The Visitor ExpeTience and Resource Protection (VERP) Process:

Robert E. Manning
David W. Lime
Marilyn Hot
Wayne A. Freimund
The Visitor ExpeTience
and Resource Protection (VERP) Process:
The Application
of Carrying
Capacity
to Arche.
National
Park
Introduction
k
the name suggests, national parks are resources of national and,
increasingly, international significance. The United States national park
ystem,for example,contains natural, historical, and cultural resources
of great importance to the nation and, in many cases, the international
community. Given the significanceof this resourcebase,public demand to see
and experiencetheseareasshould not be surprising.
Data on national park visitation in
the U.S. dramatically support this
premise. Annual visitation to the national parks is now counted in the
hundreda of millions. In the decade
of the 1970s, visitation increasedby
30 percent. In the 1980s, visitation
roseanother 35 percent. If this trend
continues,the national parks can expect to receiveover 300 million visits
by the year2000.
The increasing popularity of the
national parb presentsboth an opportunity and a challenge. The opportunity is to fulfill the mission of
the national parb "to provide for the
enjoyment of the people." The accompanying challenge, of course, is
to conserve park resources for the
enjoyment of future generations.
This canprove difficult under conditions of high visitation.
VOlume12:
Number 3
Implicit in this dual mission of national parksis the issueof the qauzlity
of the vuitor experie1u:e.
The quality
of visitor experiencesmust be maintained at a high level for the national
parksto contribute their full potential
to the enjoyment of society. Moreover, high-quality visitor experiences
are more likely to develop public appreciation of, and support for, conservationof nationalpark resources.
It is ironic that one of the greatest
threatsto the quality of national park
visits is commonly seen as their increasing popularity. To many observers,the national parb, at leastin
some places and at some times, are
crowded, and this detracts from the
quality of the visitor experience.
Moreover, natural and cultural resourcescanbe degradedby excessive
visitor use.In more formal tenDS,the
1995
.
""~1
use of some national parks, or portions thereof, have exceeded their
carrying capacity (Mitchell 1994;
Wilkinson 1995).
This paper explores the theory
and application of carrying capacity
to the national parks. Primary emphasis is placed on social carrying
capacity; The first section briefly
tracesthe theoretical developmentof
the carrying capacity concept. The
second section describes a process
now being developedwithin the U.S.
National Park Service to help determine and manage carrying capacity
in the national park system.The final
section outlines the application of
this carrying capacity process to
Arches National Park as a model for
the nationalpark system.
parks (Sumner 1936). However, the
first rigorous applications of carrying
qpacity to park managementdid not
occur until the 1960s.
These initial scientific applications suggestedthat the concept was
more complex in this new management context. At first, as might be
expected,the focuswasplaced on the
relationship between visitor use and
environmental conditions. The
working hypothesiswas that increasing numbersof visitors causesgreater
environmental impact as measured
by soil compaction, destruction of
vegetation, and related variables. It
soon becameapparent,however, that
there was another critical dimension
of carrying capacity dealing with social aspectsof the visitor experience.
Wagar (1964), for example, in his
The Concept of Carrying Capacity
early and important monograph on
The question of how much public
the application of carrying capacityto
useis appropriate in a nationalpark is recreation, reported that his study
often framed in terms of carrying ca- "was initiated with the view that carpacity. Indeed, much has been writrying capacity of recreation lands
ten about the carrying capacityof the could be determined primarily in
national parks and related areas.The
terms of ecology and the deterioraunderlying concept of carrying ca- tion of areas. However, it soon bepacity hasa rich history in the natural came obvious that the resource-oriresourceprofessions.In particular, it
ented point of view must be aughas proven a useful concept in
mented by consideration of human
wildlife and range management values."
where it refers to the number of aniWagar's point was that as more
mals of anyone speciesthat can be people visit a park, not only can the
maintained in a given habitat
environmental resourcesof the area
(Dasmann 1964). Carrying capacity be affected,but the quality of the visihas obvious parallels and intuitive
tor experience as well. Again, the
appeal in the field of park manage- working hypothesiswas that increasment. In fact, it was first suggestedin
ing numbers of visitors causegreater
the mid-193Gsasa park management social impacts as measured by
concept in the context of the national crowding and related variables.
