Scope of Dendrology in Forest Botany. 229 



trees that go to make up the forest. This is non-ecological. The 

 other deals with associations of such trees, with those dynamic, 

 organic entities known as forests, and is ecological. The former 

 of these two parts is dendrolog}% while the latter is silvics. Some- 

 times the term silviculture, which originally was reserved for the 

 art of establishing, developing, and reproducing forests, is used 

 to denote also the science back of that art, that is to say as a 

 synonym for silvics, just as, for example, the single term medi- 

 cine is often used to denote either the science or the art. Den- 

 drology will be handled in the main body of this short article. 

 Here it is necessary for a complete understanding to treat briefly 

 the subject of silvics. It appears to the writer that the natural 

 subdivision and the arrangement best suited for presenting the 

 materials to students lies in this already well recognized separa- 

 tion into dendrology and silvics. In addition to this there must 

 be remembered the powerful and all-important fact, that alone 

 should bring about such a subdivision to-day, to wit that now 

 all ecological investigation, in order to facilitate scientific de- 

 velopment in the methods of attack upon the intricate problems 

 involved, is placed in a category by itself under some one or 

 more ecological sciences. 



Silvics covers, it is believed, all ecological investigations of 

 forests. Ecological investigation of vegetation is to-day pur- 

 sued by means of the two sister sciences known as plant-geogra- 

 phy and plant-ecology. The former of these is also known inter- 

 nationally as phytogeography, while the latter has the interna- 

 tional term phytecology proposed. They cover the field of eco- 

 logical science in botany. Exhaustive expositions of the terri- 

 tories included within these respective subjects or of their present 

 stage of advancement would be both out of place here and im- 

 possible within limited space. Suffice it to say, by way of fur- 

 nishing accurate indicators of their meanings rather than ex- 

 haustive definitions, that plant-geography is essentially a regional 

 study of vegetation and proceeds along three lines, the genetic, 

 the floristic, and the ecological. The first considers the his- 

 torical origin and development of the vegetation of a region and 

 is largely geologic. The second interprets the present regional 

 flora from the point of view of its origin, migration, etc. Its 

 delimitations are largely topographic. The third puts the pres- 

 ent regional vegetation in its proper categories (ergo plant asso- 



