In Australasia and throughout the world, there is now a rapidlygrowing drive to restore terrestrial and freshwater environ-

ments. Restoration is the process of inducing and assistingabiotic and biotic components of an environment to recover tothe state that they existed in the unimpaired or original state(Bradshaw 1997).The original state may mean the state prior tohuman-induced damage, but in many cases knowledge of such astate is simply not available and return to that state is impossi-ble.The restoration effort may range from restoring populationsof a particular species to restoring an entire ecosystem.The goalor target of the restoration effort may be set by the presence ofundamaged reference areas, or by reliable historical data, or bythe compilation from many fragmentary pieces of evidence ofan idealized state or scenario.

Restoration differs from rehabilitation in that the latter seeksto improve the condition of a selected area, but not necessarilyin the direction of the pre-existing undamaged state (Bradshaw1997).Both activities may be carried out either passively (wherethe degrading forces are abated so that natural recoveryprocesses then drive the restoration) or actively (where not onlyare the degrading forces abated or stopped but the course ofrestoration is, to a greater or lesser extent, driven by interven-tions such as reinstatement of dynamic processes, removal ofexotics or reintroduction of species).

In most cases restoration and rehabilitation projects haveecological goals, whether clearly enunciated or not. Restoration,and especially rehabilitation, may have non-ecological goals,such as aesthetic or recreational improvements.

Restoration ecology

Ecological restoration — although a field of management prac-tice existing in its own right — can also be seen as a test of

ecological concepts and theory (Jordan et al. 1987, Palmer et al.1997). Restoring an ecological community, for example, can beviewed as a test of concepts in community and ecosystemecology (e.g. Bradshaw 1987; Cairns 1987; Gilpin 1987; Hobbs &Hopkins 1990; Palmer et al. 1997; Parker & Pickett 1997; Lock-wood & Pimm 1999). Restoration ecology involves not onlythe testing of ecological ideas in the execution of restorationprojects, but also involves conceiving and testing new ideasand concepts specifically to assist restoration and rehabilitation.Thus, the links between ecological restoration and restorationecology represent an effective mutualism (Clewell 1993; Palmeret al. 1997).

Restoration ecology is a new and immature branch ofecology. Like all areas of ecology, its development depends onthe steady accumulation of empirical observations and data aswell as the testing of hypotheses derived from models based onthe observations. As many restoration projects are long-termprojects, the gathering of useful data and the testing of some ofthe hypotheses in these projects will be,by necessity, a slow andlong-term process. Currently there are large-scale restorationprojects both in Australasia and internationally that have yet toreport results in-progress or final results.

Five obstacles to the development ofrestorat ion ecology

Excluding the problem of gaining results from long-term pro-jects, it is still obvious that the development of restorationecology is being impeded by five obstacles. These include thereluctance of resource managers to undertake significantrestoration projects; the poor design of many restoration pro-jects; the lack of satisfactory monitoring of projects; the astound-ing lack of reporting on the progress and outcomes of projects;and resolution of problems of spatial and temporal scale inrestoration projects.The first four of these are correctable by therestoration team itself, while the last (the recognition of theoverriding importance of spatial/temporal scale of the locationand its surrounds) is yet to be accepted by the broader commu-nity and, therefore, more readily accommodated in projects.

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On the maturing of restoration:Linking ecological research andrestorationBy P. S. Lake

P. S. (Sam) Lake holds a Personal Chair in Ecology in theDepartment of Biological Sciences and the CooperativeResearch Centre for Freshwater Ecology, Monash University(PO Box 18, Clayton, Victoria 3800.Email: sam.lake@sci.monash.edu.au).

