Design of Natural Reserves

1. Design of Natural Reserves According to designations set up by IUCN, there are 6 categories of protected areas, with different restrictions on use in each category: Category I – a) strict nature reserves – no harvesting, recreational use, or other access, principally for scientific research, and b) wilderness areas – preserving the natural condition. Both exclude mechanized transportation and have limited access. Category II – National parks – area managed for ecosystem protection and recreation. No harvesting or extractive use.

2. Category III – Natural monuments – managed to protect some natural or cultural feature (e.g. Carlsbad cavern). Generally more limited in area than either Category I or II. Category IV – Habitat/species management area – protected for conservation by active intervention. A specific habitat or species is usually the underlying interest. Category V – protected landscape/seascape – the interaction of people and nature has produced an area with distinct character deemed worthy of protection.

3. Category VI – managed resource protected area – protected mainly for maintenance of biological diversity with sustainable harvest/removal of a resource. Note that these management categories apply to both terrestrial areas and to marine reserves. The number of protected areas has grown since the first ones were designated in 1872 (Yosemite and Yellowstone National Parks, U.S.)

4. There is a parallel set of designations, classifying areas as biosphere reserves, Ramsar wetlands (named for Ramsar, Iran, where the convention was signed), and/or World Heritage Sites. Sites may be in any of the earlier categories and fit in one or more of these designations. If there are to be one or more protected areas to achieve maintenance of biodiversity in a habitat type, how should we design the area(s) to be protected? There are a set of rules, initially proposed as comparisons of better and worse strategies by Jared Diamond. These are ‘old’ rules, but act as a starting point…

6. 1. The larger the reserve, the better. There will be more species at equilibrium in a larger reserve, and a lower extinction rate. The species most likely to be endangered by isolation in limited preserves are the most 'K-type' species. These species typically have smaller carrying capacities and lower potential growth rates (r). The larger park, by favoring numerically greater equilibrium population sizes, may best insulate endangered species from chance demographic extinction, Allee effects, genetic drift, and inbreeding depression due to small population size. The larger park may also protect species with large habitat requirements and minimize edge effects.

7. 2. One large preserve is better than a number of smaller reserves with the same total area (??). The species likely to be endangered by restriction to the reserve(s) are, additionally, likely to be those with the poorest dispersal capabilities, or those with largest home range requirements. If dispersal is the problem, these are species unlikely to be rescued by renewed immigration from nearby 'islands‘. Species with minimum home range requirements may not have enough area in small reserves; even though they can move between reserves, they cannot maintain minimum viable populations in any of them.

8. 2. (cont.) – the other side of the question… Unique habitats/biotas with specific environmental requirements may be best met by preserving multiple isolated areas. Effects of natural catastrophes need to be considered. Many conservation biologists claim that a single large reserve is dangerous (putting all your eggs in one basket). This design criterion is more controversial than any of the others. Simberloff (Simberloff and Abele 1976, 1982) presented what became known as the SLOSS (Single Large or Several Small) controversy. Given what we know about species-area curves, why is there a controversy?

9. If several small reserves duplicate the habitat variation present in the large reserve, a larger number of species is preserved by the single large preserve. However, if there is habitat heterogeneity among the small preserves, then the answer is not clear. Different species may accumulate in different small preserves, and in sum the total number of species present can exceed the number in a single large reserve. The kind of reserve favoured depends on: 1) the slope of the species-area curve. The steeper it is the better the larger reserve; and 2) the number of species shared among smaller reserves. The larger the shared proportion the better the larger preserve.

10. Other factors may also become important considerations. For example: Population management considerations. Area is not the sufficient answer for species whose populations fluctuate widely in size. In that case, the larger the area the larger the management problem. This is a management problem faced by African big game parks. Elephants seem to go through a 50 year population 'cycle', and during at least part of it are remarkably capricious and destructive. Ease of access. In tropical forest areas if there are roads or major rivers that permit access, a reserve is more likely to be subject to poaching or logging.

