NREC Online Lesson - Forest Sustainability

Glossary of Terms

Annual Allowable Cut (AAC) - The amount of timber that is permitted to be sustainably cut from a particular area. AAC is the basis that many provinces use to regulate levels to ensure a sustainable supply of timber.

Annual Ring - The pattern created by one year's growth on a cross-section of a tree trunk, formed by the bands of springwood and summerwood.

Biodiversity - The total variety of life on Earth, including the diversity of genes, species and ecosystems.

Cambium - A layer of growing cells with stems and roots of vascular plants that gives rise to phloem and xylem.

Clearcutting - The removal of all trees in an area when harvesting. A method of regenerating an even-aged stand.

Commercial Thinning - The thinning of stands of trees at a stage that will yield saleable products.

Deforestation - Clearing an area of forest for an alternative long-term use.

Ecosystem - A dynamic system of plants, animals and other organisms, together with the non-living components of the environment, functioning together.

Hardwood - Broad-leaved trees that usually shed annually (e.g. oak, poplar, birch and maple).

Heartwood - The dark-colored center of a tree's cross-section, consisting of blocked xylem cells.

Hectare - Equals 100 square meters of land.

Inner Bark - A layer of phloem cells outside the cambium which conducts nutrients from the leaves to the rest of the tree.

Natural Regeneration - The renewal of forest stands following a disturbance. Occurs from roots, stems or seeds that are already present or are brought by wind.

Outer Bark - A protective layer of non-living tissue which surrounds the stem of woody plants.

Phloem - The food-conducting vessels in leaves, stems and roots.

Pre-Commercial Thinning - The removal of some trees in young stands in order to provide more growing space, nutrients and light to the chosen remaining trees.

Protected Area - An area protected by legislation, regulation or land-use policy to control the level of human activity.

Reforestation - The re-establishment of trees by natural means or by planting or seeding.

Rotation - The period of years required to establish and grow trees to a specified size or condition for harvesting and regeneration. The period from harvest cut to harvest cut.

Sapwood - The lighter colored zone of a tree's cross-section consisting of living xylem cells.

Seed Tree Cut - A system of harvesting which almost all of the trees are removed from a stand, leaving only scattered individuals or groups of trees to provide seed for the next crop.

Selection Cut - The system of harvesting individual trees or groups of trees in a forest.

Shelterwood - A harvesting system which involves the removal of a large volume (about 50% of wood from a stand so that the remaining trees provide seed and shelter for a new crop of trees.

Silviculture - Managing the establishment, composition, growth and quality of forested areas. (includes planting/seeding, site rehabilitation and fertilization).

Softwood - Comes from cone-bearing trees with needles or scale-like leaves (e.g. pine, spruce and hemlock).

Springwood - The light colored phase of the annual ring, formed by the large cells used for root sap movement in the spring.

Strip Cut - A system of harvesting narrow parallel strips of a forest at regular intervals.

Succession - The progressive development of regeneration toward its highest ecological expression, the climax forest.

Summerwood - Small, tightly-packed cells produced by the cambium during the summer; the dark area of the annual ring.

Sustainable Forest Management - Management the maintains and enhances the long-term health of forest ecosystems for the benefit of all living things while providing environmental, economic, social and cultural opportunities for present and future generations

Sustainable Development - Development which meets the needs of the present without compromising the needs of future generations.

Sustained Yield - The harvest of forest products in such a manner that the product removed is approximately equal to the amount of new growth the forest produces.

Xylem - The woody supporting vessels of a root or stem that conducts water and dissolved minerals upward through the plant.