1. Need for participation (by resource management agencies)in significant projects

Successful restoration projects are invariably centred ondegraded areas where considerable economic and social valuesexist alongside ecological values. Such areas are managed tovarying degrees of competence and thoroughness by one ormultiple resource management agencies. While ecologists canhelp in the design, monitoring and evaluation of a restoration,the active ‘works’ and ongoing maintenance of the projectrequires resource and logistic inputs from the appropriateresource management agency. Such a partnership can be effec-tively achieved by adaptive management involving the imple-mentation of the Adaptive Environmental Assessment andManagement (AEAM) process (Walters 1986). Rather than carry-ing out many small-scale restoration projects, such as under therecent NHT Program in Australia, it would be better (both for theresource management agency and for ecologists) to undertake alimited number of well-designed, large-scale projects. To date, atleast in Australia, resource management agencies have shown agreat reluctance to do this, even though we have a plethora ofcases of large-scale ecosystem degradation. This reluctance is amajor impediment to the development of restoration ecology.

2. Necessity for adequate design of restoration projects

Restoration projects may be undertaken without adequate con-sideration of such design necessities as the gathering of before-data, the need for replication (if possible), the provision ofcontrol and/or reference sites, the setting of feasible goals, andthe capacity to test even the most elementary form of hypothe-sis. In recent times, in Australia, the practice of undertakingpoorly designed restoration projects has been widespread;driven by political pressures to initiate community-based pro-jects without interference from monitoring or research. ‘On-ground works’ have been supported and funded without anyprovision for linked research (Toyne & Farley 2000). In terms ofecology, very little of value has been learnt from such projects,and in terms of restoration, design inadequacy has meant thatlessons learned on the sites cannot be reliably evaluated toimprove restoration on these sites or elsewhere.

3. Monitoring of restoration projects

Monitoring is essential if progress in a project is to be evaluated.This necessity is linked with project design. In restorationprojects, monitoring may be necessary of (i) the state of theinputs, (ii) the restoration manipulation, and (iii) the ecologi-cal responses. Inputs in projects that may require monitoringare such things as the volumes of environmental flows, thepositioning of added logs in stream channels, exotic biomassremoved, and the initial establishment of plantings or seed-lings. Ecological responses in projects that may requiremonitoring include such things as colonization by plants andanimals, accumulation of soils and soil biota, and successionaldevelopment.

In both cases, monitoring depends on the selection of appro-priate indicators. Desirable properties of indicators include easeof sampling and processing, relative low cost, lack of ambiguitysuch as taxonomic uncertainty,high sensitivity to the restorationmeasures (pragmatic in terms of the measurable characteristicsof the system), and of course, direct incorporation into thehypotheses being tested (Keddy 1999).

4. Need for reporting of restoration projects

The lack of reporting on the progress and outcomes of restora-tion projects is a major problem. Ideally, the outcomes of aproject, along with its hypotheses and its rationale, would bereported in the refereed scientific literature.There is a rapid pro-liferation of suitable journals. Even reporting in the ‘grey’ litera-ture is a step in the right direction. In gaining knowledge onrestoration, it is important to recognize that reasoned reportingof a failure may be as valuable, if not more so, than the reportingof a success. Otherwise faulty procedures may continueunchecked and money may continue to be wasted.

5.Consideration and resolution of scale in restoration projects

Temporal and spatial scale must be considered in restorationprojects. It is important to realize that there is usually a great mis-match between the rate at which humans may damage ecosys-tems and the rate at which a damaged system can be restored,even with active intervention.This discrepancy in rates, that maybe termed the hysteresis of repair, is well illustrated by activitiessuch as land clearance. Hectares may be cleared in a morning’swork with a bulldozer; while to restore such cleared land wouldprobably take decades, if not longer.

The rates at which natural processes operate, be they abioticor biotic, are usually positively correlated with the spatial scale(Wiens 1989). Thus, ecological processes, such as nutrientcycling, occur at a faster rate at the small scale (plots) than theydo when considered at larger scales, such as entire landscapes.This spatial–temporal scale correlation may govern the rate ofrestoration. It may be possible to restore an individual wetlandin a few years but the restoration of a floodplain complex maytake decades. In Florida, there is the ambitious project on theKissimmee River to restore 70 km of river channel and 11 000hectares of floodplain (Arrington 1995). This is a large-scaleproject with a 20-year plan and costing US$8 billion (Pelley2000).The time scale and the funding reflect the reality of large-scale projects. However, in many large-scale restoration projects,while the planning reflects the spatial–temporal scale or scopeof the project, funding is usually only short-term. Unfortunately,the short-term nature of funds for effective long-term restorationprojects is a function of the short-term programmes of fundingbodies and of the short-term mind set of many managers andpoliticians.