11. Another problem: the tendency for a large preserve to be 'nibbled' at the edges for alternative uses in the belief that 'there's still plenty left'. Finally, there are frequently edge effects. Multiple small reserves have relatively less core and more edge.

12. If only small reserves are available should conservation be abandoned? 80% of California's 1700 rare plant species are from three habitat types available only in small patches: valley grassland, coastal scrub, and serpentine mixed chaparral. The most diverse patches of tall grass prairie are almost all very small, in a range around 2 ha. High quality patches, e.g. along railroad rights-of-way or odd corners between agricultural fields have, for various reasons, not been grazed, plowed, or otherwise disturbed.

13. There is a legislative problem with these kinds of small patches, at least in the U.S., with aggressive protection for rare species: the area cut-off for regulatory protection is 4 ha. Size of preserved area is a far more serious problem for large mammals. Less than 22% of parks around the world will, on a probabilistic basis, support their largest mammalian carnivores (10-100kg) for a century, and none of these species are expected to persist for 1000 years (at least in the parks alone).

14. 3. If small reserves are necessary, they should be arranged spatially to maximize immigration rates among reserves. The preferred way of achieving this end is to position the reserves as closely as possibleand by protection of smaller, natural area stepping stones between them, or by protecting linking corridors.These arrangements maximize the probability of 'rescue effects'. You’ve heard about corridors before. What may not be evident is the width of corridor required to encourage movement by the large mammals among linked preserves, none of which are sufficiently large alone…

15. SpeciesLocationMinimum Corridor Width(km) Wolves Minnesota 12.0 Wolves Alaska 22.0 Black Bears Minnesota 2.0 Mountain Lions California 5.0 Bobcats South Carolina 2.5 There is a modern approach that arises from this. It is called hierarchical reserve design. Core areas are highly protected; surrounding them are buffer habitats with less protection. Core areas may be connected by corridors. The buffer areas reduce edge effects.

17. 3. (cont.) Another important concept is the minimum dynamic area. If smaller reserves are necessary, a minimum size should be an area that accommodates a complete disturbance regime, i.e. includes areas at all stages of a disturbance mediated succession. This might be achieved within a combination of core and buffer habitat areas. The minimum viable population concept (MVP for short) may also be important in setting minimum reserve sizes. MVP is the subject of another lecture.

18. 4. Reserves should be as nearly circular as possible. Round preserves minimize dispersal distances between habitat patches within a preserve, and thus act to maintain or rescue populations which may be fragmented within a reserve. It minimizes the 'peninsula effect‘. The effect shows in reduced diversity of species at the end of elongated peninsulas, e.g. the diversity of mammals in southern Florida and heteromyid rodents along Baja California. Circular preserves also maximize the core:periphery ratio.

19. heteromyids

20. There are broad criteria used to evaluate reserve designs: • Comprehensiveness (extent) – inclusion of features important in conserving the full diversity of species, • Representativeness – choosing the ‘appropriate’ variation in including the various features and species, • Adequacy – is enough preserved to permit features to persist for an extended period? The ideas of dynamic areas and minimum viable populations are important here.

21. 4. Efficiency – Achieve the conservation goals using cost (or even area) minimization. This should also minimize management and conflict costs. 5. Flexibility – There may be many differing ways to achieve conservation goals. The best plan is one that permits adjustment/expansion with little disruption. 6. Risk spreading – this was covered under the SLOSS controversy: avoid potential catastrophe to the entire reserve system. 7. Irreplaceability – make sure to consider whether there are other possible inclusions that could achieve the same goal. If not…

22. 8, 9, 10. Connectivity, Area shape, and Reserve fragmentation. All are part of the ‘rules’ you’ve already seen. With all these rules and suggestions for strategic factors in decision making, biodiversity protection typically uses one of 3 approaches: 1) protect umbrella species, 2) protect areas with high species richness, or 3) protect functioning ecosystems. Very often reserves are based on the presence of some charismatic species (e.g. buffalo – Wood Buffalo National Park) or a habitat specialist (spotted owls). How successful are conservation decisions based upon single, impact species?

