seTTing T he sCene: The naTure of naTure^3they eventually shaded out the protective thorns, but by this time they were
relatively immune to the herbivores.^6 Eventually, individual trees grew old,
or were out-competed by neighbours, and the area became open grassland
again: the landscape was thus an ever-changing mosaic. Vera’s hypothesis,
it must be said, has met with a mixed reception from researchers, one
study recently concluding that the contention that ‘the bulk of the lowland
landscape was half-open and driven by large herbivores... is not currently
supported by the evidence’.^7 Rackham has argued that the failure of oak to
seed and thrive in shade may be the result of the arrival of American oak
mildew disease in comparatively recent times, and has pointed out numerous
other problems with Vera’s model.^8 The landscape of England before the
advent of farming was almost certainly more varied and more open than we
used to believe, yet much less so than Vera has argued.
Vera’s ‘dynamic forest’ is one aspect of a wider shift in ideas about the
way that natural plant communities develop, and in particular over whether
vegetation, left to its own devices, will inexorably progress towards a stable
‘climax’. The concept of succession, as originally formulated by ecologists like
Clements in the early twentieth century, assumes that this development will
follow, in effect, a unilinear path to a fixed and predictable end.^9 In the 1940s
Tansley and others argued that different plant communities could, in theory,
develop in the same environmental circumstances through the influence of
minor and random factors – the so-called ‘polyclimax theory’.^10 But the very
idea of an ordered progression to one, or more, stable ‘climax’ began to be
questioned in the 1970s.^11 By the end of the twentieth century, some ecologists
were arguing that natural landscapes are best considered as ever-changing,
dynamic systems, comprising habitat ‘patches’ which are constantly developing,
interacting with each other and responding to a myriad of external, especially
climatic, influences.^12 No habitat or ecosystem remains ‘stable’ for long, and
its future development is always essentially unpredictable in character.
There are particular problems with applying the idea of ‘succession’ to
England’s early post-glacial vegetation, for as this was first developing, humans
were already beginning to have a significant environmental impact. Most
researchers believe that hunting communities had, in late glacial times, been
at least partly responsible for the extinction of mammals like the mammoth
and woolly rhinoceros. Levels of predation by post-glacial Mesolithic hunters
- armed now with bows and arrows – would likewise have had a significant
effect on the large herbivores which Vera believes were the main ecological
‘drivers’ in the pre-Neolithic landscape. There is certainly evidence that hunting
communities had a direct effect on the vegetation by burning substantial
tracts, probably in order to concentrate game in particular locations, although
the extent of the practice remains unclear.^13 More importantly, within a few
millennia of the ending of the Ice Age, human societies began to have a far
more profound impact, through the introduction of farming.
The ‘Neolithic revolution’ arrived in England in the fourth millennium. A new
way of life, involving the cultivation of crops and – more importantly – the