An ecological succession model applied to environmental management

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  • This article was downloaded by: [University of Strathclyde]On: 04 October 2014, At: 08:10Publisher: RoutledgeInforma Ltd Registered in England and Wales Registered Number: 1072954Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK

    International Journal ofEnvironmental StudiesPublication details, including instructions for authors andsubscription information:http://www.tandfonline.com/loi/genv20

    An ecological succession modelapplied to environmentalmanagementStephen M. Freedman a & Diane B. Rosenberg ba Department of Natural Science , Loyola University ofChicago , 6525 North Sheridan Road, Chicago, Illinois,60626, U.S.A.b Department of Biology , Loyola University of Chicago ,Chicago, Illinois, 60626, U.S.A.Published online: 24 Feb 2007.

    To cite this article: Stephen M. Freedman & Diane B. Rosenberg (1984) An ecologicalsuccession model applied to environmental management, International Journal ofEnvironmental Studies, 23:1, 11-18

    To link to this article: http://dx.doi.org/10.1080/00207238408710133

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    http://www.tandfonline.com/page/terms-and-conditionshttp://www.tandfonline.com/page/terms-and-conditions

  • Intern. J. Environmental Studies, 1984, Vol. 23, pp. 11-18 Gordon and Breach Science Publishers. Inc., 19840020-7233/84/2301-0011 $18.50/0 Printed in the United Kingdom

    AN ECOLOGICAL SUCCESSION MODEL APPLIEDTO ENVIRONMENTAL MANAGEMENT

    STEPHEN M. FREEDMAN and DIANE B. ROSENBERG

    (Received September 2, 1983)

    A model is presented which applies current ecological succession theory to land-use management. A briefhistory of succession theory is followed by a more detailed summary of the recently developed facilitation,tolerance and inhibition succession models. The five steps of the management model, designed dis-turbance, selective colonization, inhibitory persistence, removal, and regeneration, are described. Appli-cation of the model for land-use planning is given through specific examples of techniques that manipulatesuccessional processes. It is concluded that successional sequences and rates of replacement can beregulated to develop biotic communities that meet conservation needs.

    INTRODUCTION

    National and regional land-use policies are being re-assessed in light of resourcedepletion and environmental deterioration.1 Land-use policies are strongly influ-enced by current conceptualizations of ecosystem functioning. Ecological successiontheory has been used as a planning tool in agriculture and range management, as wellas other land-use management areas. This paper describes a model based on currentsuccession theory that can be used for conservation and planning purposes.

    Succession refers to an orderly process of change in vegetation, the animalcommunity, or an ecological system. The transitory communities which occur duringa succession are called serai communities, or stages; they are generally thought tolead to a climax or mature community. Since long time periods and a variety ofhabitats are often required for field succession studies, ecologists have relied upontheoretical models to guide their research.

    Among the more recent succession models are the facilitation, tolerance, andinhibition models developed by Connell and Slatyer.2 This paper presents a modifiedinhibition model that has been specificially designed for use in environmentalmanagement.

    HISTORY OF SUCCESSION THEORY

    In the early 1900s Henry Cowles and Frederic Clements formulated the initialconcept of succession. Clements viewed vegetation as an organic entity and sawsuccession as a repeatable deterministic process.3'4 The traditional view of succes-sion, associated with Clements, has been that organisms with superior disperal andecesis abilities, the pioneers, invade an environment first. The pioneer speciesmodify the environment and make it less appropriate for themselves and more

    Department of Natural Science, Loyola University of Chicago, 6525 North Sheridan Road, Chicago,Illinois 60626, U.S.A.

    Department of Biology, Loyola University of Chicago, Chicago, Illinois 60626, U.S.A.

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  • 12 S. M. FREEDMAN AND D. B. ROSENBERG

    advantageous for other organisms that replace them. A sequence of species changecontinues until no community of organisms can co-exist more efficiently than those thatare present. These organisms persist as the climax community. In addition to Clement'sclimatic climax, other final stages have been identified such as edaphic, physiographic,pyric, and biotic climaxes.5 Clement's holistic model was rejected by many ecologistsand succession began to be seen in terms of individual organisms; the properties ofplant communities depended upon the individual plants comprising them.6

    During the 1940s increased emphasis was placed on the structural and functionalcharacteristics of the community. Succession was examined in terms of competitionamong species.7 Gradually, succession came to be viewed as a process of communitydevelopment.8 Mathematical models were applied to the species replacementprocess.9'10 During the 1960s there was also a gradual resurgence of Clementsian ideasabout succession. '12 The Neo-Clementsians correlated stability with the maturity ofthe system, with succession leading to more diverse, stable and mature systems.

    Today there are two major views of succession, the ecosystem or organismic positionassociated with Clements, and the population centered or individual position which canbe traced back to Gleason.13 The difference of opinion among ecologists regardingsuccession makes it difficult to develop consistent environmental management policiesthat have general applicability. For example, the belief that over-grazed range land willrecover when grazing is prevented is based upon the traditional premise that thesuccessional series can be repeated.14 If the premise is incorrect, the managementpractice is inappropriate. If land-use policies are to be effectively employed, thesuccession theories underlying their development need to be continuously refined toreflect current ecological thinking.

    CONNELL AND SLATYERS' MODELS

    Connell and Slatyer2 developed three different succession models, facilitation,tolerance, and inhibition, to describe the mechanisms that might bring about a changein community composition after a disturbance. Each of the three models begins with achance disturbance opening a relatively large space and releasing resources. Thenumber of species replacements possible over time is related to both the intensity of thedisturbance and the size of the area disturbed.

