ADAPTATION STRATEGIES

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ADAPTATION STRATEGIES CHRIS GIBSON As naturalists we live in interesting, even exciting, times. Our flora and fauna, always dynamic, are now increasingly so, and we are seeing new species turning up on an increasingly frequent basis. Many, perhaps most, of these are species from more southern climes, the colonisation and spread of which is entirely consistent with climate change, although we should not be too quick to ascribe causal factors in the absence of hard evidence.

A few well-known examples from our part of the country include: • • • •

Little Egret Mediterranean Gull Roesel’s Bush-cricket (followed by the Long-winged Conehead) Scarce Emerald Damselfly (followed in its wake by the Small Red-eyed Damselfly) Bee-wolf Wasp Spider

• • These are previously rare or absent species, which have colonised markedly, in a way which would be expected under climatic warming. What’s more, they have been doing so for some considerable time, 20 years or more. Remember 20 years ago? – a time when climate change, if talked about at all, was just a possibility, a theory. Understandably the climatologists were cautious – climate is very variable, and changes for a variety of factors over a range of timescales – they had their professional reputations to worry about. But not so the wildlife: if the climate changes they will respond, and we as naturalists are admirably placed to see it. During the period of scientific doubt, the signs were there – the wildlife was crying it from the rooftops – our world is warming up!

The examples given thus far are just the tip of the iceberg, the more obvious cases of rare, extinct or previously absent species becoming relatively commonplace. Other more subtle, but no less important, changes are under way, including for example: • Phenological changes, as discussed at length elsewhere in this volume • Changes in wintering areas and habits: Avocets have long been valued as part of the breeding bird scene in East Anglia. It is a relatively coldintolerant species, and winter warming has encouraged the recent development of several huge wintering populations eg last winter on the Thames, they peaked at around 1500 birds.

• Changes in breeding areas and habits: The UK Cormorant breeding population is currently rocketing, a phenomenon which started at Abberton Reservoir in the 1980s, where they adopted the tree-nesting habits of the Continental race sinensis, which form a significant part of that breeding population. The early colonisers of Abberton were largely sinensis, which in addition to tree-nesting is also an early nester, and it could be argued that warmer springs led to it being able to breed here, thus triggering the population explosion.

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And of course there are likely to be many more to come, for example:

• The two recent British breeding attempts by Bee-eaters • Perhaps a recolonisation of more ‘lost’ species like the Red-backed Shrike.

But in respect of this last example, I must issue the first note of caution – they may not. Shrikes may not be directly climate-dependent, but their food – large insects – is. If they tried to return to their haunts last occupied between the Wars, would they find conditions suitable? The agricultural landscape is very different to those times, and it is quite likely that irrespective of climate features, their food supply would not be sufficient. So far from being all positive, climate change may well lead to unfulfilled promise and, as we shall see, to severe negative changes in out biodiversity.

As we consider possible adverse effects of climate change, we realise that these are many and varied. The most dramatic examples perhaps come from the uplands, where climate zones are moving both north and uphill; here we are seeing progressive change and loss in arctic-alpine habitats, threatening the species which are dependent upon those habitats eg Ptarmigan, Dotterel and Moss Campion.

Closer to home, species losses which are becoming apparent are the reduced numbers of Purple Sandpiper, Short-eared Owl and Twite, birds which traditionally winter on our coasts, but which now appear to be wintering further north.

However, the negative aspects of climate change on biodiversity are perhaps best appreciated by the impacts on our habitats, some of which have again long been apparent, if only we had the eyes to see it: • Our wetlands are drying and dying • And especially on the coast, which is at the forefront of climate change impacts.

On the coast, the impacts are several-fold:

• One component of climate change is sea level rise, due to thermal expansion of the seas of the world; this is one of the main causes of the currently observed high rate of salt marsh erosion, which in Essex and south Suffolk amounts to some 40 ha (or 1%) per annum.

• Increased wave energy in the estuaries is leading to selective removal of fine sediments, especially in the outer reaches, which is changing the feeding distribution of birds which are characteristic of certain sediment types. For example, Black-tailed Godwits, characteristic of sloppy, fine muds, are increasingly becoming concentrated into the heads of the estuaries, while Knot and Bar-tailed Godwits, both species of sandier, coarser sediments are moving into the mouths from the open, exposed coast.

• A second component of climate change is increasing instability, and increasing incidence of extreme events such as storms and tidal surges, which leads to erosion of and damage to natural sea defence structures such as sand dunes and shingle ridges.

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So while climate change can lead to interesting and exciting natural changes, it does also have very worrying adverse effects, which mean we must do something about it.

But what should we do, and what can we do? As naturalists we have a responsibility to monitor and report on those changes, to provide the observational underpinning to help inform our actions, which on a wider perspective are classed as either mitigation or adaptation.

Mitigation is essential. It is all about reducing the future potential for anthropogenic climate change, by addressing the causes; such actions include reducing climate changing emissions, by adopting greater reliance on renewable energy sources (and arguably on nuclear energy sources, although the other risks posed by that technology may override its benefits in the climate change field).

Adaptation is about learning to live with climate change, through addressing or taking advantage of the symptoms: even if all climate changing emissions stopped today (which realistically they are not going to be) we would still be committed to future climate change, possibly of a greater magnitude than the current worst case scenarios, given the recent reports of melting icecaps (reducing the reflection of solar energy) and permafrost thawing (releasing additional carbon dioxide).

Mitigation and adaptation are not alternatives – they must go hand in hand.

