| BEN |
| BOTANICAL ELECTRONIC NEWS |
|---|
| ISSN 1188-603X |
| No. 211 December 29, 1998 | aceska@victoria.tc.ca Victoria, B.C. |
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Swan Lake Nature House, 7:30 p.m.
Karen will show slides from several bogs she visited in fall 1998 and will discuss similarities/differences between European and Pacific Northwest wetland vegetation.
UVIC, 1996 Classroom Bldg. Room C 112, 7:00 p.m.
The latest issue of Natural Areas Journal (Volume 18, Number 4: October 1998) contains three articles on B.C.'s old-growth forests. Here are the Abstracts from those articles:
Increased scarcity of old forests of natural origin, and improved understanding of the ways in which they are ecologically distinct, have led to a need for standardized definitions for old-growth forests in British Columbia, Canada. Useful definitions of old growth that are simple and concise have been elusive because the old-growth stage of forest development occurs as a part of a continuum of development and varies greatly over ecological gradients at several scales. Therefore, we propose the development of ecologically based definitions in three broad categories: conceptual, quantitative, and working. We suggest that old growth be defined conceptually as a forest in which processes of gap dynamics predominate. We further propose that definitions of old growth should incorporate the distinct structural and compositional characteristics that arise from these development processes, because direct measures of gap dynamics are elusive and because structural attributes perform important ecological roles. Indices of forest structure that capture the inherent variability of structural characteristics of old-growth stands show promise for quantifying the qualitative features contained in conceptual definitions; minimum thresholds and demographic measures also have merit. In the interim, working definitions based on minimum age and height for different forest types have allowed the completion of province-wide inventories from existing databases. Future research should be directed toward determining the structural characteristics and variability of the different late-successional forest types in British Columbia so that conceptual definitions can be tested and type-specific ecological definitions can be developed. The paucity of basic information on characteristics of old-growth forests limits the ability of managers to determine the area and location of specific types of old-growth forest, and to develop appropriate management goals and methods.
We present a practical approach for the assessment of old-growth status that is consistent with stand development theory, namely that a true old-growth stage is achieved when internal stand regeneration processes have led to the replacement of individuals recruited immediately after the last stand-initiating disturbance. Age and basal area of all individual trees and a number of stand structural attributes were evaluated for 14 stands, ranging in age from 124 to 343 years since the last stand-replacing wildfire, in the Sub-Boreal Spruce biogeoclimatic zone of north-central British Columbia. Stands were ranked on a stand development continuum of "mature" to "old-growth" using age-class distributions, principal components analysis of easily measured stand attributes, and ratios of replacement cohort basal area to initial cohort basal area. The latter - the ratio of the basal area of individuals recruited under the canopy to the basal area of individuals recruited immediately following disturbance - is most consistent with the conceptual definition of old growth and can serve as a quantitative measure of old-growth status. A cohort basal area ratio of 0.045 to 0.235 denotes the beginning of functional old-growth status in these forests, that is, transitional old-growth sensu Oliver (1981, Oliver and Larsen 1990). Thresholds are identified for five easily measured stand attributes that separate clearly mature from clearly old-growth stands. An old-growth scoring system is presented, based on the ratio of observed levels of those attributes to the identified thresholds, multiplied by a weighting factor derived from the correlation of each attribute with the cohort basal area ratio, which is more difficult to measure. When summed over all five attributes, an old-growth score > 1.0 denotes stands in this forest type that are functionally old growth.
We analyzed more than 7 000 1:20 000 forest cover maps for British Columbia to determine the amount of old-growth forest in the Canadian province. For this exercise, 'old growth' was defined as: forests on the coast >250 years old; and forests in the interior >140 years old for most tree species, and >120 years old for lodgepole pine and deciduous species. Using this definition, British Columbia is 37.1% 'nonforest', 36.1% 'younger forest', and 26.8% 'old growth'. These data were analyzed by broad ecological (biogeoclimatic) zones. Old-growth forests cover more than 40% of the land base on the coast and at subalpine elevations in interior B.C., and less than 1% of the land base in the coastal rainshadow forests of southeastern Vancouver Island and the Gulf Islands. Approximately 7.7% of the province's landbase is covered with forests >250 years old. Almost 13% of B.C.'s remaining old growth is in protected areas. In the future, area of old-growth forest will decrease over the province's timber harvesting land base; this decrease may be somewhat offset by increases (due to fire suppression) outside of the timber harvesting land base.
For those who just can't get enough information about B.C.'s old-growth forests, the proceedings of the February 1998 Victoria workshop "Structure, Processes and Diversity in Successional Forests of Coastal British Columbia" make up a Special Issue of the journal Northwest Science, published in late November 1998. This workshop reports on research findings documenting differences between old-growth and second-growth forests in coastal B.C.