Wright FORUM
Thus, as applied to national parks, crowding are related: increasing
numbers of visits cause increasing
carrying capacity has two compopercentagesof visitors to report feelnents: environmentaland social.
The early work on social carrying ing crowded. However, it is not clear
capacityhas since blossomedinto an at what point carrying capacity has
extended literature on social aspects been reached. The relationships .in
of outdoor recreation and their ap- Figure 1 illustrate that some crowding is inevitable, given even relatively
plication to carrying capacity
(Stankey and Lime 1973; Manning low levels of visitor use. Thus, some
1985; Kuss et al. 1990; Shelby and level of crowding must be tolerated if
Heberlein 1986; Lime and Stankey national parks are to remain open for
1971; Manning 1986; Graefe et al. public use. For the relationship defined by line A, X 1 and X2 represent
1984). But despitethis impressiveliteraturebase,efforts to determine and levels of visitor use that result in difapply socialcarrying capacityto areas fering levels of crowding as defined
such as the national parks have often by points Yl and Y2, respectively.
failed. The principle difficulty lay in
But which of thesepoints- Y 1 or Y 2,
determining how much impact, such or someother point along this axisascrowding, wastoo much. Theoret- representsthe maximum amount of
ical development,backed up by em- crowding that is acceptable? Ultipirical research, generally confirms mately, this is a value judgement.
that increasing contacts or encoun- Again, the principal difficulty in carters between visitors leads to inrying capacity determination lies in
creasedperceptionsof crowding. But deciding how much crowding (or of
how much crowding should be al- some other impact) is acceptable.
lowed in a national park? This basic Empirical relationshipssuch as those
question is often referred to as the in Figure 1 can be helpful in making
"limits of acceptablechange" (Lime informed decisions about carrying
1970; Frissell and Stankey 1972). capacity, but they must be suppleGiven substantialdemand for public
mented with management judguse of a national park, some decline ments.
or changein the quality of the visitor
To emphasizeand further clarify
experience (e.g., some crowding)
this issue, some writers have sugappears inevitable. But how much gested distinguishing between dedecline or change is acceptable or
scriptive and evaluative(or prescripappropriate before managementintive) components of social carrying
tervention is needed?
capacity determination (Shelby and
This issueis illustrated graphically Heberlein 1986). The descriptive
in Figure 1. In iliis figure, two hypo- component of social carrying capacthetical relationships between visitor
ity focuseson factual, objective data
use and crowding are shown. It is such as the types of relationships in
clear from boili that visitor use and Figure 1. For example, what is the
Y()lume12
.Number
3
1.995
43
relationahip betWeenthe number of
visiton enteringan areaand the number of encounten that occur between
groups of visiton? Or what is the relationship betWeen the intensity of
visitor use and visitor perceptions of
crowding? The evaluative or prescriptive component of social carrying capacity detennination concerns
the seemingly more subjective iasue
of how much impact or changein the
visitor experienceia acceptable.For
example, how many contacts betWeenvisitor groups are appropriate?
What level of perceived crowding
should be allowed before management intervention ia needed?
Recent experience with canoying
capacitysuggeststhat answen to the
above questions can be found
through fonnulation of management
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VISitor Use
Figure 1. Hypotheticalrelationshipsbetweenvisitor use and crowding
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clines to an unacceptable degree
(Vaske et al. 1986; Whittaker and
planning
and management
team, and
Shelby 1988; Heberlein et al. 1986;
public involvement.
Roggenbucket al. 1991; Shelby and
Indicators of quality are more
Vaske 1991). This consensus
specific measurablevariables which
(sometimes called "social norms")
reflect the essence or meaning of amongvisitors helps to define a stanmanagementobjects; they are quan- dard of quality.
tifiable proxies or measuresof manBy defining indicators and stanagement objectives. Indicators of
dards of quality, carrying capacity
quality may include elementsof both can be determined and managed
the physical and social environment through a monitoring program. Indithat areimportant in determining the cator variables can be monitored
quality of the visitor experience. over time; once standardshave been
Standards of quality define the reached, carrying capacity has been
quantitative and measurablecondireached as well. This approach to
tion of eachindicator variable.
carrying capacity is central to conAn example of management obtemporary park planning framejectives, indicators, and standards works, including Limits of Acceptmay be helpful. Review of the U.S. able Change (LAC) (Stankey et al.
