EDAl'HIC OR SOIL FACTORS: CHEMICAL 



177 



ing action of the humus soils that the Curvuletum as the chmax 

 association of the Swiss alpine survives even in regions with large 

 deposits of drifting alkaline dust. 



Salisbury (1922, p. 237) discusses buffer curves of lime soils of 

 southern English beech woods. Owing to high humus content the 

 surface layer (2 to 3 cm. deep) showed good buffering. At 6 cm. 

 depth the flexibility to acid was increased; that is, the buffer- 

 ing was poorest there, because of decreasing humus and carbonate 

 content. In the deeper soil strata (15 to 25 cm.) buffering was found 

 to be on the increase again, owing to a large increase of carbonate. 



The following table 17 illustrates buffering of the various layers of 

 alpine rendzina (lime) soils and rendzina podsols. 



Table 17. — Resistance against Change from Additions of Acid or Alkali 



IN THE ElYNETUM AND IN THE CuRVULETUM PROFILES IN THE CENTRAL 



Alps (After Braun-Blanquet and Jenny, 1926) 

 .4. Elynetvim on Rendzina Soil 



B. Curvulotuni on Rendzina Podsol at Murtarol (Cluoza), 2,570 in. 



Strong buffering in the surface soil stratum is also responsible for 

 the fact that neither an increase of carbonic acid, HiCO;), in the soil 

 by action of soil organisms nor the formation of nitric acid, HNO3, by 



