Lesson 3: Silviculture and Nursery Operations
Unit 4 - Forest Research: Past Application
Lesson 3: Silviculture and Nursery Operations
Des Crossley, CFS Researcher 1952
Alberta Forest Protection Collection
Silviculture is the art and science of growing a new forest in
areas where trees have been harvested.
In 1955, the North Western Pulp
and Power Company appointed Desmond Crossley to be their chief forester, who began establishing the forest management program.
Crossley, previously a research scientist with the Canadian Forest Service, brought with him a wealth of knowledge in the area of pine and spruce regeneration and was well known for his solid and innovative research.
In 1955, reforestation efforts in Alberta were largely left to
natural processes and often not successful. While working for the
Canadian Forest Service, Crossley had demonstrated that post-harvest
site preparation was key to natural reforestation in
the Alberta foothills, where forest fires were a fact of life.
He believed that if foresters could mimic the conditions left behind after a forest fire, reforestation would occur naturally without the need for seedlings.
One of these conditions involved soil preparation.
Forest fires burn
away leaves, needles, twigs, woody debris, and other organic matter from
the forest floor, exposing mineral soil. Crossley believed that mineral
soil should also be exposed after the
trees had been harvested. Crossley put these research findings
to practical application, using a process known as scarification. Using a
large tractor, harvested areas of the forest were disturbed using
front-mounted plows which dragged anchor
chains.
This method worked well to stimulate natural regeneration on most lodgepole pine sites, and is still used by forestry companies today.
Spruce trees, however, were more difficult to regenerate from seed.
Crossley's experiments showed that rodents ate spruce seeds, which
interfered with the establishment of the new forest.
To address this
problem, the Company began planting spruce seedlings
grown at a government nursery. In 1965, the Company built its own
nursery and greenhouse to ensure supply and quality of seedlings.
Initially, these seedlings were grown in a split plastic cylinder about 10 cm long. The seedling was then inserted into the ground, still inside the container. However seedlings did not do well because they were unable to break out of the container.
In response, the Company began working with the Canadian Forest Service
to find a solution. Relying on recent plant
physiology research conducted by the Canadian Forest Service, they
determined that larger containers, low nitrogen fertilizer, longer
nursery periods, and less watering during the final weeks in the nursery
would result in large, hardy seedlings which
could be removed from the container before planting.
The quest for a suitable container continued and two different disposable models were tested - a styrofoam container and a folding container. The folding container was subsequently adapted for the Company's purposes and put into use. It remained the container of choice until it was replaced by the styrofoam block model in the early 1990s.