WildernessAct of 1964 suggeststhat 1985), Visitor Impact Management
areas contained in the National
(VIM) (Graefeet al. 1990), Carrying
Wilderness Preservation System are Capacity Assessment Process (Cto be managedto provide opportuniCAP) (Shelby and Heberlein 1986),
ties for visitor solitude. Thus, providQuality Upgrading and Learning
ing opportunities for solitude is an (QUAL) (Chilman et al. 1990),
appropriate management objective Recreation Management Planning
for most wilderness areas.Moreover, Process (Manning 1986), and the
research on wilderness use suggests Visitor Experience and Resource
that the number of visitors encoun- Protection (VERP) processcurrently
tered along trails and at campsitesis under development by the National
important to wilderness visitors in
Park Service (National Park Service
defining solitude. Thus, trail and
199'J;Hofetal.1994).
camp encountersbecomekey indicators of quality and help to make the Carrying Capacity in U.S. National
general management objective of
Parks: The VERP Process
solitude more operational. Further
The U.S. National Park Service
researchsuggeststhat wildernessvisihaslong recognizedthe needto apply
tors often have normative standards the concept of canoyingcapacity to
about how many trail and camp en- parks that have been experiencing
counters can be tolerated before the problems from increasingpublic use.
quality of the visitor experience de- In fact, the 1978 U.S. General Auand
planning
sideration
by
documents,
an
con-
interdisciplinary
~
45
~
thorities Act requires each park's
general managementplan to include
"identification of and implementation commitments for carrying capacities for all areasof the unit" (U.S.
Congress 1978). Although Park
Service management policies and
planning guidelinesacknowledgethis
responsibility, there hasbeenlittle direction or agreementon an approach
or methodology for how to identify a
park's carrying capacity. Park planners and managershave been reluctant to statethat parks, or areaswithin
parks, are receiving inappropriate or
excessive use because they have
lacked the rationale and empirical
data to makesuch determinations.
For the past three years, an interdisciplinary team of Park Service
planners, managers,and researchers
has been developing a framework to
identify and managecarrying capacity in the nationalpark system.As described in the previous section, this
framework is basedon identification
of appropriate resource and social
conditions-indicators and standards
of quality-to
be achieved and
maintainedin the national parks. The
process is called Visitor Experience
and ResourceProtection (VERP).
VERP consistsof nine b~ic steps
as shown in Figure 2. The first six
steps are requirements of general
park planning and ideally should be a
part of each park's general management plan (GMP). The final three
steps require periodic review and
adjustment and are most appropriately handled through park operation
and management activities. Briefly,
G1jlgj:1;;11~B
the stepsareasfollows:
. In Step 1 a project team is assembled. This should be an interdisciplinary team comprising park
planners, managers, and researchers.
. Step2 consistsof devdoping clear
statementsof park purposes, significance, and primary interpretive themes.This step clarifies the
most basic assumptionsabout the
park's use and management,and
setsthe foundation for the rest of
theprocess.
. In Step 3 the park's important resources and potential visitor experiences are mapped and analyzed. The product of this step is a
set of overlay maps showing the
spatial distributions of important
resources, landscape units, and
the rangeof visitor experienceopportunities.
. In Step 4 the team identifies potential management zones that
cover the range of desired resource and social conditions consistent with the park's purpose:
This is wherethe processbeginsto
be prescriptive. Different actions
will be takenby the Park Servicein
different zoneswith regard to the
types and levelsof usesand facilities. The zones are defined by
carefully analyzing resource constraints and sensitivities, resource
attributesfor visitor use, and managementgoals for the park. The
existingpark infrastructure(roads,
parking lots, etc.) is not a deciding
factor in detennining the zones.
. In Step 5 the teamapplies the potential managementzones on the
ground to identify a proposedplan
and alternatives.A zoning scheme
is identified by overlaying the potential managementzones on the
areaswhere the team believesthat
differen t visi tor experiences
should occur in the park. The
park's purpose, significant resources, and existing infrastructure are also factored into this
analysis. Different configurations
of the potential management
zones can lead to different alternatives.
