The Heath Association on Hindhead Common, 1910-1926

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Abstract
The general succession after fires on such a heathland as that on Hindhead Common, S. W. Surrey, England and many adjacent parts of Surrey, is as follows: In case of fire over low growth, there follows a stage of sprouting Ulex nanus, many Calluna and Erica cinerea plants sprouting, relatively few seedlings; but if the fire was in tall growth, there follows a stage of sprouting Ulex nanus, but little Calluna or Erica cinerea, many seedlings of the latter, especially in the 2nd yr.; in the former stage the ground closes up within 2 yrs.; in the latter the ground may remain open for 3 or 4 yrs.; in either case, on slopes facing south, there follows a stage of dominance of Erica cinerea, which is followed by an Erica-Ulex-Calluna stage; on terrain other than slopes facing south, the succession is to a Calluna-Ulex-Erica stage which is succeeded by a Calluna-Ulex phase. It appears that, except in the case of ground frequently burnt, the vegetation always ultimately passes over to the C-U phase, in which Calluna is completely dominant and by its tall growth more or less completely hides the codominant, but largely prostrate Ulex nanus. There is no evidence that the latter is affected by the dense shade cast by the Calluna which is probably largely responsible for the elimination of other forms. As previously pointed out, spontaneous colonization by Pinus, Betula, etc., would no doubt ultimately lead to the development of woodland, but over most parts of the common the trees are felled after they have reached a certain size.[long dash]The results tend to emphasize the stationary character of such heath vegetation. Fires cause little ultimate change and, after a number of years, the heath presents the same appearance and detailed composition as before. Its essential components are Calluna, Erica cinerea, and Ulex nanus, and all the others (Pteridium, Vaccinium myrtillus, Erica tetralix, Molinia coerulea, Aira flexuosa), though frequently abundant, are locally absent over considerable stretches of ground. Evidence has been produced of spread of Pteridium and Molinia in the first years after a fire from regions (commonly the valleys) in which they were previously abundant, but such spread no longer occurs when the vegetation has closed up and the ericaceous forms have asserted themselves. Neither of these plants has, however, appreciably extended its domain during the 16 years that the common has been under observation. Although rabbits abound on many parts of the common and evidently attack many of the plants present, there is no evidence that the biotic factor plays any considerable role in this region. Apart from fires, varying exposure is the most important factor affecting the character of the vegetation. Growth in the valleys is more rapid and denser than on the tops, where the full effects of exposure are felt; but the change is gradual and this factor does not condition any sharp boundary lines.

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