622 Forestry Quarterly. 



pine dune 140%, and in the cottonwood dune 260%. The aver- 

 age amount of water evaporated per day beneath the beech-maple 

 forest vi^as 8.1 cc. The evaporation in the various associations 

 varies directly with the order of their occurrence in the succes- 

 sion, being greatest in the youngest and least in the oldest asso- 

 ciation. Thus it may be said that the atmospheric conditions in 

 the lower stratum of the cottonwood dune association during the 

 growing season are 2.6 times as severe for plant life as those in 

 the same stratum of the beech-maple association during the same 

 period. 



Bfaporation and Plant Succession. The Botanical Gazette, 

 September, 191 1. Pp. 193-208. 



SILVICULTURE, PROTECTION AND EXTENSION. 



Of more and more intense interest are the 

 Results experiences with exotic species in Germany, 



with which are now for 30 years continued, and 



Exotic permit now the establishment of sample 



Trees. areas to secure data for an estimate of for- 



est production. 

 Dr. Schwappach brings together these experiences from all 

 the trial planting in Prussia, discussing species by species with 

 estimate of the value of each and giving a tabulation of all the 

 trial plantings with measurements — a very full report, worth 

 studying. 



Out of 1,600 acres of exotic plantations in 1900, 1,040 re- 

 mained in 1910; the Douglas spruce leading with 325 acres. 



Of the six Abies species tried, amabilis, concolor, Urma, 

 grandis, nobilis and Nordmanniana, Abies concolor has proved 

 the best, being the most rapid grower, rivaling even the Norway 

 spruce on fresh, humose loam soils. It differs from the other 

 firs by being less tolerant, especially of overhead shade; it is 

 almost light-needing. Its resistance to frost and heat and to 

 damage by mice and game is also praised. It is the only Abies 

 of special value. 



Of Picea five species, ajanensis, alcockiana, engelmanni, pun- 

 gens, sitchensis, have been tried ; only the last is found forestally 

 of value, and especially near the seashore in the northern lati- 

 tudes, where on account of its freedom from Schiitte, as well as 



