300 METEOBOLOGY. [Feb. 



Meteorology. 



TEMPERATURE OF THE TREE. 



THE following are translations of excerpts from a paper entitled 

 Temperatur del Arhol, which appeared in the January issue of 

 Revista de Monies, the " Forestry Eeview " of Spain, which was to be 

 followed by others on the same subject : — 



Amongst the repeated experiments whicli liave been mado on the 

 temperature of trees, those made by Boehm and Breitenlohner, which 

 we are about to bring under consideration, deserve special attention.^^ 

 Krutzsch, professor in the Forest Institute of Tharand, published 

 (ibservations made by him during the years 1852 and 1853,^ and 

 Becquerel has published in a series of dissertations his experiments, 

 the principal object of which was to determine the thermometric 

 or climatic influence of the forest.^ In the meteorologico-forestal 

 observations of Bavaria and Switzerland, the internal temperature of 

 trees has also been the subject of observation ; but up to tliis time 

 there has only been published a n'sitmd of the data obtained during 

 the first years.'' 



From these and other experiments, it appears that the periodical 

 and irregular changes of temperature influence differently different 

 parts of the tree, from the roots to the branches. The atmosphere 

 and the soil are two factors which almost exclusively determine the 

 temperature of the tree, botli in its aerial and its subterranean parts. 

 The influence of the temperature of the soil extends from the roots to 

 the trunk, but only to a certain height, which is determined by the 

 temperature of the air which surroimds the tree. 



The temperature of the roots is imparted by the soil. The origin 

 and nature of the soil and the subsoil, its mechanical and physical 

 properties, the degree of humidity, the absence or presence of sub- 

 terranean water, the superficial covering of the ground, and the vary- 

 ing degrees of sunshine and shade, are so many other factors which 

 influence that by modifying the character and degree of temperature 

 imparted to the roots. With change of temperature in the soil, which 

 in most kinds of land are very slight even in the warm days of 

 summer at a depth of one metre from the surface, the temperature 

 of roots must change in the same proportion. The portion of these 

 roots situated more than a metre in depth will only be affected by 

 the heat of the ground throughout the year, which varies very little ; 



1 ]'". Band LXX. Dcr Silz. dtr K. Akad. d. Wksen-'ich., I. Abth. Mai Heft. 



- Untersttchungen ucber die Temperatnr der Bautne, etc., 1854. 



3 Mimoires de UAcadimie des Sciences, 1861-64. 



' Zeitschr'ift der Osterreichisclien Gcsellschaft fuer Meteorologie, Band IV. 