    The facilitation model is basically a description of Clementsian, primary succession(see Table I). Only species with early successional, "pioneer" characteristics, initiallycolonize the area. These early successional species modify the environment, making itmore suitable for species that have poorer dispersal abilities or slower growth rates.Successive facilitory changes continue until the species present no longer modify thesite in ways that facilitate the establishment of other species.

    The tolerance model begins with the assumption that any arriving species may beable to establish itself. The modification of the environment by colonists makes theenvironment less suitable for other early successional species, but these modificationsby earlier colonists neither facilitate nor inhibit the rates of recruitment and survival oflate successional species. Species with poorer dispersal abilities and slower growth ratesare able to survive in the presence of earlier colonists due to their ability to tolerate lowresource levels. The replacement sequence continues until there are no species that caninvade and grow in the presence of the resident.

    Like the tolerance model, the inhibition model assumes that any arriving colonistmay establish itself. In general, early invaders are likely to be species with largenumbers of propagules and good dispersal ability. Once established, a colonizer

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  • ECOLOGICAL MODEL

    TABLE ISummary of Connell and Slatyers' models

    13

    Model

    Disturbance

    Invasion

    InvironmentalModifications

    Effects onIndividuals

    Continuationof thesequence

    Facilitation

    Determinedby chanceOnlysuccessionalspeciesa) Less suitable for

    early successionalspecies

    b) Advantageous forlate successionalspecies

    Late successionaljuveniles facilitatedby early successionalspeciesUntil resident nolonger facilitatesinvasion, growth ofany other species

    Tolerance

    Determinedby chanceAny colonizer

    a) Less suitable forearly successionalspecies

    b) Little or no effectlate successioalspecies

    Late successionaljuveniles grow despiteearly successionalspeciesUntil no speciesexists that can invadeand grow in resident'spresence

    Inhibition

    Determinedby chanceAny colonizer

    a) Less suitable forearly successionalspecies

    b) Less suitable forlate successionalspecies

    All other speciesinhibited

    Sequence may notoccur colonist persistsuntil removal byphysical extremes ornatural enemies

    inhibits the invasion of any subsequent species and persists as long as it continues toregenerate vegetatively, or is undamaged. Replacement is possible only when aresident is eliminated by physical extremes or natural enemies.

    The three succession mechanisms hypothesized by Connell and Slatyer have beensupported by some experimental and field evidence.15"20 In the next section amanagement succession model will be presented which is based on the inhibitionmodel suggested by Connell and Slatyer.2

    THE MANAGEMENT SUCCESSION MODEL

    The management succession model presented in this paper was developed upon thepremise that it is possible to direct successional processes, rather than alter or deflect aknown sequence in an unpredictable direction. It differs significantly, therefore, fromtraditional succession theory which anticipates a directional and repeatable series ofstages that lead to a determined climax community. The model describes the methodsthat can be used to direct species sequencing and rates of replacement. The goal is thedevelopment of a planned, stable biotic community. The management successionmodel utilizes life history characteristics, competitor and predator interactions, andabiotic factors to regulate ecosystem function. It offers an alternative approach tomanagement methods that rely upon chemical manipulation or other intensive meth-ods of environmental control.

    The management of a specific land area involves designing a particular disturbanceand selecting colonizers that will influence later patterns of community development(See Table II). The community may be designed and managed to persist andregenerate, or to persist until management directed removal. The entire series and rateof species replacement may be manipulated to achieve specific objectives. The follow-ing discussion of the model provides examples.

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  • 14 S. M. FREEDMAN AND D. B. ROSENBERG

    TABLE IIThe management succession model

    Designed Disturbance

    A selected disturbance modifies physical,spatial, and temporal structure of thecommunity. Subsequent sequence and rateof replacement regulated.

    Selective ColonizationAny management selected colonizer canbecome established. Colonizer selectedon basis of preferred characteristics.Diversity of system regulated.

    Inhibitory Persistence

    Selected colonizer persists and inhibitsundesired sequences or alters rate ofreplacement.

    Regeneration

    Management aidedregeneration.Successional sequenceprevented. 5.

    RemovalManagement directed removal.Successional sequence deliberatelyinterrupted. Subsequent sequencesand rates regulated. 4.

    1. Designed Disturbance

    The type, frequency, and intensity of a disturbance can be selected to modify thephysical, spatial, and temporal structure of a community so that the subsequentsuccessional sequence and rate of replacement can be controlled. Management tech-niques such as burning, flooding, chaining, or grazing can be designed to releaseresources or to remove or control undesired species. The techniques employed regu-late the successional sequence to maximize the persistence of desired species at latersuccessional stages.

    2. Selective Colonization

    Establishment of the colonizer is enhanced by choice of the appropriate disturbance instep 1. A management selected colonizer influences the initiation of early successionalsequences. Selection of the colonizer species may be based upon a variety of preferredcharacteristics, such as growth rate pattern, method of reproduction, allelochemicalproduction, predator defense mechanisms or ornamental value. Selecting thenumbers, proportions, and kinds of species for colonization serves to manipulate thediversity of the system and regulate subsequent competitor and predator/prey inter-actions.

    3. Inhibitory PersistenceThe objective in designing a disturbance and selecting a specific colonizer is to increasethe probability that the colonizer will persist and inhibit undesired successionalsequences, or alter the rate of species replacement. The established colonizer persistsfor three reasons. First, the disturbance is designed to optimize the population size of

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  • ECOLOGICAL MODEL 15

    that colonizer. Second, the life history characteristics of the colonizer are selected withpersistence in mind. Third, at step 2, the community interactions are manipulated toinsure survival of the colonizer. These...

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