horse riding in urban conservation areas: reviewing scientific evidence to guide management

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advocates of horse riding claimed they hadbeen discriminated against because theywere no longer allowed in some areas theyhad previously used. Many non-equestrianresidents were vocal in their disapprovalof horse riding being permitted anywherein the park, largely because of perceivedthreats to conservation values. Resolutionof the debate was hampered by a per-ceived lack of scientific evidence abouthorse-riding impacts in environments likethose in CNP. In September 1998, the ACTLegislative Assembly recommended:

That the government seek expert advice . . .on the whole issue of horse riding inCanberra Nature Park . . . In particular,advice should be sought on the competingclaims about the effect of horses onconservation areas and on how best to ensure

the present conservation priority can beupheld in the context of adjacent city use ofCanberra Nature Park.

A consultant was contracted to preparea report examining published evidence onthe impacts of horse riding in conserva-tion areas comparable to CNP. This articlepresents a summary of that report and thehorse-riding policy that was developedfrom it for areas of CNP.

The Canberra Nature Parkcontext

Environment

Canberra Nature Park consists of 27 dis-crete reserves, totalling some 6000 ha(Environment ACT 1998). It has an urban

Horse riding in urban conservation areas:Reviewing scientific evidence to guidemanagementBy Jill Landsberg, Bill Logan and David Shorthouse

This article was prepared by Jill Landsberg while

a senior research scientist with CSIRO Wildlife

and Ecology in Canberra, in collaboration with

Bill Logan and David Shorthouse (both from

Wildlife Research and Monitoring Unit, Environ-

ment ACT, PO Box 144, Lyneham, ACT 2602, Aus-

tralia. Email: [email protected]).The

work arose from a review, in February and

March 1999, of the potential effects of horse

riding in Canberra Nature Park. Jill is now based

in Cairns [School of Tropical Biology, James Cook

University, PO Box 6811, Cairns, Qld 4870, Aus-

tralia. Tel: +61-7-40421443. Email: Jill.Lands-

[email protected]].

Summary We undertook a literature review of the impacts of horse riding in conservationareas, and used it to guide management of horse riding in Canberra Nature Park (CNP), alarge, fragmented semi-natural park in and around the city of Canberra in the AustralianCapital Territory. The literature review established that, because of their relatively largeweight and small area in contact with the ground, horses have a relatively high potential fordoing environmental damage. Impacts tend to be generally lowest for hikers, followed bymotorcycles, horses and four-wheeled vehicles. One study showed horse traffic causedmore damage on established trails than motorcycles, off-road bicycles or hikers. Most pub-lished studies of horse-riding impacts in Australia have been conducted in alpine and sub-alpine environments, and in temperate woodlands and forests on sandstone near Sydney.They have shown that impacts are generally highest in previously untracked areas. Impactson established trails are generally most marked on sections of trail that are wet, boggy orsteep, and on unplanned and unmaintained trails. Impacts are lowest on constructed andmaintained trails. Trail proliferation, associated with avoidance of untrafficable sectionsand short-cutting, can be a major problem. Horses also have potential to spread weeds,because pastures and dried stock feeds contain large numbers of weed seeds that retainhigh levels of viability in horse manure. The risk of weed establishment is highest whenmanure is deposited in disturbed, damp sites, particularly when riding off-track. Much lessweed establishment is apparent when horse riders remain on-track. Horse riding is apopular activity, but one that is relatively expensive to provide for, and one that may reduceopportunities for lower-impact recreational park users. For all these reasons it appearssocially equitable that provision is made for lower numbers of horse riders compared tonumbers of park users involved in lower impact, more passive, recreational activities. Weconclude by describing how this information was used to develop principles to guide man-agement of horse riding and assess risk at individual sites in Canberra Nature Park.

Key words Canberra Nature Park, environmental impacts, horse riding, recreational opportu-nities, tracks and trails, urban conservation area, urban park.

Introduction

Horse riding in conservation areas is acontentious issue, particularly on the

outskirts of cities, where increasing use ofparks by all types of users places greaterpressure on park resources and createsgreater potential for conflict between dif-ferent user groups. This is exemplified bydebate about the appropriateness of horseriding in Canberra Nature Park (CNP), alarge, fragmented, semi-natural park in andaround the city of Canberra in the Aus-tralian Capital Territory (ACT) (Fig. 1). Thedebate was fuelled recently by the releaseof a draft Plan of Management for the parkthat rationalized pre-existing patterns ofuse by permitting horse riding along alimited number of designated routes.Some

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with regional extinction. To date, 22species and two ecological communitieshave been declared vulnerable or endan-gered in the ACT. Both of the endangeredcommunities and 11 of the threatenedspecies have been recorded or have poten-tial to occur in CNP (Environment ACT1998).

