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Selection procedures for forest nature reserves in Nova Scotia, Canada
Biological Conservation 41 (1987) 185-201
Selection Procedures for Forest Nature Reserves in Nova Scotia, Canada F. B. Goldsmith* Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4J1
(Received 11 December 1986; revised version received 22 February 1987; accepted 4 March 1987)
A BS TRA C T A series of proposed forest reserves identified by the International Biological Programme in the earl)' 1970s have been studied in Nova Scotia with the objective of selecting and ranking areas.for designation under the provincial 1981 Special Places Act. Criteria for reserve selection or priority ranking have been derived from (1) interviews with local ecologists and naturalists; (2) key words used by .field surveyors in the earl), descriptions of the sites; and (3) rigorous criticism of the criteria recommended by the Canadian Council for Ecological Areas ( CCEA ). The preferred criteria were: (1) number of plant species; (2) number of rarities; (3) area; and (4) diameter of the largest trees. Any exceptional features of the site were also noted. The four criteria were quantified and then ranked. Inspection of the.four rankings enables a priority list of sites to be drawn up but no addition or multiplication of the criteria was carried out. It is also recommended that the list should include members of each of the major theme regions, a type of ecological land classification. Thus representativeness becomes the fifth criterion. Where it is difficult to determine the total number of plant species a procedure based on a plot of number of species against time ( 15 min in tervals ) is recommended. A comparison of different reserve selection strategies is also made which suggests that permutations of the five sites with most species, the .five smallest sites (see text), or the five with most rarities give the most effective protection to the largest number of species. * Present address: Ecology and Conservation Unit, University College London, Gower Street, London WC1E 6BT, Great Britain. 185 Biol. Conserv. 0006-3207/87/$03"50 © Elsevier Applied Science Publishers Ltd, England, 1987. Printed in Great Britain
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F. B. Goldsmith The current series of sites is not representative of the province as red spruce, the most commercially valuable tree species, is under-represented. The procedure recommended provides a simple, objective, quantitative, quick, biologically-based method for site evaluation which has applications in many other regions of the world.
INTRODUCTION Nova Scotia, one of the Maritime Provinces of Eastern Canada, has two National Parks but no forest nature reserves. Although a candidate list was drawn up in the early 1970s (Taschereau, 1974) and legislation passed in 1980 (Act 29 Elizabeth II Chapter 17) no forest sites have been effectively protected (Taschereau, 1985). This is surprising as 84% of the land surface of the province is forested (Goldsmith, 1980) and forestry is a major industry. However, a Curator of Special Places was appointed in 1984 and the list of potential sites has been revised (Ogilvie, 1984). It now includes 80 sites of which 35 are predominantly forest. As designation is obviously a slow process it was considered important to rank the sites and an exercise was therefore undertaken to find the best means of evaluation. It was also hoped that the production of a methodology to cover an extensive area in three months on a limited budget would be a useful exercise as comparable objectives remain unfulfilled elsewhere in other parts of the world.
D E S C R I P T I O N OF T H E A R E A Nova Scotia lies between latitude 43 ° and 47°N and longitude 60 ° and 66°W and is connected to the rest of North America by a narrow isthmus (Fig. 1). It consists predominantly of palaeozoic igneous and metamorphosed rock. The whole surface has almost certainly been glaciated and glacial features such as drumlins are frequent in some areas (Roland, 1982). Most of the soils derived from the solid geology or glacial/fluvial till are acid but there are local areas of carboniferous geology of which small parts are limestone or gypsum. Broad valley bottoms or intervales in the gypsum areas have more basic soils and contain the less c o m m o n forest plant species. The principal forest types have been described before (Goldsmith, 1980 and references cited therein) and range from a spruce taiga zone at 500 m altitude on the Cape Breton Highlands to white spruce, balsam fir and peat bogs on the Atlantic coast to sugar maple, yellow birch and other shadetolerant hardwoods on the uplands of the northern part of the province (Cobequid Hills, Pictou-Antigonish Highlands and the dissected slopes of
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the Cape Breton Plateau). Hemlocks frequently occur on better-drained valley sides and white pine on sandy areas and the drumlins around Lunenburg and Kejimkujik National Park. Agriculture occurs on 9% of the land and is concentrated in the Annapolis Valley, around Windsor and Truro and scattered elsewhere in the province where suitable sites occur. The undulating topography is peppered with about 10000 lakes. The climate is characterised by a short growing season (90-170 days), being shortest in the Cape Breton Highlands and longest in the south-west. Precipitation (1000-1600 m m / a n n u m ) is high, and humidities are often high with a frequent freeze-and-thaw during the winter and spring. A Flora of the province has been prepared by Roland & Smith (1969), recognising seven elements (arctic-alpine and boreal disjuncts, boreal, canadian, alleghenian, southwestern, seashore, introductions and weeds). More recently a book on the natural history of Nova Scotia (Maritime Resource Management Service, 1984) has been prepared and this includes a 1:500 000 map of the nine Theme Regions of the province. It is essentially an ecological land classification.
