BRITAIN. 



257 



■i« 



Lacttstbine Moors. 

 Top destroyed. 

 7b. Upper grey spongy Sphagnum peat. 



7a. Mixed brown peat (Eriophorum, CaU 

 luna, Sphagnum). 



6. Wood peat (BetiM) in situ. 



5&. Upper sedge and reed peat {Phragmites 

 and Cladium). 



Occasional drifted Betula. 



5a. Lower sedge and reed peat. 



5 ft. 



4. Hypnum-peat. 



M^ £fz 3. Amorphous peat. 



5 ft. 



2 in. 

 6 in. 





2. Shell marl. 

 1. Lake mud. 



}l8: 



Fig. 19.— Generalized section of peat of Lonsdale lacustrine moors. After Rankin. 



The general sequence of moor consocies is the following: 



Nardetum strictae (upland only). 



Vaccinietum myrtiUi. 



CaUunelum wlgaria. 



Betulelum tomentosae (lowland only). 



Pinetum sylvestris (lowland only). 



Rhynchosporetum alhae (lowland only). 



Eriophoretum angustifolii. 



E. vaginati. 



Sdrpetum caespitosi (upland only). 



Molinietum caendeae. 



Smith (329) arranges the communities of the arctic-alpine vegetation of 

 Scotland in a diagram (fig. 20), which shows many of the successional relations. 



Arctic- 

 alpine 

 ione 



Chomophyte formation 



Chotnophytes of exposed ledges 



Shade Hydrophilous 



chomophytes chomophytes 



Chomophytes of sheltered ledges 



Arctic-Alpine grassland formation 



Formation of mountain-top detritus 

 — Moss-lichen open association 



Rhacomitrium 

 heath 



Rhacomitrium 

 moor 



Sub- 

 alplne 

 zone 



Grasslands 



Heath 



Moor 



Fig. 20. — ^Diagram of alpine communities, Ben Lawers, Scotland. After Smith. 



The sequence in the salt-marshes (330) is as follows: (1) Salicomietum 

 europaeae; (la) Spartinetum; (2) general salt-marsh association, Atriplex, 

 Aster, Suaeda, etc.; (3) Glycerietum maritimae; (4) Juncetum. maritimi. The 



