Figur 3
![](https://cdn1.cdnme.se/2434943/9-3/skarmbild_6_ny_56e95c1addf2b36395b94527.png)
Figure 3. The development of a 25-year-old plantation of h-poplar, OP42 (Populus trichocarpa × P. maximowiczii). The Plantation is located on farmland, on a clay loam, just outside Uppsala and is 1 ha in size. The length of the growing season is 185 days, temperature sum >5oC during the growing season is 1260 daydegrees, solar radiation during the growing season is 760 kWh/m2 (the whole year 970 kWh/m 2), the average annual precipitation during the growing season is 330 mm (535 mm). The area was planted with a design of 3 x 3 m and today it stands 660 stems per ha. The trees are now 30-32 m in height and the plantation is particularly worth seeing (Christersson 2011).