. Step 6 involves selecting indicaton of quality and specifying associated standards for each zone.
The purpose of this step is to
identify measurablephysical, social, or ecological variables that
will indicate whether or not a deaired resourceor social condition
is being met. This is a pivotal step
that definesthe zones, transforming subjective descriptions into
objective measurementsof conditions in thosezones.
. In Step 7 the park staff compares
desired conditions with existing
conditions. Each zoneneedsto be
monitored to determine if there
are discrepancieswith the desired
resourceand social conditions.
. Step 8 consists of identifying
probable causesof discrepancies
in eachzone.It is important in this
stepto accuratelyidentify the root
causesof the discrepancies.
. In Step 9 the park staff identifies
managementstrategiesto address
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discrepancies. Visitor use managementprescriptions should start
with the least restrictive measures
that will accomplish the objective
and move toward more restrictive
measuresifneeded.
Although Step9 is the final formal
step shown in Figure 2, the process
doesnot end there. Long-term monitoring is an essentialelement of the
VERP process.Monitoring provides
continual, systematic feedback to
park managersto ensurethat desired
resource and visitor experience
conditions continue to be achieved
over the long term. In this way, carrying capacity has been identified and
managed.
Carrying Capacity or Arches National Park
The VERP process described
above is currently being applied at
Arches National Park, Utah. The
purpose of the test is to refine the
VERP processand provide a model
for the rest of the national park system. Researchaimed at defining indicators and standards of quality for
the visitor experienceis described in
thD section. As noted earlier, indicators and standardsof quality are pivotal points of carrying capacity determination. Complimentary research has addressedindicators and
standardsfor natun! resource conditions such as soil disturbance and
compaction and destruction of vegetation.
Arches National Park is covers
73,000 acresof high-elevation desert
with outstanding slick rock forma-
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tions, including nearly 2,000 stone
arches.Most of the park's scenic attractions are readily accessible
through a well-developed road and
trail system.Visitation to Arches has
beenincreasingrapidly. The number
of visits increased91 percent in the
decade of the 1980s, and the park
now receivesover three quarters of a
million visits annually with use continuing to increase at a substantial
rate.
Following the VERP model, an
interdisciplinary project team was
created, composed of planners from
the Park Service's Denver Service
Center, Arches National Park staff,
and USNPS scientists (Step 1).
Workshops were conducted to develop statementsof park purposes,
significance,and primary interpretive
themes(Step 2). Authorizing legislation and the current General Management Plan provided important
reference sources. Park resources
and existing visitor experienceswere
then mapped (Step3) and a spectrum
of desiredresource and social conditions was constructed using a simple
matrix format (Step 4). Basedon this
analysis, a system of nine zones
ranging from developed to primitive
was createdand overlaid on the park
(Step 5).
Step 6 requires selecting indicators of quality and specifying associated standards for each zone. This
required a social science research
program iliat was conducted in two
phases.PhaseI wasaimed at identifying potential indicators of quality
(Manning et al. 1993). Personal in-
~:;]lI:'
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terviews were conducted with 112
visitors throughout the park. In addition, ten focus group sessionswere
held with park visitors, park staff, and
local community residents. Respondents and participants were selected
through a purposive rather than random samplingprocedure.Thus, data
are primarily qualitative in nature.
This exploratory effort was conducted to develop insights into potential indicators of the quality of the
visitor experience.Interviews and focus group sessionswere guided by a
standardizedquestionnaire.
The questionnaire contained two
major sectionsthat focusedon identifying potential indicators of the quality of the visitor experience.The first
section contained a battery of openended questions which probed for
park conditions and issues which
visit 0 r san
d others considered
important to determining the quality
of the park experience. The second
section contained a battery of closeended questions which also probed
for indicators of quality. Fifty-three
wide-ranging park conditions or
issueswere presentedto respondents
who were askedto indicate the extent
to which eachitem wasconsidered to
be a problem in the park. The items
presentedwere developed on the basis of literature review, discussion
with park plannersand staff, and personalobservationsin the park.
