Harvest rangers were people employed by Androzani Major to harvest trees. They wore yellow armour and used Androzani harvesters to travel. Their sensors could detect weaponry, but confused them with natural fibres.
In 5345, three harvest rangers (Droxil, Billis and Ven-Garr) were sent to harvest a living forest. They helped set up the satellites to spray acid on them to convert them to fuel. They encountered Madge Arwell, who had come to the planet while searching for her children. She fooled them and got into their Harvester, but the harvest rangers were teleported out before the acid rain started. (TV: The Doctor, the Widow and the Wardrobe)