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On the restoration of degradeddrylands

Jordi Cortina1

Beatriz Amat1

Mchich Derak2

Maria Joao Ribeiro Da Silva13

Karen B. Disante1

David Fuentes4

Jaume Tormo1

Rom�an Trubat1

1 University of AlicanteDepartment of Ecology and IMEMAp. 99 03080AlicanteSpain<jordi@ua.es><beatriz.amat@ua.es><mariaribeirinho@gmail.com><kb.disante@ua.es><jautorbla@gmail.com><roman.trubat@ua.es>2 Direction r�egionale des Eaux et Foretset de la Lutte contre la D�esertification du RifAvenue Mohamed 5BP 72293000 T�etouanMorocco<mchich78@hotmail.com>3 Coimbra UniversityDepartment of Life SciencesCentre for Functional Ecology3001 – 455 CoimbraPortugal4 Fundaci�on CEAM (Centro de EstudiosAmbientales del Mediterr�aneo)Parque Tecnol�ogicoc/Charles Darwin, 1446980 PaternaValenciaSpain<david.fuentes@ua.es>

Abstract

Drylands cover 41% of the earth’s land surface and sustain 38% of the globalpopulation. The surface area of drylands affected by desertification is estimated at10-20% of this land, making this one of the worst environmental problems worldwide.Measures to combat desertification include restoration actions. Recent advances inour understanding of dryland ecology have improved traditional restorationtechniques and fostered the development of new eco-technology. However, therefinement of eco-technological tools and the success of experimental restorationprojects have not been accompanied by parallel increases in the efficiency andreliability of management-scale restoration programs. In our experience, this is theresult of uncertainties about the long-term effects of restoration actions, scarceknowledge on population and community dynamics, and cultural and socioeconomicconstraints to the implementation of new techniques and the improvement oftraditional ones. We suggest that i) adopting the ecosystem service approach toidentify restoration targets and evaluate restoration actions, ii) integrating restorationactions into comprehensive development programs, and iii) creating networks of pilotand demonstration projects may foster participative, adaptive and integrativemanagement plans, and contribute to livelihood quality in desertified areas.

Key words : arid zone, desertification, desertification control, planning, restoration.

R�esum�eSur la restauration des terres s�eches d�egrad�ees

Les zones arides occupent 41 % de la surface terrestre et supportent 38 % de lapopulation mondiale. Environ 10 �a 20 %de la superficie des zones arides est touch�eepar la d�esertification, ce qui en fait un des pires probl�emes environnementaux de laplan�ete. L’impl�ementation de la restauration �ecologique est l’une des mesures de luttecontre la d�esertification. Les nouvelles avanc�ees dans le domaine de l’�ecologiedes zones arides ont contribu�e �a l’am�elioration des techniques traditionnellesde restauration et au d�eveloppement de nouvelles �ecotechnologies. Cependant, leraffinement des outils �ecotechnologiques et le succ�es des projets exp�erimentaux derestauration n’ont pas �et�e parall�element accompagn�es par une am�elioration del’efficience et de la fiabilit�e des programmes de gestion et de restauration. D’apr�esnotre exp�erience, cela est du aux incertitudes sur les effets �a long terme des actions derestauration, au manque de connaissance des dynamiques des populations et descommunaut�es v�eg�etales et animales, et aux contraintes culturelles et socio-�economiques qui rendent difficiles l’implantation des nouvelles techniques etl’am�elioration des pratiques traditionnelles. Nous pensons que i) l’adoption del’approche des services �ecosyst�emiques pour l’identification des objectifs derestauration et l’�evaluation de ses actions, ii) l’incorporation des actions de

To cite this article: Cortina J, Amat B, Derak M, Joao Ribeiro Da Silva M, Disante KB, Fuentes D,Tormo J, Trubat R, 2011. On the restoration of degraded drylands. S�echeresse 22 : 69-74. doi :10.1684/sec.2011.0301Tir�es �a part : J. Cortinad

oi:10.1684/sec.2011.0301

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Research Article

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Ecological restoration to combatdesertification

