Carrying capacity – it's time to let it go
by Simon McArthur
Carrying capacity is appealing for its simplicity, but this
is the very reason why it is fundamentally flawed when applied
to human beings.
Carrying capacity assumes all other variables are
removed, and that both the environment and people do not change.
Impact monitoring has proven over and over again that environmental
resilience ebbs and flows with factors such as seasonality,
intensity of use and recovery periods between use. Monitoring
has also shown that different people create different impacts,
based on a range of variables including type of activity, clothing,
behaviour and equipment.
Carrying capacity is a blunt instrument that is not designed
to accommodate these variables and it's apparent simplicity
discourages most people from considering these variables.
In the mid 1970s, recreational carrying capacity began to be
mooted as the major model for managing visitor impact.
In response, the U.S. Department of Interior reviewed the potential
of recreational carrying capacity and prepared guidelines for
its use. The review looked at existing literature, past research
and use of the model, evaluated standards currently used for
their application as indicators, then surveyed user groups and
recreation planners and heritage managers to explore attitudes
and support for the model.
Guidelines were developed to aid recreation planners and heritage
managers in determining whether to develop a recreational carrying
capacity model and if so, how to go about it at the site level.
The study revealed the following:
Park planners were more interested in protecting the resource
or meeting recreation demand than providing a high quality experience.
There were significant differences in opinion between planners
and user groups, particularly in relation to optimum capacities
for such activities as bushwalking, water skiing, pool swimming,
power boating and shoreline fishing.
Several managers had established capacity limits based on the
availability of support facilities rather than the optimum recreational
carrying capacity - in essence managers were already focusing
on a maximum number rather than the entirety of the model as
it was originally proposed.
A POPULAR THOUGH NOT EVALUATED NOTION
By 1980 the U.S. National Parks Service had established carrying
capacity limits in 21 per cent of its entire estate. Since then
the notion to develop recreational carrying capacity models
has remained popular but their actual application has been sporadic,
uncoordinated and largely not evaluated.
Within this context, the actual applications of recreational
carrying capacity have nonetheless managed to occur in planning,
site design, development, and administration. Planning use often
involved evaluating the size and character of alternative sites
and predetermining optimum levels of use for various locations.
Site design and development use have involved assigning activities
to areas according to natural limits, and identifying suitable
position between the activities. However, the emphasis by most
heritage managers has been on physical capacity applied to site
design and development. Here are a few examples.
Australia: The Daintree National Park (Queensland),
based on the physical limitations of defined vehicle parking
spaces, Green Island (Queensland) has a capacity of 1,900 visitors
per day or no more than 800 at any one time, Point Nepean National
Park (Victoria) where the limit is 600 visitors at any one moment
New Zealand: A limit of 500 visits per year
has been set for the sub-Antarctic islands, 200 persons at any
one moment in time for the Waitomo Caves, and 160 persons on
any day during the period that the Milford Track is open to
Bermuda: A capacity of 120,000 cruise ship
passengers during the peak visitation period was set by local
authorities for Bermuda.
Canada: The carrying capacity concept was used
to review tourism development strategies in Ontario; the result
was the identification of specific zones with high potential
for tourism development, based on competition for resources
between residents, owners of second homes and tourists;
Cambodia: The Angkor World Heritage Site has
a capacity of 300 to 500 visitors at any one time and an annual
capacity of 500,000 (these capacities assume visitors will make
two visits to the site during their stay;
South Africa: Capacity limits have been applied
to the Kromme River Estuary and the Infanta area, South Cape,
and in the United States Yosemite Valley, Yosemite National
Park, Cache National Forest in Utah.
The applications that have been established have been full
of assumptions and inconsistencies. A good example of the assumptions
and subjective judgements is Green Island in far north Queensland.
If the maximum daily level was reached every day, Green Island
would receive 693,500 visitors in a year, over twice the current
level. Any visitor management model that cannot be defended
is unlikely to gain or at least maintain the support of stakeholders.
