The recommended number of trees to plant per hectare varies depending upon the objectives of the landowner. In general, the number planted per hectare in Europe is higher than in New Zealand and the United States. Due to tradition, pines in Europe may be planted at 2500/ha and in the southern United States the number may be 1000-1400/ha; in New Zealand, the number may be 800-1000/ha [8]. When the delivered cost of pine logs is the same (per green tonne) for pulpwood and for fuelwood, then the economically optimum planting density (for a given species, location and discount rate) should be nearly the same.

When researchers establish a bioenergy pine plantation, they often plant more seedlings than would be recommended by an economic analysis. In one short-rotation experiment in Florida, Pinus clausa was planted at 26 900 seedlings per hectare [9]. Two factors that are often ignored are the cost of establishment and the cost of harvesting. In the southern United States, the cost of harvesting and transporting one tonne of pulpwood to a mill is about two-thirds the price paid at the mill. For example, a pulp mill might purchase green wood for $42 per Mg ($14 to the landowner, $10 for harvesting, and another $14 for transportation). Much of the time in harvesting is spent handling and processing each tree, so tree size is an important determinant in harvesting cost (Figure 10.1). For some planting densities, harvesting one green tonne might require less than 5.5 trees while planting 3000/ha may require cutting twice that many (Table 10.3). In many cases, the target planting density is selected without considering the economic impact of both establishment and harvesting costs.