Aromatic agrobiodiversity was in the news and the peer-reviewed literature today. Rosemary (Rosmarinus officinalis) got a good write-up in ScienceDaily. It turns out that one of chemicals found in its spiky leaves — carnosic acid — can protect the brain from free radicals, but is only activated by the damage caused by these compounds. Otherwise it just sits there doing nothing, which is what you want in a drug. Anyway, there are lots of different varieties of rosemary, and different levels of carnosic acid among them. There are also wild populations in the Mediterranean, as of other herbs as well, and people who make a living harvesting them from the garrigue. That can sometimes be overdone, resulting in damage to the plants, and to the environment, due to increased soil erosion when it rains. So a study from Spain just published in the journal Catena is welcome. It quantified how much harvesting of various aromatic shrubs (lavender, oregano, sage and santolina) you can do before the soil starts to suffer. The recommendation is to leave 50% of the plant biomass in the field.