ARTICLE IN PRESS

Journal for Nature Conservation 15 (2007) 26—40

1617-1381/$ - sdoi:10.1016/j.

�CorrespondE-mail addr

www.elsevier.de/jnc

Increased isolation of two Biosphere Reserves andsurrounding protected areas (WAP ecologicalcomplex, West Africa)

Nicola Clericia,b, Antonio Bodinib, Hugh Evaa, Jean-Marie Gregoirea,�,Dominique Dulieuc, Carlo Paolinic

aInstitute for Environment and Sustainability, Joint Research Centre, European Commission,TP. 440, I-21020 Ispra (VA), ItalybDepartment of Environmental Sciences, University of Parma, V.le delle Scienze, 43100 Parma, ItalycProgramme Regional Parc W/ECOPAS, 01 BP:1607, Ouagadougou 01, Burkina Faso

Received 20 October 2005; accepted 15 August 2006

KEYWORDSEcological isolation;Fragmentation;Protected areas;Agricultural expan-sion;Land-cover change;Biodiversity conser-vation;Remote sensing

ee front matter & 2006jnc.2006.08.003

ing author. Tel.: +39 033esses: nclerici@nemo.u

SummaryProtected areas such as nature reserves have been found to be effective inpreventing habitat destruction and protecting ecosystems within their borders.Recent studies however found extensive loss of tropical forest habitat aroundprotected areas, vastly contributing to increase the levels of ecological isolation.Using high-resolution satellite data we investigated the isolation trend occurring inthe W-Arly-Pendjari (WAP) ecological complex in West Africa. A land-cover changeanalysis was performed for the period 1984–2002: savanna vegetation extension andloss were derived within the complex and in a 30 km peripheral buffer. Sampleregions in the buffer were also analysed using selected spatial indicators to quantifytemporal trends in habitat fragmentation. Implications for change in relativecapacity to conserve biodiversity were discussed through the calculation of thespecies richness capacity (SRC). More than 14.5% of savanna habitat was lost in theWAP peripheral areas, while 0.3% was converted inside the complex. The degree offragmentation of remnant savanna habitat has also drastically increased. Despite theeffectiveness of the park conservation programme, we found through the SRCapproach that the WAP complex is decreasing its potential capacity to conservespecies richness. This process is mainly due to the rapid and extended agriculturalexpansion taking place around the complex. A better understanding of the ecological

Elsevier GmbH. All rights reserved.

2 789215; fax: +39 0332 789073.nipr.it, nicola.clerici@jrc.it (N. Clerici), jean-marie.gregoire@jrc.it (J.-M. Gregoire).

ARTICLE IN PRESS

Isolation of WAP ecological complex 27

dynamics occurring in the peripheral regions of reserves and the consideration ofdevelopment needs are key variables to achieve conservation goals in protectedareas.& 2006 Elsevier GmbH. All rights reserved.

Introduction

Protected areas are the cornerstones of conser-vation strategies worldwide. They preserve keyecosystems against biodiversity loss (Myers, Mitter-meier, Mittermeier, da Fonseca, & Kents, 2000),promote sustainable management and offer unique‘laboratories’ to investigate ecosystem functioningand complexity. In tropical areas especially, naturereserves have been found to be effective inpreventing habitat destruction and protectingecosystems within their borders (Bruner, Gullison,Price, & da Fonseca, 2001). Although their exten-sion represents 11.5% of the Earth’s land surface(Rodrigues et al., 2004), some studies suggestedthat at least 50% of total land would be needed toprotect the actual global biodiversity (Soule &Sanjayan, 1998).

Protected areas are important targets of re-search on insularity, i.e. the isolation and frag-mentation by anthropogenic conversion of naturalhabitats (Ramade, 2003). Recent research high-lighted extensive loss of tropical forest habitataround protected areas with consequent increasingecological isolation (DeFries, Hansen, Newton, &Hansen, 2005; Struhsaker, Struhsaker, & Siex,2005). Reserves where surrounding original bio-topes have been degraded or converted to non-natural cover can be subject to a series of changesin microclimate, soil, and vegetation compositionthat affect population structure and dynamics ofspecies living inside the core protected areas(Gascon, Williamson, & Da Fonseca, 2000; Margules& Pressey, 2000). Such a process of isolation canreduce the likelihood of persistence of certainspecies, decrease population sizes and increasetheir extinction risk (Brooks, Pimm, & Oyugi, 1999;Davies, Margules, & Lawrence, 2000; Pimm, Jones,& Diamond, 1988). Species extinction in protectedareas is in fact often linked with reserve isolationand limited size (Wilcove & May, 1986; Woodroffe &Ginsberg, 1998). The overall functional size ofprotected areas can comprise their surroundingregions of preserved habitats or a mosaic of naturalbiotopes and human-managed land; as a conse-quence, peripheral lands are strongly linked to theecological processes occurring in the core reserve.Outside the reserve, animals can find nutrients,

water and accomplish processes such as feeding,reproduction and migration. Population dynamicsmay take advantage of higher reproduction ratesoccurring outside the reserve, contributing tomaintain inner sink populations or, the contrary,be subjected to human-induced mortality (Hansen& Rotella, 2002). In many protected areas, popula-tion sinks are located beyond the reserve’s periph-eral areas, where conflicts with humans are moreevident and higher number of individuals are killed.Hence, for some species such as large carnivores,conservation priority should be given to counteracthuman persecution within peripheral areas, and tomaximise the reserves’ size (Woodroffe & Ginsberg,1998). Reserves’ edge areas, due to changes inland-use and to the action of exogenous factorsacting from the surrounding lands (e.g. cattlegrazing, fires, hunting, etc.), are more prone toimpoverishment of vegetation and changes in bioticcomposition (Laurance et al., 2002). As they act asexchange interfaces, their structure plays a keyrole for the future of the internal protectedhabitats (Gascon et al., 2000). To counteract theeffects of isolation and external disturbances,buffer zones around the protected core areas areoften adopted in the architectural strategy ofnatural reserves planning (Laurance & Gascon,1997): here restrictions are applied on resourcesuse, and development policies and actions aretaken to enhance conservation of valuable habitats(Sayer, 1991).

Habitat conversion into human exploited landsproduces harmful effects on biodiversity con-servation not only by decreasing portions ofvaluable natural habitats but also by fragmentingthe continuum of eco-mosaics constituting thelandscape (sensu Forman, 1997). Habitat frag-mentation is in fact recognised as one of themajor threats to species survival in human-disturbed environments by contributing to theisolation of inhabiting populations and by de-creasing their size (Lienert, 2004; Saunders, Hobbs,& Margules, 1991). Biotopes isolation dependingon species characteristics and the intensity ofthe phenomenon, can lead to local populationextirpation (Vos & Stumpel, 1995; Young, Boyle, &Brown, 1996), can decrease available resourcesand modify the abiotic conditions of the landscape,

ARTICLE IN PRESS

N. Clerici et al.28

e.g. by altering the amount of radiation andnutrients exchange with the surrounding land(Lienert & Fischer, 2003).

Detecting extent of native vegetation lossand habitat fragmentation around protected areasis of fundamental importance to identify the socialand physical driving forces running the modi-fication processes at the landscape level and topermit eventual responses towards conservationactions. This is the case especially for deve-loping countries, where the conversion of naturalhabitat represents also a loss of one of their morevaluable source of income (Costanza et al., 1997;Velazquez et al., 2003). In Africa, biodiversityconservation targets contrast dramatically withdemographic expansion and development needs,which constantly require productive lands toexploit (Musters, de Graaf, & ter Keurs, 2000).Africa’s 1999 population (767 million people) wasprojected to nearly double by 2035 and Sub-Saharan Africa’s population had growth rateshigher than any other world region over the past40 years (UNPF, 2005). Trends of conversion ofnatural habitats in the continent are likely tocontinue increasing, and thus the need of constantmonitoring activities. Assessing landscape modifi-cations by quantifying both changes in nativevegetation extent and its spatial structure iscritical to the management of protected areas(Margules & Pressey, 2000).

