Durability and ease of preservation
The American Lumber Standard Committee (ALSC) oversees accreditation and standards for grading lumber. Several agencies accredited by the ALSC publish gradng rules. The "treatability" of lumber by wood preservatives is determined by the porosity of the lumber: highly porous lumber is more treatable than relatively less porous varieties. Note that sapwood has different characteristics to heartwood, and is discounted—except for certain lumbers, which are predominantly sapwood and therefore not durable.
Lumbers can change and deteriorate for a various reasons, some which can be addressed by lumber selection at felling or in the mill, and some of which need to be addressed in construction:
To protect lumber from ...