| BEN |
| BOTANICAL ELECTRONIC NEWS |
|---|
| ISSN 1188-603X |
| No. 476 April 9, 2014 | aceska@telus.net | Victoria, B.C. |
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For her Ph.D. thesis at UBC, Jenny McCune has produced some fascinating insights into the vegetation history on southern Vancouver Island in recent decades and over the past several hundred years. She successfully defended her thesis in November 2013:
Briefly, Jenny's thesis had two major parts. First, Jenny followed in Hans Roemer's footsteps and surveyed vegetation in 180 plots in locations as close as possible to the plots Hans surveyed some 40 years ago (see Roemer 1972 in the Editorial Footnote below).
The results demonstrate some major increases in the frequency and abundance of non-native species on the Saanich Peninsula, such as Epipactis helleborine and Anthoxanthum odoratum, as well as the surprising increase in the local richness of native species in Douglas-fir forests. Second, Jenny studied small siliceous bodies called phytoliths, which are deposited in soil after plants die, to assess century-scale changes in forest vs. open habitat at several sites. Indeed she was able to distinguish Douglas-fir forest from open habitats using phytoliths, and found some intriguing suggestions of savanna-to-prairie conversion predating European settlement. Each of these parts of her thesis is presented in two chapters, and they are preceded by a chapter presenting a synthetic overview of different lines of research into Garry oak ecosystems, such as short-term experiments, landscape surveys, paleoecology and anthropological studies.
Three chapters have been published in peer-reviewed journals already:
Here is the abstract of Jenny McCune's thesis:
Terrestrial plant communities are complex systems, and major storehouses of global biodiversity. The composition of a plant community today is contingent on conditions that have occurred throughout its history. Therefore, an understanding of current plant community structure requires an understanding of its origin and its variability over time. In this thesis, I investigate the history of plant communities on southeastern Vancouver Island, Canada, at two time scales. These communities are now highly fragmented and threatened by human disturbance, but they also have a long history of management by indigenous peoples.
To quantify changes due to recent urbanization, I resurveyed 184 vegetation plots originally surveyed in 1968. I documented striking increases in plot-level and total species richness, but a decline in the variation in plant community composition between plots, a phenomenon called 'biotic homogenization'. Exotic species were more likely than natives to increase over time, but exotic colonizations were not correlated with biotic homogenization or native declines. Plant life history traits predicted colonizations based on landscape context within 500m of a plot, but extirpations were rare and much less predictable, suggesting time lags in plant community response to landscape disturbance and fragmentation, and a potential extinction debt.
I used plant microfossils called phytoliths extracted from soil to investigate changes in plant communities prior to European settlement. I established that the ratio of asterosclereid phytoliths produced in the needles of Douglas-fir (Pseudotsuga menziesii) to the rondel phytoliths produced by most grasses can accurately distinguish between Douglas-fir dominated forests and Garry oak (Quercus garryana) savannah habitats today. I then examined changes in this ratio with depth at seven local sites, finding that infilling by Douglas-fir forest first began at different times, depending on the site. However, some savannah sites have supported grassy vegetation for at least two thousand years. Active management to maintain open conditions will be necessary to preserve rare species that evolved in these conditions.
These investigations demonstrate that examining the history of plant communities can reveal surprises and challenge assumptions about how they respond to disturbance. This knowledge can improve ecological theory, and inform management and conservation strategies.
Editorial Footnote: For Hans Roemer's PhD Thesis see:
The Kamloops Herbarium (acronym ACK, from "Agriculture Canada Kamloops", Holmgren et al. 1990) was started at the Range Experiment Station of Agriculture and Agri-Food Canada (AAFC) at Kamloops in 1935 by A.W. Tisdale (Tisdale 1939, Boivin 1980). This was the same year that the station was established at Kamloops as a substation of the Dominion Range Experiment Station at Manyberries, Alberta (McLean 1986). The station was to conduct research aimed at developing solutions for a variety of range problems including losses due to toxic native plants (e.g Bruce 1927, Thomson 1932, Tisdale 1939, and McLean 1986). Wartime economy led to the closing of the substation in 1940 and the herbarium was moved to AAFC Swift Current until 1947 when it was returned to Kamloops where the Dominion Range Experiment Station was opened.
The collection is estimated to contain 3008 vascular plant specimens based on the database representing the entire main collection which was initiated by the Collection Manager Barb Brooke and continued in the past few years by Barb Wheatley. The specimens are in very good condition and identifications are remarkably accurate as a result of over 95% of the material being checked by experts, including particularly Dr. J.A. Calder (see Cody & Cayouette 1991). Most specimens were collected in the late 1930s and early 1960s with a less pronounced period of collecting around 1980.
The plants mostly originated from rangelands of British Columbia including grasslands and dry, open Douglas Fir and Ponderosa Pine, but also came from alpine areas that were used for sheep which were once herded over extensive areas ranging from low Sagebrush grassland to the alpine zone.