This study investigates the trend in isolation oftwo biosphere reserves and surrounding protectedareas (W-Arly-Pendjari ecological complex, WestAfrica) by analysing the conversion of inner andperipheral savanna habitats and their degree offragmentation. The W-Arly-Pendjari site (hereafterWAP) has been selected for its exceptional im-portance for the conservation of West Africanbiotopes and because of the presence of twoUNESCO-MAB Biosphere reserves. The ‘W du NigerTransnational Park’ is also part of the sitesmonitored by the European Commission JointResearch Centre (JRC) through the Global Environ-ment Monitoring Unit’s research activities (http://www-gem.jrc.it). Specific objectives of this studyinclude:

�

Identify through a quantitative assessment theloss of natural savanna vegetation in the coreand peripheral areas of the WAP complex for theperiod 1984–2002 (isolation trends). � Analyse landscape fragmentation of peripheral

remnant savanna habitats using selected spatialmetrics.

� Discuss ecological implications and conservation

issues.

Study area

The WAP transfrontier ecological complex ofprotected areas is located between 0.41E and3.151E and 12.61N to 10.71N, at the triple pointbetween southern Niger, eastern Burkina Faso andnorthern Benin (West Africa). The complex (Fig. 1,2002 boundaries) extends for more than 26,500 km2

and it is composed by the W du Niger TransfrontierPark, the national parks of Arly and Pendjari, and acomplex of contiguous protected areas and huntingreserves regulated by different statutory regula-tions, restrictions and type of rights. The reservescan be broadly divided into four classes: nationalparks, total or partial faunal reserves and huntingconcessions. In partial faunal reserves some ex-ploitation activities are allowed, such as hunting,fishing and fruit collection. These activities are notallowed in total faunal reserves and national parks,with some regional exceptions (ritual hunting insome regions of Pendjari National Park or commer-cial fishing in total reserves in Burkina Faso).Hunting zones are given in concession by govern-ments to local entities and were created to blockthe more threatening practice of conversion intofarmlands.

Management of protected areas in the WAPdepends also on country ownership. In Benin theadministration of natural parks and reserves isguided by the Strategic Plan for the Conservationand Management of Protected Areas (1994); this ledto the creation of the National Centre for WildlifeReserves Management (CENAGREF), which outlinedand implemented the Action Plan for the manage-ment and conservation of protected areas (to-gether with buffer zones and transition areas).Locally, CENAGREF co-finances the Village Associa-tions for Wildlife Reserve Management (AVIGREF),who participate in management decisions and havethe right to organise hunting in specific areas. InBurkina Faso a legislative reform in 1995 increasedthe role of private involvement and communityparticipation in the administration and manage-ment of protected areas. Twelve Wildlife Conserva-tion Units (WCU) control protected areas in thecountry through the supervision of a governmentofficer, while local management and commercialexploitation are assigned to private entities thatpay fees. In Niger protected areas are under thecontrol of the Directorate of Fauna and Fisheries(DFPP). The country adopted a National Strategyand Action Plan for Biodiversity (NBSAP) and aNational Environmental Action Plan for SustainableDevelopment (NEAP), however a specific nationalprogramme for protected areas management is stillabsent.

ARTICLE IN PRESS

Figure 1. Location of the W-Arly-Pendjari (WAP) ecological complex in Africa (left). The WAP administrative boundariesof protected areas (in 2002, ECOPAS data) and the 30 km buffer around the complex are shown on the right. Reservesand their correspondent IUCN category (in parenthesis) are: (1) Transfrontalier National Park of ’W du Niger (II); (2)Pendjari National Park (II); (3) total faunal Reserve of Tamou (I); (4) Cynegetic zone of Djona (VI); (5) Cynegetic zone ofMekrou (VI); (6) Cynegetic zone of Atakora (VI); (7) Cynegetic zone of Pendjari (VI); (8) partial faunal reserve ofKourtiagou (IV); (9) hunting concession of Koakrana (VI); (10) total faunal reserve of Arly (IV); (11) partial faunal reserveof Arly (IV); (12) hunting concession of Pagou (VI); (13) hunting concession of Tandougou (VI); (14) hunting concession ofOuamou (VI); (15) total faunal reserve of Singou (I); (16) partial faunal reserve of Pama(IV) and (17) total faunal reserveof Madjori (I). No data was present for the white areas in the buffer zone.

Isolation of WAP ecological complex 29

The WAP has heterogeneous climate conditionsand vegetation distribution. The complex is char-acterised by the presence of a rainy season(approximately from May to October) and a dryseason (November–April); climate characteristicsbelong to the SoudanianWhite/UNESCO bioclimaticclassification (White, 1983), although the WAP hasdrier conditions in the northern part (averagerainfall of 500mm) and more humid in the south(average rainfall of 1200mm). Vegetation cover inthe northern part of the complex is characterisedby grasslands and open shrublands (brousses)degrading towards open savanna woodlands withsparse trees. From the central to the southern partof the complex, shrub savanna gradually becomessavanna woodlands, while the climate tends to theGuinean domain. The northern parts are oftendominated by bush species and representatives ofthe Combretum–Terminalia association, such asAcacia ataxacantha, Combretum glutinosum, Bom-bax costatum and Anogeissus leiocapus. The her-baceous layer is frequently represented byLoudetia spp. and Andropogon spp. In the southernregions the tree component often becomes domi-nant and the vegetation is characterised byrepresentative species like Anogeissus leiocarpus,Terminalia avicennioides and Isoberlinia spp. (Du-

lieu, 2004). Other characteristic habitats aregallery forests, riparian vegetation and marshlands,of high interest for conservation issues.

The WAP complex represents the biggest conti-nuum of terrestrial and aquatic ecosystems in theWest African savanna belt, and one of the mostimportant areas for the conservation of westernAfrican ecosystems and fauna (Lamarque, 2004).The complex hosts the bigger population of elephantLoxodonta africana in West Africa (more than 3800individuals), which represent 50% of total abundancein the region (UNDP, 2004). The WAP system is one ofthe last refuges in West Africa for a number ofthreatened species and it is of critical importancefor the conservation of Sahelian and Sudanesemammal populations, such as dwarf buffalo (Syn-cerus caffer brachyceros), kobs (Kobus kob kob),roan antelopes (Hippotragus equinus koba), giraffes(Giraffa camelopardalis peralta), hippopotami (Hip-popotamus amphibious), lions (Panthera leo), andseveral monkey species. The presence of rarespecies such as the manatee (Trichecus senegalensis)or the leopard (Panthera pardus) was demonstrated,and new butterfly species were also recentlydiscovered (Lamarque, 2004). Overall, at least 670plant species were identified in the complex, someof them endangered or vulnerable species. The fact

ARTICLE IN PRESS

N. Clerici et al.30

that between the three countries sharing the WAPthe relevant conservation legislation is often notconsistent is a factor that threatens conservationefforts. Many species have a different statusdepending on the national regulation, producingincongruent situations where, for example, hippo-potami can be hunted in Benin while they areprotected in Burkina Faso.

For the complex’s outstanding biodiversity sig-nificance, the ‘W du Niger’ Transfrontier Park(hereafter W Park) was accepted in 2002 as thefirst Transboundary Biosphere Reserve in Africa bythe Man and the Biosphere Programme of UNESCO(MAB). Part of the complex is also an UNESCO WorldNatural Heritage Site (W National Park of Niger, in1996), while extended areas are protected by theRamsar Convention (total reserve of Arly). At itssouth-western portion the WAP complex hosts thePendjari National Park, which has been a BiosphereReserve since 1986.

