 0 to 9 to 10 persons/km2, and from there any value equals 10.
land uses fingerprint value 10 are human constructions of any kind. The values \u200b\u200b8, 7 and 6 are reserved for different types of crops, while lower values \u200b\u200bare assigned to mixed use little anthropogenic.
To measure the accessibility of the territory generate buffers at different distances on roads, rivers, coastlines, giving low values \u200b\u200bof trace to these areas of influence.
As an indicator of energy infrastructure using visible lights at night from satellite images, assigning values \u200b\u200bfootprint as the percentage of days per year that remain lit in different regions. Finally add
different factors for human footprint index.
lowest values \u200b\u200bin this map are "the last of the wild", or areas less influenced by man.
The main applications of this map revolve around the selection of reserves according to the human footprint. Where the human footprint is low, it may raise more ambitious conservation goals in those places with high mark.
A fundamental problem of this map is the relevance of the data. All baseline information comes from large data sets that take several years to be drawn up, so that errors may occur local consideration. Another problem is the scale (1 km), slightly more coarse than that used for the design of conservation plans.
Another highly recommended article on the same topic is "rescaling the Human Footprint: A tool for conservation planning at an ecoregional scale" (
Woolmer et al. 2008), which is improved by increasing human footprint map resolution (90 m). The change of decision involves the use of better data, and some changes in methodology. For my taste, this second article is more complete in terms of methodology.
And this is the go scour in which my students now master, creating a human footprint map of Andalusia. I will tell you the result of student work, and I will provide the data and code necessary to calculate GRASS yourselves.
That's all!
PS: Thanks to my mate Ricardo Moreno iEcolab Llorca for introducing me to this interesting topic.