S E L E C T I O N OF C R I T E R I A The choice of criteria to select nature reserves is a complex and difficult exercise (Goldsmith, 1975, 1983; Ratcliffe, 1977; Adams & Rose, 1978; Usher, 1986), but the first essential step is to identify the objectives of the exercise. Why are the reserves needed? Who is likely to need them? Here the intention is to set aside the best areas (1) for reference purposes in the future, (2) as a protected gene pool, (3) for teaching and research, and (4) for naturalists. Usually we encounter a dichotomy between those who wish to select 'representative' areas, i.e. reserves typical of particular theme regions (Katz, 1986), and those who wish to protect the best sites with the largest number of species, rarities, areas of old-growth forest or large trees. I favour the latter as the former approach could result in setting aside areas of often mediocre land which may already be relatively abundant. The latter takes less land, and is therefore cheaper and easier to justify to the public and to politicians. However it is also possible, and desirable, to select the best examples of each of a series of representative areas or theme regions (Maritime Resource Management Service, 1984). In order to assess the wishes of ecologists within the province, as many experts as possible were interviewed and asked which criteria they would use to select forest reserves in Nova Scotia. Nine people were prepared to participate and their criteria are shown in Table 1. Whilst 'representativeness' was the most frequently mentioned single criterion, 'uniqueness', which
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Selection of forest nature reserves TABLE 1
Criteria used by Nine Local Ecolgoists Representative (including theme regions) Uniqueness Climax, old growth Diversity, richness Rarity Successional stages Conspicuousness Threat, endangered Age of trees, naturalness, stability, size of area, research potential, cultural, N O T representativeness, N O T diversity
5 4 4 3 2 2 2 2
1
is almost opposite in meaning, was mentioned four times and supporting criteria such as 'richness' and 'rarity' were the next most frequently mentioned. Another means of identifying criteria is to refer to an International Biological Program (IBP) Report (Taschereau, 1974). No rigid instructions were given to the field surveyors who collected the original information about the sites but the ensuing report indicates the principal reason or reasons why each site was chosen. Table 2 shows the frequency with which various criteria were mentioned. This time 'representativeness' is referred to very infrequently but the emphasis is on the 'finest', 'undisturbed' areas of 'old-growth' forest especially where they contain 'rare' plants. This supports TABLE 2
Frequency with which Criteria were Mentioned in Taschereau (1974) Mature stand, old growth Finest/excellent/good example Undisturbed Rare plants/species rich Large trees, tall Research data/previous studies Size of area Representative Regeneration, healthy, buffer zone, oldest trees, beautiful, natural, educational potential Rich bryophytes, second growth, abundant wildlife, scenic, cultural, vegetation transition, fragility
15 14 8 7 4 4 3 3
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the contention that these criteria are more important to the type of person who is likely to be the consumer, i.e. naturalists and ecologists, than a series of sites that are 'representative' of the main land systems or theme regions. Recommended national criteria The Canadian Council for Ecological Areas (CCEA) recommends criteria for use in selecting reserves in Canada (Beechey, 1986). Two main approaches are identified which are referred to as the use of representational concepts and the use of functional principles. Representational concepts emphasise the need to select sites that are representative of regional types or theme regions. My criticism of this is that the themes are often difficult to identify, highly subjective and the boundaries are often artificial. Fortunately for Nova Scotia, and if one wishes to pursue this route, a comprehensive study of theme regions has recently been published and the IBP candidate list (Taschereau, 1974) has been checked against the nine main theme regions (Ogilvie, 1984). Forest sites occur in all themes on the mainland, that is everywhere except Sable Island. Old-growth hemlock and shade-tolerant hardwoods are over-represented whilst the commercially valuable red spruce has been under-represented. The 'functional' principles include diversity, rarity, size, condition and fragility. These, with various modifications, are used in many different countries, and have been discussed elsewhere (e.g. Ratcliffe, 1977; Goldsmith, 1983; Usher, 1986). They all have some merit but most are susceptible to some criticism.
Diversity This is usually agreed to have two components: richness and equitability. The latter is of limited conservation value whereas the former, whilst important because it represents the number of species on a site, is known to be a function of area. So the bigger the area under consideration the more species it is likely to contain. It is also a function of altitude, latitude, soil type, base status, etc. Another problem for those carrying out a rapid site survey is that richness is also a function of time spent on site so this needs to be either standardised or taken into consideration in some way. Some vegetation types are likely to be species-poor, e.g. old-growth hemlock stands, but are nevertheless considered to be of high conservation value. In spite of these criticisms species richness is a useful criterion that is used by many field naturalists to indicate valuable areas.
Rarity Most naturalists place considerable value on the chance of seeing a rare
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species and m a n y sites are protected because they contain rarities. However, this suggests that value increases with rarity and therefore a species is most valuable just before extinction. If we extrapolate this argument then a site can be made more important by making its rarities even rarer!
Size This can apply to either size of site or size of individuals. When it applies to the size o f site then 'island biogeographic principles' apply and the larger the site the more species it is likely to contain. W h e n it applies to individuals, e.g. trees, big game, birds o f prey, the larger the individual the more it is valued. In forests, big trees are valued, and also very old ones as they are likely to have more species o f beetles, lichens and bryophytes, provide sites for holenesting birds and are aesthetically pleasing.
Integrity This criterion, although r e c o m m e n d e d by CCEA, appears to be rather generalised and difficult to measure. Whilst it has some meaning which most people would endorse, it is not particularly useful.
Condition The same criticisms apply here as to 'integrity'. It is equivalent to the criterion 'naturalness' used in other countries, and whilst most people would endorse the concept in general terms it is difficult to measure and therefore becomes subjective and is best avoided in the early stages of site selection.
Endangerment This is a measure of threat rather than a characteristic o f the site. As such it is an extrinsic factor and should only be used in association with other criteria. On its own it does not contribute to the evaluation of the site.
Fragility The relationship o f this criterion to 'value' is unclear. It does not indicate whether a fragile site is m o r e valuable or less valuable. It is therefore not very useful.
Replication It is usually desirable to have more than one example o f a habitat but if there are too m a n y replicates the value o f each could be interpreted as being lower. This criterion is therefore not independent o f other criteria and works in the opposite direction to some.
Significance This is defined as the cumulative measure of the importance o f the area but
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the various criteria listed here are non-additive. There does not appear to be any way of measuring criteria in comparable units although a comparison of the rankings of sites for a selection of criteria can be useful (see below). Therefore it is probably better not to consider 'significance' as defined here as a criterion. Of the various criteria considered above only richness, rarity, area and size are considered desirable and it is preferable not to add them together or to formulate an overall index of conservation value. Information available There are at least a dozen different types of information available or easily collected for the forests of Nova Scotia. It was noted earlier that the procedure adopted should be rapid and reproducible in other parts of the world. Some systems based only on physiognomy or vegetation structure are considered inadequate so systems based on floristics are preferred and it is assumed that some taxonomic information is available, at least for the flowering plants. However, the method used here is not dependent on a high level of taxonomic expertise, simply the identification of most of the species and some knowledge of rarities. The emphasis has been placed on plants because they do not move and are relatively easy to identify for several months of the year. Comparable data are needed for animals but so far a quick, accurate and representative sampling procedure to cover several phyla remains elusive. It may be that the structure and species composition of the vegetation is as good an indicator of faunal diversity as any other. The information that was available at the start of the project came from two sources, maps and fieldwork. Maps could provide data about area, geology, soils, climate, theme region, altitude and distance from the sea. Information, such as land capability for forestry, was extracted partially from air photos. Fieldwork could supply information about site species richness, the number of rare species, tree size (from diameter tapes) and tree age (from increment boring). Tree basal area could either be recorded from sample plots or from a basal area angle gauge.
