Note: The mid-seral stage, between early and mature, is not designated.

[a] Seral stages can be defined by the ages presented in this table or by stand-level attributes.

• The early seral column should be used for partially cut stands with less than 30% of natural stand volume.
• Younger stands or partially cut stands can be considered mature if they provide the important habitat attributes of a mature-aged stand (see Appendix 5).
• Older mature stands or partially cut stands can be considered old if they provide the important attributes of an old-aged stand (see Appendix 5).
• Silvicultural treatments may be used to accelerate the development of these attributes.
• Stand-level attributes and partial cutting prescriptions to meet mature and old seral stage objectives should be developed for each biogeoclimatic subzone or variant, based on natural stand characteristics, and approved by the resource agencies. Silvicultural systems should then be developed to create these attributes in young stands. Until these attributes and silvicultural systems are developed, managers can use the following approximation for partial cutting: A stand can meet the mature seral criteria if, after partial cutting, the residual stand volume and stand attributes (see Appendix 5) are greater than 70% of the natural stand (all original diameter classes are represented in proportion to the average stand profile for the subzone and variant).

[b] This represents an average value over large geographic areas for each NDT. Consequently, forests can be found that are older than the mean event interval, as the age definition of old seral sometimes specifies.
[c] Some portions of the CWH have a much more frequent disturbance history due to extensive windthrow. For those areas see the tables in NDT3.