Different biota have different rates of responding to restora-tion measures. This is obvious; annuals grow faster than trees.These differences largely govern the rate of succession inrestoration. In the Kissimmee River project in Florida, it is

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projected that aquatic plants will recover in 3–8 years, inverte-brates in 10–12 years and fish in 12–20 years (Trexler 1995).Such differences in recovery rates of biota also mean that thesedifferences need to be considered in selecting indicators. Differ-ent rates of responses by different ecological indicators maymean that a graded sequence of hypotheses, from the short termto the long term,may be nested and tested in any one large-scalerestoration project.

Initial steps in a restoration project

Assessment of condi t ion and‘restorabi l i ty ’

In any restoration project, as stressed by Hobbs and Norton(1996), a considerable amount of reconnaissance and assess-ment needs to be carried out prior to carrying out the restora-tion measures. In any landscape/waterscape selected forrestoration, initial steps are to identify the degrading forces, toassess their current status and strength, to rank them in a prior-ity order of severity, and to determine the likelihood of whetherrestoration will allow abatement of degradation and consequentrecovery.Such an exercise may be difficult and, invariably, is mul-tidisciplinary. In a stream restoration exercise such as theGranite Creeks Project (of the Cooperative Research Centres forFreshwater Ecology and of Catchment Hydrology) near Euroa,Victoria, this assessment involved hydrologists, geomorpholo-gists, biologists, resource managers and Landcare staff. The out-comes were compiled into a report (Davis & Finlayson 2001)detailing the current geomorphological condition of the creeksand their catchments as well as the history of stream degrada-tion. This study was then followed by an assessment of the eco-logical condition of the creeks, as judged by invertebrate andfish fauna; and from this assessment, indicators were selected.The whole 3-year exercise stresses the very desirable necessityof obtaining reliable before-data in any restoration project.

Assessment of l inkages

Even if the main focus is the restoration locality itself, it is alsovery important to determine the form and strength of linkagesbetween the locality and its surrounds. In cases of streamrestoration, for example, it is critical that linkages with catch-ments are recognized. Catchment land use is usually a dominantdriver of stream condition. Harding et al. (1998) found that‘whole watershed use in the 1950s was the best predictor ofpresent-day diversity’ in the streams they studied.

In both terrestrial and freshwater restoration projects, con-nections between the restored locality and sources of colonistsand resources are important. Disruption of such linkages candisrupt restoration. In the case of streams, the maintenance ofhydrological connectivity (Ward 1989; Townsend 1996)upstream–downstream and between streams, is critical for themovement of biota. Dams and barriers can break the connectiv-ity. Levees on floodplains can break the connectivity between ariver and its floodplain.

In assessing linkages, it is important to realize that there maybe critical buffer zones or transition zones that mediate linkagesbetween major types of environment. Riparian zones betweencatchments and their streams are an example. In constrainedstreams, riparian zones are usually narrow vegetated strips andare particularly susceptible to damage. Most of the damagecomes from the terrestrial side and includes such forces as fireand grazing. Such damage may break the continuity of riparianzones, impeding the movement of biota and disrupting thecatchment-stream linkages.

The concerns about linkages and investigating the surroundsof a selected locality raise the need to determine whether thereare influences in the surrounds that may impede the restorationeffort. There may be a conflict between aquatic and terrestrialmanagement practices; an example of which may be the poten-tial conflict between restoring a stream in an area susceptible tocontamination by chemical weed control in adjacent terrestrialsites.

A further critical step in planning a restoration project is toascertain the whereabouts and state of undamaged areas har-bouring intact communities and viable populations; and if possi-ble, to make sure that these areas are protected. Such areas mayserve two key functions: they may be sources of colonists, andthey may act as reference areas for both the setting of restora-tion goals and for statistically evaluating the progress of therestoration effort.

