838 EXPERIMENT STATION EECOED. 



The author finds that in Gelderland. where the loess rests on preglacial 

 sand and gravel, the loess contains a nmch larger amount of coarse 

 sand than where it rests on a chalk formation, as in Liml)urg. In 

 the second appendix arc given the results of chemical analyses of 

 2 samples of loess. 



The author gives a chart showing the location of the moraine caps 

 in a portion of the Velmve plateau. — ii. m. pieteks. 



On the causes of the treeless conditions of the steppes, S. 

 Kkavkov {Schk. Khoz. i Lyemv.^ 196 {1900), Jan.,x>p. i-iJ).— This 

 article is essentially a criticism of the views of G. Tanlilyev relating 

 to the causes of the treeless condition of the steppes, which are 

 advocated by such authorities as A. N. Beketov and V. \ . Dokou- 

 chayev. The resume given of the views of Tanfilj-ev is as follows: 



The geobotanical investigations of Tanfilj^ev have led him to the 

 conclusion that chernozem (black earth) everywhere lies on rocks rich 

 in lime and must be considered, from the nature of its vegetation, as 

 belonging to the calcareous soils. The presence of lime in considerable 

 quantity, as well as of an excess of common salt, is accompanied by 

 the development of a peculiar vegetation. The difference in the vege- 

 tation of calcareous and noncalcareous soils can not be explained by 

 the relation of these soils to humidity ; nor are the heat properties of 

 the soils of essential importance in this regard. Consequently the 

 action of lime on the distribution of plants is chiefl}' chemical or due 

 to its solubility in water. Tanfih^ev concludes that the cause of the 

 treeless condition of the steppes must be looked for in the character 

 of the chemical composition of the chernozem. The fact that the 

 latter lies everywhere on rocks rich in soluble salts, and especially in 

 calcium carbonate, leads to the view that the treeless condition of the 

 steppes is closeh' connected with the abundance of these salts in the 

 soils of the steppes. Hence it follows that forests will be established 

 only in localities where the conditions favor leaching of the soils, ^'. e.^ 

 on the slopes of ravines and on divides. In invading the steppes the 

 forests descend from the divides along the declivities, advancing as the 

 reduction of the soluble salts proceeds. Taking into consideration 

 that chernozem lies everywhere on rocks rich in lime, and that the 

 forest collects and holds the moisture which permeates the soil under 

 it to a great depth, the author further infers that the forest soils must 

 be leached out to a greater depth than those of the steppes. As an 

 index of the degree to which this leaching has proceeded he selects 

 calcium carl)onate, which is always a constituent of the normal cher- 

 nozem soils and subsoils and whose presence is easih^ detected ))y the 

 addition of an acid. By the aid of the "method of effervescence" 

 fore.st soils can be distinguished from those of the steppes. — p. fire- 

 man. 



