"Natural Resource Economics" or just "Resource Economics"

Hi. I have been searching on the Internet the right expression, but I am not sure yet. I need to translate "Economía Ambiental y de Recursos Humanos". I found "Environmental and Natural Resource Economics" and "Environmental and Resource Economics", both in the site of reliable organizations. I would like to know what is the best expression in this case. The second expression, just "Resource Economics" without "Natural" is not my favorite, I feel that "Natural" is required, however, I saw it in many sites, for instance: http://www.eaere.org/ and http://enviro.colorado.edu/Ws/ .

Thanks for your help.


Hellen