I’ve been prompted to think about ‘invasive species’ by a debate currently raging in the Calder Valley, about woodland management, and in particular, the felling of mature Beech trees. As an animist and social scientist (I’m not an ecologist), I find myself frustrated by the terms in which this debate is often conducted. I’ll come back to this. But first, an example that gets to the heart of the matter.
A fine specimen of Purple Loosestrife has been growing in our semi-wild garden for many years. This old friend has a wonderful woody rhizome, and each summer sends up proud spikes taller than me, bursting with rich purple flowers. The species is one of my partner’s favourite flowers. On those rare occasions when we see it growing in the wild, we get quite excited. Sadly, the species (which is native to Europe, Asia, North West Africa, and Southeastern Australia) has been introduced into New Zealand and North America where, because the beetles that normally control its spread are absent, it forms dense monotypic stands that disrupt wetland ecosystems. So, ironically, a plant that was introduced into North America as a medicinal herb (and garden plant) finds itself described as an ‘infestation’. Attempts are now being made to re-instate biological controls by introducing the relevant Beetle species in order to restore some kind of equilibrium.
Peter Coates, who has written about the cultural reception of introduced species in North America, points out that certain landforms, places, and creatures (the Redwood, Bison, etc) have been appropriated, at various times, to create a sense of national identity. Conversely the ‘faunal or floral citizenship’ of biotic forms that are not American in origin, have been embroiled in cultural politics. Alien (=other) origin is often inscribed into species names. In America we find English Sparrow and European Gorse, and the U.K has American Mink and American Grey Squirrel.(1) Introduced species have caused major ecological disruption in many parts of the world, and their presence sometimes poses acute ethical dilemmas. For Mark Woods and Paul Veatch Moriarty it’s important to address the complexity of such situations. Citing the ecological damage caused by Feral Pigs in Hawaii, they argue that all values (in this case conservationist and animal rights) need to be articulated.(2) At the time of writing, millions of Norwegian Brown Rats are being poisoned on South Georgia in the interests of what was once probably the most important sea-bird colony on Earth. Several endemic bird species, that evolved in an environment without mammalian predators, are perilously close to extinction, whilst only about 1% of the island’s burrowing sea-birds remain.(3)
The U.K. has been relatively fortunate insofar as most introduced species have not caused major adverse ecological impacts here. In fact some have had beneficial ecological effects. Sara Manchester and James Bullock note that a few charismatic non-natives (defined as having colonised the British Isles since the Neolithic, c6,000 B.P), such as the Little Owl and Horse Chestnut, are now widely accepted as part of U.K. biodiversity. They also point out that neither dating the arrival of a species, nor defining human agency, are necessarily straightforward. Should species that have found a niche in the U.K because of climate change, for example, be regarded as ‘introduced’, or as ‘natural’ arrivals? They conclude that its not possible to generalise about introduced species. (4)
Our local authority, Calderdale, has drawn up a habitat action plan for the valley’s native woodland, most of which has been neglected and is in poor condition. Not surprisingly, factors in its decline include invasive species. Listed amongst these are ‘non-indigenous tree species such as sycamore and beech’. They associate beech trees with poor ground flora (they can nevertheless co-exist stunningly with bluebells!), reduced carbon sequestration and storage, and soil erosion. In Colden Clough the plan is to thin them by 60 per cent. Calderdale argue that many of the Beeches here are coming to the end of their life, and suffering from fungal infections and limb drop. There may be a case for gradually replacing beech monocultures (that may encourage disease) with mixed woodland, whilst retaining beeches as a valued feature, but the way this has been approached has upset a lot of people.
There has been vigorous local debate and in some cases opposition to felling has been successful. Opponents of the National Trust’s management regime in Hardcastle Crags have pointed out that beeches are thought to have been in the UK since the Pleistocene. According to Richard Mabey, a prominent advocate for the species, beeches arrived in Britain some 500 years before the Channel opened, and therefore qualify as ‘native’. Prehistoric traces have been found in West Yorkshire. For many of us, it would, in any case, not matter if they had only arrived here due to a fashion for planting them that began in the late 18th Century. They are naturalised and highly valued. One commentator points out that the biggest threat to beeches in Northern England now comes from conservationists. Given that so many of our other tree species are threatened by diseases, it seems perverse to remove healthy mature trees that people clearly love. As I’ve noted elsewhere, conservationists in New England, where European Beeches are valued, are trying to keep older trees going by treating fungal disease. Mabey, describes 400 year old pollarded beeches in the Chilterns, and celebrates their character, beauty, and cultural importance (Paul Nash, for instance, described them as ‘the Pyramids of my small world’).(5)
So, we have an un-necessarily polarised debate, not least because the ecological-forestry discourse of woodland management (adopted uncritically by local green groups?) appears to be privileging a version of scientific rationality at the expense of the (often well informed) feelings of local people. Personally I’d like to see them take a leaf out of the Woodland Trust’s book, and register notable trees; trees that are culturally important, or ‘of personal significance‘. In the context of advancing Ash Die Back, Mabey makes a case for valuing Sycamore (‘the weed of the woods’) as a replacement for Ash trees. Now, more than ever, conservationists should be ‘welcoming outsiders’ rather than ruling non-native species out of court.
