An effective scheme for species grouping needs to meet the needs of silviculture and forest management. Simple commercial groups are not adequate for this purpose. A scheme which applies the following criteria based on tree size and ecology, wood density and durability, and commercial status will distinguish species sufficiently for practical management and planning. The following is an example of a classification and coding system.
| Economic status | Tree size | Timber type |
|
1 High-value timber 2 Low-value timber 3 Non-economic |
A Emergent, large trees C Upper canopy trees L Lower canopy trees U Understorey trees X Pioneer species |
d Hard, dense, durable h Medium hard, durable m Medium density, non-durable s Soft, non-durable v Very soft, low density |
Thus a code such as 2Ah indicates a species that typically occurs as a large emergent, has moderately dense, durable timber, and is marginally economic in the market. The code letters and numbers in this scheme have been arranged so that they will sort into a natural order. It is generally better to have the economic code first, as this will give best results in the MYRLIN tables.