Benin, Burkina Faso and Niger are involved in co-ordinated trans-boundary conservation effortsthrough specific programmes regarding the WAP,for instance:

�

Regional programme ‘Park W-ECOPAS’ (Ecosys-temes Proteges en Afrique Soudano-Sahelienne),which is funded by the European Union develop-ment funds and it is designed to control thedegradation of natural resources, ensure sustain-ability and safeguard biodiversity; � Regional project ‘‘Building Scientific and Tech-

nical Capacity for Effective Management andSustainable Use of Dryland Biodiversity in WestAfrican Biosphere Reserves’’ financed by GEF-UNESCO-MAB and whose objective is to strength-en scientific and technical competence foreffective management of the reserves;

� Renewable Energy Programme, funded by Elec-

tricite de France, designed to provide solarenergy to tourist structures and riparian popula-tion to reduce wood and charcoal collectionwithin the WAP.

Furthermore, the three countries have alsosigned an anti-poaching agreement.

Research activities in the WAP are the result of anumber of agreements with international organisa-tions, regional research institutes and local orforeign universities (especially from Germany, Italyand France). In the case of the W ecologicalcomplex, a Scientific Council of the reserve withinthe ECOPAS programme coordinates the researchactivities to support the biosphere managementplan, covering themes like: dynamics of animalpopulations (Lamarque, 2004); agriculture (Doussa,

2004); social dynamics, ecological characterisation(Dulieu, 2004; Fournier et al., 2003); fires (Eva,Gregoire, & Mayaux, 2004) and transhumance.

Within the peripheral areas of the WAP, agricul-ture (sorghum and cotton especially) and huntingactivities are widespread. The elevage (cattleraising) is also a common practice for somepopulations. Poaching is still a diffused phenomen-on and a major threat to the reserves.

Evidence shows human presence has existedaround the WAP area for thousands of years(Lamarque, 2004). Equilibrium, or an adaptation,was found between human disturbances and eco-logical conditions, particularly relating to vegeta-tion cover. However, some drastic changes occurredduring the 1970s and 1980s with the developmentof new villages around the W Park (Boluvi, 2005).There is therefore an increasing anthropic pressurearound the reserves which, as a probable conse-quence, are creating a breaking of the equilibriumbetween the ecological conditions and level ofhuman disturbance. Currently, around the W Park aperipheral region limits productive activities onlyto agriculture, acting as buffer against the pressureof grazing, hunting and expansion of urban centres.In some other areas of the WAP complex no buffersare present and reserves and hunting concessionsare directly connected to villages and agriculturalareas.

From outside the complex and from the WAPhunting reserves, fire is commonly propagating intothe protected areas through the continuum ofsavanna vegetation layer, often due to poachingand illegal grazing activities (ECOPAS data). Addi-tionally, park managers set prescribed fires everyyear to open vegetation and increase visibility offauna for tourists. The ecological effects of thesefires are still not well understood (Dulieu, 2004;Sawadogo & Fournier, 2004; Sawadogo et al.,2005). Fires are considered fundamental regulationelements of savanna’s vegetation structure and apermanent driving force that initiated the forma-tion of savanna ecosystems (Goldammer, 1993). InAfrican savannas, fires and vegetation coexisted atleast since the Quaternary period (Kershaw et al.,1997), however the human-driven control of bio-mass burning is currently producing more frequentfires, and unnaturally lit at the beginning of the dryseason (Saarnak, 2001). These practices decreasethe intensity of combustion, which in turn poten-tially affects the savanna tree-grass ratio andproduces effects such as the ‘bush encroachment’phenomenon (Roques et al., 2001; Scholes &Archer, 1997), as observed in southern W Park.Outside the WAP, fires are lighted annually, begin-ning at the end of September at the north and

ARTICLE IN PRESS

Isolation of WAP ecological complex 31

ending in late April at the south (Eva et al., 2004).Fires are widespread and are used to generateresprouting for grazing activities, to hunt and inagricultural or other land management practices(Gregoire, 1996). Fire can be considered as one ofthe main indicators of land-cover change (Eva &Lambin, 2000; Turner et al., 1995): in the periph-eral areas of the WAP decrease in burned surfaceand modification in spatial properties of burnedareas are processes that accompany savannahabitat loss and landscape fragmentation (Clerici,Hugh, & Gregoire, 2005).

Materials and methods

Data sources

From the United States Geological Survey (USGS)we acquired images by Landsat Thematic Mapper(TM) and Enhanced Thematic Mapper+ (ETM+),respectively from 14th to 23rd November 1984and 17th to 24th November 2002 (early dry season)covering the WAP complex; the images have anominal pixel resolution of 30m. To help theinterpretation process 12 scenes of the ASTER(Advanced Spaceborne Thermal Emission and Re-flection Radiometer, onboard the NASA Terra plat-form) were acquired for the periods of November2001 and 2002, as the 15m resolution of thevisible/near infrared bands can provide significantadditional information. Thematic layers (adminis-trative boundaries, vegetation maps, etc.), wereprovided by the ECOPAS project. Landsat TM andETM+ data were acquired in the same season inorder to minimise variations in vegetation phenol-ogy and weather conditions; however, differencesin soil moisture level and intensity of vegetationsignal were still present in some areas of theimages. The TM and ETM+ images were co-registered using 172 ground control points and asecond-order polynomial function to achieve a sub-pixel precision (26.4m RMSE).

Analysis of isolation: savanna vegetation loss

The isolation analysis was performed consideringa 30 km wide peripheral zone delineated outsidethe WAP administrative border, and all the areainside the complex. The periphery is shared byBenin, Burkina Faso, Niger and Togo; limitedportions of the buffer were not covered by thesatellite images. As some techniques of imagedifferencing and rationing are less effective ifphenological and radiometric variations are evident

(Coppin, Jonckheere, Nackaerts, Muys, & Lambin,2004), we adopted a post-classification changedetection approach (Jensen, 1996) to analysechanges in savanna vegetation extension andcritical land-cover changes, e.g. agriculture dis-tribution. In this method independent classifica-tions of the datasets are performed using asupervised or unsupervised classification algorithm;one of the main advantages of such approach is thatit minimises radiometric calibration betweendates. We performed an unsupervised classificationbased on an ISODATA classifier, excluding TM/ETM+band 1 (0.45–0.53 mm) because of its sensitivity tohaze and fire smoke.

Main land-cover classes were identified based onprevious validated vegetation maps (DeWispelaere,2003), high-resolution imagery (Terra ASTER data),waypoints collected during field missions and visualinterpretation. A detailed analysis of the land-cover change trajectories is not reported here as itis not within the scope of the paper. The initiallyover-segmented classified images were interpretedby cross-referencing all information sources, andclasses assigned to seven broad categories (galleryforests and riparian vegetation, wooded savanna,shrub savanna, open savanna dominated by herbac-eous vegetation, agriculture, water, other). Overallextension of vegetation was derived by merging thefour vegetation types (hereafter savanna vegeta-tion class). Change statistics were derived for thecountries sharing the WAP complex and peripheralareas. Formal overall accuracy assessment was notperformed because of the extension of the studyarea (ca. 57,000 km2) and the costs associated witha prolonged field mission. However, field validationpoints were collected in the Pama, Diapaga andTapoa Djerma regions.

