| BEN |
| BOTANICAL ELECTRONIC NEWS |
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| ISSN 1188-603X |
| No. 168 July 5, 1997 | aceska@freenet.victoria.bc.ca Victoria, B.C. |
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Professor Emeritus of the University of British Columbia on the occasion of his 70th birthday. Through his work in the fields of bryology and phytogeography, Dr. Wilf Schofield has made significant contributions to our botanical knowledge of the Pacific Northwest, Canada, and other parts of our planet.
The Journal of the Hattori Botanical Laboratory is planning to publish a special Festschrift issue dedicated to Dr. Schofield with over thirty papers. Although BEN cannot compete with the Hattori Journal, I hope that even those BEN readers not really interested in mosses will appreciate the special focus of this issue.
Dr. Wilf Schofield will celebrate his 70th birthday (July 19) on a field trip to Alaska. All the best success on this and all other endeavours!
A number of bryological and vegetational studies in the boreal and north-temperate regions have shown a generally high resemblance in the bryophyte flora and bryophyte ecology throughout the northern wetlands (e.g. in Japan Suzuki and Fujiwara acc. to Tuxen et al. 1972, in Quebec Gauthier 1980, and in Minnesota Janssens 1992).
Sjors (1963) compared boreal wetlands in Ontario and Fennoscandia, and was able to identify corresponding ecological gradients in mire (peatland) vegetation of these two regions primarily on the basis of the bryophyte composition and water chemistry, while the similarity in vascular strata was lower.
During the past 10-20 years, great advances have been made in vegetational research of wetlands both in North America and in Europe. Wetland classifications of extensive regions, such as Canada (National Wetlands Working Group 1988) or Alaska (Viereck et al. 1992) tend to emphasize large, mappable landscape units and contain vegetational classes at lower levels utilizing one or two dominant species of each layer.
The question is then: if bryophytes are a significant component of these systems, particularly in peatlands, and if they are widely distributed, common indicators of wetland ecology across the circumarctic and circumboreal bioclimatic zones, what is their role in vegetational classifications?
The traditional Braun-Blanquet system (BB) basically utilizes the information of all plant species of community. Within Europe, a number of national vegetation classifications have been published recently, based on the European phytosociology (Braun-Blanquet school), e.g. those of Rodwell (1991) for Britain, and Schaminee et al. (1995) for the Netherlands.
There have been attempts to expand the BB system also to other regions than continental Europe. Tuxen et al (1972) compared Sphagnum bogs of Europe with selected North American and Japanese materials and developed a tentative global phytosociological classification of bog hummock communities. Recently, Wells (1996) summarized his detailed vegetation studies in Newfoundland developing a phytosociological classification for peatlands of Atlantic Canada. Wells (1996) discusses the relationships with the European vegetation types and develops in most cases a new nomenclature for his study region.
In his new book (Vegetation of North Europe, in German), Dierssen (1996) who has earlier studied especially the NW European mires, expands the BB system to the north. The problem is that the traditional nomenclature of vegetation units developed originally for central Europe, is retained, and this nomenclature clearly runs into complications in N Europe where boreal and subarctic vegetation prevails. Bryophytes appear mostly at lower levels as community types named by one or two species, and for example the large class of rich fens is called Caricion davallianae - the name refers to a sedge, Carex davalliana which is practically absent from the boreal and subarctic regions of Europe.
Instead of linking rich fen vegetation to higher plants of generally limited distribution, it would be preferable to define circumboreal rich fens (Braunmoore, see Pakarinen 1995) by one or several bryophyte species characteristic of these wetland habitats: Campylium stellatum, Cinclidium stygium, Tomentohypnum nitens.
Literature cited
We have been surprised to find that that mosses are one of the most conservative plant groups. The oldest known bryophyte fossils from the Palaeozoic era compare well with the recent plants and can be assigned to living families or genera.