The papers from this issue of Northwest Science are also available at the workshop web site:
In Canada:
John Wiley & Sons Canada, Ltd.
22 Worcester Road,
Etobicoke, Ont. M9W 1L1
Phone: 416-236-4433, 1-800-567-4797
Fax: 416-236-8743, 1-800-565-6802
The book describes ecology of the main biomes encountered in North America (tundra, boreal forest, eastern deciduous forest, grasslands, deserts, chapparal, montane forest, and temperate rain forest). An introductory chapter explains the main ecological terms and principles and the final chapter covers special environments (e.g, caves, Grand Canyon, Niagara Escarpment) that don't fit into the major biomes. The author is a wildlife biologist and the main focus of the book is on the relationship between plants communities and animals. A general description of the ecology of vegetation formation is accompanied by the "Highlights" - a collection of interesting interactions, conservation problems, or historical vignettes related to the particular vegetation. Each chapter has a copious bibliography, useful for further study.
The book is meant as a college textbook and it is written in a clear style and is richly illustrated. It is a valuable source of information and nice link between plant communities and animal community ecology. On the other hand, the importance of the climate as a determining factor in the vegetation structure and composition is not stressed enough. I would have liked to see Walter & Lieth's climatic diagrams to illustrate climates dealt with in this book. I was annoyed that the author uses only the common names in the text until I found a list of common vs. scientific names of all the mentioned organisms in the Appendix. I agree with the publishers who regard Ecology of North America to be "an ideal first text for students interested in natural resources, environmental science, and biology, and a useful and attractive addition to the library of anyone interested in attempting to understand and protect the natural environment."
Other recent books from the same author:
This pocket field guide contains descriptions and illustrations of 114 species of Carex from the Intermountain area. Each species is described on one page and illustrated on the opposite page. Descriptions contain synonymy, and morphological, habitat and distribution information. Illustrations combine line drawings with colour macrophotographs. The line drawings are mostly taken from the "Vascular plants of the Pacific Northwest" or from the "Intermountain Flora" (with additional line drawings by E.G. Hurd). The colour photographs show details of the inflorescence and a set of scales, perigynia and achenes. The photographs were taken by the senior author and they are excellent. The book has an extensive terminology section that is fully illustrated. It also has dichotomous keys to all 114 species, plus a few more uncommon species that are not treated in the description section. Tables in the appendix give discriminant characters for identification of species in eleven groups of similar species. These tables contain both the species treated in the special part and the uncommon species that are not covered by the guide.
This is an excellent guide, useful not only for the Intermountain area (Nevada, Utah, and parts of Oregon, Idaho and Wyoming), but also for the neighbouring regions that have many species in common with this area. Its format is an excellent example for similar field guides and I especially like the superb combination of line drawings with colour macrophotographs. The guide is printed on heavy, glossy paper. The cover, however, is a low grade paper, almost a blotter. I had it laminated immediately when I received my copy and you should do the same.
The book covers the following topics: Definition of the mediterranean climate, plant and climate origins, plant adaptations, plant communities, and vegetation of California, Central Chile, Western Cape-South Africa, Australia, and the Mediterranean Basin; planning a trip (to visit areas with mediterranean climates & plants). The bibliography contains over 240 references.
Dr. Robert Ornduff wrote in the Preface: "In this engaging and beautifully illustrated book, Peter Dallman describes the five regions of the world with a mediterranean climate (their climates are not so similar as I once believed [R. Ornduff]), the diverse adaptations that enable plants to survive the prolonged summer droughts typical of these regions, the plant communities found there, and human influences that have shaped the physical and botanical landscapes. For each region, he describes and illustrates significant features of the terrain, environmental influences, and vegetation types. As a traveler, Dallman has first-hand knowledge of these places, is well-read, and has distilled a myriad of facts into a highly readable and engaging synthesis for those interested in the rich array of plants that grow in these regions. Chapter 10 presents useful suggestions for those planning a trip to any of these regions and recommends books that will enhance their visits."
I would like to thank all the authors who submitted their notes and articles to BEN in 1998. BEN would not be able to survive without your articles. I would like to thank especially to those of you from whom I solicited contributions: it is always difficult to write on command. My thanks go to the readers for their patience, to all BEN subscribers for remaining faithful to BEN, and to all those, who know how and when to use the delete button. I have to thank the Victoria Freenet Association and the (mysterious to me) "cue.bc.ca" for the simple mailing system they created for me that enables me to mail BEN without any glitches. Quite a few people in my vicinity know English better than I do, and I would like to thank them for their ghost writing and editing of what I write. Last but not least, I would like to thank Dr. Scott Russell for converting BEN issues to the web pages.
- Adolf Ceska