| BEN |
| BOTANICAL ELECTRONIC NEWS |
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| ISSN 1188-603X |
| No. 281 January 31, 2002 | aceska@freenet.victoria.tc.ca | Victoria, B.C. |
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By "iceman" I mean an ancient male human body melted from glacier ice, as in the case of the 5,300 year old Tyrolean Iceman, or Ötzi as he was quickly nicknamed after the discovery high in the Alps in 1991. Ötzi's corpse has been studied by a great variety of scientific techniques among which investigations of both microscopic and macroscopic plant remains, found both internally and externally, have revealed much on diet, other aspects of ethnobotany, season of death and environment (contributions by Dickson, Oeggl, and Rott in Bortenschlager & Oeggl 2000; Dickson 2000; Fowler 2000). We know what Ötzi ate during the last few days of his life, we think that his homeland was to the south not to the north, we think his provisions may have been wrapped in moss, we think he died in Spring/early Summer not in autumn as first claimed and these studies and others are continuing and much has changed recently.
The first ever North American Iceman is Long Ago Person Found, Kwäday Dän Ts’ínchi in the local First Nation language (KDT for short). He was a male of about twenty years when he died about 550 years ago. His remains were found on the 14th August 1999 protruding from a melting, lateral part of the Samuel Glacier (Beattie et al. 2000). [At the very moment of discovery I was about 50 miles away!]
The elevation of the site is approximately 1500 m (about 5000 feet) and the place is Fault Creek in the Tatshenshini-Alsek Provincial Park in northernmost British Columbia (59 deg. N 136 deg. W). KDT had lived and died long before Europeans penetrated into the region and he died on a full stomach.
Such icemen as Ötzi and KDT pose questions different from those arising from frozen burials such as those of the Inuit, the Siberians in tombs, the sacrificed Andean children, or even the lead-poisoned sailors of the Franklin expedition. What had the icemen been doing where they were found, had they traveled far or not, what exactly were the events immediately before death and what happened thereafter, what were their racial and geographic affinities? In the case of Ötzi we know some of these answers and for KDT we are in the process of finding out. Richard Hebda of the Royal British Columbia Museum and I are working away merrily on the plant remains (pollen, seeds, leaves and mosses) and interesting findings are emerging.
References
Dr. Jim Dickson, Professor of Archaeobotany and Plant Systematics in the University of Glasgow, will talk about "Life and death of the Tyrolean Iceman: clues from plants" in Victoria B.C., on Tuesday, February 19, 2002, 7:30 p.m., UVIC - Elliott 168. This lecture is a part of the Botany Night series organized by the Victoria Natural History Society. Admission is free.
Alien species are a world-wide problem of much concern. Nobody can doubt the supreme importance of controlling aliens in, say, Hawaii or New Zealand. Many popular books give the impression that all introduced species eventually become problems. However, the impact of introduced species does vary from place to place and from group to group. Here I want to consider just vascular plants in the British Isles.
It is customary to distinguish different stages of invasion. A plant may be brought into a country alive but not found outside cultivation. It could just occur as seeds in a herbarium, it could be grown in a botanic or other garden. This stage I have called 'imported' (Williamson 1996). The next stage is for it to escape captivity, often called, for plants, 'casual' (Richardson et al. 2000). A short or long time later, it may be found that the plant species has a fully established, self-sustaining population, the 'established' stage. Some established species are, for various reasons, disliked, attacked, controlled. These are usually called weeds, or pests. Weeds may also be casual species as in volunteers from some crops. It is common (e.g. Lonsdale 1999) to compare the numbers of non-indigenous or alien species with the numbers of natives, often, but by no means always, using the number of established aliens.
Excluding micro-species, the number of natives is around 1400. There are 1350 listed in the forthcoming Atlas 2000 (Preston et al. in press), 1407 in the Ecological Flora Database (Fitter and Peat 1994), 1481 in Preston & Hill (1997). Other counts are given in Williamson (in press). One reason for the variation is uncertainty about which are native and which introduced, particularly which were introduced long ago. A central European habit is to talk of archaeophytes for plants introduced before 1492 or thereabouts (which excludes American species) and neophytes (a word with other meanings) for those introduced later. The Atlas 2000 is the first time that this concept has been used in a book in Britain and some species previously listed as native have been reclassified. This has caused unnecessary alarm in some conservation circles, partly from a misunderstanding that the Convention on Biodiversity urges countries to control all aliens. What Article 8 actually says is "as far as possible and as appropriate ... prevent the introduction of, control or eradicate those alien species which threaten ecosystems, habitats or species" which refers, as will be seen, to a small sub-set of aliens and even so allows plenty of flexibility.
Counts of British aliens are much more variable than those of natives, partly because different botanists have very different ideas of where to draw the line between casual and established and of whether casuals should be included. In Williamson (1993) I distinguished between widely naturalized (67 species), fully naturalized(143 more) and locally naturalized (348 more), naturalized being a term often equivalent, as here, to established, but often meaning growing in native vegetation (Richardson et al. 2000). The fully naturalised figure of 210 is quite close to the number in the Ecological Flora Database (196) (Fitter and Peat 1994) and in the British Ellenberg tables (239) (Hill at al. 1999). My locally-or-more naturalized number (558) is close to the numbers in the records behind the 1958 Atlas (Perring & Walters 1962) and the 1988 Sample Survey (Palmer & Bratton 1995), namely 588 in 1958, 605 in 1988, 468 in both, 725 in either (Williamson et al. in press). But we found only 118 neophytes reliably mapped in both those surveys (Williamson et al. in press). If casuals are included the total numbers are much larger, 1642 in Williamson (1993), 3467 in Clement & Foster (1994) with Ryves et al. (1996).
