Biodiversity: A shortening of the term "biological diversity." The diversity of life on Earth. The variability among living organisms and their interactions, both within species and between species, between ecosystems and across landscapes.

Carbon dioxide (CO2): A colorless, odorless, non-combustible gas, present in low concentrations in the air we breathe (about three hundredths of one percent by volume). Carbon dioxide is produced when any substance containing carbon is burned. It is also a product of breathing and fermentation. Plants absorb carbon dioxide through photosynthesis.

CO2 emissions: Carbon dioxide emissions, which increase the concentration of this gas in the Earth’s atmosphere. CO2 has become the most common greenhouse gas, contributing to global warming. Major sources of CO2 emissions include the burning of fossil fuels for energy and transportation, and the destruction of forests. Numerous studies have shown that human activity has contributed to increased atmospheric CO2. Prior to the start of the Industrial Revolution, atmospheric CO2 concentrations were about 280 parts per million by volume (ppmv). Current levels are about 370 ppmv.

Carbon emission reduction credit (or "offset"): The definition varies in the absence of an organized carbon market, but we use it to mean a metric ton of carbon permanently removed from the atmosphere or permanently prevented from entering the atmosphere. Forest carbon credits reflect the prevention of forest CO2 emissions and the increase in carbon storage through the conservation and good management of forests.

Carbon sequestration: The ability of forests or other natural systems to "sink" or store carbon, thereby preventing it from collecting in the atmosphere as CO2. Forests absorb carbon when they break down CO2 during photosynthesis.

Carbon sink: A carbon pool, such as a well-managed, older forest, which has more carbon flowing into it than flows out. Forests are the best sinks because they are the most efficient means of taking carbon out of the atmosphere and storing it for the long term.

Carbon source: The opposite of a carbon sink. Natural systems and technologies both can be sources of CO2. For instance, a natural carbon pool that is being depleted can become a net source, such as a forest that is excessively harvested or lost altogether to development. Industrial facilities burning fossil fuels are major technological sources.

Carbon transaction: An exchange involving the transfer of carbon credits (including buying, selling and trading) between carbon-emitting entities and carbon-reducing entities. Forest owners committed to increasing the amount of carbon sequestered in their forests can provide credits to companies seeking to offset their own carbon dioxide emissions.

Conference of the Parties: The conference is the decision-making group of representatives from nations that signed the United Nations Framework Convention on Climate Change. This group meets annually to further the convention’s objectives.

Conifers: Trees belonging to the order Gymnospermae, comprising a wide range of trees that are mostly evergreens. Conifers bear cones and have needle-shaped or scalelike leaves. In the wood products industry the term "softwoods" refers to the conifers.

Conservation easement: A restriction deeded to a qualified third party that permanently limits certain activities on real property, in order to protect conservation values such as biodiversity, water quality, wildlife habitat or carbon sequestration. The restriction stays with the property through successive owners. The restriction reduces the "highest and best" economic use of the property so that the property’s value reflects only the allowed uses. If the landowner donates the easement as a gift, this reduction in value becomes a charitable tax deduction. An easement also can be sold to non-profit or government agencies to provide revenue.

Conversion: The permanent clearing of forestland for a non-forest use, such as residential development.

Ecosystem: The interacting system of a biological community and its nonliving environmental surroundings.

Forest: A biological community of plants and animals that is dominated by trees and other woody plants.

Forestland: Land that can support at least 10 percent native tree cover under natural conditions. Forestland may include areas of grassland, shrubland, wetland, or other land classes. Forest carbon: The carbon stored in a forest, including living and dead tissues: tree trunks, branches and foliage as well as soils, litter, understory plants and woody debris.

Forest Stewardship Council: An independent non-profit organization founded in 1993 that supports environmentally appropriate, socially beneficial and economically viable management of the world's forests. FSC promotes responsible forest management by evaluating and accrediting certifiers, who in turn certify the sustainability of managed forests on behalf of the council.

Forest certification: A determination by an FSC certifier that a forest is responsibly managed. The certification is reflected in an FSC label found on wood products from such forests. The FSC system verifies claims from the forest all the way to the final product with "chain of custody" monitoring.

Global warming: The steady, documented rise in the Earth’s average surface temperature over the last century. The trend is largely attributable to the increased accumulation of greenhouse gases in the atmosphere. Climate change believed to be linked to global warming (e.g., more frequent droughts, new hurricane patterns, melting of glaciers) is already occurring in some regions of the globe.

Grantor: The land owner who conveys a conservation easement to the recipient organization.

Grantee: The organization receiving or being granted the conservation easement.

Greenhouse gases: Heat-trapping gases that are increasingly present in the Earth’s atmosphere, creating a warming of the planet. Carbon dioxide (CO2) is the main greenhouse gas but others include methane (CH4), nitrous oxide (N2O), hydrofluorcarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6). Water vapor also is an important greenhouse gas.

Industrial forestland: Forestland owned by a company that also has sawmills or other wood-processing facilities.

Kyoto Protocol: An international agreement reached in Kyoto at the Third Conference of the Parties to the U. N. Framework Convention on Climate Change (COP 3) in 1997. The Protocol established specific targets and timetables for reductions in greenhouse gas emissions to be achieved by the framework’s signatories. The United States and 83 other countries now have signed the Protocol; many countries, including the U.S., have yet to ratify it.

Land trust: A non-profit, non-governmental charitable organization that helps interested landowners and communities find ways to protect their land from over-development so it can continue to provide open space, habitat, clean water, scenic beauty and other values of public benefit.

Non-industrial forestland: Forestland owned by an entity that does also own sawmills or other wood-processing facilities.

Stewardship Forestry: Managing forests to provide the full range of forest goods and services, including biodiversity, wildlife habitat, carbon sequestration, water quality, and commercial timber and non-timber products. Stewardship Forestry works with natural processes and structures, native species composition, and mixed age classes of trees (including old trees) to provide public and private benefits.

Sustainable Forestry: Forest management practices that provide goods and services from a forest ecosystem without degradation of the site quality, and without a decline in the yield of goods and services over time. Similar to "stewardship forestry."

United Nations Framework Convention on Climate Change: An international agreement reached in 1992, now signed by more than 175 countries, that aims to stabilize anthropogenic greenhouse gas emissions to the atmosphere at levels that will prevent dangerous interference with the Earth’s climate. The convention called for annual meetings of its Conference of the Parties, which led to later, more specific agreements, such as the Kyoto Protocol.