Introduced species - attitudes and management: Book Review
Invasive & introduced plants & animals. Human perception, attitudes and approaches to management. Edited by Ian D.Rotherham & Robert A.Lambert. Earthscan 2011, 374pp. RRP £65.
There is a lot to ponder in this book, but what it isn't is a pest management manual - it doesn't tell you how to control rhododendron invading your permacultural oak-with-coppice & pigs under. In many ways it's two books in one, divided between parts 1,2 & 4 which look at the human perceptions and attitudes mentioned in the subtitle (11 contributions), while part 3 explores case histories at various levels of scale and detail from around the world (13 articles).
To one who has been involved in issues of invasive plants on fragile island ecosystems for 35 years, the perceptions & attitudes sections are, to say the least, jarring. Several contributors attempt to minimize the impacts, and blame wanting to eliminate the invaders on a kind of eco-racism-cum-xenophobia. One, the St.Andrews historian Chris Smout, even considers people trying to save the Spanish white-headed duck by eliminating invasive ruddy ducks as promoting a kind of apartheid by preventing these species from interbreeding. Let's be clear, as is Dan Simberloff in his welcome chapter rubbishing these theorists (who are social historians, not ecologists), we are dealing here with protecting ecosystems under threat, not human proxies. These are real animals and plants, not some kind of Disneyland talking bambis. Yes, grey squirrels are from America, and knotweed from Japan, and yes, some popular tabloids write up the stories sensationally in a pseudo-xenophobic way, but ecologists and conservationists only care where they come from when seeking clues on controlling them - the geopolitical designation of their homeland is totally irrelevant. Perhaps the conventional designation 'alien', originating in the 19thC, is too loaded, and one should simply call the incomers 'introduced'.
Attitudes are however often at the crux of how to deal with species that become, or threaten to become, pests - whether to us as humans, or to the ecosystems we try nowadays to preserve. Grey squirrels are enjoyed as tame and attractive wildlife in town parks, while if you grow nuts, trees or protect red squirrels they are a major menace. Buddleia is widely recommended and planted to attract butterflies, recently much in decline, yet germinating anywhere its roots can unpick buildings and cause huge and expensive damage. Rabbits can be very damaging to crops, yet are needed to maintain various prized, if perhaps not entirely natural, short turf habitats, and make very convenient burrows for puffins. Chapter 21 explores the remarkable assimilation of the horse into Maori culture in New Zealand following its introduction by Europeans - a classic example of how an 'alien' goes 'native'.
And then what is native ? Hares, introduced by the Romans, are protected priority species, yet try to re-introduce beavers or boars, both countryside staples in the Middle Ages, and there's an outcry from those who, rightly or wrongly, fear their impact. Wild boar and eagle owls are even included on DEFRA lists of non-native species, despite being known to have been present naturally in the UK before humans messed up the ecosystem.
Several contributors contrast the 19th century attitude of 'acclimatization' (releasing foreign species to 'enhance' nature) with current attitudes attempting to preserve the integrity of biogeographically separate biomes and their long evolutionary histories - though none of them actually point out that it was ultimately the understanding of evolution, biogeography and the complexity (and fragility) of ecosystems that drove the change. Most of our worst invasive weeds originate in garden plants once promoted as spectacular and beautiful - when William Robinson wrote The Wild Garden in 1870 little did he realise his favourite Japanese knotweed and giant hogweed would be public enemies little over a century later. While mammals and fish introduced for 'sport' have not been as noxious in Britain as in many countries, animals escaped or released from fur farms (coypu, mink) or hatcheries (signal crayfish) have had devastating effects. I have always found it ironic, if not in any way pleasing, that animal rights activists who liberate mink from fur farms not only rapidly cause the death by road-kill or starvation of many they release, but then that of countless ducks, water voles etc. killed by the survivors and their offspring.
The chapters on examples from around the world are in many ways more enlightening than the theoretical ones, as they are more grounded. They range from a broad discussion of invasive plants in Africa to detailed histories analyses of single species, Japanese knotweed and wild boar in the UK, and Prunus serotina, an American cherry, in France. Hawaii and New Zealand are amongst the most notorious and heavily impacted recipients of 'outside contributions' to their biota, and the latter gets a short chapter on the history of settler introductions and recent attempts to delete them to protect the remnant native fauna and flora. Oddly though, the Kiwi author does not cite any of the ecologists active in actually planning and carrying out eradications of invasive species or even those scientists who have forensically documented the problems.
Academic publishers appear to like publishing compilations of this sort, although the lack of coherence in the material presented and the huge gaps in geographical discussion make one wonder why. Perhaps only 10% of the authors approached responded ? The main benefit appears to be that a wide range of potentially useful references are assembled together in one place, while the book is a lot more readable than a bare bibliography. There is a summarising chapter by the editors which is balanced and sensible, but an integrated review of the subject, rather than this disparate set of contributions, would have been more useful.
Finally, what's the relevance of this to UK Permaculture ? Not a great deal, though some will have problems with grey squirrels, muntjac, knotweed and rhododendron - but no more than with native foxes & deer, starlings, bracken or couch-grass. However there are a lot of interesting things to ponder, some useful, some not.
Dr Anthony Cheke graduated in botany from Cambridge and has worked in both plant and animal ecology in Europe, Asia and Africa, and most particularly since the early 1970s on Indian Ocean islands, where introduced invasive species are rife and extremely detrimental to the original ecosystems.
In the early1980s he changed career to co-run a bookshop in Oxford, but from the late 1990s returned on and off to the islands to write 'Lost Land of the Dodo, an ecological history of Mauritius, Réunion and Rodrigues' (Poyser 2008).
He currently chairs a small local conservation group in Oxford (http://friends of astonseyot.org.uk), and despairs of keeping grey squirrels off the nuts in his Permaculture garden.