To illustrate the potential implications of ecolo-gical isolation of the WAP, we calculated the changein relative capacity of conserving species richnessof the reserve complex, species richness capacity(SRC). Following DeFries et al. (2005) and Brookset al. (1999), SRC can be calculated through theequation:

SRC ¼ ðIt þ StÞ=ðII þ SIÞ� �z

,

where It and St represent, respectively, the area ofhabitat inside the complex and the surroundingregion at time t, while II and SI correspond to theareas inside and surrounding the WAP in the case ofcompletely intact habitat. Coefficient z depends onhabitat conditions and species; we adopted thevalues z ¼ 0.25 as a previously used value esti-mated for fragmented tropical and subtropicallandscapes, with values interval of 70.10 (Brookset al., 2002; DeFries et al., 2005). The SRC is an

ARTICLE IN PRESS

N. Clerici et al.32

index based on the direct proportionality betweenspecies richness and habitat extension (species–ar-ea relationship, e.g. Brooks et al., 1999), andrepresents a loss of potential capacity of maintain-ing biodiversity richness for the reserve, postulat-ing that all areas surrounding the reserve would besuitable habitat if intact.

Fragmentation analysis of remnant savannahabitats

The land-cover change map identified the regionswhere there is evidence of conversion of savannahabitat. These areas are subject to higher anthro-pic pressure and where it is more urgent to assessthe conditions of habitat spatial alteration due toland-cover conversion. We assessed the degree oflandscape fragmentation of remnant savanna ve-getation habitats by selecting five subset regions.The choice of using sampling regions (subsets)instead of the whole study area was made asotherwise the fragmentation trends of the entirestudy region would be an average of surfacescharacterised by a high degree of fragmentationwith ones with low degree or absence, hence givingan overall less meaningful result (trend). Usingsubsets we can focus on hot-spots, understandinglocal fragmentation dynamics and landscape mod-ification processes.

One method to analyse landscape fragmentationis through the use of quantitative indicators basedon the spatial arrangement of habitat patcheswithin the eco-mosaic (Herzog & Lausch, 2001;Narumalani, Mishra, & Rothwell, 2004). Numerousstudies adopted these indices to measure thedegree of fragmentation of habitats as a basis tounderstand potential harmful effects on ecosys-tems and biota (see Cumming & Vernier, 2002;

Table 1. Spatial indices adopted in the landscape fragmen

Index category

Patch density and size metrics

Edge metrics

Shape metrics

Isolation/proximity metrics

Nagendra, Munroe, & Southworth, 2004). Moreover,modifications in spatial pattern over time alsoprovide help in identifying and understanding socialand ecological processes driving landscape change(Brown, Duh, & Drzyzga, 2000).

Through the use of dedicated software (FRAG-STATS, McGarigal, Cushman, Neel, & Ene, 2002) wecalculated a series of habitat patch-based indicesselected from the ecological literature to assessthe degree of fragmentation of savanna vegetation(Forman, 1997; O’Neill et al., 1988; Southworth,Munroe, & Nagendra, 2004). The analysis wasperformed for 1984 and 2002 on a vegetation/non-vegetation layer (savanna habitat) to investi-gate trends in increase/decrease in habitat frag-mentation. These metrics (Table 1) take intoaccount habitat patch dimension, number, shape’scomplexity and their spatial arrangement withinthe landscape (see McGarigal & Marks, 1995).Number of patches in a landscape (NP) or patchdensity (PD, number of patches over total land-scape area) is a simple measure of the extent ofsubdivision or fragmentation of a patch class. Theyare the simplest metrics of fragmentation but theresults of their interpretation are more meaningfulin conjunction with other indicators. Habitat patchsize (PA_MN) measures the surface extension ofpatches and it is related with population extirpa-tion risk and with the number of species that apatch generally holds (Farina, 1998). Largest PatchIndex (LPI) measures the area of the largest patchof the class of interest. Edge density (ED) providesinformation on density of habitat patch peri-meters. Shape metrics as SHAPE_MN and PA-FRAC_MN detect the complexity of patch geometryand have been previously used to assess the level ofanthropic pressure on landscapes (McGarigal &Marks, 1995). LSI and Contiguity Index (CON-TIG_MN) measure, respectively, the aggregation

tation analysis

Fragmentation indices

Number of patches (NP)Mean patch size (PA_MN)Patch density (PD)Largest Patch Index (LPI)

Edge density (ED)

Mean Shape Index (SHAPE_MN)Contiguity Index (CONTIG_MN)Mean patch fractal dimension (PAFRAC_MN)Landscape Shape Index (LSI)

Mean Proximity Index (PROX_MN)Mean nearest neighbour distance (ENN_MN)

ARTICLE IN PRESS

Figure 2. Total area of savanna vegetation (in black) andagriculture (blue) classes for the countries within the30 km peripheral areas of the WAP (1984 and 2002).

Isolation of WAP ecological complex 33

and ‘‘spatial connectedness’’ of a habitat class(Major, Christie, Gowing, & Ivison, 1999). Isolationand proximity metrics (PROX_MN, ENN_MN) aremeasures of patch context and assess the degree ofpatch isolation (Gustafson & Parker, 1992). This hasimportant consequences for the disruption ofmovement patterns to other neighbouring habitatpatches and the isolation of local populations (Vos& Stumpel, 1995).

Additionally, a field mission was conducted inNovember 2004 around Diapaga (west of W Park,Burkina Faso) and Ougarou (north-west of WAP).The field mission had multiple objectives thatsought to assess the degree of discontinuity in thelandscape at a field scale in a mosaic of cultivated/uncultivated areas and within the WAP, combinedwith the understanding of the mechanisms that areat the basis of land-cover change. We collecteddata from three transects (each 1 km in length)located inside and outside the protected areas; foreach transect we recorded a GPS waypoint everytime there was clear presence of a discontinuity inland-cover/land-use (e.g. from bare soil to setaside). This provided a first indication of the degreeof discontinuities present inside and outside theWAP and on what processes create landscapefragmentation.

Results

Isolation analysis

Our analysis documents an extended conversionof natural savanna vegetation in the peripheralareas of the WAP complex. Within the 30 km-widebuffer surrounding the outer perimeter of thereserves, more than 14.5% of savanna vegetationwas lost from 1984 to 2002 revealing a rapidprocess of land conversion (3514.4 km2). The higherrate of native vegetation loss is found within theBenin portion of the WAP peripheral areas, i.e.17.3% of its 1984 extension, corresponding to anapproximated 1764 km2 loss (Fig. 2). Lower ratesof habitat loss are found in the territories ofBurkina Faso (13.1%), Niger (11.2%) and Togo(5.2%). Overall, change trajectories revealed thatconversion of native savanna habitats in thecomplex’s periphery resulted primarily from thestrong expansion of agricultural activities, in totalthis class represented 15.8% of land-cover in 1984and 26.9% in 2002. The greatest agriculturalexpansion is found in the Benin region, where15.1% of its peripheral territory was converted intoproductive lands during this temporal interval,

followed by Burkina Faso (9.1%) and by Niger(7.5%), where the presence of tabular hills (mesas)often characterised by unproductive ferralithiccuirasses represent strong physical constraints toagriculture expansion. A major change is located atthe south of Pama partial reserve, where a largeportion of woodland savanna was converted intoflooded lands following the construction of theKompienga dam, current surface of approximately106 km2.

As expected, within the WAP complex the rate ofhabitat loss is much lower. Overall inside the wholecomplex we detected the loss of 82.5 km2 of nativesavanna habitat (1984–2002), corresponding to0.3% of the overall complex extension. The hot-spots of habitat conversion are located in theenclaves within the partial reserves of Pama(Tintangou) and Arly (Madjoari), and to a lowerextent in Tamou total reserve and in the southernpart of the Cynegetic zone of Pendjari. Arly andPendjari National Parks revealed no significant lossof habitat, but in the Benin portion of the W Park alimited number of cultivated fields have appearedwithin the southern border revealing explicitly thehigh pressure of agriculture expansion towards thepark’s edge.