Findings from the Phase I researchsuggestedseveralindicators of
quality for the park, including the
number of people at frontcountry attraction sites and along trails, the
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number of parties encounteredalong
backcountry trails and at campsites,
the number of vehicles encountered
along roads, the number of social
trails and associatedsoil and vegetation impacts, the level of trail development, and visitor knowledge of
regulationsregardingofT-trailhiking.
PhaseII of the researchprogram
wasdesignedto identify specific indicators of quality and set associated
standards (Lime et al. 1994). The
primary objectivesof this phaseof researchwere to determine the relative
importance of indicator variables
acrossthe nine park zonesand to set
standardsfor the most important indicator variables. A survey of park
visitors was conducted, covering all
nine park zones. The survey was
administered to a representative
sampleof over 1,500 park visitors by
means of both personal interviews
and mail-back questionnaires.
The survey instruments contained
two major sectionsrelatedto carrying
capacityand the VERP process.The
first section focused on determining
the relative importance of indicator
variables identified in Phase I research. Fourteen indicator variables
were distilled from the previous
phase of research, and respondents
were askedto rate the importance of
each variable in determining the
quality of their experienceat the park
zonein which they were interviewed.
This sectionof the questionnairewas
neededfor two reaaons.First, Phase
I researchwas qualitative in nature;
its purpose was simply to explore for
potential indicators of quality. Phase
II research was needed to become
more quantitative by asking respondents to rate the relative importance
of thesepotential indicators of quality. This required a larger and more
representativesample.Second,it was
hypothesizedthat indicator variables
would vary by park zone. Sampling
was conductedin all nine park zones,
and questionswere keyed directly to
those specific areas.This zoning approach is appropriate to carrying capacity and the VERP process as relatively large areas such as national
parks can and probably should provide a variety of visitor experiences.
The second major section of the
surveyquestionnaireswas directed at
determining standards of quality for
selectedindicator variables. Five indicator variablesreceived special attention: 1) the number of people at
one time at major frontcountry attraction sites, 2) the number of people at one time along frontcountry
trails, 3) the amount of environmental impact causedto soil and vegetation by ofT-trailhiking, 4) the number
of parties encountered along backcountry trails and at campsites, and
5) the number of vehicles encountered along unpaved roads. The first
three of these variables were addressed by a series of photographs
which illustrated a range of impact
conditions. Photographswere developed using a computer-basedimage
capture technology (Pitt 1990; Lime
1990; Nassauer 1990; Chenoweth
1990). Basephotographsof park sites
were taken, and these images were
then modified to present a range of
TbeGeorseWrightFORUM
impact conditions (e.g., number of for each of the nine park zones.
visitors present, amount of environ- Where appropriate, at least one social indicator was chosen for each
mental impact). A set of sixteen
photographs was developedfor each zone and standardswere set for each
major attraction site and trail, pre- indicator variable. For example, the
senting a wide-ranging number of "pedestrian" zonecontains severalof
visitors present. An analogousset of the most prominent attraction sites in
photographs was developed for a the park, including Delicate Arch.
Visitors reported that the number of
range of environmental impacts
caused by ofT-trail hiking. Respon- people at such attraction sites at any
dents rated the acceptability of each one time was important in determining the quality of their experiences.
photograph on a scaleof -4 (very unThus,
the number of people at one
acceptable)to +4 (very acceptable).
Representativephotographs for the time (PAOT) at Delicate Arch was
selectedas an indicator of quality for
number of visitors at Delicate Arch
and environmental impact along the that zone. Moreover, findings from
trail to Delicate Arch are shown on the seriesof 16 photographs of Delithe Cover and in Figure 3, respec- cateArch (asshown in Figure 4) sugtively. Questions regarding encoun- gestedthat visitors generallyfind up
to 30 PAOT to be acceptable.(It can
ters in the backcountryand along unpaved roads were asked in a more be seenfrom the figure that the line
tracing visitor evaluationsof the sixconventional narrative format.
