The Koiwainojo complex is located in Shizukuishi city, west of Morioka in Iwate Prefecture (39˚ 46' 11" N; 141˚ 00' 10" E). The forest plantation is formed of larch (Larix kaempferi) and red pine (Pinus densiflora). The uniqueness of this plantation is that they have been planted chronosequentaly in plots of 1000 m2 from 1964 to 2020 for larch trees and from 1964 to 2010 for red pine trees. In this forest, we can observe the growth of trees from saplings to mature trees for two common species in Iwate Prefecture. Even at the same age red pine grows much bigger and taller than larch trees.  With the use of UAVs, it has been possible to observe very clearly the number of trees and consequently the tree density in each plot, the tree height, single tree canopy area and ultimately tree biomass. This is possible because of the change of needles color in late autumn and finally their shedding, which allows the observation of each of the thousand of trees (stems). However, this is not possible for red pine trees, which keep their needles in winter.  For this last tree species, we have been able to observe that because of partial shedding of leaves in autumn, it is possible to roughly distinguish one tree from each other. The collection of pictures in different seasons offers the possibility to extract different type of data. As shown in the right picture, in winter it is possible to see individual stems of larch trees.