Developing restoration ecology byhypothesis testing

While there has been an ever-increasing interest in restoration,there has not been an accompanying growth in knowledge andthe development of principles of restoration ecology (Hobbs &Norton 1996; Palmer et al. 1997, Ehrenfeld 2000). As mentionedbefore, there are at least five major impediments to the develop-ment of restoration ecology. Four are rectifiable by the restora-tion team within relatively confined time scales, while theproblems due to scale require cooperation from a much broaderbase, often over long time periods. Linked with spatial–temporalscale in impeding progress in restoration ecology is the fact that,in many projects (especially large-scale ones) the gathering ofuseful data may be a long drawn-out process.

Lamenting the lack of progress in restoration ecology, Hobbsand Norton (1996) stated that it has ‘largely progressed on an adhoc, site- and situation-specific basis, with little development ofgeneral theory or principles that would allow the transfer ofmethodologies from one situation to another’. Thus, seeking toplace restoration ecology on a more solid footing and to allow itto develop general principles, Hobbs and Norton (1996) pro-posed a set of seven sequential steps or processes that need tobe considered in restoration projects. However, while their keyprocesses are valuable, if not crucial, to the success of a restora-tion project, they did not propose the need to incorporatehypothesis testing into restoration ecology. In many restorationprojects, monitoring of varying degrees of rigour has been

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carried out to assess and evaluate progress, but explicit hypoth-esis testing is rare.As stressed by Michener (1997) and Chapmanand Underwood (2000), it is imperative for scientific progress inrestoration ecology that explicit hypothesis testing be carriedout. Understanding the causal links and the critical steps in arestoration project does not come from generating models andsimply carrying out monitoring. There is the clear need to gen-erate hypotheses based on observations, available informationand the project’s goals and to test the hypotheses in the contextof the project.Within the large spatial–temporal scope of largerestoration projects, elucidation of some of the critical causallinks in the restoration may be gained from well-designedhypothesis-testing experiments at smaller scales (Havens &Aumen 2000).

The setting of goals and selection ofindicators in restoration

In any restoration project there is the clear need to set goals.Ecological goals or targets may be set at various ecologicallevels: species populations, communities, ecological processesand ecosystem services.Targets may be set by regulation, requir-ing certain levels of compliance to be met. This particularlyapplies to environmental quality attributes such as water quality.Targets may be quantified in terms of their biotic and statisticalproperties, may be informed by specific attributes of referencesites (Hobbs & Norton 1996), or may be drawn from referenceinformation found in historical and contemporary sources(White & Walker 1997). Reference sites need not be in perfectpristine condition (in fact, such sites are becoming increasinglyimpossible to find) but may simply be in good condition andtypical of undamaged sites in the region.

To monitor changes in the project it is necessary to selectindicators. In the case of single species restoration, the targetsand the indicators may be identical. For communities andecosystems, however, separate indicators have to be selected.This selection must cover the parameters postulated in anyhypothesis. Desirable properties of indicators include theirbeing relatively easy and inexpensive to measure (very impor-tant in long-term projects); they must have no taxonomic diffi-culties or measuring uncertainties; they need to be sensitive tothe restoration measures; they need to respond at different ratesover different time spans; and preferably they need to be linkedwith each other in their ecological functioning. In setting indi-cators,progress in a project may be either detected by increasesin desirable biota or properties or by decreases in undesirablebiota, such as weeds or exotics. In large-scale, long-term projects,it is a good tactic to select abiotic and biotic parameters thatrespond at different rates, short term to long term; hence, forexample, the use in the Kissimmee River project of a range ofindicators (Dahm et al. 1995;Trexler 1995).

In setting goals or targets and in subsequent monitoring, itshould be borne in mind that at least three major types of diffi-culties may arise. First, the hypothesized response in the targetbiota may show a marked lag response (Huxel & Hastings 1999).

