vi PREFACE 



For these alterations I am mainly responsible, but the new 

 classification of the formations is largely due to Dr. Vahl, who 

 has thus materially remodelled parts of the book. In place 

 of the four Sections discussing hydrophytic, xerophytic, halo- 

 phytic, and mesophytic communities respectively, thirteen 

 Sections (IV-XVI) have been devoted to thirteen oecological 

 classes established on the basis of edaphic and climatic distinc- 

 tions. The arrangement of the subject-matter dealing with 

 the several Formations is new in many respects, the changes 

 involved being due partly to myself (for instance, in connexion 

 with halophytes and lithophytes) and partly to Dr. Vahl (notably 

 in Sections XI-XV). 



So far as my other varied work, including administrative 

 duties, would permit, I have endeavoured, with the assistance 

 of Dr. Vahl, to take into consideration the vast amount of 

 pertinent literature issued since 1895. Since that year there 

 have been published, not only the large general works by 

 Schimper (1898, English Edition 1903), Solms-Laubach (1905), 

 and Clements (1904, 1905, 1907), which contain much that is 

 original and suggestive, but also an immense number of original 

 papers in various periodicals and countries. So far as possible, 

 recognition has been made of all important contributions issued 

 up to the present moment, and their titles will be found in 

 the appended Bibliography. But there is considerable difficulty 

 in selecting the most important from such a vast accumulation 

 of literature. 



In many places I have felt the lack of definite, detailed, 

 and truly oecological information concerning various questions, 

 and, as in 1895, I must confess that my ideal is far from being 

 realized. The oecology of plants is a subject still in its infancy ; 

 numerous investigations must be made before the foundations 

 can be truly and rightly laid, and before a consistent, clear, 

 and natural classification of plant-communities is achieved. 



In conclusion, I must express my thanks to Dr. Martin Vahl 

 for the great interest he has shown in efforts to improve the 

 book, and to my colleagues in Britain for the exceeding care 

 which they have bestowed upon the production of the book 

 in English. 



EUG. WARMING. 

 COPENHAGEN, 



March, 1909. 