For the Atlas 2000 project (Preston et. al. in press) there are numbers for the species mapped in the book and listed on the accompanying CD. These are, in both, 1350 natives (as mentioned above), 44 species which may be native or alien, and 147 archaeophytes. The book maps 505 neophytes, the CD lists 651 more. Surprisingly, the book maps a further 40 as casuals and the CD adds 199 more, even though many botanists would probably regard at least the 651 extra neophytes as casuals.
All that seems to me to indicate that there are in Britain (or the British Isles, it makes no difference at this accuracy) about 1400 native species, around 200 definitely established aliens, 300-500 more that may be established somewhere, and some thousands more that have been recorded as casuals at some time.
There are two further complications, one to the totals, one to the definitions. To the totals could be added microspecies, mostly in three genera. Stace (1997) states that there are currently 261 such listed in Hieracium, including "a considerable number of aliens", 320 in Rubus, apparently almost all native, and 229 in Taraxacum, probably over half of them alien. At a guess that adds about 600 natives and 200 established aliens, quite a big addition.
The other complication comes from the distinction between non-indigenous and alien. Spartina anglica is the allotetraploid formed in England late in the 19th century from Spartina x townesendii, the hybrid, formed earlier in the 19th century, between the native S. maritima and the American alien S. alterniflora. British floras list Spartina anglica as native. It is not alien (brought in from elsewhere) but it is non-indigenous (not found in Britain in the Mesolithic period). The German term is heimatlos (homeless), with no native range on one obvious interpretation. Two notable species listed as aliens should perhaps be listed in the same way. Senecio squalidus (Oxford ragwort) arose in the Oxford Botanic Gardens in the 17th and 18th centuries from hybrids collected in Sicily (Abbott et al. 2000). British Rhododendron ponticum is at least partly, possibly largely, hybrid, formed in Britain between Spanish R. ponticum, American R. catawbiense and other species (Milne & Abbott 2000).
The concern about aliens is, broadly, about their environmental and economic costs. Some, notably some crop plants, produce considerable economic benefits. Any benefits should be balanced against costs. Valuing environmental effects is well known to be difficult (Perrings et al. 2000).
On the cost side, there has been one useful attempt to estimate the control costs of all British plants treated fully in floras (Prus 1996). From the national costs of herbicides, information on which plants were controlled by which herbicide, supplemented by information on other forms of control, he was able to derive a figure, in pounds sterling per year, for effectively all species. A graphical presentation of his results for the more costly species classified as native, archaeophyte and neophyte is given in Williamson (1998). More recently I (Williamson in press) have tried to estimate the costs and benefits of thirty interesting (widespread, potential pests, etc.) non-indigenous species. The Prus cost for these varies from 58 million pounds to a fraction of a pound. Clearly the cheaper ones are in no sense a pest on this measure, indeed only nine score more than GBP 22,000, which is still a trivial cost nationally. Indeed I cannot take two of them (Galinsoga parviflora, Matricaria discoidea) seriously as threatening invasives in the CBD sense, but two others (Heracleum mantegazzianum, Impatiens glandulifera) represent more serious threats not reflected in their Prus cost. That makes just nine alien species which are in some sense threatening in the British Isles.
These nine species can be classified as:
That's a remarkably small proportion of however many hundred species are regarded as established non-indigenous species. A few tens more might sometimes be regarded as weeds (like Galinsoga parviflora and Matricaria discoidea mentioned above). Williamson & Brown (1986) counted 39. Depending on what you regard as a pest and what as established, the proportion of current pests among the currently established seems to be only between one and ten percent.
The cost of control is far from being the only impact that can be measured. In Williamson (1998) I reported five other measurable impacts. Briefly, British established alien plants have, species for species, the same impact as native plants when measured as weediness in various ways or as local abundance but have a lesser impact measured as range. This is partly because most British aliens are still increasing their range. Typically it takes a century or two to achieve a full range in Britain; curves for the spread of three alien Impatiens are given in Williamson (1996) which demonstrate this.
Of the thirty interesting non-indigenous species considered in Williamson (in press) - see Appendix below - all except eight, i.e. 22, have significant increases from 1958 to 1988. The eight are Acer pseudoplatanus, Aegopodium podagraria, Cymbalaria muralis, Galinsoga parviflora, Matricaria discoidea, Mimulus guttatus s.l., Spartina anglica and Veronica persica. These are all introductions of the mid-nineteenth century or earlier except Spartina anglica which has been much spread deliberately. All eight are widespread in the British Isles except Galinsoga parviflora which is only found in central and southern England. So some of those 22 species still spreading may yet have much more serious impact than they have had so far; Crassula helmsii being a particular cause for concern in taking over ponds and similar water bodies. But as new species are still becoming established, it may well be that the proportion of pests will scarcely change.
Some non-indigenous plants in Britain cause serious economic and environmental damage. These species appear to be only one to ten percent of those that establish permanent populations. The numbers of both established and pest species can be expected to increase, though fairly slowly, for the foreseeable future.
References
Appendix
The thirty interesting non-indigenous British plants considered in Williamson (in press).
Species & Family
Royal Botanical Gardens, Canada's largest botanical garden whose holdings include 1100 ha of formal gardens, wetlands and woodlands is seeking a Field Botanist. This a two year term position [the incumbent is on a leave of absence] and begins on April 1st 2001. The successful candidate will have at least 5 years experience in field botany, herbarium curation and documentation, supervision of students and interns and managing a budget.
The ideal candidate will also be a team player who is innovative, creative and finds work challenging and rewarding. Experience in preparing budgets is also an asset. An undergraduate degree in botany is essential.
Please forward your resume in confidence by February 18th 2002 to:
We thank all applicants: however, only those selected for an interview will be contacted. [Not very nice, eh? - AC]