For example, colonists may take time to reach and establishthemselves; some key resource may be in short supply, or unan-ticipated disturbance may set back progress. Second, instead ofprogressing to the set goal, the system may proceed to an unfore-seen and stable alternative state (Westoby et al. 1989; Hobbs &Norton 1996), and recovery of a system to its natural state ‘mayrequire massive management inputs’ (Hobbs & Norton 1996). Itmay be that the system is now being exposed to a disturbanceregime that did not exist in the original state. Indeed, settinggoals that are resistant and/or resilient to the prevailing distur-bance regime is an important consideration (Westman 1991).Third, the system undergoing restoration may not have any cleartrajectory and stability.This may be because the system is beingexposed to unforeseen disturbance and/or the system is but afragment of the original state (which, with a high perimeter toarea ratio, means it is being influenced by surrounding factors).In this case, restoration may require continual intervention, suchas controlling weed in small patches of native vegetation.

Design of monitoring programs inrestoration projects

Along with the needs for developing hypotheses from observa-tions, establishing available information and modelling, selectingindicators, and setting goals, a further crucial need exists.This isthe need for designing the project and the monitoring regimesuch that information can be gained to evaluate progress and totest hypotheses. Both inputs and outcomes may be monitored.In a stream restoration project, for example, it may be the con-dition and persistence of added coarse woody structures(inputs) and the diversity and population sizes of fish in thetreated stream reaches (outcomes) that are monitored. Whileboth inputs and outcomes require monitoring, it is imperativethat selected indicators of projected outcomes are rigorouslymonitored.

In situations where reference sites are available, it shouldbe possible to design a monitoring programme that both allowsthe testing of hypotheses and the evaluation of restorationprogress.This would involve a monitoring design where before-intervention (B) and after-intervention (A) data are collectedfrom the sites to be restored where intervention occurs (I) aswell as the reference (R) sites (a multiple BARI design). In someinstances, there may be only one site to be restored but anumber of reference sites. Replication is very desirable as itincreases the certainty of statistical analyses and increases thelevel of generalization.

In many cases, reference sites are simply not available. Thisparticularly applies in urban and densely settled areas wheresites are either less available or all of the sites are earmarked fortreatment within a relatively short period. In other scenarios,however, there may be many degraded control (C) sites so thathypothesis testing and evaluation of progress may be carried outby determining departure in the restored site (I) from the stateof the control sites (M BACI design). In the most powerfuldesign, both reference and control sites are available and the

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project design (M BARCI design) incorporates both into themonitoring programme (Chapman & Underwood 2000). Depar-ture from the control sites and convergence with the referencesite conditions may be carried out with the bioequivalence sta-tistical procedure detailed by McDonald and Erickson (1994).

As the spatial scope of the restoration project increases (suchas from a small upland stream to a large lowland river), not onlyis it inevitable that the temporal scope will increase,but it is alsoinevitable that the presence of replicated control and/or refer-ence locations will disappear. In this case it may be only possi-ble to compare the ‘to-be restored’ site (I) with a degradedcontrol (C) and/or a fairly intact reference location (R): BARCI,BARI or BACI designs.

Finally, and this is quite common, one may attempt to restorea location for which controls and reference locations aremissing. If goals cannot be readily set for either departure fromthe degraded condition or convergence to the intact state, thenit may be possible to set directions of restoration from historicaldata or from information from analogous but not identical loca-tions. Evaluation of progress may be by a ‘levels of evidence’approach outlined in Downes et al. (2001). Alternatively ortogether, a Bayesian analysis (Wade 2000) may be appropriate.

To carry out large-scale restoration projects as large-scalehypothesis-testing experiments, it is absolutely essential thatsolid and durable partnerships are formed between resourcemanagement agencies, concerned stakeholders and scientists.Until now such partnerships are rare. Thus, building partner-ships that are centred on large restoration projects that involvethe implementation of strong restoration measures is a criticaladvance. Even when such partnerships are formed and projectsinitiated, it is important to be aware that such partnerships mayfracture and break causing the project to fail (Walters 1998).

Acknowledgements

I am grateful to Dr Ralph MacNally of the Department of Bio-logical Sciences,Monash University for urging me to present thispaper in draft form at the 2000 Annual Conference of the Eco-logical Society of Australia and to two referees for valuable criti-cism and comments.

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