23. Species from the Columbia plateau, Washington Charismatic species Habitat specialist In A the x axis indicates how many occurrences of the charismatic species are protected, the Y axis the percentage of species conserved. In B it is habitat specialists chosen for protection.

24. When decisions have been made about what species to protect, how do you determine what areas to protect? The procedure is called gap analysis. 1. Identify on separate maps the distribution of the species and those areas already under protection. 2. Overlay those maps to determine which species are present in already protected areas (and with sufficient representation), and which are not. 3. Those not represented are called gap species. Overlay maps of gap species distributions to identify where new protected areas are needed.

26. An example of gap analysis applied to Hawaiian finch species – numbers identify distribution areas for the species.

27. Practical examples (and problems): One major area is human impact at the boundaries of reserves. There are a number of approaches to mix human culture, economics, and biological concerns. One approach views the boundary as a filter. Management and enforcement sets the way the filter functions. In the tropics economics and government policy limit manpower and enforcement. In Brazil there are 29 nature reserves (in addition to production (i.e. multiple use) reserves and large areas set aside for indigenous peoples) in which there are 23 guards deployed.

28. On average, that means each guard is responsible for 6053 km2, which can be compared to standards in the U.S. In the U.S. there are 367 nature reserves covering 326,721 km2, but 4002 guards, so that on average each is responsible for 82 km2. In practice, only a small fraction of Brazilian reserves have any guards (31%), so that most reserves have no protection. Further, the guards do not carry arms or have the power to arrest violators. So, how can reserves be designed to minimize damage under those conditions?

29. 1. Designing reserves to protect the Amazon basin Peres and Terborgh (1995) suggest the sitting of reserves to minimize access, and thus damage from logging or poaching. Most reserves have been set alongside water courses or roadways to ease access. That, of course, is exactly the wrong approach when the objective is protection of biodiversity and habitats. The maximum distance potential violators are likely to travel into the interior of a reserve from points of access is about 10km (this is a different view of 'edge effects'). Very large fractions of current reserves are accessible according to the 10 km criterion.

30. Most of the inaccessible area lies in the largest reserves. Many habitats and species remain unprotected. Is there a more efficient way to achieve protection in Amazonia?

31. Peres and Terborgh suggest setting reserves along watershed divides, minimizing access by navigable rivers, and where roads don't provide access to internal areas. In the Brazilian rainforest, most access is by navigable rivers. If new reserves are targeted for headwaters areas, access can be further limited. Defensibility can be maximized with lower costs. How can products be moved out of a protected area? Only on navigable rivers? A single post, placed at the boundary of the reserve along the river access, with the power of enforcement, can guard a reserve. Larger areas may have multiple river accesses, and would need protection at each access point.

32. Single guard post Posts at each end Of a reserve area Another problem, peculiar to Brazil, is that where reserves are bordered by rivers, there are frequently settlements, native and otherwise, across the rivers from the reserves, with no easy way to supervise access from the settlements. Nevertheless, commercial harvest from reserves can be controlled.

33. 2: protecting the Cape Floristic Region of South Africa • Here we consider the systematic design and selection of reserve areas. There should be obvious ways to select fragments which remain pristine or nearly so to maximize the number of species which are protected. However, codifying this fairly apparent goal in a systematic way has rarely been attempted. One approach to ‘rules’ was developed by Margules et al. (1988): • Select all fragments containing species which only occur in that fragment. This ensures that rare species are included first.

34. 2. Starting with the rarest species not represented by fragments already selected, select from among all fragments on which it occurs, those contributing the maximum number of additional, previously unrepresented species. 3. Where 2 or more fragments contribute an equal number of previously unrepresented species, choose the one which contains the least frequently occurring additional species. 4. Where criterion 3 doesn't end up selecting a fragment (2 or more are equal in all comparisons) then, to avoid subjective bias, choose the first fragment in the list among them.