Earlier in this paper, it was noted teen photographs crosses from the
that socialnorms often exist concern- acceptablerange to the unacceptable
ing important elementsof the visitor range at 30 PAOT). Based on these
experience. That is, there is often findings, 30 PAOT was selectedby
someconsensusamongvisitors about the project team as the standard of
how much impact can be tolerated quality. Indicators and standards of
before the quality of the experience quality were set for all zones in this
declines to an unacceptable degree. manner. A companion set of reMethodological techniques have source-based indicators and stanbeen developed and refined to mea- dards of quality was set based on a
sure such social norms of park visi- program of ecological research
tors (Heberlein et al. 1986; Manning (National Park Service 1995).
A monitoring program focused on
1985;Shelbyetal. 1992; Shelby and
indicators
of quality has been deHeberlein 1986; Vaske et al. 1986;
Whittaker and Shelby 1988). The re- signed and is now being implesearch program at Arches National mented in the park. This will allow
park staff to addresssteps7, 8, and 9
Park wasbuilt on thesetechniques.
Findings from Phase II research of the VERP process.This monitorprovided the basis for selection of ing program will determine the extent to which standardsof quality are
indicators and standards of quality
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12 15 21 22 26 36 45 52 63 66 68 78 108
People at One Time (P AOT)
Figure 4. Visitor evaluationof 16 photographsof DelicateArch showing
alternativelevelsof visitoruse.
sourceand social conditions through
a seriesof indicators and standardsof
quality. Indicators are monitored
over time, and when associatedstandards of quality have been reached,
carrying capacityhasbeenreachedas
well. If standards are violated, the
VERP process requires that managementaction be taken.
VERP is now being applied at
Arches
National Park. The park has
Conclusion
been
divided
into a series of zones,
N earlythirty yearsof researchand
developmenton the concept of carry- and, through a program of research,
ing capacity has led to development social and resource indicators
of severalplanning and management andbeing met, and will help develop
frameworks.All of thesecarrying ca- insights into the causesof any violapacity frameworks rely on a similar tions of standards.Park managersare
series of steps. VERP is specifically planning to use parking lot size at atdesignedto identify and managecar- traction sites and trailheads as a prirying capacity in the national park mary managementtool. The monisystem. Carrying capacity is deter- toring program will help detennine
mined by developing desired re- the appropriatesizeof parking lots to
SOPAOT at Delicate Arch) are not
violated. Parking lot size can be adjusted up or down depending upon
monitoring results. The VERP process requires management action
whenever standards of quality have
been violated. Park managersmust
be prepared and committed to initiating such managementactions.
i1""
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53
ensurethat standardsof quality (e.g.,
standardsof quality have been specified for each zone. A monitoring
program is now being instituted in
the park to insure that standards of
quality are not violated and to determine when and where management action is needed to keep park
use within carrying capacity. Additional applicationsof VERP are now
being undertaken at several Park
Service areas,including Acadia National Park, Glacier National Park,
Mount Rainier National Park, and
Saint Croix National Scenic Riverway.
VERP provides a theoretically
sound and rational process for determining and managingcarrying capacity in the nationalpark system.An
associated research program can
provide a strong empirical basis for
applying the VERP process. Arches
National Park provides a model for
applying the VERP processthroughout the nationalpark system.
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Univcnity of MinnelOta, pp. 549.552.
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Q
Robert E. Manning
Schoolof Natural Resources,Recreation Management Program, GeorgeD.
Aiken Center,University of Vermont,Burlington, Vermont05405-0088
David W. Lime
National Par! SeroiceCooperativeParis Studies Unit, Collegeof Natural Resources,110 GreenBaa, 1530 North ClevelandAvenue,St. Paul, Minnesota
55108
Marilyn Hof
National Park Seroue,Denver ServiceCenter,P.O. Box 25287, Denver, Colorado 80225-0287
A. Freimund
Schoolof Forestry, University of MMltana, Missoula,Montana 59812
Wayne
;'-oIume.12
~
55
THE GEORGE
WRIGHT
A JOURNAL OF CULTURAL AND NATURAL PARKS AND RESERVES
VOLUME12
THE JOURNAL
1995
0'
THE
SEORGE
NUMBER 3
WRISHT
Dedicated to the ProteCtion,Preservation and Management
or Cultural and Natural Parks and Reserves
ThrOURhResearchand Education
SOCIETY