2l6 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



experience are hidden away in the records of many old forest 

 divisions in Germany, waiting to be lifted by the magic touch 

 of intelHgent inquiry. 



Dr Graebner concludes a most convincing article on root 

 formation in pure spruce and pine forests, in the plains of 

 Northern Germany, with a most powerful indictment. 



The degeneration of the soil, observed in numerous areas in 

 the heather tracts of Northern Germany, wherever they are 

 covered with pure pine and spruce forest, demands the rehabilita- 

 tion of the natural original vegetation ; that is, a forest mixed 

 with deciduous species, and the removal of the (under existing 

 conditions of climate and soil) unnatural pure coniferous forests, 

 even in cases where no present outturn or income can be 

 expected from the intermixture of broad-leaved species. 



Future generations, he points out, will benefit by a wise 

 return to the laws of nature, just as the present one has to 

 suffer by a departure therefrom on the part of their predecessors. 

 Dr Graebner is thus another powerful advocate of a radical 

 change in a policy, which, dictated by greed, ended in national 

 loss. 



It may be accepted, without prejudice, that both spruce and 

 pine were original inhabitants of all the German heather tracts, 

 but that neither of them ever formed pure natural forests 

 within these districts. This is quite in accordance with Zimmer- 

 mann's observations, discussed by us in previous notes. 



It would absorb more space than is available for these notes, 

 were we to follow in detail Graebner's careful and most interest- 

 ing observations, made almost invariably in the presence of 

 competent witnesses ; and it must suffice to state that he has 

 proved that the root-systems of spruce and pine rise, year by 

 year, nearer to the surface by a more pronounced development 

 of the far-spreading upper side roots, and the gradual death 

 of the lower ones, in proportion to the exclusion of air caused 

 by the annual fall of the needles, which, as they decompose, 

 form a more or less airtight covering of pine humus. The 

 observations have shown that the struggle against gradual 

 asphixiation cannot be permanently maintained ; the far- 

 spreading roots near the surface interfere and interlace with 

 those of the neighbouring trees, nourishment for each becomes 

 scarcer, and the forests lose their vitality ; and as the flat 

 spreading roots can draw moisture only from the surface layer 