DATA COLLECTION AND EVALUATION Of the map information available at the start, only the size of the proposed sites was utilised. The other information was not considered essential in selecting the best areas, although it would be useful in trying to find other possible sites for rare species, as suggested by Katz (1986). F r o m fieldwork,
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tree girth and diameter were recorded but not age because this is highly correlated with the other measures and increment boring damages the trees. Basal area was recorded but not used because it did not match any o f the relevant criteria discussed earlier. Thus the main criteria evolved from those o f the users, the IBP report and the critique o f the C C E A recommendations. These were number o f species, n u m b e r o f rarities, area and girth o f largest trees. They were recorded at each site. In addition, after the fieldwork was completed, other features on the site were noted, such as waterfalls, rivers, caves, historical or research
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connections. Whilst these do not add to the value of what is in the forested area they make the overall area more attractive and may be seen as features of additional interest. No attempt has been made to add, multiply or otherwise synthesise the various criteria. The determination of which species should be considered rare was more difficult than originally expected. Some are rare in Nova Scotia but are relatively common elsewhere in Canada, e.g. Trillium erectum, whilst others are rare in Nova Scotia but common in other parts of the world, e.g. Dryopterisfelix-mas. The definition used by Maher et al. (1978) was adopted, viz. a small population within the province or territory. Maher et al. (1978) produced a list of rare species for Nova Scotia but that used here is somewhat longer (25 species; Table 3) and was produced after reference to The Flora o f Nova Scotia (Roland & Smith, 1969), plant ecologists in the province and the staffofthe Nova Scotia Museum. The number of rarities could easily change as (1) new records are discovered; (2) some of the rarities die out; or (3) criteria for defining national and provincial rarities change. Hence even the more objective criteria must be seen as being plastic. The number of species was plotted against time for 15-min intervals for each site and a sample of the graphs of five sites from the eastern end of the province is shown in Fig. 2. In practice, different sites are sampled for different lengths of time so it may be preferable to take the number of species recorded after, say, 150 min as an index of site richness. However, the curves became steeper as fieldwork progressed and identification became quicker, and the procedure would only be valid for the same worker and for sites sampled within a few days of each other. Therefore total species number was used unless the site could only be visited for a short period of time and then the curves were used for extrapolation, e.g. for Grand Anse (Fig. 2).
RESULTS Table 3 shows the number of rare species recorded at each site; as no list was prepared for Kemptown, the information was obtained from other ecologists. However, as explained earlier it may be preferable to record the number of species per unit time and then extrapolate the curves. The graphs suggest that Grand Anse River is richer than Lake O'Law and MacFarlane Woods, which are also on Cape Breton Island, a conservative value of 89 species has therefore been used. The actual total could be more. Table 4 shows the data for total number of species, number of rarities, area and the girth of the largest tree for each of the 19 sites visited and one that was not (Kemptown). Other notable features and the status of each site are also indicated.
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Ranking of the Top Five Sites for Each Criterion Sites are listed in order of overall priority.) Site
South Maitland Kentville Ravine Meander River Hemlock Ravine St. Croix Lake O'Law Pipers Glen Kemptown Grand Anse Clydesdale Macfarlane Woods Economy Smileys Shelburne River Melrose Point Pleasant Moose River Fleming Park Sixth Lake Abrahams Lake
Number of Number of species rarities
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Largest girth
1
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3
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2 Waterfall (National Park)
The information m each column o f Table 4 has been ranked, the top five values of each being presented in Table 5. This enables the best sites to be seen at a glance, and whilst these values have not been added or multiplied to give a final index of conservation value, the sites have been ranked on the basis of the values in the columns. Basically only two rules are needed: (1) the higher the ranking for any criterion the better the site; and (2) the more criteria with a high ranking the better the site.
