Current annual growth:

Current annual growth is the plant tissue produced in the current year, exclusive of radial growth of older stems in shrubs and below-ground growth of all plants.  For herbaceous plants, it is the total above-ground biomass.  For shrubs and trees, it is the current year’s twigs and leaves.  Current annual growth is almost always of much higher nutritional quality than is older growth (dead, previous year’s herbaceous material and older shrub or tree stems); in fact, the older growth is usually of such low nutritional quality that we do not consider it “food.”  However, the user can choose to include whatever they wish to include as food.  For example, if you want to include old stems, then include them, but be sure to measure their nutritional quality separately from current year’s twigs.

            Notice that we analyze shrub twigs separately from shrub leaves.  In other words, we treat them as different foods, or forages, even though they are the same plant species.  We do that because the nutritional quality of twigs is very different from that of leaves.  The choice of what constitutes a separate food, or forage, is entirely up to the user.  The important factor is that whatever the user’s choice for “forage,” the biomass and nutritional measures must be made accordingly.