Controversial Conservation (II)

Following on from this vague post, here are some vague ideas about rewilding, starting with…

>>A very brief natural history of Britain.

We’ll begin in the Palaeolithic; a cycle of glacials and interglacials, during which Britain was repeatedly colonised and evacuated by European plants, animals and people. As the climate warmed and the ice retreated for the final time (something like 15,000 years ago), humans recolonised Britain, initially via the huge estuarine landscape of Doggerland (now under the North Sea). As sea levels rose, the English channel cut Britain off from the rest of Europe, probably curtailing its colonisation by many animal and plant species.

It’s not totally clear how humans interacted with this post-glacial landscape. There would have been some hunting, some forest clearance, and some agriculture. Some species were hunted to extinction, others were assisted in colonising our island, and others still benefited from novel ecological niches provided by humans. Some probably went extinct ‘naturally’ as open-ish tundra gave way to more-or-less closed forest. The details aren’t important (well, not right now – convenient). I think the key point is that, since the ice sheets last wiped the slate clean, British wildlife has evolved, to a greater or lesser extent, alongside humans and a changing climate.

The result of this co-evolution has, I reckon, been an increase in ‘biodiversity’; both in terms of total species richness (due to the introduction of plants and animals from Europe and further afield) and spatial turnover from place-to-place (due to the maintenance of a mosaic of pre-successional habitats). In other words, a blanket of pristine Atlantic woodland would probably harbour fewer species (or at least fewer individuals of many species) than a patchwork of various natural and semi-natural habitats. (I haven’t given this much thought, but I think it’s probably a fair generalisation.)

Functional diversity, on the other hand, might well have been eroded (again, this is a hunch) due to the extirpation of several large-bodied, ecosystem-engineering, ‘keystone’ species (beaver, boar, aurochs, wolf). Many of the ecological functions once provided by these species – disturbance, grazing, predation, fear – are now provided partly or wholly by humans and their domesticated livestock. Unfortunately – at least away from a few nature reserves – this replacement of natural processes by anthropogenic ones has started to crumble as agricultural production across much of our countryside has (buzzword) intensified.

Moo

So, this is the context in which we find ourselves – or at least my interpretation. A transformed landscape within which ecological succession is interrupted by resource extraction and physical disturbance. A species inventory filtered, supplemented and moulded by a few millennia of co-evolution with humans. And an absence of many keystone species, leaving it up to humans to replicate extinct ecological processes. Importantly, a ‘pre-human’ baseline is hard to identify because we recolonised Britain at about the same time as many wildlife species, and during a period of climatic change.

>>Rewilding or ‘traditional’ management?

I think this leads on to one of the key conservation debates of the last few years; should conservationists attempt to actively mimic the traditional management practices which have replaced past ecological processes, or should we take a more hands-off approach (perhaps after kick-starting the system with a few species re-introductions) and let natural processes flourish?

Rewilding is exciting, and is catalysing a much-needed discussion. But, to my knowledge, evidence is pretty sparse when it comes to understanding what happens when humans step back. How will nature cope unaided in a landscape so fragmented and transformed as the British countryside? We’ve lost apex predators and mega-herbivores, and gained some pretty disruptive alien species; the climate has warmed, and the geochemistry has been tampered with. My gut feeling is that a ‘purist’ rewilding strategy – by definition relying on unimpeded natural processes – may result in some pretty negative biodiversity consequences, however we choose to measure these.

Most British rewilding projects might so far, I think, be better described as habitat recreation. Most rely on semi-feral domestic livestock, which are periodically controlled – humans stepping in to replicate the extinct process of predation (at whatever stocking density is decided upon by the reserve manager). I think for rewilding to work in its strictest sense, it needs to operate over larger areas, where nature can be left to its own devices.

Of course, this assumes a fairly strict definition of rewilding, and rather than getting hung up on semantics, maybe we should just get on with trying stuff out. ‘Rewilding’ is happening in Britain; these projects are reinvigorating and inspiring in their confrontation of the conservation status quo. In particular, I think the rewilding movement has a crucial role to play in:

1. Encouraging process- rather than outcome-driven habitat management
2. Thinking seriously about species re-introductions
3. Thinking seriously about the ‘landscape scale’
4. Reminding us of the past, even if a meaningful baseline is hard to grasp