THE DEVELOPMENT OF COMMUNITIES 



327 



be followed, by notable displacements of the species. These may 

 best be classed as climax fluctuations (Furrer, 1922). Very marked 

 changes in the appearance of the climax occur where two climax 

 communities meet and compete for the supremacy. In such cases 

 it is often difficult to decide whether a new climax community has 

 taken possession of the habitat or there is simply a cHmax fluctuation. 

 Many cases where forest is converted into moor may be considered 

 as climax fluctuations. A typical example of this is the Flahult moor 

 near Jonkoping, Sweden. According to Anderson and Hesselman 

 (1910, p. 153), there is a 3-m. layer of Sphagnum peat covering a min- 

 eral soil which was originally forested. After the forest was burned off, 



Fig. 163. — Artificial creation of the Ononidetum angustissimae by sowing; first step in 

 fixing sand. {Photo by Maire.) 



the drying effect of the tree layer (transpiration, interception of rain) 

 ceased. Immediately physicochemical changes took place in the soil. 

 Favored by these conditions Syhagnum became very actively con- 

 structive and pushed a high moor with low shrubs and isolated dis- 

 torted pines directly over the burned ground. 



Practical Significance of Syngenetics. — The universal application of 

 syngenetics to forestry and agriculture has long been recognized but has 

 never been urged with sufficient emphasis, and these subjects have 

 never been treated connectedly. The immense agricultural value of 

 studies of the development of vegetation is shown by the history of the 

 advance of moor in cool, humid chmates, by the combat with the 

 savoka and the dreaded fire steppes of Madagascar, by stabilization of 

 moving dunes, and by draining of lagoons. 



