Sample shape, spatial scale and species counts : Implications for reserve design

Abstract The optimal design of nature reserves has been a hotly debated topic for some years. One contentious issue has concerned the ideal shape of reserves, with several researchers suggesting that reserves should be as nearly circular as possible to minimize edge-related degredation and potential ‘peninsularity’ effects. This paper demonstrates an advantage to non-circular reserves: given the spatial autocorrelation of environmental conditions and species ranges, elongated samples should tend to capture a greater diversity of conditions and, consequently, a greater number of species. To test this idea, samples of 16 cells, arranged as 4 × 4 squares, 2 × 8 rectangles and 1 × 16 lines were considered in mapped plant distributions at spatial scales ranging from cells of 1 m2 to 2500 km2. Overall, elongated samples tended to capture significantly larger numbers of species than did their square counterparts, as predicted. The degree of elongated sample advantage was very similar at all but the smallest of the scales considered, suggesting that the pattern of species turnover (β-diversity) is nearly scale-independent or fractal in nature. As the advantages of elongation are largely scale-independent and the only documented disadvantages (edge effects) are very scale-dependent, the optimal shape of a reserve for species sampling should shift as a function of reserve size, with large reserves becoming increasingly elongated.

[1]  S. Fraver.  Vegetation Responses along Edge‐to‐Interior Gradients in the Mixed Hardwood Forests of the Roanoke River Basin, North Carolina , 1994 .

[2]  George Gaylord Simpson,et al.  Species Density of North American Recent Mammals , 1964 .

[3]  C. Loehle,et al.  Landscape habitat diversity: a multiscale information theory approach , 1994 .

[4]  C. Schonewald-Cox,et al.  The boundary model: A geographical analysis of design and conservation of nature reserves , 1986 .

[5]  S. Hedges,et al.  Is the Peninsular Effect a Red Herring? , 1984, The American Naturalist.

[6]  Chris Margules,et al.  Patterns in the distributions of species and the selection of nature reserves: An example from Eucalyptus forests in South-eastern New South Wales , 1989 .

[7]  Bruce T. Milne,et al.  Lessons from applying fractal models to landscape patterns , 1991 .

[8]  George Sugihara,et al.  Fractals: A User's Guide for the Natural Sciences , 1993 .

[9]  R. L. Seib.  Baja California: A Peninsula for Rodents But Not for Reptiles , 1980, The American Naturalist.

[10]  John K. Horne,et al.  Spatial variance in ecology , 1995 .

[11]  R. S. Smith,et al.  The Flora and Vegetation of County Durham , 1988 .

[12]  R. W. Sims,et al.  Evolution, time, and space : the emergence of the biosphere , 1984 .

[13]  Robert M. May,et al.  Theoretical Ecology: Principles and Applications , 1977 .

[14]  J. Lawton,et al.  Fractal dimension of vegetation and the distribution of arthropod body lengths , 1985, Nature.

[15]  R. Whittaker.  Communities and Ecosystems , 1975 .

[16]  Margaret Game,et al.  Best shape for nature reserves , 1980, Nature.

[17]  The design of wildlife preserves , 1975, Nature.

[18]  Daniel Simberloff,et al.  The Contribution of Population and Community Biology to Conservation Science , 1988 .

[19]  V. Kapos.  Effects of isolation on the water status of forest patches in the Brazilian Amazon , 1989, Journal of Tropical Ecology.

[20]  R L Pressey,et al.  Beyond opportunism: Key principles for systematic reserve selection. , 1993, Trends in ecology & evolution.

[21]  M. Palmer,et al.  The Coexistence of Species in Fractal Landscapes , 1992, The American Naturalist.

[22]  M. Hill,et al.  Data analysis in community and landscape ecology , 1987 .

[23]  Peter W. C. Paton,et al.  The Effect of Edge on Avian Nest Success: How Strong Is the Evidence? , 1994 .

[24]  J. Diamond,et al.  Ecology and Evolution of Communities , 1976, Nature.

[25]  R. Macarthur,et al.  The Theory of Island Biogeography , 1969 .

[26]  D. Simberloff,et al.  Conservation and Obfuscation: Subdivision of Reserves , 1984 .

[27]  M. Avery,et al.  Predation on artificial nests adjacent to forestry plantations in northern Scotland , 1989 .

[28]  Jay M. Savage,et al.  Zoogeography: The Geographical Distribution of Animals , 1958 .

[29]  B. A. Maurer.  Geographical Population Analysis: Tools for the Analysis of Biodiversity , 1994 .

[30]  Bruce T. Milne,et al.  Spatial Aggregation and Neutral Models in Fractal Landscapes , 1992, The American Naturalist.

[31]  P. Burrough.  Data Analysis in Community and Landscape Ecology: Spatial aspects of ecological data , 1995 .

[32]  J. Lousley.  Flora of Surrey , 1976 .

[33]  W. Laurance,et al.  Predicting the impacts of edge effects in fragmented habitats , 1991 .

[34]  James A. Cox,et al.  Consequences and Costs of Conservation Corridors , 1987 .

[35]  Arthur L. Spingarn.  Forest Fragmentation and Alien Plant Invasion of Central Indiana Old‐Growth Forests , 1992 .

[36]  G Sugihara,et al.  Applications of fractals in ecology. , 1990, Trends in ecology & evolution.

[37]  Mike P. Austin,et al.  Vegetation survey design for conservation: Gradsect sampling of forests in North-eastern New South Wales , 1989 .

[38]  S. M. Walters,et al.  Atlas of the British Flora , 1962 .

[39]  Áskell Löve,et al.  Atlas florae Europaeae , 1977 .

[40]  Jared M. Diamond,et al.  THE ISLAND DILEMMA: LESSONS OF MODERN BIOGEOGRAPHIC STUDIES FOR THE DESIGN OF NATURAL RESERVES , 1975 .

[41]  R. Arnett,et al.  Flora of the East Riding of Yorkshire , 1991 .

[42]  A. O. Nicholls,et al.  Selecting networks of reserves to maximise biological diversity , 1988 .

[43]  F. Perring,et al.  Flora of Hertfordshire. , 1967 .

[44]  A. Higgs,et al.  Island Biogeography Theory and Nature Reserve Design , 1981 .

[45]  D. Streeter,et al.  Ecological Flora of the Shropshire Region. , 1986 .

[46]  Anthony G. Rebelo,et al.  Where Should Nature Reserves Be Located in the Cape Floristic Region, South Africa? Models for the Spatial Configuration of a Reserve Network Aimed at Maximizing the Protection of Floral Diversity , 1992 .

[47]  Daniel P. Faith,et al.  Application of a taxon priority system for conservation planning by selecting areas which are most distinct from environments already reserved , 1996 .

[48]  R. Gardner,et al.  Quantitative Methods in Landscape Ecology , 1991 .

[49]  E. Connor,et al.  Is there a best shape for nature reserves , 1985 .

[50]  B. Hopkins.  THE SPECIES-AREA RELATIONS OF PLANT COMMUNITIES , 1955 .