Changes in potential capacity of the complex topreserve biodiversity were assessed through thecalculation of the SRC, derived from the empiricalarea–species relationship (DeFries et al., 2005;Pimm & Raven, 2000). Based on this relationship, in1984 the WAP complex capacity to conserve speciesrichness is 97.770.9% of the ideal intact case(Fig. 3). In 2002, mainly due to the loss of naturalsavanna habitat in the peripheral areas, thecomplex decreased its SRC to 95.971.6%. In thecase of a complete isolation case (total loss of

ARTICLE IN PRESS

Figure 3. Relative species richness capacity (SRC) for theyear 1984, 2002 and for the complete isolation case(C.I.), calculated with z ¼ 0.2570.10.

sample

region

swithinthe30

kmperiphe

ralarea

sof

WAP

LSI

PROX_M

NCONTIG_M

NEN

N_M

NPA

FRAC

5689

.018

7144

7.28

30.35

390

.434

1.50

810

36.809

1770

71.390

0.38

486

.187

1.44

4

9615

8.67

816

3334

.585

0.36

086

.091

1.53

260

136.48

625

7213

.242

0.28

581

.100

1.52

2

8112

5.28

176

897.35

10.35

092

.841

1.49

568

71.747

2635

09.069

0.32

080

.461

1.51

9

2119

3.46

824

715.34

40.33

889

.564

1.53

308

115.68

738

561.39

10.40

910

6.53

41.50

1

0029

3.65

012

289.60

00.37

090

.067

1.59

210

168.19

049

763.84

00.38

110

0.84

21.50

9

N. Clerici et al.34

surrounding areas) the WAP complex would reach aSRC equal to 83.076.2%.

Table

2.

Frag

men

tation

indices

valueof

sava

nnaha

bitat,ca

lculated

for19

84an

d20

02in

five

selected

Sample

region

(km

2)

Year

Sava

nna

habitat

(%/tot.

region

)

Agriculture

(%/tot.

region

)

Frag

men

tation

indices

PA_M

N(km

2)

NP

SHAPE_

MN

PD(n/k

m2)

LPI

ED

1.Yaob

ereg

ou-Kan

di,

Ben

in(167

5.3)

2002

73.6

25.3

0.39

631

081.46

1682

.31

52.271

56.0

1984

89.8

9.6

2.36

766

01.35

356.20

69.625

26.1

2.Ko

urtiag

ou,

Burkina

Faso

(255

9.4)

2002

74.2

25.1

0.43

143

731.43

1874

.42

65.406

98.2

1984

85.1

14.6

0.92

623

041.38

987.89

75.574

89.9

3.Mek

rou

–Ban

ikoa

ra,

Ben

in(243

2.3)

2002

67.8

30.9

0.32

648

761.45

1589

.55

38.480

53.9

1984

89.7

9.8

2.20

099

01.37

323.87

58.956

36.2

4.Zo

ukwara,

Niger

(195

1.8)

2002

58.3

27.6

0.20

751

261.53

1844

.10

24.649

90.6

1984

64.1

20.3

0.35

635

161.48

1264

.90

30.535

58.9

5.Pa

ma-Man

dou

ri,

Burkina

Faso

(328

1.2)

2002

43.7

34.9

0.09

012

,820

1.65

1761

.30

4.52

036

.919

8457

.125

.10.15

699

171.47

1365

.48

14.290

25.6

Fragmentation analysis

In all the five regions analysed we detected anextended loss in savanna vegetation; this is mainlyderived from agricultural expansion that consis-tently increased from 1984 to 2002 for all sampledregions (Table 2). Analysis of spatial indices(1984–2002) revealed that eight out of 11 indica-tors showed an increase in fragmentation ofremnant savanna habitat for every subset region(first eight indices columns in Table 2). Number ofsavanna patches (NP) tends to increase, sometimesdrastically (Region 1), while at the same time theirmean dimension decreases (PA_MN). As a conse-quence savanna patches’ density is increased (PD).This is especially clear when large homogeneouspatches of native vegetation (especially densewooded savanna) are involved in the conversioninto little dense crop fields (Fig. 4) thus theintensity of fragmentation appears more intenseat the south of the WAP where this type ofvegetation dominates the landscape. At the northof the WAP (e.g. Region 4), vegetation patches aresmaller and characterised by open sparse savannaand brousse, with bare soil fields often interposedin the vegetation matrix. In this situation where ahigh degree of heterogeneity is already present inthe landscape, changes in fragmentation are lessevident, however always present. Degree of dom-inance of the savanna class in the landscape isalways reduced (lower values for LPI). The processof fragmentation has increased the ED of alteredhabitat patches: ED reveals an increase in overalllength of savanna patches’ boundaries, following

ARTICLE IN PRESS

Figure 4. The expansion of the ‘‘cotton front’’ is vastly converting and fragmenting savanna habitats around the WAP(vegetation in green, fields in pink, burned areas in black). North of Kourtiagou-Kondio (Burkina Faso) in 1984 (A) and in2002 (B). Landsat TM/ETM+ data.

Isolation of WAP ecological complex 35

ARTICLE IN PRESS

N. Clerici et al.36

human interventions. Also, these change processesproduced an increase in complexity of habitatpatch shape, as observed by the augmentation ofthe mean Shape Index (SHAPE_MN), and an increasein disaggregation of patches as observed by anincreased LSI. Other fragmentation indices, meanperimeter/area ratio, mean nearest neighbourdistance and mean patch fractal dimension showedtrends that vary depending on the test region. Insome cases the limited number of savanna patchesand size due to their gradual disappearing, alsoinfluences the simplicity of patches shape and theirspatial/distribution properties. This is also re-flected in the CONTIG_MN, ENN_MN and PAFRACindices, which at a first analysis can providecounter-intuitive results.

Discussion

The outcomes of the isolation analysis carried outfor the period 1984–2002 require careful interpre-tation. A certain amount of savanna habitat (14.5%of 1984 extension) has been lost in the peripheralareas of the WAP complex. Land-cover changetrajectories showed that this was mainly theconsequence of agricultural expansion taking placein the area, with the greatest expansion in the partunder the jurisdiction of Benin and Burkina Faso,where the remunerative business of cotton isdriving an already fast growing agriculture (Doussa,2004; Palm, 2005). At the same time no significantproportion of habitat conversion was detectedwithin the national parks of W, Arly and Pendjari,which witnesses the level of effectiveness reachedby the conservation and management programmesimplemented in the parks (e.g. ECOPAS). Africanprotected areas are not, contrary to what issometimes said, purely administrative entities butthey can really play a key role in supporting habitatconservation policies. Concerning the overall ex-tension of the WAP complex, a limited proportion ofnative savanna habitat was lost due to the expan-sion of enclaves within some partial reserves (e.g.Tintangou and Pama). In particular the expansion ofthe Madjoari area can play an important role in thepotential spatial division of the complex.

Apart from the fact that the overall savannahabitat loss corresponds to a large area in absoluteterms, concern is generated by the way such loss isdistributed in the peripheral area. Certainly therisk to the integrity of the WAP would be lower iferosion of natural habitats, in favour of cultivatedfields, occurred uniformly starting from the ex-ternal border of the buffer zone. However, frag-

mentation analysis in all areas of investigationreveal that habitat loss has followed a patchy trendand this may have consequences well beyond theeffective damage associated to the simple exten-sion of the habitat loss. From 1984 to 2002 thenumber of habitat patches has increased noticeablyin all the five areas that have been monitored; insome cases (Regions 1 and 3) this number more thandoubled. Given that any habitat patch couldrepresent, at least in principle, a new front ofexpansion for further colonisation, patchy erosionhas brought converted areas closer to the parkborder than a colonisation front that uniformlymoved from the external border.

