HISTORICAL. 17 



during the rains, and a superficial root system. The latter point is of great 

 importance, inasmuch as it leads to the roots being situated in those layers of 

 soil the water-content of which is reduced to the death-limit in the dry 

 season. It will thus be seen that the results obtained go far to explain the 

 natural distribution of sal, and also indicate those grasslands and forest less 

 areas in which afforestation with sal offers the greatest chance of success. 

 Finally, it has been shown that, owing chiefly to the heavy shade, the aeration 

 of the superficial soil layers in dense sal forest is commonly below the death- 

 limit for several weeks during the rains and that this factor is responsible (1) 

 for the holocaust of sal seedlings which takes place during the rains in shady 

 forests in years of heavy rainfall and (2) for the development of a superficial root 

 system which, in the hot season when the sal sheds its leaves and the forest 

 canopy thins out, leads to widespread damage from drought among those 

 plants which survive the rains. Opening of the cover and temporary removal 

 of the humus are obvious expedients by means of which the soil-aeration can be 

 improved. Firing would also in some cases probably be beneficial in this 

 respect." (p. 38.) 



"It will be seen that the management of any particular sal forest to a great 

 extent depends on the fact whether the seedlings in it suffer chiefly from 

 drought or from bad soil-aeration and therefore the determination of this point 

 is of primary importance. Observations regarding the season when the seed- 

 lings chiefly die and the dryness of the soil at the time naturally indicate to a 

 great extent which factor is primarily concerned. In addition to this, how- 

 ever, the work which has been carried out at Dehra during the last few years 

 has shown that the dominant grasses on an area are, as a rule, excellent indi- 

 cators of the soil conditions. Thus in northern India, where Saccharum 

 narenga and Anihistiria gigantea arundinacea tend to be dominant, the soil 

 moisture and aeration are as a rule suitable for the best development of sal and 

 sal forests of the moist type prevail. In shady forest in such localities, the 

 seedlings suffer chiefly from bad soil-aeration and the most efficient remedy 

 consists in opening the cover and exposing the soil. On the other hand, such 

 grasses as Saccharum munja, S. spontaneum, Eragrostis cynosuroides, Imperata 

 arundinacea, Vetiveria zizanoides, Andropogon contortus, and Ischcemum angus- 

 tifolium usually indicate a soil too dry or too dense for the best sal development, 

 and such forests as occur are of the dry sal type. The recognition of the domi- 

 nant grasses in the sal tracts therefore is a matter of considerable practical 

 importance, and a subsequent paper will deal in more detail with the grasses 

 of the sal tracts, in their capacity as soil indicators." (p. 83.) 



Korstian, 1917. — In a study of permanent quadrats on the Datil National 

 Forest of New Mexico, Korstian (1917:267) gives the increment data for 

 Pinus ponderosa on sites I and II, and points out that the growth of a domi- 

 nant tree is the best indication of the quality of forest sites. The differences 

 in the native vegetation on the two sites were so great as to suggest its cor- 

 relation with tree-growth and its use as an indicator of forest sites. A large 

 number of list quadrats were employed, but the lack of previous successional 

 studies makes their accurate interpretation difficult and probably explains in 

 part the conclusion that 



"In studying the indicator significance of the native vegetation it is neces- 

 sary to go directly to the individual species instead of attempting to stop at 

 the association, society, or community. 



"The writer believes that the native vegetation found on deforested areas 

 may be considered as a criterion of the latent potentialities of the site for forest 

 production provided the vegetation has not been too seriously or too recently 