Drylands cover more than 40% of theland, sustain more than 1/3 of the globalpopulation and host a significant numberof hot-spots of biological diversity. Dry-lands worldwide are however currentlythreatened by desertification (Reynoldset al., 2007) Over the last decades,international organizations launchedambitious initiatives to evaluate the extentof desertification, understand its causesand, ultimately, combat dryland degra-dation. The attention of restoration ecol-ogists concerning actions to combatdesertification has been comparativelylimited. For example, the number ofrestoration projects from arid, semiaridandMediterranean areas included in theSociety for Ecological Restoration Interna-tional (SERI) Global Restoration Data-base1 is relatively low (22 of a total of226 projects). Similarly, the number ofscientific papers on dryland restorationappearing in international environmentaljournals, including Restoration Ecology,the official journal of the Society forEcological Restoration International, isalso low (8 of a total of 183 articles;[Aronson et al., 2010]). Of thesepapers, very few deal with passiverestoration (the release of the stressfactor; [Aronson et al., 2010], whereasthis is one of the most commonlyemployed management options to revertdryland degradation (Requier-Desjardinset al., 2009).The ‘‘desertification’’ research commun-ity seems to be aware of the principles ofecological restoration. United NationsConvention to Combat Desertification(UNCCD2) Article 2.2 explicitly men-tions as one of its objectives ‘‘. . .therehabilitation, conservation and sustain-able management of land and waterresources, leading to improved livingconditions, in particular at the commun-

ity level’’, which is largely in agreementwith the aims of ecological restoration3.Indeed, National Action Plans (NAP)within UNCCD go a step further byexplicitly mentioning ecological restora-tion as one of their objectives and linesof action (e.g., the SpanishNAP4). But towhat extent have the aims of ecologicalrestoration been adopted by projects tocombat desertification?There is no simple answer to thisquestion. First, projects have multipleobjectives, including unwritten ones thatcan be critical. For example, the officialaims of the Spanish National Reforesta-tion Program, a vast endeavor launchedin 1939, were biophysical (wood pro-duction, hydrological control and soilprotection), whereas the creation ofemployment was probably the main(implicit) priority in a ruined post-warcountry (Pem�an et al., 2009). Anevaluation of these actions that doesnot take into account their socio-economic impact, is biased and of littleuse. Second, societal aims and aspira-tions change across generations andacross regions. The success of a par-ticular action cannot be measured in thesame way in areas where consumptionof local natural resources is high asin areas where natural resources areimported. Similarly, priorities maychange in the time lapse betweenproject inception and process evalua-tion. This is particularly important indrylands, where climate and societiescurrently change at a faster rate than doecosystems. Third, our understanding ofcommunity dynamics, ecosystem proc-esses and the benefits provided byrestored ecosystems is often too poorto accurately predict the outcomes ofmanagement practices. Because of thisuncertainty, evaluating the distance

between restored and reference ecosys-tems and the rate at which the formerapproaches the latter becomes a chal-lenging task. Fourth, reference ecosys-tems may no longer exist, or may not beparticularly functional or diverse, andthus not necessarily desirable (Cortinaet al., 2006). Last but not least, mostprojects to combat desertification havehardly been evaluated and monitored.The strong emphasis on the control oftechnical aspects of project implementa-tion contrasts with an almost totalabsence of integrated a posteriorievaluation. With no proper evaluation,there is no way to verify if the outcomesof a project to combat desertificationqualify as ecological restoration or not.The previous considerations may help toharmonize opposing views on theobjectives of ecological restoration indrylands. For example, the spread ofalien species constitutes a major environ-mental concern in the drylands ofCalifornia, theNorthernMediterranean,South Africa and Australia, where con-trol of aliens such as Acacia saligna,Opuntia sp. and Eucalyptus sp. isa major management priority (VanWilgen et al., 2001). Conversely,species that are removed from theseareas are currently being planted indrylands of Africa and Asia (figure 1). Insome cases, the use of alien species maybe justified for the production of goodssuch as forage and fuelwood, and theprovision of ecosystem services such ascarbon sequestration and soil protectionbecause they facilitate the establishmentof native species or because alienplanting is one of the various actionsincluded in a larger management plan.Similarly, agreement is lacking onthe impact of shrub encroachment (theincrease in density, biomass and coverof native shrubs in former grasslands) instudies from different dryland areas(Schlesinger et al., 1990; Valone et al.,2002; Maestre et al., 2009). Disagree-ment may reflect the complexity of thisprocess (Huxman et al., 2005), butalso cultural bias against/in favour ofgrasslands and shrublands. As a result,depending on the context, both theremoval and planting of woody speciesbecome major priorities of ecological

