TWO FOREST ARBORETUMS NEAR BRUSSELS. 3 



When in the larger of the two arboretums, I was so fortunate 

 as to meet M. Drion of Brussels, who, most kindly, has looked 

 through my MS., checked a number of the measurements, and 

 given me notes regarding the growth of various trees in Belgium 

 which are incorporated here. The diameters are measured, at 

 5 feet above the ground, to the nearest inch ; the heights are 

 estimated. In a few of the plots there may be a little loss of 

 growth from a too long deferred thinning in the case of certain 

 light-demanding species, but this is rare. There is also lost 

 growth in a few cases with species that have special soil 

 proclivities. Thus black Austrian pine does not get in the 

 forest of Soigne the lime it wants. This is referred to in the 

 note on its growth. 



The soil in both the arboretums is a good average loam ; 

 running into blackish meadow loam in the lower part of the 

 Tervueren arboretum. The rainfall is 28 inches : the elevation 

 not enough to effect the climate. All the arboretum plots are 

 grown close and kept under normal forest conditions. It will 

 be noted that most of the plots of trees in those two arboretums 

 range between 15 and 30 years of age. The ages given here 

 are from seed. In the Groenendaal arboretum Picea sitchensis, 

 ChamcRcyparis pisifera, Picea Schrenkiana, and many Japanese 

 conifers suffered severely from the drought of 191 1. 



In cases where only two figures are mentioned, as 7 x 34, 

 the meaning is 7 inches of average diameter at 5 feet above the 

 ground level, and 34 feet total height. 



Douglas fir is the fastest-growing conifer in both arboretums, 

 and averages about half an inch diameter and 2-3 feet 

 height-growth per year. 



In certain places in this list, there are two references to the 

 same tree. That refers to two plots in the arboretum where 

 there is some striking difference of growth or other point that 

 seemed worthy of note. 



Groenendaal Arboretum. 



Larix leptolepis (Japanese larch). At 15 years old is about 

 5 inches diameter by 30 feet high, and at 22 years 7 inches by 

 34 feet. It compares very favourably with the European larch, 

 but M. Drion considered that the latter here is not a fair sample. 

 He adds that the Japanese larch in Belgium suffered badly from 

 the dry summer of 191 1 : trees 20 and 25 feet high were killed 



