The Breckland 221 



(C) THE ECOLOGY OF BRECKLAND 



By A. S. Watt, ph.d. 



From west to east in England, as the oceanic influence decreases, there is a 

 fall in the Atlantic element of our flora, and a new element — not homo- 

 geneous, but commonly referred to as the "continental" element — 

 becomes significant. Breckland is its headquarters in this country;' on 

 the Continent it ranges from the far north of Europe to the south, and 

 eastwards to the steppes of Russia and beyond. In a chmate which is 

 permissive to it, two other sets of factors condition its survival, namely, a 

 soil with a liigh base status and/or freedom from competition. This last is 

 freely offered by abandoned arable fields, disturbed soil, and open com- 

 munities. 



Freedom from competition very likely explains the presence of the 

 liverworts, Lophozia harhata and L. hatcheri, and the hchens, Cladiiia 

 rangiferina and Stereocaulon evoliitum, in this outpost to the south-east of the 

 main area of their occurrence in tliis country. It also explains the high 

 percentage of annuals in the flora: half the "continental" element are 

 annuals, and so are 40 per cent of the flora of the grasslands described later 

 in this chapter. 



The flora is essentially heliophilous and xerophytic. The annuals are 

 drought evading, the peremiials drought resistant. In soil preferences, 

 there is a wide range represented, but calcicoles and species of slightly 

 acid soils are numerous, while calcifuges are few and there are noteworthy 

 absentees, e.g. Erica cinerea. The same numerical representation character- 

 ises both the continental element and the annuals : tlie bulk of each class is 

 found on soils with a relatively liigh base status, a few only grow on very 

 acid soils. But interest in the rarer species ought not to blind us to the fact 

 that most of the species in Breckland have a wide English and British 

 distribution. 



THE VEGETATION 



While the interest of the flora of Breckland is enhanced by the presence 

 and frequency of the continental contingent, the dominants of the vegeta- 

 tion do not suggest continentaUty : rather the reverse. These dominants 

 are Festuca ovina and Agrostis^ spp., the chief constituents of die variable 



' See p. 43 above; and also A. S. Watt, "Studies in the Ecology of Breckland. 

 I. Climate, Soil and Vegetation", /oMr. Ecol. xxiv, 117 (1936). 



' The species of Agrostis require revision as the result of W. R. Phihpson's work. 

 Jour. Linn. Soc. U, 73 (1937). 