restauration dans les programmes de d�eveloppement int�egr�e, et iii) la cr�eation der�eseaux de projets pilotes et de d�emonstration, peuvent encourager les programmesde gestion participative, adaptative et int�egr�ee et contribuer au bien-etre humain dansles zones d�esertifi�ees.

Mots cl�es : d�esertification, lutte contre la d�esertification, plannification, restauration, zonearide.

1 Society for Ecological Restoration Interna-tional (SERI). Global Restoration Network Data-base. www.globalrestorationnetwork.org/[Oct. 10th 2010].2 United Nations Convention to Combat Deser-tification, UNCCD (www.unccd.int/).

3 Society for Ecological Restoration Interna-tional Science & Policy Working Group. TheSER International Primer on Ecological Restora-tion. www.ser.org & Tucson: Society for Eco-logical Restoration International, 2004.4 Programa de Acci�on Nacional contra laDesertificaci�on. 2008. www.mma.es/portal/secciones/biodiversidad/desertificacion/pro-grama_desertificacion/pdf/PAND_a-gosto_2008.pdf.

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restoration in different drylands (Brudvigand Asbjornsen, 2009; Cortina et al.,2011). How can we reconcile suchcontrasting views? Do they all qualifyas ecological restoration? We suggestthat the definition of restoration targets interms of community composition, ecosys-tem functioning and the provision ofgoods and services represents a suitableway to integrate such disparate manage-ment practices into a general frameworkof dryland restoration.

A new frameworkfor dryland restoration

As mentioned above, integrated evalua-tion andmonitoring were not consideredfundamental parts of management pro-grams to combat desertification, andthis failure was partly responsible forunwanted outcomes of these actions.Their targets were usually defined on thebasis of one or only a few objectives (the

establishment of tree cover, the increasein biodiversity, the introduction of aparticular species), disregarding theirimpacts on the provision of other goodsand services. For example, informationon the effects of conifer plantations onbiodiversity, water and carbon balanceor aesthetics is often scarce, despite thesignificance of these plantations in dry-lands worldwide ([Maestre and Cortina,2004; Pausas et al., 2004, [figure 2].Over the last decades, this lack ofinformation has fuelled bitter discussionson the benefits of these plantations thatare frequently based on partial viewsand subjective perceptions.By the end of the 20th century, a newparadigm based on the incorporation ofan integrated ecosystem approach intoactions to combat desertificationemerged in response to programs thatwere excessively focused on single or afew services (Le Hou�erou, 2000). Thisnew paradigm was based on the use ofnative species, low impact techniquesaimed at keeping what was left of theoriginal community composition andecosystem functioning, and the develop-ment of new ecological knowledge. Thistrend was promoted by innovativetechnological tools, which were oftenbased on traditional practices. Theseinclude expertise on a wide array ofspecies, innovations in the production ofquality seedlings, the use of amend-ments to improve soil fertility, the designof low-impact and efficient techniquesfor soil preparation (figure 3), runoffcapture and water harvesting, the assem-blage of protocols to control unwantedspecies, and the use of mutualistic andfacilitative interactions (Sheppard et al.,2006; Bainbridge, 2007; Cortina et al.,2011). Still, despite these advances, thesuccess of restoration actions is notguaranteed.

