4 CONCEPT AND CAUSES OP SUCCESSION. 



and the reproduction of a complex organism. In this larger aspect succession 

 includes both the ontogeny and the phylogeny of climax formations. 



Succession and sere.— In the thorough analysis of succession it becomes evi-. 

 dent that the use of the term in both a concrete and an abstract sense tends.to 

 inexactness and uncertainty. With the recognition of new kinds of succession 

 it seems desirable to restrict the word more and more to the phenomenon 

 itself and to emptey a new term for concrete examples of it. In consequence, 

 a word has been sought which w6uld be significant, short, euphonic, and ea^y 

 of combination. These advantages are combined in the word sere, from a root 

 common to both Latin and Greek, and hence permitting ready composition m 

 either. The root ser- shows its meaning in Latin sero, join, connect; sertum, 

 wreath; series, joining or binding together, hence sequence, course, succession, 

 lineage. In Greek, it occurs in elpta, to fasten together in a row, and in 

 veipd, fffipA,, rope, band, line, lineage. Sere is essentially identical with senes, 

 but posses^s the great advantage of being distinctive and of combining much 

 more readily, as in cosere, geosere, etc. 



Sere and cosere. — ^A sere is a unit succession. It comprises the develop- 

 ment of a formation from the appearance of the first pioneers through the final 

 or climax stage. Its normal course is from nudation to. stabilization. All 

 concrete successions are seres, though they may differ greatly in development 

 and thus make it necessary to recognize various kinds, as is shown later. On 

 the other hand, a unit succession or sere may recur two or more times on the 

 same spot. Classical examples of this are found in moors and dunes, and in 

 forest burns. A series of unit successions results, in which the units or seres 

 are identical or related in development. They consist normally of the same 

 stages and terminate in the same chmax, and hence typify the reproductive 

 process in the formation. Such a series of unit successions, i. e., of seres, in 

 the same spot constitutes an organic entity. For this, the term consere or 

 cosere (cum, together, sere; consero, bind into a whole) is proposed, in recogni- 

 tion of the developmental bond between the individual seres. Thus, while 

 the sere is the developmental unit, and is purely ontogenetic, the cosere is the 

 sum of such units throughout the whole life-history of the climax formation, 

 and is hence phylogenetic in some degree. Coseres are likewise related in a 

 developmental series, and thus may form larger groups, eoseres, etc., as indi- 

 cated in the later discussion (plate 1, a, b). 



Processes in succession. — The development of a climax formation consists 

 of several essential processes or functions. Every sere must be initiated, and 

 its life-forms and species selected. It must progress from one stage to 

 another, and finally must terminate in the highest stage possible under the 

 climatic conditions present. Thus, succession is readily analyzed into initia- 

 tion, selection, continuation, and termination. A complete analysis, however, 

 resolves these into the basic processes of which all but the first are fimctions 

 of vegetation, namely, (1) nudation, (2) migration, (3) ecesis, (4) competition, 

 (5) reaction, (6) stabilization. These may be successive or interacting. They 

 are successive in initial stages, and they interact in most complex fashion in 

 all later ones. In addition, there are certain cardinal points to be considered 

 in every case. Such are the direction of movement, the stages involved, the 

 vegetation forms or materials, the climax, and the structural units which 

 result. 



