The Implication of Past and Present Landscape Patterns for Biodiversity Research Introduction and Overview

Landscape Ecology 18: 223–225, 2003. © 2003 Kluwer Academic Publishers. Printed in the Netherlands. 223 The implication of past and present landscape patterns for biodiversity research: introduction and overview Isabelle Poudevigne 1 & Jacques Baudry 2 1 Landscape Systems Research Group, Facult´ e des Sciences, Universit´ e de Rouen, 76821 Mont Saint Aignan, (E- mail: 2 INRA – SAD Armorique, CS 84215, 65 Rue de Saint Brieuc, 35042 Rennes C´ edex, Franc
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   Landscape Ecology  18:  223–225, 2003.© 2003  Kluwer Academic Publishers. Printed in the Netherlands.  223 The implication of past and present landscape patterns for biodiversityresearch: introduction and overview Isabelle Poudevigne 1 & Jacques Baudry 2 1  Landscape Systems Research Group, Facult´ e des Sciences, Universit´ e de Rouen, 76821 Mont Saint Aignan, (E-mail: 2  INRA – SAD Armorique, CS 84215, 65 Rue de Saint Brieuc, 35042 Rennes C´ edex, France Since its development in the early 1980s, the aim of landscape ecology is to understand both the effectsof spatial patterns on ecological processes and thedevelopment of those spatial patterns. In Europe, hu-man activities have had a pronounced long term rolein shaping this heterogeneity so that Europe is nowthe most modified of any continent (Godron and For-man 1983). Therefore, research on how humans haveshaped landscapes is of utmost importance (Burel andBaudry 1999). If changes following the World War IIare a frequenttopic, long term changes are also impor-tant (Berlung 1991) as they have, in interaction withthephysicalenvironment,selectedtheregionalspeciespool. Indeed, present co-existence of species in thelandscape is thought to be the end product of a seriesof long term responses between species requirementsand environmental gradients of both natural and hu-man srcin (Huston 1994). Despite potential adverseeffects, many long-term human disturbance regimeshave promoted biodiversity. In western Europe, tra-ditional ‘low intensity’ agriculture has often promotedhigh levels of diversity, or provided relict habitat forrare or threatened taxa (Green 1990). By analysingecologicalpatterns andfunctioningat largespatial andtemporal scale, landscape ecology offers some of themost successful examples of the uptake of ecology inpolicy or management (Ormerod et al. 2002). If re-gionalapproachesare increasing(Suárez-Seoaneet al.2002), landscape studies of a lesser extent (few km 2 )are still dominant.One of the most important current areas in which thestudy of landscape patterns, past and present, offers amajor path of research is in understandingthe sustain-able management of biodiversity. This was the themeof a meeting of landscape ecologists held in Rouen,France in October 2001. Our aim with this array of selected papers from the meeting is to share our out-look on current European trends and approaches tolandscape ecology. Patterns of human activities in landscapes, what heritage? Cubizolle et al. (2003) give evidence that human ac-tivities, as early as the Iron age in France, had animportantinfluenceonplantbiodiversitywhosereflec-tion we see today. Their analysis of mires in France,based on radiocarbondates and pollen analysis, revealthat someactivities suchas thebuildingof smalldams,forest clearing, and cattle grazing have favoured peatinception. Ernoult et al. (2003) provide an analysisof changes in agricultural landscapes during the lastdecades. They do so by proposing two measures of landscape organisation,i.e., how patterns deviate fromrandomness. The first measure deals with the spatialrelationships among the different categories of landuse intensity that form the landscape mosaic. The sec-ond measure assess the relationships between land usepatches and the physical environment. They demon-strate that changes in agriculture have led to morestochastic patterns.  Assessing the risks to biodiversity This historical background explains why today manyrepresentative or threatened species are dispersedthrough environments, such as farmland, that are ineconomic use (Robinson and Sutherland 2002). Un-fortunately, recent changes in agricultural manage-ment and intensification have altered subtle equilibriabetween biota and patterns of use in both farmedand natural landscapes even on areas with strongconstraints to development (Poudevigne et al. 2002).  