Ecological uncertainties

Re-establishing functional and self-sus-taining landscapes under semiarid con-ditions is particularly challenging. Thecombination of harsh climatic condi-tions, degraded soils and impoverishedcommunities increases the probability offailed successional trajectories leadingto undesired communities, further degrad-ation and wasted efforts. We suggestthat failures are frequently related to poorunderstanding of species ecology andcommunity dynamics, along with inabil-ity to integrate climatic variability.The literature shows many exampleswhere management techniques were

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Figure 1. An example of opposing views on environmental problems and restoration targetsfrom the western Mediterranean.A) Opuntia ficus-indica f. inermis Weber plantation in South Tunisia; B) invasive Opuntia ficus-indica L. Mill inSierra Filabres (Almerıa, Spain.Contrasting management techniques are used to expand or eradicate this species on both shores of theMediterranean.

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applied before enough informationon their consequences was available.These include the use of alien herba-ceous species in burnt areas of theAmerican West (Robichaud et al.,2000) and the establishment of Lupinusnootkatensis in eroded slopes on Ice-land (Magn�usson, 1997). For example,woody species such as Quercus cocci-fera, Pistacia lentiscus and Rhamnuslycioides have been extensively usedfor the restoration of Stipa tenacissimasteppes in South East Spain (Cortinaet al., 2011), where they are consid-ered keystone species. However, our

knowledge on the natural dynamics ofthese species, on their long-term recruit-ment rate, longevity, sensitivity to soilproperties and ability to face longintense drought is scarce.The success of restoration actions alsodepends on climatic variability. Yearswith less moisture than average take atoll on forest plantations. Two alternativemanagement options may be taken:assume that sporadic recruitment is anintrinsic trait of these species and planinterventions on time scales that matchnatural processes (i.e., the traditionalapproach), or compensate harsh envi-

ronmental conditions with increasingtechnological inputs (including water-ing, mulching, runoff harvesting, etc.) ata higher economic cost. In both cases,it would be good to improve our abilityto forecast climatic conditions, a goalthat looks closer now than some decadesago (Holmgren and Scheffer, 2001;Mariotti et al., 2002). This topic isparticularly relevant, as climatic condi-tions in drylands worldwidemay becomeeven harsher in the near future (Giorgiand Lionello, 2008). As dryland resto-ration is planned on a time scale ofdecades, further knowledge on speciesability to cope with new climatic con-ditions is urgently needed.Finally, identifying the underlyingcauses of failures in restoration actionsdemands the design and implement-ation of comprehensive evaluation andmonitoring programs (Bautista andAlloza, 2009). They should be basedon suitable indicators that can beapplied by practitioners and designedto feed back on management. It is worthnoting that a proper evaluation ofrestoration actions should include indi-cators of stakeholder perceptions. Toachieve this and other goals discussedbelow, social participation is a must.

Beyond ecology

Ecological restoration represents aunique way of improving the provisionof goods and services while enhancinglivelihoods in degraded drylands. How-ever, restoration actions are too oftencarried out by the Forest Administrationor particular groups of interest with nofurther social involvement. This is notonly a source of conflict, but a missedopportunity to develop adaptive man-agement, promote people involvementand motivation and to improve restora-tion success.Various tools may contribute to thesegoals:1. People may not be sensitive tospecific aspects of community composi-tion and ecosystem functioning, but theymay better understand changes in eco-system services such as water and fuel-wood production and soil protection,services that affect their day-to-day life(Safriel and Adeel, 2005). Ecosystemservices provide a common language tonegotiate and reach consensus;2. Restoration should not be imple-mented in isolated actions but integratedinto comprehensive development pro-grams. There are many examples of thisapproach in developing countries that

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Figure 2. Examples of Pinus halepensis plantations used to restore plant cover in South EastSpain.A) Pinus halepensis Mill. plantations in Elx ; B) Pinus halepensis Mill. plantations in Ricote valley (South EastSpain).This species has been widely used to restore plant cover in semiarid Mediterranean areas with contrastedsuccess. Knowledge on the ecological impact of these plantations however remains limited.

