Christmas tree cultivation has shifted toward the production of higher-quality trees, increasing land quality expectations as well. Indeed, some species of tree, such as the Fraser fir, are unable to grow on low-quality, marginal farmland. Flat or gently rolling land is preferred to that with steep slopes and inclines, which is prone to erosion and fluctuations in fertility. Noticeable obstructions, such as rocks, fences or significant underbrush, are also undesirable. Like all crops and plants, Christmas trees require a specific set of nutrients to thrive. There are 16 elements crucial for growth; of those, three are obtained through air and water: hydrogen, carbon,
Douglas (surname) form of the given name is "Dùbhghlas"; the Irish language form it is "Dúghlas", and "Dubhghlas", which are pronounced . According to George Fraser Black, in southern Argyllshire the surname is an Anglicised form of the surnames "MacLucas", "MacLugash" (which are derived from the Gaelic "Mac Lùcais"). ---- ^ Mark Douglas professor of Christian ethics at Columbia Theological Seminary Field Marshal Robert Douglas was firstly created baron, and then count, in Sweden. His main fief was the town of Skänninge, and his wife brought in the estate where they had the manor of Stjernorp erected. His descendants generally continued to