224Habitat alteration (including habitat loss, degradationand fragmentation) is now among the major risksof ecosystem degradation by these human activities(Whitfield et al. 2002). Many of these empirical stud-ies seek the variable that at different scales, frompatch to landscapes drive species distribution. Land-scape ecologists have proposed many measures toassess the relationship between spatial heterogeneityand biodiversity in landscapes (Cullinan and Thomas1992; McGarigal and Marks 1995), but few effec-tively relate pattern to process (Levin 1992). Classicalmetrics remain dissatisfying as correlation betweenspecies diversity indices and heterogeneity indices arenot always meaningful. A step further is to identifythe thresholds to which ecosystems can be modifiedwithout being irreversibly altered (Suter 1993).Jeanneret et al. (2003) compare the distribution of carabids, spiders and butterflies in two Swiss agri-cultural landscapes. They conclude that landscapemetrics are of little use, while information on habitatmosaic provide information. It also appears that thevariables explaining most of the variance in speciesdistribution are different in the two landscapes, asare the reactions of the different groups of species.This work calls for comparative studies along land-scape gradients. Millán de la Peña et al. (2003) foundlittle correlation between the landscape descriptorsthey investigated, such as the amount of cropland,and the richness and species composition of smallmammal communities on agricultural land in westernFrance. They nevertheless found effects on mammaldemography: intensification of agriculture had re-duced the density of rare and habitat specialist specieswhile favouring habitat-generalists. Mennechez et al.(2003), investigating on the effects of habitat loss andfragmentationonbutterflypopulationfunctioningwithclassical measures, argue that spatial heterogeneity intheir case study affects dispersal more than demog-raphy. With this organism-centred point of view, theauthors then propose the definition of a new parame-ter, the minimal patch area needed to establish a localpopulation in highly fragmented landscapes.Looking beyond France, in Africa, Fritz et al.(2003) observe that the extension of agriculture alongrivers in the Mid Zambezi valley, Zimbabwe, impactson most wild species. But they also define a thresh-old value of field size above which there seems tobe an acceleration of the decrease in wildlife densityand diversity. Definition of such thresholds may bean important asset in determining priorities for themanagement of degraded ecosystems.  Modelling and field testing the risks Rather than synthesising the landscape system withmetrics, some scientists have chosen to model thesesystems, in an attempt to capture manageable aspectsof their complexity that are often beyond field exper-imentation and assessment (Jaberg and Guisan 2002).Baudry et al. (2003)modeldairy farm landscapes witha measure which both considers the landscape andthe species. Connectivity is described as a measure of landscape structure and species characteristics basedonindividualarearequirementsanddispersaldistance.Results reveal that for one farming system, landscapeconnectivity remains the same over years (in a 7-yearmodel experiment), while it is significantly differ-ent between two intensive and traditionally extensivefarming systems). This work also suggests the im-portance of considering the temporal dimensions of spatial heterogeneity metrics. Similarly, Cousins et al.(2003) present a model which explores the effects of grazing frequency and intensity on plant persistence,and the relative effects of grassland size and pattern.These models aim at exploring the effects of furtherfragmentation and habitat loss on the persistence of species or plant functional groups. This generation of models aim to be valuable tools for managers, both todefine threshold risk values, and do simulations of thepotential impacts of landscape planning decisions.Most landscapeecologyresearchis based on a cor-relative approach, mainly because of the scale andcomplexity of the landscape systems. Large scale andin vivo experimentation, because it is either unaf-fordable or technically unfeasible, is rarely, with fewexceptions (Bradley and Ormerod 2002; Donlan et al.2002), a possible way of testing hypotheses proposedby the correlative studies that often characterize land-scape ecology. Equally, landscape ecologists have sofar rarely moved beyond the realms of pattern amongspecies and communities. Yet, in that field, analy-sis of spatial genetic structuring can yield interestingpossibilities. Arnaud et al. (2003), working the landsnail  Helix aspersa , test landscape-basedgeographicaldistance to an isolation by distance model. This analy-sis allowed them to test the hypothesis that migrationarises along functional pathways such as roadsideverges, hedges or irrigation canal embankments.  