44 EXPERIMENT STATION RECORD. 



FORESTRY. 



The influence of forest cover on the temperature of the soil at different 

 depths, E. CuiF {Bui. Soc. ScL ^'(Ulcu, 3. ser., 10 {1000), No. 1, pp. 51-63, pis. 

 J/). — This paper contains a summary of the ix'sults and conclusions thus far 

 secured at the Nancy Forestry Station on the ahove line of investigation. The 

 geothermic ohservations were carried on in the forest domains of Amance and 

 filieux, by methods which are described. Besides comparing the temperatures 

 of exposed soils and those under forest cover, observations were also made of 

 soil temperatures under different kinds of forests. 



The data secured at Amance led to the following conclusions : The forest 

 soil under deciduous stands is about 2° C warmer in winter and about 3° colder 

 in the summer than exposed soil, for all depths up to SO cm. The variations 

 in the soil temperature are about 3^° less under the forest cover than outside 

 of the forest. For all the depths the presence of a deciduous forest is prac- 

 tically the same whether the stand is high-standard or reserve sprout forest. 

 In the summer, other conditions being equal, the soil is about i° cooler under 

 a reserve sprout forest 16 years of age than under a high-standard forest 100 

 years old. With reference to the daily variations of the temperature of the air 

 and soil under forest and outside of forest, the studies led to the conclusions 

 that the amplitude of the daily oscillations of the temperature of the soil at 

 a depth of 20 cm. is relatively very feeble when compared with the daily oscil- 

 lations of the tempex'ature of the air over exposed soil. The presence of the 

 forest appears to reduce the temperature about 1°. At a depth of SO cm. these 

 daily oscillations are practically inappreciable, both under forest conditions 

 and outside of the forest. The maximum daily temperature of the air over 

 exposed soil occurs about 2 o'clock in the evening, while that of the soil tem- 

 perature at a depth of 20 cm. is reached at about 6 o'clock in the evening. 



The observations made at Elieux led to similar results. The results as a 

 whole confirm the conclusions reached l)y stations in other countries. 



Investigations on the pruning of forest trees, E. Zederbauer {Ccntbl. 

 Gesam. Forstw., 35 {1909), No. 10, pp. J,13-.'i27, pi. 1).—The effect of pruning 

 at different times of the year and different methods of pruning forest trees, 

 including the beech, oak, Douglas fir, and spruce, was studied for a number 

 of years. The details are given of the work, together with the practical deduc- 

 tions made. 



Contrary to the common opinion that fall and winter are the best times for 

 pruning the trees, the present investigations show that pruning is less injurious 

 to the trees when carried on in the early spring, at which time an active devel- 

 opment of healing tissue takes place. When the wounds are covered with tar, 

 however, pruning can be carried on in the fall without much danger of disease 

 entering the wounds. With the coniferous trees the exuding pitch answers as 

 a protection for the wounds. 



Fall pruning usually results in a brownish discoloration of the bark about 

 the wound, thereby increasing its size. This was more noticeable with the 

 hardwood species. The smallest amount of subsequent injury is experienced 

 by the tree when the cuts are made smooth and close to the trunk. The prun- 

 ing of dry limbs does not exert a harmful influence on the development of the 

 tree, but the removal of a considerable number of green limbs checks the 

 growth of the tree to a greater or less extent. 



Silvical leaflets (U. S. Dept. Agr., Forest Serv. Sili: Leaflets, 'iS-'t'i, pp. .'/ 

 each). — These leaflets discuss, respectively, the red or Norway pine {Piniis 

 remnosa), and the jack pine iP. divaricata), their range, climate, associated 

 species, habit, soil and moisture, tolerance, growth and longevity, susceptibility 

 to injury, reproduction, and management being considered. 