Mosses have changed very little in the last 300 million years. Their origin goes even further back than this. Initial studies of mosses fossilized in Dominican amber showed that even 25 to 40 million years ago the same species that we know today occurred on the Island of Hispaniola. Most of the fossil finds of mosses in the last century were from the Tertiary and Quaternary period. People believed that mosses did not preserve well as fossils because they have no woody parts. Only at the beginning of this century the first moss from the Carboniferous period was discovered in England. But by the year 1957 33 species were known from the Palaeozoic and Mesozoic era (Savicz-Lyubitskaya & Abramov 1959), and by 1967 the number grew to 68 species (Jovet-Ast 1967, Oostendorp 1987). Since then more fossil mosses have been found in the Upper Permian rocks in Russia (Ignatov 1990) and in the Permian rocks in the Antarctica (Smoot & Taylor 1986).
Originally, fossil bryophytes were placed in several artificial "form" genera (e.g., Muscites, Hepaticites, Thallites etc.). New studies show that even the oldest known fossil mosses are often so similar to the living mosses that they can be placed into the recent families or genera. Because of this, we cannot make any conclusions about the evolution of mosses based on fossil records.
The origin of mosses goes further back than can be documented by known fossils and we have to guess from what plant groups mosses evolved. The oldest known bryophyte is Pallavicinites devonicus from the U.S.A., about 350 million years old. It can be placed in the recent liverwort order Metzgeriales. In the Devonian period we can find thallose liverworts that are similar to Anthoceros or Riccia. The oldest "true" moss is Muscites plumatus from Carboniferous period, found in England that can be placed into recent order Bryales. In the Permian period we can find the first fossils related to peat moss (cells are differentiated into green cholorocysts and empty water-storing hyalocysts), but having leaves with midrib. These fossils were placed into a separate fossil order Protosphagnales, but it is questionable if they are indeed the ancestors of our recent peat moss (Sphagnum). The first pleurocarpous mosses are also known from the Permian period.
Mesozoic strata are relatively poor on moss fossils due to larger extent of dry regions that were not so favourable to fossilization as the Palaeozoic or the Tertiary swampy forests were. From the recent areas of distributions we can conclude that in this time happened the differentiation of the mosses adapted to dry environments. Fossils from this time resemble Anthoceratales, Marchantiales, Metzgeriales, Jungermaniales, Sphagnales and Bryales.
In Europe, forty species of mosses are known from Miocene and seventy-nine from Pliocene (Dickson 1973). All except four are mosses that still exist today. The species composition of Miocene and Pliocene mosses of Europe is similar to the recent bryoflora of southern parts of North America or of Macronesian Islands (Canary Islands, Madeira, Azores). Genera such as Gollania or Echinodium spread to these volcanic islands from continents, but have disappeared from Europe during the glaciation. The bryoflora of some parts of Macronesian Islands gives a good impression of the late tertiary bryoflora of Europe.
Amber is an important source of fossils, including those of mosses. Mosses are known from Baltic, Saxon, Mexican and Dominican amber, all from the Tertiary. While the Baltic amber originated from the pitch of conifers, Dominican amber came from leguminous tree (Hymenaea spp. - Caesalpinaceae [recent trees of this genus are source of copal - AC]) and is extremely clear and transparent.
There are eighteen species of liverworts known from Baltic amber and twelve from the Dominican amber (Grolle 1988). If they are identifiable, these are all extinct species and they were described and classified as artificial form-genera. A recent review of these samples resulted only in one new identification, i.e., the type of Muscites hauchecornei has been identified as the recent Trachycystis flagellaris that now occurs from eastern Asia (China, Korea, Siberia) to Alaska. In the Miocene this species occurred in Poland.
Two other now extinct species of Trachycystis have been described from Miocene in Silesia and from the Pliocene of the border area between Germany and Holland (Miller 1984). These species represent examples of Asiatic elements in the Tertiary flora of Europe that were (as many flowering plants, e.g. Ginkgo, Sequoia, Metasequoia) wiped out in Europe during the glaciation.
