Poplar
Poplar is a general name given to trees of the genus Populus, family Salicaceae, marked by simple, alternate leaves which are usually broader than those of the willow, the other American representative of this family. Poplars have scaly buds, bitter bark, flowers and fruit in catkins, and five angled pith. This fast growing group of trees has gained substantial attention among the biomass feedstock researchers, particularly in the United States. Its productivity can be up to eight times greater than native aspen (Populus tremuloi — des Michx.; Populus grandidentata L.). In fact, the aboveground productivity of nearly 9 Mgha-1 per year is common, and selection of genotypes adapted to site and climatic conditions has resulted in
|
Table 3.19 Chemical composition of populus nigra L (wt% on dry basis) [196].
|
nearly 2.5 times as much growth [194, 196]. Traits such as productivity and cold/drought tolerance are important factors in selecting poplar clones for fiber uses and environmental benefits. However, for the biochemical conversion, wood recalcitrance is important for evaluating processing energy and economics. Therefore, quantitatively evaluating genotypic recalcitrance and its effect on sugar and ethanol production is critical. Chemical composition of different poplar species can change in minor amounts; the composition of a common species, populus nigra L., is given in Table 3.19.