An essay written by Dr. Martha Groom and colleagues from the University of Washington, presents some guidelines related to assessing and certifying biodiversity-friendly feedstocks: (1) biofuel crop cultivation must use environmentally safe and biodiversity-friendly agricultural practices, (2) “the ecological footprint of a biofuel, in terms of the land area needed to grow sufficient quantities of the feedstock, should be minimized”, and (3) high priority should be given to biofuels which have net negative or zero carbon balance, when “viewed over the entire production life cycle”. Corn as feedstock for bioethanol is said to be one of the most “environmentally damaging” among current biofuel feedstocks. The use of algae and fast growing trees as biofuel sources are seen to have more fuel yield per acre, compared to other currently used feedstocks. The paper is published in the journal, “Conservation Biology” (URL above)..