In summary, bryophytes are very old in an evolutionary sense. Liverworts existed in the Devonian era 350 million yers ago. Today's bryophyte orders were already differentiated in the Paleozoic period. Today's genera are known from Tertiary fossils. More than 90 % of the species of mosses present towards the end of the Tertiary are still extant today. Apart from fluctuations in abundance of certain species, the bryophyte flora of the Quaternary was already identical with the recent one.
Literature cited
A few weeks ago Herbarium COLO received a gift from the Herbarium at Gothenburg, Sweden. In moving into a new building for the herbarium there the remains were discovered of a long-standing bryophyte exchange club that operated out of the botanical garden. The club dissolved many years ago, and my friend Uno Eliasson felt that since I know the Swedish language well enough to decipher thousands of hand-written labels, I might be the best place to send them inasmuch as no American institutions received material from the club. Specimen dates range from 1824, then mostly between 1860 and 1900, and a few from the 1930s. The collection came in ten big cartons, each containing at least 2,000 specimens. I have made a list of over 250 contributors, each with a distinctive handwriting, All but a few of the labels are hand-written on the packets. The collection is of very fine quality, and many of the well-known professionals, such as Zetterstedt, Du Rietz, Bryhn, Hagen, Blomberg, Kindberg, S. O. Lindberg, Wilhelm and Sigfrid Arnell, Schiffner, Schimper and Warnstorf are represented, along with laymen, priests, teachers, and landed gentry. This collection represents a great addition to our Scandinavian collections.
Botanical exchange clubs were very important in the nineteenth century; there were several of them on the continent, and in America cryptogamic exchange clubs are still operating although at a declining rate. They brought together all levels of activity and knowledge among devotees of mosses, hepatics, and lichens. A very vigorous exchange club in Lund dealt with all groups of plants, especially vasculars, and died only a few decades ago. The specimens fill the herbaria of Europe, and the geographical coverage is extraordinary, despite the difficulties of travel at the time. One large segment of this collection consists of brophytes collected in Spitzbergen and North Greenland from 1861 to 1870 by Sven Berggren and A. L. Malmgren labelled "Plantae in itineribus Succorum polaribus collectae" (plants collected in the course of polar rescue expeditions)! The data are sparse, merely the country, province, parish, and village; rarely is there any mention of the habitat.
When an interesting plant was found, it appears that many people visited the spot over a period of years and collected at the same site. An important offshoot of this extraordinary collecting activity was not only the creation of museum collections and the instruction of hundreds of serious amateurs in the sub-science of bryology (certainly a lot more than we have today). Some years ago I encountered scientific papers in which it was shown that the accumulation of heavy metals, especially lead, "frozen" and dated in moss specimens in the herbaria enabled scholars to trace the origin and spread of pollution over the course of the Industrial Revolution in Scandinavia!
The curator at Gothenburg should be congratulated on not letting this collection go into the dumpster, as it well might have, and certainly would have in many an American institution where space is a problem, and where "classical" taxonomy is considered a waste of good academic space. I receive many letters in my present "exile" from the COLO herbarium that tell me horror stories of herbaria everywhere being sent down the drain, their value and importance being denied in favor of the more glitzy new aspects of biology. Every innovational aspect of biology is surprisingly important, but the museum collections must be preserved at all costs, because they are our ultimate basis of understanding biodiversity. We are also losing history. I shudder at the loss of the life works of professors, whose notes and unpublished work is tossed along with their human usefulness upon retirement. Our library is now discarding journals because they take up too much space, and will replace them with microfilm unless they have colored plates and maps. Is western civilization about to lose its Alexandrine library? Who is going to rally the troops?
Molecular techniques can contribute to the solving of taxonomic problems e.g., involving polyploidisation, the distinctness of closely related taxa and phylogenetic relationships. The distribution of molecular markers can also give new insights to biogeographic problems. Thirdly, they can be used to identify genotypes which is useful in the study of clonality and the balance between genotypic and phenotypic control of morphological traits.
The clonal bryophyte Hylocomium splendens is widespread in arctic and boreal regions of the Northern Hemisphere. Arctic populations, morphologically differentiated from the boreal populations, are sometimes referred to as H. alaskanum. Most bryologist, however, prefer to use the name H. splendens also for this material since the variation between the two extremes is continuous.