SELECTION STRATEGIES The main set of data concerning the species recorded and the sites where they occurred can be used to consider various possible strategies for selecting reserves; that is, the total number o f species that would be protected can be determined if, say, five reserves were initially selected on the basis o f various criteria, such as total number o f species, total number o f rarities or sites with the largest diameter trees. G a m e & Peterken (1984) used this approach,
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selecting ten out of a total number of 78 ancient woods. In this exercise I have used five out of a total of 20 sites considered. This is an arbitrary number but represents the number of forest sites that might be expected to be designated in the next few years by the provincial authorities, although as shown later it is insufficient to adequately protect the flora. Five such 'selection criteria' were used and compared with a random selection and the total number of species possible, the results being presented in Fig. 3. Of course, the total number of plant species protected is not the only criterion for evaluating the selection process but it does present a simple means of comparing different reserve criteria. For example, a mature stand of red spruce would be universally agreed to be an important candidate type for
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Nova Scotia but would inevitably have fewer species than a stand on baserich gypsum. The result shows that the five largest sites are not particularly species-rich (166 species) and are little better than the random selection. Although at first surprising, this is because size was determined by complex factors other than ecological ones such as ownership boundaries, land values and uniformity of forest type. The five smallest candidate areas would result in safeguarding a relatively large number of species (192), since the smallest sites included intervales which have high fertility, base-status and areas with considerable heterogeneity as well as a riverside site and a deep ravine. The selection of five sites with the largest trees (163 species) would protect a similar number of species as five sites selected at random (average = 157). The most effective permutation of five sites would be the five with the most species (211), as might be expected, but even so the total number of species protected would be 80 fewer than the total number recorded, or 72.5% of the total. These are likely to be the less c o m m o n species and therefore more highly valued. The five sites with the most rarities might be expected to be species-rich and were found to contain 189 species and are therefore almost as effective as a selection strategy as the five smallest sites. These at first glance appear to be surprisingly rich but are similar to the five with the most rarities and include intervales, ravine, riverside and cliff. The selection of sites from five different theme regions selected lists from a wide geographic range (Cape Breton in the east to Sixth Lake in the south-west) and as might be expected produced a better result than a random permutation. However, the selection based on theme regions is not sufficiently high to warrant strong recommendation for it to be the most important criterion to use. Clearly the question of selection strategies is extremely complex and these results concur with those of Game & Peterken (1984), who claim that 'no simple strategies were found which guaranteed the best results, but certain guidelines emerged which may improve the complex judgements which are unavoidable in practical conservation'. Instead, conservationists might be better advised to select on the basis of species-richness and rarity and then, as a later sieve, check that a wide range of forest types or theme regions are represented. Many people are overemphasising 'representativeness' which can easily result in the designation of large numbers of uniform and rather uninteresting areas. If this route is widely pursued few rarities will be protected. These results suggest that some criteria are at least mutually exclusive, i.e. if we pick the largest or oldest stands of trees then the total number of species protected is likely to be low. Similarly large uniform areas may be less species-rich than the same number of smaller, more heterogeneous areas. One of the most worrying suggestions, however, is that any permutation of five reserves is only going to protect about 72.5% of the total number of
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species and that the rarer ones are more likely to be excluded. More than five reserves are therefore needed to protect even the small number of sites sampled in this survey, which were all candidate reserves from a previous survey. Some of these results may be at variance with others reported in the literature. For example, Harris (1984), citing Bowles (1963), suggests that birds have twice as many rare species in old-growth areas as salvage-logged areas. However, the present study has not involved any vertebrates nor salvage-logged land, and it may be that criteria for other taxonomic groups may be very different from those for plants as used here. CONCLUSIONS The procedure outlined here is simple and applicable to a wide range of habitats in various parts of the world. It is based on a survey of the resource rather than indirect measures that serve as substitutes for the vegetation, such as geology, soils and topography. Other systems of evaluation include a variety of externalities which are sometimes human factors but are often concerned with threat, vulnerability or potential value rather than with the value of the resource. These are continuously varying and should be part of a separate evaluation. The procedure described here is essentially biological and permits the addition of new sites without difficulty. They can be surveyed and then easily inserted into the ranking. The procedure is also quantitative, the process is mathematically valid and avoids addition or multiplication of non-additive criteria. A certain amount of experience is required to identify the flora and the method is easier to apply if the region has a local Flora to aid identification. Otherwise it can be pursued by different people who would all obtain a similar result, i.e. it is repeatable or objective and has applicability in many areas other than Nova Scotia. ACKNOWLEDGEMENTS I would like to thank Alex Wilson and Bob Ogilvie of the Nova Scotia Museum; Dr Pierre Taschereau of the School for Resource and Environmental Studies and Dr M. J. Harvey of the Biology Department, Dalhousie University; and Dr Paul Keddy of the Department of Biology, University of Ottawa for assistance and encouragement with this project. The views expressed are, however, not necessarily endorsed by them. I am also very grateful to the Royal Society of Great Britain and the National Science and Engineering Research Council of Canada for funding.
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REFERENCES Adams, W. M. & Rose, C. J. (eds) (1978). The selection of reserves for nature conservation. Discussion Papers in Conservation, 20, University College London. Beechey, T. (1986). Guidelines for the selection of protected areas. Montreal, Canadian Council for Ecological Areas. (Mimeographed.) Game, M. & Peterken, G. F. (1984). Nature reserve selection strategies in the woodlands of central Lincolnshire, England. Biol. Conserv., 29, 157-82. Goldsmith, F. B. (1975). The evaluation of ecological resources in the countryside for conservation purposes. Biol. Conserv., 8, 89-96. Goldsmith, F. B. (1980). An evaluation of a forest resource--a case study from Nova Scotia. J. environ. Manage., 10, 83-100. Goldsmith, F. B. (1983). Evaluating nature. In Conservation in practice, ed. by A. Warren and F. B. Goldsmith, 233-46. Chichester, Wiley. Harris, L. D. (1984). The fragmented forest: Island biogeographic theory and the preservation of biotic diversity. Chicago, University of Chicago Press. Katz, G. E. (1986). Planning for ecological reserves in Nova Scotia. Curatorial Report, 56, Halifax, Nova Scotia Museum. Maher, R. V., White, D. J., Argus, G. W. & Keddy, P. A. (1978). The rare vascular plants of Nova Scotia. Syllogeus, 18. Ottawa, National Museum of Canada. Maritime Resource Management Service (1984). Natural history of Nova Scotia, 2 Vols. Halifax, Nova Scotia Museum & Department of Land and Forests. Ogilvie, R. (1984). Important ecological sites in Nova Scotia. Curatorial Report, 49. Halifax, Nova Scotia Museum. Ratcliffe, D. A. (ed.) (1977). A nature conservation review, 2 vols. Cambridge, Cambridge University Press. Roland, A. E. (1982). Geological background and physiography of Nova Scotia. Halifax, Nova Scotia Institute of Science. Roland, A. E. & Smith, E. C. (1969). Theflora of Nova Scotia. Halifax, Nova Scotia Museum. Taschereau, P. M. (ed.) (1974). Ecological reserves in the Maritimes. Halifax, IBP. Taschereau, P. M. (1985). The status of ecological reserves in Canada. Ottawa, Canadian Council on Ecological Areas. Usher, M. B. (ed.) (1986). Wildlife conservation evaluation, London, Chapman & Hall.