Despite the concept of recreational carrying capacity being
over 30 years old, it remains, in practice, highly elusive.
It is commonly recognised that there are no fixed or standard
tourism recreational carrying capacity values. Rather, carrying
capacity varies, depending upon place, season and time, user
behaviour, facility design, patterns and levels of management,
and the dynamic character of the environments themselves. Moreover,
it is not always possible to separate tourism activity from
other human activities.
Clearly then it is relatively easy to argue that there is no
such thing as a single recreational carrying capacity for any
given heritage site and that any capacity put forward is highly
subjective, and thus difficult to defend.
Recreational carrying capacity is multi-faceted or multi-dimensional.
Its determination will therefore be all the more difficult because
of the range of activities and environmental variables involved;
and because we still do not know sufficient about the relationships
between varying levels of use and changes in the biological
and physical character of the site on the one hand and changes
in the degree of personal satisfaction obtained in the other.
A somewhat paradoxical situation exists: in fact there is ‘spare
capacity' in the areas which are already intensively used, but
the visitors frequenting the less used parts may already consider
existing levels of use to be too high and the area over used.
Nearly a decade later, with a considerable amount of impact
related research undertaken, academics and practitioners continued
to have problems with the complexities of recreational carrying
capacity and continued to question the reality of ever establishing
a reliable model. One of the architects of recreational carrying
capacity, George Stankey once wrote:
Physical-biological impact is a complex phenomena. It does not
bear a direct linear relationship to use; in fact, use intensity
is less helpful than other variables (eg. method of travel,
season of use) in explaining the degree of impact sustained...
In general, knowledge of other ecological consequences associated
with recreation use is poor. Impacts on wildlife behaviour,
air quality, or water quality are understood in only descriptive
We lack the ability to predict, in quantitative terms, the
consequences of alternative levels, types and patterns of use
on the physical-biological environment, a serious shortcoming
in our efforts to develop the potential carrying capacity concept.
Stankey suggested four propositions about the nature of recreational
carrying capacity nature:
1. Its determination is ultimately a judgmental decision
2. Decisions depend on clear management objectives
3. The range of available alternative opportunities must be
taken into account
4. It is a problematic concept, not an absolute measure
Policies concerning carrying capacities are based on the assumption
that recreational impacts are directly related to the amount
and type of use. However, ecological and human behaviour factors
do not allow for such a simple and direct relationship between
amount of impact and use.
Carrying capacity is the lazy man's answer to visitor management,
just like fences and regulations! Sophisticated models that
incorporate feedback (monitoring) and adaptive management are
more accountable and socially just.
Models such as the Limits of Acceptable Change, Tourism Optimisation
Management Model and Visitor Experience and Recreation Program
can be set up as small scale models that can be progressively
expanded as their value is proven. The challenge is to acknowledge
that the complexity of visitor management requires an integrated
and long term approach.
Simon has 16 years experience working with ecotourism planning,
development and operations across the world, and straddles the
divide between the tourism industry and heritage managers. He
specialises in creating special interest tourism operations
that are authentic, minimal impact and sufficiently viable to
conserve the site that they depend on.
Simon's practical experience is backed up by several books and
numerous papers on heritage and visitor management, a PhD in
tourism impact management, and regular speaking engagements
on ecotourism, cultural tourism and tourism impact management
across the world.
Simon works as Product Development Manager for EcoPoint
Management, an ecotourism company based in Australia. His
current focus is the adaptive reuse of Sydney's historic Quarantine
Station into a 90 room resort with health retreat and interpretive
tours). He is completing a Master of Business Administration.
This paper represents a synthesis of a PhD thesis 'Visitor
management in action, an analysis of the development and implementation
of visitor management models at Jenolan Caves and Kangaroo Island,'
by Simon McArthur, and held at the University
of Canberra, Australia. References are available on request.