35. What happens when you want to include habitat types in your scheme to select fragments? Fragments include a number of different habitat types. Rules are fairly similar, but come at species preservation by first ensuring that each habitat type is included. The rules then are: 1. Select the fragment from each habitat type which has the greatest number of species in the taxon used to develop the strategy. If all species are included using only the most diverse fragment in each habitat type, then stop.

36. 2. Select a 2nd fragment in each habitat type which adds the most new species. If no fragments of some habitat type add new species, skip any further additions of that habitat type. If all species are included, then stop. 3. Continue selecting additional fragments in each habitat type not yet fully represented using the criterion of rule 2 until all species are included. It is this approach that was used to protect fynbos in the Cape Floristic Province. Grid lines divide the region into 3km by 3km squares, and species lists were developed for each square.

38. Part of the concern for fynbos is the development of agriculture in the region, the increasing urbanization, and the effects of alien species in the area. Towns are the very dark areas, alien vegetation is dark grey, and cultivated lands are pale grey. White indicates land remaining largely in native vegetation.

39. Vertebrate species can also be incorporated into decisions. Table 14.2 (text) indicates presence/absence for vertebrates at locations in fynbos…

40. And here’s the distribution of the vertebrate species across 3 types of fynbos:

41. Modern conservation strategies try to use communities, instead of just species, to establish optimum reserve designs. One example of this approach is the Multiple Species Conservation Plan for southern California (Hierl, et al. 2008). What are the general principles that should already be clear: 1) extent, 2) representativeness, 3) fragmentation and 4) endangerment. Here is a diagram of the area studied:

44. The community types identified as most endangered were: coastal sage scrub (high endangerment, underrepresented within the reserve relative to the region, and moderately fragmented), freshwater wetlands, and coastal habitats (both have high fragmentation, moderate endangerment and representativeness, and low areal extent). While these particular communities are particular to the study area and high urban development in the region, the ideas underlying the identification and potential conservation actions are more general. Are there general approaches to design?

45. A Synthesis ofModern Reserve Design Models: A number of reserve design approaches were summarized by Williams et al. (2004) based upon different objectives. These 4 approaches can be shown graphically (2 slides on) and described: 1) Identify a reserve core that contains all species, then add buffer around it, minimizing total cost of land to acquire; may promote connectivity and compactness of the reserve (image b in figure). 2) Highly connected and tightly clustered set of mini-reserves; summed distances between pairs is minimized and connectivity achieved by selecting adjacent pairs of cells (image c in figure).

46. 3) Tight clustering achieved by minimizing the summed distances between selected pairs AND minimizing the total diameter of the reserve (image d in figure). 4) Compactness is achieved by minimizing total perimeter length (image e in figure).

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49. Peres, C.A. and J.W. Terborgh. 1995. Amazonian nature reserves: an analysis of the defensibility status of existing conservation units and design criteria for the future. Conservation Biology 9:34-46. Rodenberg, D.K., B.R. Noon, E.C. Meslow. 1997. Biological corridors: form, function, and efficacy. Bioscience 47:677-687. Schonewald-Cox, C.M. and J.W. Bayless. 1986. The boundary model: a geographical analysis of design and conservation of nature reserves. Biological Conservation 38:305-22. Schultz, C.B. 1998. Dispersal behavior and its implications for reserve design in a rare Oregon butterfly. Conservation Biology 12:284-292. Schwartz, M.W. 1999. Choosing the appropriate scale of reserves for conservation. Annual Review of Ecology and Systematics 30:83-108. Shafer, C.L. 2001. Inter-reserve distance. Biological Conservation 100:215-227. Sierra, R., F. Campos and J. Chamberlin. 2002. Assessing biodiversity conservation priorities: ecosystem risk and representativeness in continental Ecuador. Landscape Urban Planning 59:95-110. Simberloff, D. and L. Abele, 1976. Island biogeographic theory and conservation practice. Science 191:285-6. Simberloff, D. and L. Abele, 1982. Refuge design and island biogeographic theory: effects of fragmentation. American Naturalist 120:41-50.

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