No data are available on the totalnumbers of recreational park users. Of the550 respondents who supplied individualsubmissions to the draft Plan of Manage-ment,77% visited the park more than oncea month (Environment ACT 1998). Theirmost popular recreational activity waswalking (around 90% of respondents). Inaddition to passive enjoyment (walking,jogging, picnicking etc.), the other recre-ational activities that have been permittedin the park are:

• bicycling (permitted in all 27 reserves,but restricted to formed vehicle trails)

• dog walking on leash (permitted in 17reserves, with no restrictions about trails)

• horse riding (permitted in 12 reserves,and restricted to authorized trails).

Cars and motorcycles are not permitted inany of the reserves (except for manage-ment purposes).

Although there are no data on thenumber of horse riders using CNP, the ACTEquestrian Association estimated it hadapproximately 2000 members in 1992(Manning 1993), many of whom wouldpresumably ride regularly in CNP. Therehas been extensive provision for eques-trian trails on public land in the ACT,including within conservation areas; theCanberra’s Equestrian Trails pamphlet(ACT Government undated) shows108 km of trails close to urban areas andan additional 60 km in Namadgi NationalPark, well to the south of the city. Nearly40 km of trails are shown in CNP. Theremaining urban trails skirt around resi-dential areas and traverse areas of publicopen space, including softwood plantationforests. Underpasses and bridges havebeen constructed in a number of loca-tions.The trail system has been planned tolink government horse-holding paddocksand equestrian activity areas, and toconnect with rural trails. The Bicentennial

temperate, with an annual average rainfallof 634 mm and temperature of 19.4°C.

Park management and pre-ex ist ing provis ion forhorse r id ing

Conservation of the natural environmentis recognized in legislation as the para-mount management objective for CNP;provision for public use is a secondaryobjective (Land Planning and Environ-ment Act 1991). Sites with special conser-vation significance include habitat fornative flora or fauna, and sites of particularcultural, landscape or geological signifi-cance (Environment ACT 1998). Speciallegislative provisions under the NatureConservation Act 1980 apply to nativeplants and animals declared as threatened

fringe of around 200 km and more than6000 residential leases adjoining its bound-aries. This means there are managementissues for CNP that are typical of manyother peri-urban parks such as: fragmenta-tion, high rates of visitor use, provision ofareas for public utilities, and greater vul-nerability to domestic pets and urbanencroachment. Canberra Nature Parkoccurs mainly on isolated hills and ridgesof erosion-resistant rock and rollingcountry formed on moderately weatheredrocks. The native vegetation is a mosaic ofdry open eucalypt forest, grassy woodlandand grassland, some of which retainshabitat for threatened flora and fauna(Environment ACT 1998). Some areascontain mostly exotic species or mixturesfollowing tree clearing or prior land uses.The regional climate is sub-humid and

Figure 1. Map of the northern section of the Australian Capital Territory, showing thefragmented nature of Canberra Nature Park and its close association with the city of Canberra.

National Trail uses part of the trail systemto pass through the ACT (Canberra’sEquestrian Trails pamphlet, ACT Govern-ment undated).

Equestrian trails are rarely singlepurpose, however, and are frequently usedby walkers, joggers and cyclists (Manning1993). This can cause problems for horseriders, particularly when dogs, trailbikesand cyclists frighten horses. Also, ACTequestrians have identified a number ofother problems with the trail system,including poor maintenance of trails,prob-lems with lack of separation from trafficwhen the trail travels along road verges,and unsafe road crossings (Manning 1993).These problems place greater pressure onthe trails within CNP. Within the Park,there is a relatively low level of provisionfor rider satisfaction, with authorized looptrails designated in two reserves only.

Socia l a t t i tudes

Many local residents have been vocal intheir disapproval of pre-existing horse-riding policies in CNP, largely because ofperceived risks to conservation values.ROASTING Inc. (Residents of AdjoiningSuburbs Taking Interest in Nature reserveGovernance) is a community group set upin 1998 for the purpose of ‘defending theconservation values of the nature reservesof CNP’ (P. Bell, convenor of ROASTINGInc., pers. comm., 2000). It has madenumerous submissions to government thatare critical of management of horse ridingin CNP. There is also an active, volunteer,Park Care program supported by Environ-ment ACT. Because weed control is one ofthe major activities undertaken by ParkCare groups, they are understandably veryconcerned about the potential for horsesto contribute to spreading weeds intonatural areas of the park.

