ECOLOGICAL SUCCESSION OF MOSSES 209 



as well. The latter is a depressed region, more or less completely 

 encircling the bog, and commonly free of sphagnum unless 

 invaded by it as described in the last paragraph. It is a widely 

 distributed feature of sphagnum bogs, and various explanations 

 have been suggested for it, which need not be discussed here. 

 In the marginal zone of all bogs that possess it, and in the bog 

 forest in general of those without abundance of sphagnum, the 

 moss contingent is remarkable for its variety rather than for its 

 bulk. .Conditions of moisture and shade are apparently at the 

 optimum for the average moss requirements. In one small area 

 twenty-two species were collected, and the complete list of these 

 will be of interest. 



Aulacomnium palustre (L.) Schwaegr. Hylocomium proliferum (L.) Lindb. 



Aulacomnium palustre var. polycepha- Hypnum crista-castrensis L. 



lum B. & S. Leucobryum glaucum (L.) Schimp. 



Calliergon Richardsonii (Mitt.) Kindb. Mnium punctatum L. var. elatum 

 Collier gon Schreberi (Willd.) Grout. Schimp. 



Campylium stellatum (Schreb.) Bryhn. Mnium subglobosum B. & S. 



Dicranum flagellare Hedw. Oncophorus Wahlenbergii, Brid. 



Dicranum fuscescens Turn. Plagiothecium denticulatum (L.) B. & S. 



Dicranum scoparium (L.) Hedw. Plagiothecium turfaceum Lindb. 



Dicranum undulatum Ehrh. Pohlia nutans (Schreb.) Lindb. 



Drepanocladus uiicinatus (Hedw.) Sphagnum papillosum Lindb. var. inter - 



Warnst. medium (Russ.) W. 



Georgia pellucida (L.) Rabenh. Splachnum ampullaceum L. 



We have seen that the mosses of the climax forest have already 

 established themselves to some degree. The same is true of 

 the climax trees, which are often found growing with the bog 

 trees even during the open bog stage. The transition to the 

 climax state consists merely in the gradual increase of the char- 

 acteristic species, trees, mosses, and other plants, at the expense 

 of the bog forest forms, until the dominance of the former is 

 complete. 



The successional ranges of twenty-three important species of 

 the Bog Succession are shown in figure 6. 



III. THE CLIMAX FOREST 



The climax forest is not homogeneous throughout in character 

 and appearance. It is made up of small patches of diverse 