Selection Procedures for Forest Nature Reserves in Nova Scotia, Canada F. B. Goldsmith* Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4J1
(Received 11 December 1986; revised version received 22 February 1987; accepted 4 March 1987)
A BS TRA C T A series of proposed forest reserves identified by the International Biological Programme in the earl)' 1970s have been studied in Nova Scotia with the objective of selecting and ranking areas.for designation under the provincial 1981 Special Places Act. Criteria for reserve selection or priority ranking have been derived from (1) interviews with local ecologists and naturalists; (2) key words used by .field surveyors in the earl), descriptions of the sites; and (3) rigorous criticism of the criteria recommended by the Canadian Council for Ecological Areas ( CCEA ). The preferred criteria were: (1) number of plant species; (2) number of rarities; (3) area; and (4) diameter of the largest trees. Any exceptional features of the site were also noted. The four criteria were quantified and then ranked. Inspection of the.four rankings enables a priority list of sites to be drawn up but no addition or multiplication of the criteria was carried out. It is also recommended that the list should include members of each of the major theme regions, a type of ecological land classification. Thus representativeness becomes the fifth criterion. Where it is difficult to determine the total number of plant species a procedure based on a plot of number of species against time ( 15 min in tervals ) is recommended. A comparison of different reserve selection strategies is also made which suggests that permutations of the five sites with most species, the .five smallest sites (see text), or the five with most rarities give the most effective protection to the largest number of species. * Present address: Ecology and Conservation Unit, University College London, Gower Street, London WC1E 6BT, Great Britain. 185 Biol. Conserv. 0006-3207/87/$03"50 © Elsevier Applied Science Publishers Ltd, England, 1987. Printed in Great Britain
186
F. B. Goldsmith The current series of sites is not representative of the province as red spruce, the most commercially valuable tree species, is under-represented. The procedure recommended provides a simple, objective, quantitative, quick, biologically-based method for site evaluation which has applications in many other regions of the world.
INTRODUCTION Nova Scotia, one of the Maritime Provinces of Eastern Canada, has two National Parks but no forest nature reserves. Although a candidate list was drawn up in the early 1970s (Taschereau, 1974) and legislation passed in 1980 (Act 29 Elizabeth II Chapter 17) no forest sites have been effectively protected (Taschereau, 1985). This is surprising as 84% of the land surface of the province is forested (Goldsmith, 1980) and forestry is a major industry. However, a Curator of Special Places was appointed in 1984 and the list of potential sites has been revised (Ogilvie, 1984). It now includes 80 sites of which 35 are predominantly forest. As designation is obviously a slow process it was considered important to rank the sites and an exercise was therefore undertaken to find the best means of evaluation. It was also hoped that the production of a methodology to cover an extensive area in three months on a limited budget would be a useful exercise as comparable objectives remain unfulfilled elsewhere in other parts of the world.
D E S C R I P T I O N OF T H E A R E A Nova Scotia lies between latitude 43 ° and 47°N and longitude 60 ° and 66°W and is connected to the rest of North America by a narrow isthmus (Fig. 1). It consists predominantly of palaeozoic igneous and metamorphosed rock. The whole surface has almost certainly been glaciated and glacial features such as drumlins are frequent in some areas (Roland, 1982). Most of the soils derived from the solid geology or glacial/fluvial till are acid but there are local areas of carboniferous geology of which small parts are limestone or gypsum. Broad valley bottoms or intervales in the gypsum areas have more basic soils and contain the less c o m m o n forest plant species. The principal forest types have been described before (Goldsmith, 1980 and references cited therein) and range from a spruce taiga zone at 500 m altitude on the Cape Breton Highlands to white spruce, balsam fir and peat bogs on the Atlantic coast to sugar maple, yellow birch and other shadetolerant hardwoods on the uplands of the northern part of the province (Cobequid Hills, Pictou-Antigonish Highlands and the dissected slopes of
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the Cape Breton Plateau). Hemlocks frequently occur on better-drained valley sides and white pine on sandy areas and the drumlins around Lunenburg and Kejimkujik National Park. Agriculture occurs on 9% of the land and is concentrated in the Annapolis Valley, around Windsor and Truro and scattered elsewhere in the province where suitable sites occur. The undulating topography is peppered with about 10000 lakes. The climate is characterised by a short growing season (90-170 days), being shortest in the Cape Breton Highlands and longest in the south-west. Precipitation (1000-1600 m m / a n n u m ) is high, and humidities are often high with a frequent freeze-and-thaw during the winter and spring. A Flora of the province has been prepared by Roland & Smith (1969), recognising seven elements (arctic-alpine and boreal disjuncts, boreal, canadian, alleghenian, southwestern, seashore, introductions and weeds). More recently a book on the natural history of Nova Scotia (Maritime Resource Management Service, 1984) has been prepared and this includes a 1:500 000 map of the nine Theme Regions of the province. It is essentially an ecological land classification.