Furthermore, the ecological integrity of theprotected area strongly depends on the ecologicalfunction that its surrounding environment canperform. This can be also detected by using indicesof fragmentation. Landscape patterns metricsoperate as quantitative links between landscapestructure and the ecological or environmentalprocesses taking place. Particular attention shouldbe given to their theoretical understanding andselection. We chose a set of fragmentation indicesbased on landscape ecology literature and ourexperience. This set of metrics can hold a certainamount of information redundancy. As univocalconsensus does not exist on the choice of individualmetrics we preferred to analyse a larger set ofindices instead of a parsimonious set in search ofmore robust conclusions on habitat fragmentationtrends.

Given these premises, the results we obtainedfrom fragmentation indices all point to a reducedecological functionality of the peripheral border.Average size of savanna patches (PA_MN, seeTable 2) has decreased all around the peripheralarea. Smaller size reduces the potential of patchesto host animal species (Farina, 1998), whichconsequently need to move in search of moresuitable habitats. Average distances betweenpatches have increased in three out of five regions(ENN_MN, see Table 2). Also, the index of proximity(PROX_MN, Table 2) has diminished in all fiveregions. Although not the case in all regions, resultsdemonstrated patches were less connected func-tionally with one another because mean distancesdecreased, with the consequence that animalmovement is made more difficult by the presenceof cultivated fields that may act as barriers. Moreand more isolated patches, as is the case presentedhere, may give rise to higher sensitivity toenvironmental and demographic stochasticity,decrease access to resources, genetic drift ofpopulations and alteration of landscape-levelprocesses necessary for population survival and

ARTICLE IN PRESS

Isolation of WAP ecological complex 37

persistence (Leach & Givnish, 1996; Suarez, Bolger,& Case, 1998).

The ED index increased in all cases, revealing ageneral increase in the overall length of savanna’spatch boundary following human intervention.Increase in edge relative to core areas can haveprofound effects on ecological processes and biota(‘edge effects’), like increased vulnerability toinvasion by exotic species or augmented abioticinfluences as radiation and wind (Debinski & Holt,2000; Saunders et al., 1991).

Moreover, these change processes produced anincrease in complexity of habitat patch shape,highlighted by augmentation of the mean ShapeIndex (SHAPE_MN). The degree of complexity ofpatch shape can have strong influences on ecolo-gical processes, e.g. animal space-use behaviour,dispersion dynamics and population structure(Cumming, 2002; Harper, Bollinger, & Barrett,1994; Major et al., 1999). Increase in LSI shows adisaggregation of savanna patches due to theaugmentation of distance between them, provokedby the increased amount of interposed convertedland. All these effects potentially produce highersusceptibility to disturbance by environmental andanthropic agents (Lienert & Fischer, 2003).

We believe the combination of isolation analysisand fragmentation analysis presents an overallscenario of concern. Despite the presence ofadministrative borders inside the WAP a limitedextension of native habitat was lost, the type andextension of savanna loss produced in the periph-eral areas has reduced significantly the complex’spotential capacity to conserve biodiversity. In afully eroded case of the buffer areas (completeisolation of the complex), the WAP can loose morethan a quarter of this capacity. Isolation andfragmentation analysis, read in conjunction, sug-gest that the relative capacity to preserve biodi-versity may be underestimated by the SRC. Thechart in Fig. 3 shows that complete isolation, whichwould lower SRC to some 85% of the presentcapacity, would occur in more or less 100 years;this type of analysis makes use of an index that isbased upon the extension of the reference areas,and does not take into account other importantfactors such as the way in which the reduction insurface takes place. It follows that the loss ofconservation capacity estimated between thereference periods (1984 and 2000) has beenpotentially underestimated. Also, the calculationof SRC is affected by the uncertainty implicitlypresent in the species–area approach. However, itdoes provide a preliminary quantitative indicationof the effects of isolation trends on potentialcapacity of the reserves to conserve biodiversity.

The SRC can be a very valuable tool if combinedwith results obtained from other types of investiga-tion, such as fragmentation analysis.

The present approach more than provides precisequantitative results showing the harmful trend thecomplex is experiencing and highlights the poten-tial consequences of its isolation. The analysesperformed on five different test regions revealedan increasing trend of fragmentation within rem-nant savanna habitat in the peripheral areas of theWAP. This potentially produces harmful effects, asit isolates inhabiting populations (Stratford &Stouffer, 1999), increases their demographic sto-chasticity, and alters crucial ecological processes(e.g. dispersal, feeding, reproduction) taking placein the ecological continuum between core pro-tected areas of the WAP and the surroundinghabitat (Lienert, 2004; Wu, Thurw, & Whisenant,2000).

The methods involved in this study have somelimitations: first of all the extension of savannavegetation in the peripheral areas can be poten-tially overestimated by the satellite classification,due to its spectral similarity with fallow fields(jacheres). This type of ephemeral habitat is notecologically suitable for many species living withinthe WAP: the overall loss of savanna extension thuscan be potentially underestimated. Moreover, theSRC approach does not consider other factors thatare currently contributing to threaten the conser-vation capacity of the WAP, like poaching, illegalforaging and the unclear ecological effects of fireson parks ecosystems (Fournier, Sawadogo, & Gre-goire, 2003).

Extension of valuable habitat and its degree offragmentation are fundamental indicators of biodi-versity conservation (Balmford et al., 2005). Theisolation and fragmentation trends documented inthis study for the WAP complex illustrate the needfor a better understanding of the relationshipsbetween protected areas and the surroundinghabitat, finalised to increase the performance ofconservation programmes. Hence, we stress thefundamental importance to understand sink–sourcedynamics taking place in protected areas withinmore extended regional settings, and the need toconciliate the inevitable conversion of peripheralnative habitat with the preservation of landscapeecologically important elements (e.g. spatial con-nectivity or ED). From a management point of view,our results show that interventions should becurrently concentrated on the peripheral areas ofthe WAP, and more particularly in the Beninportion. The presented approach appears to be aneffective tool for prioritisation of activities in thegeographical context.

ARTICLE IN PRESS

N. Clerici et al.38

Protected areas are not entities confined in theiradministrative limits; they depend upon, andinteract with the surrounding habitat, influencingtheir fundamental ecological flows and capacity toconserve biodiversity (Chape, Harrison, Spalding, &Lysenko, 2005). As economic development isconsidered an essential condition for conservationprojects in Africa (Kramer, van Schaik, & Johnson,1997), it is of crucial importance to integrateprotection with compensating mechanisms thatpromote the value of the ecosystems surroundingthe parks, such as benefit sharing from tourismactivities, local community-based wildlife manage-ment and sustainable agriculture. Developing sys-tems of sustainable use and appropriatecompensation could in fact achieve conservationgoals while respecting the aspirations of theassociated population. Local human welfare is infact one of the most important elements to betaken into account when directing protected areasinto effective conservation strategies (Wells &Brandon, 1992).

Acknowledgments

Nicola Clerici is supported by a grant from theItalian Ministry for Scientific Research and Univer-sity (MURST). NASA is acknowledged for providingTerra ASTER data. The present study is part of theresearch activities of the African Observatory ofthe Terrestrial Ecosystem Monitoring Action (TEM)of the European Commission, developed by theGlobal Environment Monitoring Unit of the EC JointResearch Centre (JRC), and by the ECOPAS Pro-gramme, funded by the European DevelopmentFund (EDF).

