953 



on humous peaty soil, which contains onl}' a moderale proportion 

 of water; at times the water-content may be scanty, but at other 

 times the soil may be saturated with water or even completely 

 flooded. 



This alternate drying and saturating of the soil has the effect 

 of rendering it less acid than the boggy moor, consequently the 

 Eriophorum and Carices which were dominant on the boggy moor 

 are replaced by Nardiis, Jiincus sqiiarrosiis and Scirpiis caespitosiis. 

 These three piants which in Denmark frequently occur on rather 

 dry heaths, seem to prefer rather more moisture on the Færoes. 

 There, on fairly moist peaty soils, they constitute the vegetation, 

 and in my opinion, the plant-associations formed bj^ them are to 

 be regarded as somewhat equivalent to a moist heather-moor with- 

 out heather. The grass-moor is found everywhere on the slopes, 

 when heather-moor might have been expected if the exposure to- 

 wards the sun had been more favourable. The aspect or lie with 

 respect to the direction of the sun's rays is a factor of so much 

 importance that one always finds a marked difference belween the 

 two sides of a valley running east and west. The south side, ex- 

 posed to the north is moister, richer in mosses and without heather, 

 whereas the opposite side lying towards the south is drier, poorer 

 in mosses, but has heather. 



The grass-moor is what in the account of my journey to the 

 Færoes (1901) was called »Nardus-Eng« (Nardus-pasture) or »Nardus- 

 formation«. It has a wide distribution on the Færoes extending 

 from the sea upwards on the mountains to an altitude of 300—400 

 meters. In the higher zones of this area Grimmia hypnoides plays 

 so important a part that we find there a transition association 

 (The »Grim mia- Nardus formation« of my account of travels). 

 On the summit-plateaux of the mountains we find the third link 

 of the chain, the pure Grimmia heath. The grass-moor attains its 

 best development on the lower zone of the mountains where the 

 slope is distinct, yet so slight that movement of water is slow. 

 The habitat lies, therefore, between the valley-boltom with its moors 

 and the drier grass-slopes (Græsli), or in the case of a southern ex- 

 posure, the heather-moor. 



The three Glumifloræ, Nardiis, Scirpiis caespitosiis and Jiin- 

 ciis sqiiarrosiis are dominant, and occur in such a way, that fre- 

 quently one may prevail and almost entirely exclude the other two ; 

 thus we get three facies of the grass-moor, viz: 