S E L E C T I O N OF C R I T E R I A The choice of criteria to select nature reserves is a complex and difficult exercise (Goldsmith, 1975, 1983; Ratcliffe, 1977; Adams & Rose, 1978; Usher, 1986), but the first essential step is to identify the objectives of the exercise. Why are the reserves needed? Who is likely to need them? Here the intention is to set aside the best areas (1) for reference purposes in the future, (2) as a protected gene pool, (3) for teaching and research, and (4) for naturalists. Usually we encounter a dichotomy between those who wish to select 'representative' areas, i.e. reserves typical of particular theme regions (Katz, 1986), and those who wish to protect the best sites with the largest number of species, rarities, areas of old-growth forest or large trees. I favour the latter as the former approach could result in setting aside areas of often mediocre land which may already be relatively abundant. The latter takes less land, and is therefore cheaper and easier to justify to the public and to politicians. However it is also possible, and desirable, to select the best examples of each of a series of representative areas or theme regions (Maritime Resource Management Service, 1984). In order to assess the wishes of ecologists within the province, as many experts as possible were interviewed and asked which criteria they would use to select forest reserves in Nova Scotia. Nine people were prepared to participate and their criteria are shown in Table 1. Whilst 'representativeness' was the most frequently mentioned single criterion, 'uniqueness', which
189
Selection of forest nature reserves TABLE 1
Criteria used by Nine Local Ecolgoists Representative (including theme regions) Uniqueness Climax, old growth Diversity, richness Rarity Successional stages Conspicuousness Threat, endangered Age of trees, naturalness, stability, size of area, research potential, cultural, N O T representativeness, N O T diversity
5 4 4 3 2 2 2 2
1
is almost opposite in meaning, was mentioned four times and supporting criteria such as 'richness' and 'rarity' were the next most frequently mentioned. Another means of identifying criteria is to refer to an International Biological Program (IBP) Report (Taschereau, 1974). No rigid instructions were given to the field surveyors who collected the original information about the sites but the ensuing report indicates the principal reason or reasons why each site was chosen. Table 2 shows the frequency with which various criteria were mentioned. This time 'representativeness' is referred to very infrequently but the emphasis is on the 'finest', 'undisturbed' areas of 'old-growth' forest especially where they contain 'rare' plants. This supports TABLE 2
Frequency with which Criteria were Mentioned in Taschereau (1974) Mature stand, old growth Finest/excellent/good example Undisturbed Rare plants/species rich Large trees, tall Research data/previous studies Size of area Representative Regeneration, healthy, buffer zone, oldest trees, beautiful, natural, educational potential Rich bryophytes, second growth, abundant wildlife, scenic, cultural, vegetation transition, fragility
15 14 8 7 4 4 3 3
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F. B. Goldsmith
the contention that these criteria are more important to the type of person who is likely to be the consumer, i.e. naturalists and ecologists, than a series of sites that are 'representative' of the main land systems or theme regions. Recommended national criteria The Canadian Council for Ecological Areas (CCEA) recommends criteria for use in selecting reserves in Canada (Beechey, 1986). Two main approaches are identified which are referred to as the use of representational concepts and the use of functional principles. Representational concepts emphasise the need to select sites that are representative of regional types or theme regions. My criticism of this is that the themes are often difficult to identify, highly subjective and the boundaries are often artificial. Fortunately for Nova Scotia, and if one wishes to pursue this route, a comprehensive study of theme regions has recently been published and the IBP candidate list (Taschereau, 1974) has been checked against the nine main theme regions (Ogilvie, 1984). Forest sites occur in all themes on the mainland, that is everywhere except Sable Island. Old-growth hemlock and shade-tolerant hardwoods are over-represented whilst the commercially valuable red spruce has been under-represented. The 'functional' principles include diversity, rarity, size, condition and fragility. These, with various modifications, are used in many different countries, and have been discussed elsewhere (e.g. Ratcliffe, 1977; Goldsmith, 1983; Usher, 1986). They all have some merit but most are susceptible to some criticism.
Diversity This is usually agreed to have two components: richness and equitability. The latter is of limited conservation value whereas the former, whilst important because it represents the number of species on a site, is known to be a function of area. So the bigger the area under consideration the more species it is likely to contain. It is also a function of altitude, latitude, soil type, base status, etc. Another problem for those carrying out a rapid site survey is that richness is also a function of time spent on site so this needs to be either standardised or taken into consideration in some way. Some vegetation types are likely to be species-poor, e.g. old-growth hemlock stands, but are nevertheless considered to be of high conservation value. In spite of these criticisms species richness is a useful criterion that is used by many field naturalists to indicate valuable areas.
Rarity Most naturalists place considerable value on the chance of seeing a rare
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species and m a n y sites are protected because they contain rarities. However, this suggests that value increases with rarity and therefore a species is most valuable just before extinction. If we extrapolate this argument then a site can be made more important by making its rarities even rarer!
Size This can apply to either size of site or size of individuals. When it applies to the size o f site then 'island biogeographic principles' apply and the larger the site the more species it is likely to contain. W h e n it applies to individuals, e.g. trees, big game, birds o f prey, the larger the individual the more it is valued. In forests, big trees are valued, and also very old ones as they are likely to have more species o f beetles, lichens and bryophytes, provide sites for holenesting birds and are aesthetically pleasing.
Integrity This criterion, although r e c o m m e n d e d by CCEA, appears to be rather generalised and difficult to measure. Whilst it has some meaning which most people would endorse, it is not particularly useful.
Condition The same criticisms apply here as to 'integrity'. It is equivalent to the criterion 'naturalness' used in other countries, and whilst most people would endorse the concept in general terms it is difficult to measure and therefore becomes subjective and is best avoided in the early stages of site selection.
Endangerment This is a measure of threat rather than a characteristic o f the site. As such it is an extrinsic factor and should only be used in association with other criteria. On its own it does not contribute to the evaluation of the site.
Fragility The relationship o f this criterion to 'value' is unclear. It does not indicate whether a fragile site is m o r e valuable or less valuable. It is therefore not very useful.
Replication It is usually desirable to have more than one example o f a habitat but if there are too m a n y replicates the value o f each could be interpreted as being lower. This criterion is therefore not independent o f other criteria and works in the opposite direction to some.
Significance This is defined as the cumulative measure of the importance o f the area but
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F. B. Goldsmith
the various criteria listed here are non-additive. There does not appear to be any way of measuring criteria in comparable units although a comparison of the rankings of sites for a selection of criteria can be useful (see below). Therefore it is probably better not to consider 'significance' as defined here as a criterion. Of the various criteria considered above only richness, rarity, area and size are considered desirable and it is preferable not to add them together or to formulate an overall index of conservation value. Information available There are at least a dozen different types of information available or easily collected for the forests of Nova Scotia. It was noted earlier that the procedure adopted should be rapid and reproducible in other parts of the world. Some systems based only on physiognomy or vegetation structure are considered inadequate so systems based on floristics are preferred and it is assumed that some taxonomic information is available, at least for the flowering plants. However, the method used here is not dependent on a high level of taxonomic expertise, simply the identification of most of the species and some knowledge of rarities. The emphasis has been placed on plants because they do not move and are relatively easy to identify for several months of the year. Comparable data are needed for animals but so far a quick, accurate and representative sampling procedure to cover several phyla remains elusive. It may be that the structure and species composition of the vegetation is as good an indicator of faunal diversity as any other. The information that was available at the start of the project came from two sources, maps and fieldwork. Maps could provide data about area, geology, soils, climate, theme region, altitude and distance from the sea. Information, such as land capability for forestry, was extracted partially from air photos. Fieldwork could supply information about site species richness, the number of rare species, tree size (from diameter tapes) and tree age (from increment boring). Tree basal area could either be recorded from sample plots or from a basal area angle gauge.
