KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 50. N:0 3. 



105 



Tlie Empetrum-associatioii. (Pl. VI: 2, VII.) 



This association is found on comparatively dry ground. It is best developed 

 on the mountain-ridges, on stony plateaus etc. and thrives well even on places where 

 the subsoil is formed by very coarse material, but seems to keep away from the moister 

 depressions. Round the stoneruns is always an E)npetru7n-hea,th, where Bolax plays 

 an important part, and the most pure type of heath forms patches and strips in 

 the block-fields; on such places Blechnum magellanicum and Marsi'pposper'mum are 

 more or less common. In Lafonia, where solifliiction must have played a minor 

 part, Cortaderia prevails; elsewhere it inhabits the moist depressions and the lower 

 parts of the slopes. Transitions between the two principal associations are foimd 

 everyvvhere, thus there are meadows witli more scattered grasses and numerous dwarf- 

 shrubs, and a dwarf-shrub heath with mucli Cortaderia. This seems quite natural 

 — more difficiilt was it to explain, why on quite uniform slopes of hills, covered by 

 a Cortaderia-ass., one may find strips of Empetriun, running with the dip of the slope 

 and very sharply delimited. I was struck by this fact already on the occasion 

 of my first visit to Stanley Harbour, and I suspected some difference in the com- 

 position of the subsoil. After that I had studied the vegetation of the magnificent 

 Darwin-stonerun near Port Salvador, I came to the conclusion that such strips of 

 Empetrimi-hesith occur on areas of coarse material, and that they of ten enough 

 distinctly mark the direction of the ancient soil-flow (see Plate IX). For particulars 

 I refer to the more detailed descriptions given in my previous paper (34). 



The soil in the heath is a kind of close, härd and dry peat, a filted mäss of 

 roots and rhizomes, branches and leaves of the dwarf-shrubs, grasses and herbs; 

 mosses, especially Campylopus are of great importance in many places. 



There is generally very little brushwood; Chilioirichiim is scattered and poorly 

 developed as it avoids peaty soil (also see below); evidently it does not like the raw 

 or acid humus. 



The following list was not afforded by a survey of a certain, limited area, but 

 was compiled from all my observations on the Empetrum-heaiXh. round Port Stanley. 



3. General composition of the heath. 



Scattered shrubs of Chiliotrichum diffusum. 



Dwarf-shrubs, herbs and grasses: 



Soc.-greg. Empetrum riibrum 



Cop. Baccharis magellanica 

 Pernettya pumila 

 Spårs. Ayrosfls canina var. 

 » magellanica 

 Aira prcpxox 

 Cerasfhim arrcnse 

 Dcschampsia flexuosa 

 f!all)im avtarctintm 

 K. Sv. Vet. Akad. Handl. Band. 



Marsippospermum gran- 



diflorum 

 Sisi/rinch him fdifoHum 

 Spårs. -sol. Accena adsconlcns 

 Astcr VaJdii 

 Blechnum magellanicum 

 Carcx fuscula 

 Cardamine glacialis 

 Crrastium vulgäre 

 50. N:o 3. 



Chlonea Gaudichaudii 

 Codonorcliis Lcssonii 

 Cortaderia pilosa 

 Festuea erecta 

 Gaultheria microphylla 

 Qentiana magellanica 

 Jnncus sclieuchzerioides 

 Lagenophora nudicaulis 

 Leitceria suaveolens 



14 