Richard Mabey also speaks up for the reviled Indian or Himalayan Balsam, Impatiens glandulifera.(6) Prized by Victorian gardeners as the Poor Man’s Orchid, its energetic romp along British watercourses has seen its ratings plummet. ‘The Himalayan Terror’ has long been the subject of ‘balsam bashing’ events. I wonder how many local conservation volunteers in my area use Bach Flower Rescue Remedy, one of the ingredients of which (Impatiens) is derived from this very plant? Flushed from the success of one such operation, one balsam basher recently commented that her local river “looks more like a British river now, and less like a jungle”(!). Given that (i) many residents in nearby towns (including some of my former colleagues) are from, or have families in, areas where Impatiens glandulifera is a native species, (ii) that ‘bashing’ is a term often used by the perpetrators of visceral violence against those perceived as in some way different, and that (iii) venting rage against other-than-human species that happen to be non-native is a disrespectful way to remove such a potent plant, I find this terminology highly problematic. Thankfully volunteers are now increasingly being invited to take part in ‘balsam pulling’, ‘control’, ‘clearing’ (etc) rather than bashing. Impatiens, by the way, is said to be a remedy for irritability.
Mabey points out that balsam likes disturbed muddy ground not favoured by native species, and claims (on the basis of watching its progress since the 70’s) never to have seen it colonize an area occupied by native riverside vegetation. The species is highly valued by Bee Keepers, for its late pollen. Again there has been vigorous local debate, with one contributor arguing that balsam is a nitrophilus plant that converts human pollution into large quantities of valuable nectar. If this is correct, its contribution to local ecosystems may, in some situations, be extremely benign. Once again, debate tends to be polarised between absolute positions, with little space for nuanced views, and dissenters from the dominant scientific orthodoxy dismissed as ‘contrarians’.(7) There may well be a case for controlling balsam within our local woodland, but hopefully this can be done in a way that is respectful to the plant, and without resorting to emotive militaristic or xenophobic metaphors (blitzing, invading aliens, etc). We are all constantly learning about the intricacies of the natural world. Debate needs to be facilitated in such a way that all values are articulated, and where possible, addressed.
Beneath all the controversy I sense a deeper anxiety, about loss of wildness. As health and safety notices, direction signs, way marks, over sized information boards, corporately approved sculptures, and sundry installations presumably intended to ‘enhance the visitor experience’ -the calling cards of ostensibly benevolent management- go up everywhere, I am beginning to feel quite claustrophobic. Someone recently quipped that Hardcastle Crags (run by the National Trust) increasingly resembles Disneyland. Sylvia Plath – who wrote a striking poem about walking there on a Full Moon night in 1957 – would, I suspect, be ‘turning in her grave’ at nearby Heptonstall.
In his wonderful conclusion to a chapter about ‘the weirdness of Manannán’s subjects’, the denizens of the intertidal zone at Mannin Bay, Connemara, Tim Robinson has one of the most vivid descriptions of an alien species I’ve yet come across. “And the beach watched as we, perhaps the strangest of all creatures, with glacial slowness lifted our gigantic heads out of the seaweed, blinked our meagre allowance of eyes, balanced ourselves on towering appendages, locomoted by a succession of arrested fallings forward, communicated by waves of agitation of air molecules, … bent our spinal cords to coil ourselves into our waiting coccospheres and, rolling on wheels, a device unknown amongst the people of Mannanán, departed – strange to each other, strange to ourselves.” (8)
B.T 10/7/13, updated 10/9/13 to include reference to the status of beech as a native species in the U.K.
(1) Peter Coates, American Perceptions of Immigrant and Invasive Species; Strangers in a Strange Land, University of California Press, 2006.
(2) Mark Woods and Paul Veatch Moriarty, Strangers in a Strange Land, the Problem of Exotic Species, Environmental Values 10 (2001) 163-91. (available online, search title).
(3) Karl mathiesen, World’s Largest Rat Extermination Returns South Georgia to its Bird Life, Guardian 4/7/13.
(4) Sarah J. Manchester and James J Bullock, The Impacts of Non-native Species on UK Biodiversity and the Effectiveness of Control, Journal of Applied Ecology, Vol 37, Issue 5, pp845-864, October 2000. (available online, search Google Scholar).
(5)Richard Mabey, Beechcombings, the Narratives of Trees, Vintage Nooks, 2007. and (6) Mabey in the Wild, B.B.C. Radio 4, July 2011 and 2013. (available online for a year from the date of broadcast).
(7) despite citing the Botanical Society of the British Isles. Alien Invaders?
For a different view of Himalayan Balsam, as a valued medicinal herb threatened by climate change in Pakistan, see: Ghazala Nasim and Asad Shabbir, Shifting Herbivory Pattern due to Climate Change: A Case Study of Himalayan Balsam from Pakistan, Pakistan Journal of Botany (available online).
(8) Tim Robinson, Connemara, The Last Pool of Darkness, Penguin, 2009 p287. note: Manannan Mac Lir(‘son of the sea ) was/is a sea god, the Celtic Poseidon.
Sylvia Plath, Collected Poems, Faber, 1981.
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