DATA COLLECTION AND EVALUATION Of the map information available at the start, only the size of the proposed sites was utilised. The other information was not considered essential in selecting the best areas, although it would be useful in trying to find other possible sites for rare species, as suggested by Katz (1986). F r o m fieldwork,
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tree girth and diameter were recorded but not age because this is highly correlated with the other measures and increment boring damages the trees. Basal area was recorded but not used because it did not match any o f the relevant criteria discussed earlier. Thus the main criteria evolved from those o f the users, the IBP report and the critique o f the C C E A recommendations. These were number o f species, n u m b e r o f rarities, area and girth o f largest trees. They were recorded at each site. In addition, after the fieldwork was completed, other features on the site were noted, such as waterfalls, rivers, caves, historical or research
Selection of forest nature reserves
195
connections. Whilst these do not add to the value of what is in the forested area they make the overall area more attractive and may be seen as features of additional interest. No attempt has been made to add, multiply or otherwise synthesise the various criteria. The determination of which species should be considered rare was more difficult than originally expected. Some are rare in Nova Scotia but are relatively common elsewhere in Canada, e.g. Trillium erectum, whilst others are rare in Nova Scotia but common in other parts of the world, e.g. Dryopterisfelix-mas. The definition used by Maher et al. (1978) was adopted, viz. a small population within the province or territory. Maher et al. (1978) produced a list of rare species for Nova Scotia but that used here is somewhat longer (25 species; Table 3) and was produced after reference to The Flora o f Nova Scotia (Roland & Smith, 1969), plant ecologists in the province and the staffofthe Nova Scotia Museum. The number of rarities could easily change as (1) new records are discovered; (2) some of the rarities die out; or (3) criteria for defining national and provincial rarities change. Hence even the more objective criteria must be seen as being plastic. The number of species was plotted against time for 15-min intervals for each site and a sample of the graphs of five sites from the eastern end of the province is shown in Fig. 2. In practice, different sites are sampled for different lengths of time so it may be preferable to take the number of species recorded after, say, 150 min as an index of site richness. However, the curves became steeper as fieldwork progressed and identification became quicker, and the procedure would only be valid for the same worker and for sites sampled within a few days of each other. Therefore total species number was used unless the site could only be visited for a short period of time and then the curves were used for extrapolation, e.g. for Grand Anse (Fig. 2).
RESULTS Table 3 shows the number of rare species recorded at each site; as no list was prepared for Kemptown, the information was obtained from other ecologists. However, as explained earlier it may be preferable to record the number of species per unit time and then extrapolate the curves. The graphs suggest that Grand Anse River is richer than Lake O'Law and MacFarlane Woods, which are also on Cape Breton Island, a conservative value of 89 species has therefore been used. The actual total could be more. Table 4 shows the data for total number of species, number of rarities, area and the girth of the largest tree for each of the 19 sites visited and one that was not (Kemptown). Other notable features and the status of each site are also indicated.
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Selection of forest nature reserves TABLE 5
Ranking of the Top Five Sites for Each Criterion Sites are listed in order of overall priority.) Site
South Maitland Kentville Ravine Meander River Hemlock Ravine St. Croix Lake O'Law Pipers Glen Kemptown Grand Anse Clydesdale Macfarlane Woods Economy Smileys Shelburne River Melrose Point Pleasant Moose River Fleming Park Sixth Lake Abrahams Lake
Number of Number of species rarities
1 3
1 5
1
2
5 5
Area
Largest girth
1
Other features
3
Cave Research
1
History
2 Waterfall (National Park)
The information m each column o f Table 4 has been ranked, the top five values of each being presented in Table 5. This enables the best sites to be seen at a glance, and whilst these values have not been added or multiplied to give a final index of conservation value, the sites have been ranked on the basis of the values in the columns. Basically only two rules are needed: (1) the higher the ranking for any criterion the better the site; and (2) the more criteria with a high ranking the better the site.