225 Acknowledgements TheguesteditorswouldliketothankDavidMladenoff for his support, Steve Ormerod for his enthusiasticcomments, the new born IALE France associationfor their participation and the Agence de l’Eau SeineNormandie for financing this special issue. References Arnaud, J.F. 2003. Metapopulation genetic structure and migrationpathways in the land snail  Helix aspersa : influence of landscapeheterogeneity. Landscape Ecology 18: 333–346.Baudry, J., Burel, F., Aviron, S., Martin, M., Ouin, A., Pain, G.and Thenail, C. 2003. Temporal variability of connectivity inagricultural landscapes: do farming activities help? LandscapeEcology 18: 303–314.Berlung, B.E. (Ed.) 1991. The cultural landscape during 6000years in southern Sweden. Ecological Bulletin. MunskgaardInternational Booksellers and Publishers. CopenhagenBradley, D.C. and Ormerod, S.J. 2002. Long-term effects of catch-ment liming on invertebrates in upland streams. FreshwaterBiology 47(1): 161–171.Burel, F. and Baudry, J. 1999. Ecologie du paysage: concepts, méth-odes et applications, Lavoisier. Paris 359 p. Spanish edition.2002. Ecologia del paisaje, Mundi Prensa. Barcelona. Englishedition: in press. Landscape Ecology, Oxford & IBH PublishingCo., Oxford, UK.Cousins, S.A.O., Lavorel, S. and Davies, I. 2003. Modelling theeffects of landscape pattern and grazing regimes on the persis-tence of plant species with high conservation value in grasslandsin south-eastern Sweden. Landscape Ecology 18: 315–332.Cubizolle H., Tourman A., Argant J. Porteret J., Oberlin C. andSerieyssol K. 2003. Origins of European biodiversity: palaeo-geographic signification of peat inception during the Holocene inthe granitic eastern Massif Central (France). Landscape Ecology18: 227–238.Cullinan, V.I. and Thomas, J.M. 1992. A comparison of quantitativemethods for examining landscape pattern and scale. LandscapeEcology 7: 211–227.Donlan, C., Tershy, J., Bernie R. and Croll, D.A. 2002. Islandsand introduced herbivores: conservation action as ecosystemexperimentation. Journal of Applied Ecology 39(2): 235–246.Godron, M. and Forman, R.T.T. 1983. Landscape modificationand changing ecological characteristics.  In : H.A.G. Mooney,M. (Eds), Disturbance and ecosystems. Springer verlag, Berlin,Germany, pp. 12–27.Green, B.H. 1990. Agricultural intensification and the loss of habi-tat, species and amenity in British grasslands: a review of histori-cal change and assessment of future prospects. Grass Forage Sci.45: 365–372.Ernoult, A., Bureau, F. and Poudevigne, I. 2003. Patterns of organi-sation in changing landscapes: implications for the managementof biodiversity. Landscape Ecology 18: 239–251.Fritz, H., Saïd, S., Renaud P-C., Mutake, S., Coid, C. and Monicat,F. 2003. The effects of agricultural fields and human settle-ments on the use of rivers by wildlife in the mid-Zambezi valley,Zimbabwe. Landscape Ecology 18: 293–302.Huston, M.A. 1994. The coexistence of species on changing land-scapes. Biological Diversity 3: 64–74.Jaberg, C. and Guisan, A. 2002. Modelling the distribution of bats in relation to landscape structure in a temperate mountainenvironment. Journal of Applied Ecology 38(6): 1169–1181.Jeanneret, Ph., Schüpbach, B., Pfiffner, L. and Walter, Th. 2003.Arthropod reaction to landscape and habitat features in agricul-tural landscapes. Landscape Ecology 18: 253–263.Levin, S.A. 1992. The problem of pattern and scale in ecology.Ecology 73: 1943–1967.McGarigal, K. and Marks, B.J. 1995. FRAGSTATS: Spatial patternanalysis program for quantifying landscape structure. Portland:USDA Forest Service General Technical Report PNW-GTR-351,Pacific Northwest Research Station, Portland, Oregon, USA.Millán de la Peña, N., Butet, A., Delettre, Y., Paillat, G., Morant,P., Le Du, L. and Burel, F. 2003. Response of the small mammalcommunity to changes in western French agricultural landscapes.Landscape Ecology 18: 265–278.Mennechez, G., Schtickzelle, N. and Baguette, M. 2003. Metapop-ulation dynamics of the bog fritillary butterfly: comparison of demographic parameters and dispersal between a continuous andahighly fragmented landscape. Landscape Ecology 18: 279–291.Ormerod, S.J., Barlow, N.D., Marshall, E.J.P. and Kerby, G. 2002.The uptake of applied ecology. Journal of Applied Ecology 39:1–7.Poudevigne, I., Chabrerie, O., Jackson, A., Van der Berg, S.,Bourcier, J.C. and Alard, D. 2002. Patterns of landscape dy-namics and their consequences on ecological communities.  In Application of Geographic Information Systems and RemoteSensing in River Studies. (Edited by R. S. E. W. Leuven, Poude-vigne, I. and Teeuw, R.M.), pp. 183–200. Backhuys Publishers,Leiden, The Netherlands.Robinson, R.A. and Sutherland, W.J. 2002. Post-war changes inarable farming and biodiversity in Great Britain. Journal of Applied Ecology 39(1): 157–176.Suárez-Seoane, S., Osborne, P.E. and Alonso, J.C. 2002. Large-scale habitat selection by agricultural steppe birds in Spain:identifying species-habitat responses using generalised additivemodels. Journal of Applied Ecology 39(5): 755–771.Suter, G.W. 1993. Ecological risk assessment. Lewis Publishers,Chelsea, Michigan, USA.Whitfield, D.P., McLeod, D.R.A., Fielding, A.H., Broad, R.A.,Evans, R.J. and Haworth, P.F. 2002. The effects of forestry ongolden eagles on the island of Mull, western Scotland. Journal of Applied Ecology 38(6): 1208–1220.
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