The valuable "Prince George Collection" was apparently developed to assist with identification of local flora, and was sent to ACK after closure of the AAFC unit at Prince George. It consists of 350 sheets with transparent protectors in eight boxes. The specimens were collected mostly by J. Sawitski and R.D. Marsh in 1960, 1969, 1970 and 1971.
The collection has been used by many botanists in British Columbia, especially at the University of British Columbia and the Royal British Columbia Museum. These experts have annotated the specimens, thus increasing their value. The collection has been at least partly examined and recorded by the British Columbia Conservation Data Centre. Exchanges of specimens include some with the Royal British Columbia Museum resulting in 100 year old material which predates the start of the collection. Periodically ranchers with livestock problems, or provincial government advisors, would visit the herbarium for help with identification of toxic plants or weeds. The collection was also used to a limited degree by students in Natural Resource Science at Thompson Rivers University. Recent staff at ECORC (Mitrow, Cayouette and Catling) have visited the collection, utilized it, and have also assisted in its curation by training staff and checking specimen identities.
ACK includes vouchers for AAFC research on rangelands and cooperative AAFC work with the British Columbia Forestry Service related to maximizing use of forested range. Many of these studies were done in the Kamloops area, and especially in the Tranquille and Lac du Bois Grasslands, over a period of more than half a century (examples in Appendix Table 1). ACK is one of the best sources of material and information for the Kamloops area and the aforementioned nationally significant grasslands. As well as irreplaceable agricultural research vouchers, the collection contains some century-old material acquired through exchange.
The major collectors for ACK are easily discerned from the database. Almost all of the collectors were publishing researchers with few students involved. Major collectors along with number of specimens collected include: G. Beke (169) V.C. Brink (123), B. Brooke (200), D. Demarchi (59), J. W. Eastham (41), J. Finstad (88), L. Haupt (198), L. Marchand (95), K. McLaren (45), A. McLean (960), W.L. Pringle (150), B. Storey (39), E. W. Tisdale (658), B. Wikeem (42), and others with 30 or less.
A report (Catling et al. 2013) is available from the DAO archives and other information is available in the references below. As with all acquired collections, ACK will be incorporated in the main DAO herbarium (not kept separate).
The AAFC National Vascular Collection of Plants employees thanks Kamloops herbarium staff Barb Brooke, Barb Wheatley, Carol Fagan, Harriet Douwes and Directors Linda Wilson and Kenna McKenzie for assistance in preparing and shipping this material to Ottawa at the time of closure of the Kamloops Station in 2013.
How often have you seen the name of a new taxon listed in the table of contents of a mycological journal, and wondered just where it fitted in the over-all fungal scheme of things?
In general, I believe authors would do their readers a service by including a familial or ordinal name in the title of the paper (though this stricture does not apply to many anamorphs [asexual reproductive stages], which in the absence of molecular or cultural data still have no formal affiliations of this kind). But sometimes, even when authors have adopted this helpful strategy, many of us will remain baffled if the location of the new taxon is remote from our own areas of expertise. If I see Diversisporaceae, I am at a loss until I can discover that this name was coined in 2004 for a group of Glomeromycota. That is just the kind of query this book answers perfectly.
The book was published in 2007, but I had not seen a copy until I came across it recently on Amazon. Now I have it in my hands, I wonder how I coped without it for so long. The authors have provided us with as much, and as recent, information as possible, and are to be congratulated on an invaluable achievement. Constant reference to this book will aid mycologists in the construction of their cognitive map to the fungi.
The authors have given us details of all 536 accepted families of true fungi, and included colour photographs and photomicrographs, and some drawings, of over 400 of them [Oomycetes and slime moulds were deliberately excluded, as not being members of the true fungi - Kingdom Eumycota].
It has been a delight to discover the inclusion of very many anamorph connections, and even more so to see illustrations covering, for example, not just ascomata, but also frequently asci and ascospores, and even the anamorphs.
Although I have been studying fungi for 60 years, and teaching mycology in its broadest sense for many of those years, I encounter information that is new to me at almost every turn of the page. How many of us, even seasoned professionals, are aware of all those 536 families, or have seen examples of so many of them? Are we all sure of the difference between Gigasporaceae and Gigaspermaceae? Everyone knows the Erysiphaceae, but what about the Eremascaceae, Eremomycetaceae and Eremotheciaceae. Or the Gasterellaceae and the Gastrosporiaceae?
The entry for each alphabetically arranged family incorporates a detailed diagnostic definition, names of significant genera, known distribution, economic significance, ecology, notes, and major references, and in most cases, diagnostic illustrations. Repeated reference to this book will almost certainly help all of us in the construction of our cognitive map of the fungi.
I feel almost guilty at registering one complaint, that some of the illustrations are not of the highest quality. I am sure that this can be remedied in a second edition, since I believe that the mycologists of the world would be more than happy to contribute their best images in such a worthy cause.
Every mycological society should have a copy of this book in their library, and professional mycologists certainly need one in theirs. [See also http://www.fungaldiversity.org/fdp/sfdp/32Book_review.pdf
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