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 Cole (historian) Print". They divorced in 1983. Cole later married Christine Mullins. Cole's papers are held at the Simon Fraser University archives as the "Doug Cole fonds". Douglas Cole (historian) Douglas Lowell Cole (9 December 1938 – 18 August 1997) was an American-Canadian historian. Cole specialized in the art and culture of the Northwest Pacific Coast, and from 1966 until 1997 served as a professor in the history department at Simon Fraser University. Douglas Cole was born at Coulee Dam, Washington. His father was a construction worker and labor union activist. His mother taught elementary school. In 1960 Cole earned his bachelor's