254 Forestry Quarterly. 



Dr. Biihler has published interesting in- 



Forest vestigations of the detail of forest influ- 



Influences ences. Under loo-year-old beech in a year 



on only 75 per cent, of the precipitation in the 



Soilwater. open was measured ; under 20-year-old fir 



only 20 per cent., and under spruce, 32 per 



cent. 



Placing the water percolating through sand as 100, loam will 

 allow 76 to 87; clay 84 per cent, to percolate; but loam with a 

 litter cover percolated 147, sand with moss 134 of what sand un- 

 covered did. On the other hand, on loam soil with spruce only 

 70; on loam with beech, 50; on loam under very dense beech 60 

 per cent, of the water percolated of what uncovered loam would 

 produce. 



A constant relation between water contents of the upper (8 

 inch) soil layer and the lower (12-16 inch) does not exist; re- 

 lations are much more complicated than at first appears. On the 

 whole, the lower strata were found only 2.3 per cent, moister than 

 the upper ; sometimes, however, the lower strata were drier than 

 the upper. 



As to evaporation from soil under forest cover, former find- 

 ings are confirmed. Leaf and moss cover reduced evaporation 

 by 30 and 35 per cent. ; but 100-year-old oak reduced it by 53 ; a 

 low stand (25 feet) of Douglas Fir by 75 per cent, the shade 

 efifect being superior to the mulch effect. The character of the 

 soil seemed to make no difference, except that a humose soil 

 reduced evaporation considerably. 



An interesting fact is that a small opening of 30 qm in a beech 

 stand did not show any less reduction than the full stand, namely 

 45 per cent, of the water evaporated in the open field ; especially 

 was there no difference in the hot summer months. 



The temperature of dry and wet soils was also carefully studied ; 

 the soil kept constantly wet was found 1-2° colder than the dry or 

 occasionally wet soil, sometimes the difference rising to 4-6° C. 



Mitteiluiigen der Wilrttembergischen Forstlichen Verstichsanstalt. All- 

 gemeine Forst- u. Jagdzeitung. March, 1913. Pp. 95-96. 