In a first study H. splendens s. l. was sampled in a hierarchical fashion from populations representing four Scandinavian vegetation zones (S boreal, N boreal, subalpine, subarctic-alpine). Allozyme electrophoresis revealed variation at 11 out of 13 screened loci, allowing accurate identification of genotypes. Clonal diversity was high; from a total sample of 298 shoots 79 genotypes could be detected. Surprisingly, clonal diversity was highest at the subarctic-alpine site, even at the level of 10x10 cm patches. The mean number of genotypes detected from samples of 5 shoots taken from each of 15 such patches was 2.9 at the subarctic-alpine site.
The total allelic diversity (HT) based on polymorphic loci was 0.274, which is comparable to the more variable vascular plants. The relative differentiation among populations was low, only 7%, indicating a high level of gene flow. As matter of fact, the genetic structure of the Hylocomium populations appears to be similar to the genetic structure of the conifer species, under which canopy it is often growing.
The 7% variation distributed among populations indicated that the subarctic-alpine population (belonging to "H. alaskanum") was slightly differentiated versus the three lowland population. Preliminary results from ongoing studies (including material also from Siberia) confirm this observation. Most probably, H. splendens s. l. contains several geographic races with different postglacial history, some of which share morphological traits attributed to H. alaskanum. These races are only weakly differentiated genetically and therefore expected to have evolved recently.
Dr. Wilf Schofield loves poetry and classical music. As a part of this Festschrift I wanted to include an essay on the use of bryophytes in these two fields. The task proved too difficult considering a short time available and the amount of poetry one would have to read or the amount of music one would have to listen to. I can only present few suggestions that the Internet gurus brought to my attention.
In the anthology "A Book of Luminous Things" (edited by Czeslaw Milozs) a poem "Moss-Gathering" by Theodore Roethke describes techniques of moss collecting. This technique is exactly the same as that applied by Dr. Wilf Schofield:
To loosen with all ten fingers held wide and limber
And lift up a patch, dark-green, the kind for lining
cemetery baskets,
Thick and cushiony, like an old-fashioned doormat,
The crumbling small hollow sticks on the underside mixed
with roots,
And wintergreen berries and leaves still stuck to the top,-
That was moss-gathering.
[Roethke feels remorse for gathering so much moss:]
And afterwards I always felt mean, jogging back over the
logging road,
As if I had broken the natural order of things
in that swampland;
Disturbed some rhythm, old and of vast importance.
By pulling off flesh from the living planet;
As if I had committed, against the whole scheme of life,
a desecration.
Dr. Schofield does not feel a similar guilt, on the contrary, he can be proud of his collecting record. As of June 15, 1997, he has collected 107,990 specimens (not counting duplicates) and made them immortal in the herbarium collections.
In classical music, mosses are only seldom mentioned. In Richard Wagner's Parsifal, Kundry describes to Parsifal how his mother took care of him as a child:
Gebettet sanft auf weichen Moosen
den hold geschlafert sie mit Kosen.
or
Gently bedded in soft moss
she lulls carressingly her darling boy.
Czech composer Bedrich Smetana was a follower of Wagner and as such had a similar moss theme. In his opera "Tajemstvi [Secret]" the smuglers walk through a forest and sing (quite loudly) a nice chorus:
Quiet, quiet, [step] on moss ...
If you are really interested in moss and classical music, I was told, you should try the music of American composer Lawrence Moss (1927 - ), although most of it sounds rather academic. My anonymous advisor said that Flight for brass quintet is pretty good, as is Incidental Music for two pianos & percussion.
I have not found any references to liverworts, hornworts or Takakiopsida in poetry or classical music.
Submissions, subscriptions, etc.: aceska@freenet.victoria.bc.ca. BEN is archived on gopher freenet.victoria.bc.ca. The URL is: gopher://freenet.victoria.bc.ca:70/11/environment/Botany/ben