So much for fine words, but what can we do by way of adaptation? Every sector of society must adapt to its own issues – for example, agriculture must explore more drought-tolerant crops; tourism must promote holidays in our warmer land, rather than in the increasingly arid parts of southern Europe.

Two sectors I shall discuss in more detail are gardening and nature conservation.

Perhaps the key need in the gardening sector is to reduce water use, to reduce exploitation of this increasingly scarce resource. Much can be achieved with cultural practices, especially placing more reliance on mulching. But more fundamentally, the choice of plants must reflect the resources available – we should ditch the water-hungry hybrid tea roses in favour of more droughttolerant plants. The good news is that this can be entirely consistent with biodiversity conservation, in the form of wildlife gardening. Many drought tolerant plants come from Mediterranean regions, and any visitor to that region can attest to the fact that these plants in their natural habitats teem with insect life.

We must challenge one of the great dogmas of wildlife gardening, that a wildlife garden must have only native species – what I call the ‘worthy but dull’ approach. Look at it from the perspective of the insects – provided they get their necessary resources of nectar or pollen, they don’t really mind whether it comes from native or non-native plants. So lets lose the waterhungry natives, bring in drought tolerant aliens, do our bit for climate change and have a successful wildlife garden (a great example is the waterless garden at RHS Hyde Hall), which can be both attractive, dramatic and functional.

And we can also use creative planting to address some of the issues arising from phenological changes. With insects emerging earlier due to global

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warming – I have seen honeybees and bumblebees foraging in my garden in early January – if their natural forage plants do not respond as quickly, they can find themselves in a barren landscape, as there are no native plants providing the nectar and pollen they need. So by planting winter flowering species, such as Mahonia and Lonicera × purpusii, you can help bridge the winter gap for these early emergers.

Yes, you heard it here first: English Nature says ‘bring on the aliens’!

So how about the conservation sector applying adaptation measures? In some respects we are doing it already, by for example creating new salt marshes through managed realignment, to restore our eroding habitats.

But the species which are suffering may be a little more difficult. Those which can move in response to climate change will do so, and we have seen examples of this already. But some won’t or can’t move, especially those with poor dispersal powers. A fine example is the Heath Fritillary butterfly – even if suitable habitat is available a short distance away, a single arable field can be an insurmountable barrier to movement.

The truly sustainable approach to the problem of fragmentation is to reverse it, to reconnect our landscape. The new Environmental Stewardship scheme may go some way towards this, but the problem is that it lacks strategic planning. There is little point in creating a wildlife corridor is part of that corridor is missing – a road from A to B is useless if there’s a chunk missing in the middle. We really should be taking a leaf out of the book of some of our European partners: in the Netherlands for example, someone has drawn a series of lines across the country, and their Government has set about buying these strips and creating strategic wildlife corridors, by compulsory purchase if necessary.

But realistically that isn’t going to happen, or not quick enough to meet the demands of wildlife which wants and needs to move: rebuilding the fabric of our countryside takes time, and that is a commodity which is in short supply.

So we will have to take a more interventionist approach, and give those less mobile features we value a helping hand.

This used to be called translocation or reintroduction, both of which are alien to some conservationists’ philosophy: perhaps assisted migration would be better. Actually, we have come a long way in our thinking on this over the past 20 years, especially through the auspices of Biodiversity Action Planning; in many respects it is now a respectable conservation tool – we now have Red Kites over the M40 and Heath Fritillaries flying in several Essex woods.

One of the first regulatory tests in considering such projects is to ascertain that the species to be moved used to be where we propose to put it. That is no longer tenable – indeed, we should be actively seeking to move them to habitats north of their current/historic range, to put them into their future climate space.

But still that is not the full solution. As species move north, there is one huge barrier to movement – the Channel – a physical, conceptual and legal barrier. The risk is the south becomes less favourable to the current suite of species, our species move north and some of those which want to move in from the south can’t cross the channel, and the south becomes an ecological

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vacuum. This includes species which can’t disperse over the sea, and those which won’t – one possible example is the Crested Lark, which we should perhaps be viewing as the ecological replacement for our more northerly Skylark.

So how do we get over this hurdle? Firstly we should be visiting those parts of the Continent which are like what we are going to become in climatic terms, identify the keystone species that we are going to need, assess their dispersal potential, and if it is low, pick them up and bring them here. Not only conservation heresy, but also illegal!

If that is a step too far, perhaps we need to consider a stepping stone approach, and for this I look to our friends at the Port of Felixstowe. Take one redundant container ship, establish some habitat on deck, moor it in northern France for a year, and watch the wildlife come aboard; then bring it over to Kent, open the gates and let the wildlife we need walk, fly or otherwise move into Britain. Repeat for a few years, and lo and behold, we have a range of the wildlife relevant to our new climate. I call this the New Ark project (and I must stress this is not English Nature policy – yet!).

The key message is that we have to ‘think outside the box’, and take some risks. Clearly, taking risks must not be equated with recklessness. A corollary of all I have suggested is that we need some form of Biodiversity Customs Control, people (another role for we naturalists here) to screen species which are brought here, or allowed to get here, or indeed allowed to escape from gardens, to allow us to screen out those which may become the next Floating Pennywort or Hottentot Fig, so that we can head off future problems before they arise.

Now is not the time to be risk averse or over-precautionary; the risks of not doing something are simply so great - our future biodiversity depends on it.

Chris Gibson English Nature Harbour House Hythe Quay Colchester Essex CO2 8JF

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