SELECTION STRATEGIES The main set of data concerning the species recorded and the sites where they occurred can be used to consider various possible strategies for selecting reserves; that is, the total number o f species that would be protected can be determined if, say, five reserves were initially selected on the basis o f various criteria, such as total number o f species, total number o f rarities or sites with the largest diameter trees. G a m e & Peterken (1984) used this approach,
198
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291
211
200 189 166
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173
163
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selecting ten out of a total number of 78 ancient woods. In this exercise I have used five out of a total of 20 sites considered. This is an arbitrary number but represents the number of forest sites that might be expected to be designated in the next few years by the provincial authorities, although as shown later it is insufficient to adequately protect the flora. Five such 'selection criteria' were used and compared with a random selection and the total number of species possible, the results being presented in Fig. 3. Of course, the total number of plant species protected is not the only criterion for evaluating the selection process but it does present a simple means of comparing different reserve criteria. For example, a mature stand of red spruce would be universally agreed to be an important candidate type for
Selection o f forest nature reserves
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Nova Scotia but would inevitably have fewer species than a stand on baserich gypsum. The result shows that the five largest sites are not particularly species-rich (166 species) and are little better than the random selection. Although at first surprising, this is because size was determined by complex factors other than ecological ones such as ownership boundaries, land values and uniformity of forest type. The five smallest candidate areas would result in safeguarding a relatively large number of species (192), since the smallest sites included intervales which have high fertility, base-status and areas with considerable heterogeneity as well as a riverside site and a deep ravine. The selection of five sites with the largest trees (163 species) would protect a similar number of species as five sites selected at random (average = 157). The most effective permutation of five sites would be the five with the most species (211), as might be expected, but even so the total number of species protected would be 80 fewer than the total number recorded, or 72.5% of the total. These are likely to be the less c o m m o n species and therefore more highly valued. The five sites with the most rarities might be expected to be species-rich and were found to contain 189 species and are therefore almost as effective as a selection strategy as the five smallest sites. These at first glance appear to be surprisingly rich but are similar to the five with the most rarities and include intervales, ravine, riverside and cliff. The selection of sites from five different theme regions selected lists from a wide geographic range (Cape Breton in the east to Sixth Lake in the south-west) and as might be expected produced a better result than a random permutation. However, the selection based on theme regions is not sufficiently high to warrant strong recommendation for it to be the most important criterion to use. Clearly the question of selection strategies is extremely complex and these results concur with those of Game & Peterken (1984), who claim that 'no simple strategies were found which guaranteed the best results, but certain guidelines emerged which may improve the complex judgements which are unavoidable in practical conservation'. Instead, conservationists might be better advised to select on the basis of species-richness and rarity and then, as a later sieve, check that a wide range of forest types or theme regions are represented. Many people are overemphasising 'representativeness' which can easily result in the designation of large numbers of uniform and rather uninteresting areas. If this route is widely pursued few rarities will be protected. These results suggest that some criteria are at least mutually exclusive, i.e. if we pick the largest or oldest stands of trees then the total number of species protected is likely to be low. Similarly large uniform areas may be less species-rich than the same number of smaller, more heterogeneous areas. One of the most worrying suggestions, however, is that any permutation of five reserves is only going to protect about 72.5% of the total number of
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F. B. Goldsmith
species and that the rarer ones are more likely to be excluded. More than five reserves are therefore needed to protect even the small number of sites sampled in this survey, which were all candidate reserves from a previous survey. Some of these results may be at variance with others reported in the literature. For example, Harris (1984), citing Bowles (1963), suggests that birds have twice as many rare species in old-growth areas as salvage-logged areas. However, the present study has not involved any vertebrates nor salvage-logged land, and it may be that criteria for other taxonomic groups may be very different from those for plants as used here. CONCLUSIONS The procedure outlined here is simple and applicable to a wide range of habitats in various parts of the world. It is based on a survey of the resource rather than indirect measures that serve as substitutes for the vegetation, such as geology, soils and topography. Other systems of evaluation include a variety of externalities which are sometimes human factors but are often concerned with threat, vulnerability or potential value rather than with the value of the resource. These are continuously varying and should be part of a separate evaluation. The procedure described here is essentially biological and permits the addition of new sites without difficulty. They can be surveyed and then easily inserted into the ranking. The procedure is also quantitative, the process is mathematically valid and avoids addition or multiplication of non-additive criteria. A certain amount of experience is required to identify the flora and the method is easier to apply if the region has a local Flora to aid identification. Otherwise it can be pursued by different people who would all obtain a similar result, i.e. it is repeatable or objective and has applicability in many areas other than Nova Scotia. ACKNOWLEDGEMENTS I would like to thank Alex Wilson and Bob Ogilvie of the Nova Scotia Museum; Dr Pierre Taschereau of the School for Resource and Environmental Studies and Dr M. J. Harvey of the Biology Department, Dalhousie University; and Dr Paul Keddy of the Department of Biology, University of Ottawa for assistance and encouragement with this project. The views expressed are, however, not necessarily endorsed by them. I am also very grateful to the Royal Society of Great Britain and the National Science and Engineering Research Council of Canada for funding.
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REFERENCES Adams, W. M. & Rose, C. J. (eds) (1978). The selection of reserves for nature conservation. Discussion Papers in Conservation, 20, University College London. Beechey, T. (1986). Guidelines for the selection of protected areas. Montreal, Canadian Council for Ecological Areas. (Mimeographed.) Game, M. & Peterken, G. F. (1984). Nature reserve selection strategies in the woodlands of central Lincolnshire, England. Biol. Conserv., 29, 157-82. Goldsmith, F. B. (1975). The evaluation of ecological resources in the countryside for conservation purposes. Biol. Conserv., 8, 89-96. Goldsmith, F. B. (1980). An evaluation of a forest resource--a case study from Nova Scotia. J. environ. Manage., 10, 83-100. Goldsmith, F. B. (1983). Evaluating nature. In Conservation in practice, ed. by A. Warren and F. B. Goldsmith, 233-46. Chichester, Wiley. Harris, L. D. (1984). The fragmented forest: Island biogeographic theory and the preservation of biotic diversity. Chicago, University of Chicago Press. Katz, G. E. (1986). Planning for ecological reserves in Nova Scotia. Curatorial Report, 56, Halifax, Nova Scotia Museum. Maher, R. V., White, D. J., Argus, G. W. & Keddy, P. A. (1978). The rare vascular plants of Nova Scotia. Syllogeus, 18. Ottawa, National Museum of Canada. Maritime Resource Management Service (1984). Natural history of Nova Scotia, 2 Vols. Halifax, Nova Scotia Museum & Department of Land and Forests. Ogilvie, R. (1984). Important ecological sites in Nova Scotia. Curatorial Report, 49. Halifax, Nova Scotia Museum. Ratcliffe, D. A. (ed.) (1977). A nature conservation review, 2 vols. Cambridge, Cambridge University Press. Roland, A. E. (1982). Geological background and physiography of Nova Scotia. Halifax, Nova Scotia Institute of Science. Roland, A. E. & Smith, E. C. (1969). Theflora of Nova Scotia. Halifax, Nova Scotia Museum. Taschereau, P. M. (ed.) (1974). Ecological reserves in the Maritimes. Halifax, IBP. Taschereau, P. M. (1985). The status of ecological reserves in Canada. Ottawa, Canadian Council on Ecological Areas. Usher, M. B. (ed.) (1986). Wildlife conservation evaluation, London, Chapman & Hall.