References

Balmford, A., Bennun, L., Brink, B. T., Cooper, D., Cote,I. M., Crane, P., et al. (2005). The Convention onBiological Diversity’s 2010 target. Science, 307,212–213.

Boluvi, M. (2005). Parc Regional Transfrontalier du W: 1Parc pour 3 Pays. Chroniques Frontalieres, September,17–32.

Brooks, T. M., Mittermeier, R. A., Mittermeier, C. G., daFonseca, G. A. B., Rylands, A. B., Konstant, W. R., etal. (2002). Habitat loss and extinction in the hotspotsof biodiversity. Conservation Biology, 16, 910–923.

Brooks, T. M., Pimm, S. L., & Oyugi, J. O. (1999). Time lagbetween deforestation and bird extinction in tropicalforest fragments. Conservation Biology, 13,1140–1150.

Brown, D. G., Duh, J. D., & Drzyzga, S. A. (2000).Estimating error in an analysis of forest fragmentationchange using North American Landscape Characteriza-tion (NALC) data. Remote Sensing of Environment,71(1), 106–117.

Bruner, A. G., Gullison, R. E., Price, R. E., & da Fonseca,G. A. B. (2001). Effectiveness of parks in protectingtropical biodiversity. Science, 291, 125–128.

Chape, S., Harrison, J., Spalding, M., & Lysenko, I.(2005). Extent and effectiveness of protected areas asan indicator for meeting global biodiversity targets.Philosophical Transactions of the Royal Society (B),360, 443–445.

Clerici, N., Eva, H., & Gregoire, J.-M. (2005). Assessingmodifications in burned areas characteristics tomonitor land-use changes and landscape fragmenta-tion around the WAP Complex of protected areas(West Africa). In Proceedings of the conference ofIALE France: Landscape ecology, pattern and pro-cesses: What is present state of knowledge? Whichresearch for the future? University Paul Cezanne,Marseille, France, November 15–17, 2005.

Coppin, P., Jonckheere, I., Nackaerts, K., Muys, B., &Lambin, E. (2004). Digital change detection methodsin ecosystem monitoring: A review. InternationalJournal of Remote Sensing, 25(9), 1565–1596.

Costanza, R., d’Arge, R., de Groot, R., Farber, S., Grasso,M., Hannon, B., et al. (1997). The value of the world’secosystem services and natural capital. Nature, 387,253–260.

Cumming, G. S. (2002). Habitat shape, species invasions,and reserve design: Insights from simple models.Conservation Ecology, 6(1), 3 [online] URL: http://www.consecol.org/vol6/iss1/art3/.

Cumming, S. G., & Vernier, P. (2002). Statistical models oflandscape pattern metrics, with applications toregional scale dynamic forest simulations. LandscapeEcology, 17(5), 433–444.

Davies, K. F., Margules, C. R., & Lawrence, J. F. (2000).Which traits of species predict population declines inexperimental forest fragments? Ecology, 81,1450–1461.

Debinski, D. M., & Holt, R. D. (2000). A survey andoverview of habitat fragmentation experiments. Con-servation Biology, 14, 342–355.

DeFries, R., Hansen, A., Newton, A. C., & Hansen, M. C.(2005). Increasing isolation of protected areas intropical forests over the past twenty years. EcologicalApplications, 15, 19–26.

Dewispelaere, G. (2003). Carte de vegetation du Parc W;notice succincte. ECOPAS/CIRAD Press.

Doussa, S. (2004). Les impacts de la culture cotonnieresur la gestion des ressources naturelles du Parc W: Casde l’anclave de Kondio. Ouagadougou: Universite deOuagadougou 123pp.

Dulieu, D. (2004). La vegetation du Complexe WAP. In F.Lamarque (Ed.), Les grands mammiferes du ComplexeWAP (pp. 16–24). ECOPAS Press.

Eva, H.D., Gregoire, J.-M., & Mayaux, P. (2004). Supportfor fire management in Africa’s protected areas. The

ARTICLE IN PRESS

Isolation of WAP ecological complex 39

contribution of the European Commission’s JointResearch Centre (63pp.). EUR 21296 EN. Luxembourg:Office for Official Publications of the EuropeanCommunities, ISBN 92-894-8192-7.

Eva, H. D., & Lambin, E. F. (2000). Fires and land-coverchange in the tropics: A remote sensing analysis at thelandscape scale. Journal of Biogeography, 27,765–776.

Farina, A. (1998). Principles and methods in landscapeecology. Cambridge: Chapman & Hall.

Forman, R. T. T. (1997). Landscape mosaics: The ecologyof landscapes and regions. Cambridge: CambridgeUniversity Press.

Fournier, A., Sawadogo, L., & Gregoire, J.M. (2003).Mission d’appui scientifique pour l’etude des feux debrousse et leur utilisation dans le cadre d’une gestionraisonnee des aires protegees du Complexe WAP(61pp.). Report, Ouagadougou: Parc W/ ECOPAS Press.

Gascon, C., Williamson, G. B., & Da Fonseca, G. A. B.(2000). Receding forest edges and vanishing reserves.Science, 288, 1356–1358.

Goldammer, J. G. (1993). Historical biogeography of fire:tropical and subtropical. In P. J. Crutzen, & J. G.Goldammer (Eds.), Fire in the environment (pp.297–314). New York: Wiley.

Gregoire, J.-M. (1996). Use of AVHRR data for the studyof vegetation fires in Africa: Fire managementperspectives. In G. D’Souza, et al. (Eds.), Advancesin the use of NOAA-AVHRR data for land applications(pp. 311–335). Brussels, Luxembourg: ECSC, EEC,EAEC.

Gustafson, E., & Parker, G. R. (1992). Relationshipbetween land-cover proportion and indices of land-scape spatial pattern. Landscape Ecology, 7, 101–110.

Hansen, A. J., & Rotella, J. J. (2002). Biophysical factors,land use, and species viability in and around naturereserves. Conservation Biology, 16(4), 1–12.

Harper, S. J., Bollinger, E. K., & Barrett, G. W. (1994).Effects of habitat patch shape on population dynamicsof meadow voles (Microtus pennsylvanicus). Journalof Mammalogy, 74, 1045–1055.

Herzog, F., & Lausch, A. (2001). Supplementing land-usestatistics with landscape metrics. Some methodicalconsiderations. Environmental Monitoring and Assess-ment, 72, 37–50.

Jensen, J. R. (1996). Introductory digital image proces-sing: A remote sensing perspective (2nd ed.). Engle-wood Cliffs, NJ: Prentice-Hall 316pp.

Kershaw, A. P., Bush, M. B., Hope, G. S., Weiss, K.-F.,Goldammer, J. G., & Sanford, R. (1997). The con-tribution of humans to past biomass burning in thetropics. In J. S. Clark, H. Cachier, J. G. Goldammer, &B. Stocks (Eds.), Sediment records of biomass burningand global change. NATO ASI Series, 51 (pp. 413–442).Berlin: Springer.

Kramer, R., van Schaik, C., & Johnson, J. (1997). Laststand: Protected areas and the defense of tropicalbiodiversity. New York: Oxford University Press.

Lamarque, F. (2004). Les grands mammiferes du com-plexe WAP. ECOPAS Press.

Laurance, W. F., & Gascon, C. (1997). How to creativelyfragment a landscape. Conservation Biology, 11, 577.

Laurance, W. F., Lovejoy, T. E., Vasconcelos, H. L., Bruna,E. M., Didham, R. K., Stouffer, P. C., et al. (2002).Ecosystem decay of Amazonian forest fragments: A 22-year investigation. Conservation Biology, 16, 605–618.

