Glossary (D-G)

Drying Defect
Any irregularity occurring in or on wood, as a result of drying, that may lower its strength, durability, or utility value. The following are some commonly encountered drying defects:
Bow
The longitudinal distortion, flatwise, from a straight line drawn end to end of lumber;
Casehardening
A term applied to dry lumber with nearly uniform moisture content but characterized by the presence of residual compressive stresses in the outer layer of cells (shell), and tensile stresses in the inner layer or core;
Check
A lengthwise separation of wood that extends along the wood grain. It develops during drying and is commonly caused by differences in radial and tangential shrinkage or because of uneven shrinkage of the tissues in adjacent portions of the wood;
Chemical Stain
A chemical discoloration of wood that is believed to be caused by the concentration and modification of extractives;
Collapse
The flattening of single cells or row of cells which occurs during drying of some species with very wet heartwood; it is often evidenced by a caved-in or corrugated appearance of the wood surface;
Cup
A distortion of a plank or board resulting in a troughlike shape with the edges remaining more or less parallel to each other;
Honeycomb
Internal splitting, often not visible at the wood surface, that develops during drying. It is caused by internal stresses or by the closing of surface checks;
Mineral Stain
An olive to greenish-black or brown discoloration believed to show regions of abnormal concentrations of mineral matter in some hardwoods. It is common in hard maple, hickory, and basswood. See also Mineral Streaks;
Shake
A separation along the the grain, the greater part of which may occur at the common boundary of two rings or within a growth ring. It is usually considered to have occurred in the standing tree or during felling;
Surface Checks
Checks that occur on the wood surface during seasoning; they may extend to varying depths into the wood;
Twist
A distortion caused by the turning or winding of the edges of a board so that one corner is no more in the same plane as the other three;
Warp
Any variation from the true or plane surface in a piece of wood that may occur during seasoning. It includes bow, crook, cup, and twist, or any combination thereof.

Extinct Rating
Species that are currently known to be out of existence in the wild after repeated attempts to locate them in their natural habitats or other known or likely habitats have failed.
Endangered Rating
Species whose extinction is imminent if the factors which are currently threatening their survival persist. This category include species whose numbers have been diminished to critical levels or whose natural habitats have been so reduced that they are deemed in immediate danger of extinction.Vulnerable Rating
Species that will definitely move into the Endangered category if the conditions which caused their Vulnerability continue. Included in the Vulnerable category are species whose numbers are decreasing because of over-exploitation, extensive habitat destruction or other environmental disturbances, species whose long term security is uncertain because their numbers have been seriously reduced, and species which currently exist in large numbers but are threatened by serious destructive factors throughout their natural habitat.
Rare Rating
Species which naturally occur in small numbers and which are currently not Endangered or Vulnerable but are at risk. Such species are usually confined to small habitats or are scattered in very small numbers over a wide area.
Indeterminate Rating
Species that are known (after officially assessing its environmental status) to be Extinct, Endangered, Vulnerable, or Rare but which cannot be placed in a single class because of incomplete of information.
‘Insufficiently Known’ Rating
Species that are suspected but are not definetely known to be Extinct, Endangered, Vulnerable, or Rare. The specific category cannot be determined, even after environmental assessment, due to inadequate information.
Candidate Rating
Species whose environmental status is being assessed, and which is suspected to be Extinct, Endangered, Vulnerable, or Rare. The actual conservation category has not been definitely determined.
‘Out of Danger’ Rating
Species which used to belong to one of the above classes but which have now deen determined to be relatively secure because of effective conservation measures, or because of the removal of previously existing conditions that threatened their survival.
‘Not Threatened’ Rating
Species that do not belong to any of the above conservation categories.
No Information
Species for which there is no information regarding their current conservation status.