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developed countries should adopt toimprove the efficiency of these interven-tions (Dongier et al., 2003; Raddaoui,2009). This point is particularly challeng-ing, as it demands collaboration betweendifferent government Departments andeffective participative management. Fur-thermore, integrated projects provide theopportunity to adjust the duration of the

actions to ecologically and sociallymeaningful time scales;3. A network of pilot and demonstrationprojects needs to be established to testnew techniques at a management scale,provide evidence of good managementpractices and contribute to knowledgeexchange [Li et al., 2007; Vilagrosaet al., 2008], figure 4).

Ecological restoration is expensive. Forexample, the cost of a 3-hectare planta-tion in SE Spain is similar to the total costof a graduate student (ca. 7,000 eurosper year5. Thus, we must be very carefulbefore advocating public expenditure inrestoration actions. Some alternatives tofund restoration programs aimed atcombatingdesertificationmaybe forward-ed. First, the economic benefits derivedfrom restoration programs may pay forthe costs. For example, in Morocco thecosts of desertification may be 5 timesthe costs of restoration (4.6% versus0.8% of the Gross Domestic Product,respectively [Requier-Desjardins et al.,2009]. Second, the involvement of non-governmental organizations (NGOs),communities and most directly affectedstakeholders may reduce the costs ofrestoration actions. Finally, integratingrestoration actions into developmentprograms may provide access to othersources of funding. As an example,European programs such as the Agri-cultural Fund for Rural Development(EAFRD), the Regional DevelopmentFund (ERDF), the Cohesion Fund andthe LIFE-Environment and LIFE-Natureinclude measures related to ecologicalrestoration.

Conclusions

Actions to combat desertification shouldadopt the principles of ecological resto-ration tomeet the challengesposedby thisworldwideenvironmental problem.At thesame time, restoration ecologists shoulddevote further attention to degradeddrylands in accordance with the magni-tude of this problem. Technological toolsand strategies to combat desertificationhave significantly improved over thelast decades, but uncertainties aboutthe outcomes of restoration actions, parti-cularly in response to climate change,are still substantial. Our understandingof the ecology of key species should beincreased to improve our ability toprescribe efficient restoration actions.But ecological and technological impro-vements will have a modest impact ondryland capacity to provide ecosystemservices and contribute to human welfareunless participative, adaptive and inte-grated management strategies areimplemented. &

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Figure 3. Technological tools and deeper knowledge of biotic and abiotic interactions arepartly responsible for recent improvements in restoration practices.A) The spider back-hoe facilitates the establishment of target key species, avoiding deleterious effects of largeslope modifications; B) Stipa tenacissima L. shadow benefits seedlings of woody species such as Pinushalepensis (Gasque and Garcıa-Fayos, 2004).

5 CRUE. La Universidad espa~nola en cifras.Conferencia de Rectores de las UniversidadesEspa~nolas (CRUE). 2010. Available at www.crue.org.

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Acknowledgements

This text was written thanks to the fundingreceived from project RECUVES (SpanishMinistry of the Environment, Rural andMarine Areas; 077/RN08/04.1), proj-ect GRACCIE (Spanish Ministry of Sci-ence and Innovation, Consolider-Ingenio2010 Program; CSD2007-00067) andGeneralitat Valenciana (Programa G.Forteza; FPA/2009/029). We thankMarjolein Visser for her kind invitationandRamonVallejo for his common sense,effort and inspiration. CEAM Foundationis partly funded by Generalitat Valenci-ana and Fundaci�on Bancaja.

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