Leach, M. K., & Givnish, T. J. (1996). Ecologicaldeterminants of species loss in remnant prairies.Science, 273, 1555–1558.

Lienert, J. (2004). Habitat fragmentation effects onfitness of plant populations. A review. Journal forNature Conservation, 12(1), 53–72.

Lienert, J., & Fischer, M. (2003). Habitat fragmentationaffects the common wetland specialist Primula far-inosa in north-east Switzerland. Journal of Ecology,91, 587–599.

Major, R. E., Christie, F. J., Gowing, G., & Ivison, T. J.(1999). Age structure and density of red-capped robinpopulations vary with habitat size and shape. Journalof Applied Ecology, 36, 901–908.

Margules, C. R., & Pressey, R. L. (2000). Systematicconservation planning. Nature, 405, 243–253.

McGarigal, K., Cushman, S. A., Neel, M. C., & Ene, E.(2002). FRAGSTATS: Spatial pattern analysis programfor categorical maps. Computer software programproduced by the authors at the University ofMassachusetts, Amherst. Available at the followingweb site: /http://www.umass.edu/landeco/re-search/fragstats/fragstats.htmlS.

McGarigal, K., & Marks, B. J. (1995). FRAGSTATS: Spatialpattern analysis program for quantifying landscapestructure. USDA Forest Service General TechnicalReport PNW-351.

Musters, C. J. M., de Graaf, H. J., & ter Keurs, W. J.(2000). Can protected areas be expanded in Africa?Science, 287, 1759–1760.

Myers, N., Mittermeier, R. A., Mittermeier, C. G., daFonseca, G. A. B., & Kents, J. (2000). Biodiversityhotspots for conservation priorities. Nature, 403,853–858.

Nagendra, H., Munroe, D. K., & Southworth, J. (2004).From pattern to process: Landscape fragmentationand the analysis of land use/land cover change.Agriculture, Ecosystems and Environment, 101(2–3),111–115.

Narumalani, S., Mishra, D. R., & Rothwell, G. G. (2004).Change detection and landscape metrics for inferringanthropogenic processes in the greater EFMO area.Remote Sensing of Environment, 91(3–4), 478–489.

O’Neill, R. V., Krummel, J. R., Gardner, R. H., Sugihara,G., Jackson, B., DeAngelis, D. L., et al. (1988).Indices of landscape pattern. Landscape Ecology, 1,153–162.

Palm, S., (2005). Le Parc regional W entre conservationet activities extra–conservatrices: Le coton biologi-que, une activite agricole alternative dans la periph-erie du W (Burkina Faso) (75pp.+annexes). Memoired’Ingenieur du Developpement Rural: Parc W/ECOPAS.

Pimm, A. L., Jones, H. L., & Diamond, J. (1988). On therisk of extinction. American Naturalist, 132, 757–785.

ARTICLE IN PRESS

N. Clerici et al.40

Pimm, S. L., & Raven, P. (2000). Extinction by numbers.Nature, 403, 843–845.

Ramade, F. (2003). Introductory conference: On therelevance of protected areas for the research onconservation ecology: From fundaments to applica-tions. Comptes Rendus Biologies, 326, S3–S8.

Rodrigues, A. S. L., Andelman, S. J., Bakarr, M. I.,Boitani, L., Brooks, T. M., Cowling, R. M., et al.(2004). Effectiveness of the global protected areanetwork in representing species diversity. Nature,428(6983), 640–643.

Roques, K. G., O’Connor, T. G., & Watkinson, A. R. (2001).Dynamics of shrub encroachment in an Africansavanna: Relative influences of fire, herbivory, rainfalland density dependence. Journal of Applied Ecology,38, 268–280.

Saarnak, C. F. (2001). A shift from natural to human-driven fire regimes: Implications for trace-gas emis-sions. The Holocene, 11(3), 373–375.

Saunders, D. A., Hobbs, R. J., & Margules, C. R. (1991).Biological consequences of ecosystem fragmentation:A review. Conservation Biology, 51, 18–32, p. 200.

Sawadogo, L., & Fournier, A. (2004). Mission d’appuiscientifique pour l’etude des feux de brousse et leurutilisation dans le cadre d’une gestion raisonnee desaires protegees du Complexe WAP. Ouagadougou(RES.2003.040). Parc W/ECOPAS, Juin 2004_29p.+an-nexes.

Sawadogo, L., Tiveau, D., & Nyg(ard, R. (2005). Influenceof selective tree cutting, livestock and prescribed fireon herbaceous biomass in the savannah woodlands ofBurkina Faso, West Africa. Agriculture, Ecosystems &Environment, 105(1–2), 335–345.

Sayer, J. (1991). Rainforest buffer zones: Guidelines forprotected area managers. IUCN’The World Conserva-tion Union, Forest Conservation Programme, Gland,Switzerland.

Scholes, R. J., & Archer, S. (1997). Tree–grass interac-tions in savannas. Annual Review of Ecology andSystematics, 28, 517–544.

Soule, M. E., & Sanjayan, M. A. (1998). Conservationtargets: Do they help? Science, 279, 2060–2061.

Southworth, J., Munroe, D., & Nagendra, H. (2004). Landcover change and landscape fragmentation—Compar-ing the utility of continuous and discrete analyses for aWestern Honduras region. Agriculture, Ecosystemsand Environment, 101(2–3), 185–205.

Stratford, J. A., & Stouffer, P. C. (1999). Local extinctionsof terrestrial insectivorous birds in a fragmented

landscape near Manaus, Brasil. Conservation Biology,13, 1416–1423.

Struhsaker, T. T., Struhsaker, P. J., & Siex, K. S. (2005).Conserving Africa’s rain forests: Problems in protectedareas and possible solutions. Biological Conservation,123(1), 45–54.

Suarez, A. V., Bolger, D. T., & Case, T. J. (1998). Effectsof fragmentation and invasion on native ant commu-nities in coastal southern California. Ecology, 79,2041–2056.

Turner, B.L., et al. (1995). Land-use and land-coverchange. science/research plan. HDP Report 7/IGBP,Report 35.

UNDP—United Nations Development Programme (2004).Enhancing the effectiveness and catalyzing thesustainability of the W-Arly-Pendjari (WAP) protectedarea system. UNDP Project Document PIMS 1617.

United Nations Population Fund, website: /http://www.unfpa.org/SS (updated 2005).

Velazquez, A., Duran, E., Ramırez, I., Mas, J. F., Bocco,G., Ramırez, G., et al. (2003). Land use-cover changeprocesses in highly biodiverse areas: The case ofOaxaca, Mexico. Global Environmental Change, 13(3),175–184.

Vos, C. C., & Stumpel, H. P. (1995). Comparison ofhabitat-isolation parameters in relation to fragmenteddistribution patterns in the tree frog (Hyla arborea).Landscape Ecology, 11, 203–214.

Wells, M., & Brandon, K. (1992). People and parks:Linking protected areas management with localcommunities, World Bank, World Wildlife Fund andUS Agency for International development, Washing-ton, DC.

White, F. (1983). The vegetation map of Africa. Paris:UNESCO Press.

Wilcove, D. S., & May, R. M. (1986). National parkboundaries and ecological realities. Nature, 324,206–207.

Woodroffe, R., & Ginsberg, J. R. (1998). Edge effects andthe extinction of populations inside protected areas.Science, 280, 2126–2128.

Wu, X. B., Thurw, T. L., & Whisenant, S. G. (2000).Fragmentation and changes in hydrologic function oftiger bush landscapes, south-west Niger. Journal ofEcology, 88, 790–800.

Young, A., Boyle, T., & Brown, T. (1996). Populationgenetic consequences of habitat fragmentationfor plants. Trends in Ecology and Evolution, 11,413–418.