A questionnaire survey conducted bypark rangers between December 1995 andApril 1996, however, provides some inter-esting indications that the wider commu-nity of CNP users appears to be relativelytolerant of current levels of horse riding inthe Park. The survey’s results need to beinterpreted with caution as it is far fromdefinitive; it was not prepared by qualifiedresearchers,was undertaken in an unstruc-

tured manner, and may not have accessedthe full range of users (Odile Arman,Manager, Canberra North District, pers.comm.,2000).The survey sought the opin-ions of 81 people using The Pinnacle, oneof the Park reserves where horse ridinghas been particularly contentious. Therespondents were engaged in a range ofactivities including walking (49%), dog-walking (16%),mountain-bike riding (16%)and jogging (11%). None was engaged inhorse riding.Nearly all (94%) had used ThePinnacle before and many (81%) wereregular users. Nearly all (95%) knew thathorse riders used the reserve and nearly all(95%) were happy with the current levelof use. Fewer people said they would behappy with an increased level of horseriding but they were still in the majority(62%).

Scientific evidence abouteffects of horse riding

A review of the scientific literaturerevealed there has been relatively littlequantification of the effects of horse ridingin Australian conservation areas, particu-larly in environments like CNP. However,numerous studies have been conducted inother areas, as summarized below.

Environmenta l impacts oftrampl ing

Mechanical forces exerted by a horseand rider

The most immediate impacts on soil andvegetation caused by a horse or any otheranimal are those due to forces transmittedthrough the animal’s feet.The size of these

forces is a function of the gravitationalforces associated with the animal’s weight,and the greatly increased forces created bymovement (Liddle 1997). Gravitationalforce can be converted to pressure bydividing weight by the area in contactwith the ground. Calculations of this sortshow that the static pressure exerted by ashod horse and rider is more than 20 timesthe pressure exerted by a man wearingboots and more than twice the pressureexerted by a trail bike or four-wheel-drivevehicle (Table 1).

These pressures apply to static forcesonly; the combination of horizontal, lateraland vertical forces that come into playduring movement are much greater, butalso much more complex. The forcesrequired to accelerate, decelerate or turnincrease the complexity even further,as dointeractions among these various forcesand the ground surface (Liddle 1997).Rather than attempting to measure thesecomplex forces, most studies focus ontheir net impacts on soils or vegetation.

Development of trails in previouslyuntrodden areas

The greatest impacts of trampling generallyoccur on previously untrodden ground,where some disruption of the soil surfaceand damage to vegetation invariablyoccurs. This is particularly so in themontane areas where most scientificstudies of the impacts of trampling onpreviously untracked soils have been done.Gillieson et al. (1987) quantified relation-ships between soil and vegetation changeson newly developing horse tracks insubalpine grassland in Kosciusko NationalPark in Australia. They found that


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Table 1. Total weight, area in contact with the ground, and calculated stationary pressureexerted on the ground in association with a range of outdoor recreational activities

Source of pressure Average weight Contact area Static pressure (g) (cm2) (g cm2)

Man wearing boots 80 000 388 206Woman wearing boots 57 000 356 160Unshod horse and rider 613 000 478 1282Shod horse and rider 613 000 140 4380Trail-bike 229 000 114 2008Four-wheel-drive Toyota, empty 2 100 000 1355 1550Four-wheel-drive Toyota, with four

people and gear 2 500 000 1483 1686

Source: Liddle (1997).

vegetation damage was apparent after only10 passes by two horses, but soil damagewas not apparent until 30 passes hadoccurred. The first soil change observedwas the formation of a distinct runnel thatthe authors suggested would channeloverland flow; at this stage of track devel-opment (30 × 2 horse passes) no signifi-cant changes were detected in soil bulkdensity or crust hardness or infiltrationrate. They suggested that this intensity ofuse, equivalent to one commercial party,was probably within the use-threshold ofthis particular tussock grassland.

Difference among users and vegetationtypes. Differences among users and vege-tation types. In one of the earliest studiesof trampling effects, Weaver and Dale(1978) compared the effects of hikers,horses and motorbikes on previouslyuntracked soils in natural grassland andshrubby pine forests in the mountains ofMontana, USA. After 1000 passes theyfound that damage tended to be least ongrassy and stony sites, and was generallygreater on slopes than on level ground.Motorcycles were most damaging whengoing uphill while hikers and horses weremost damaging when going downhill. Inall the environments studied, horsestended to cause most damage and hikersthe least. However, the motorbike in theirstudy was small (90cc) and slow moving(20 km/h); they cautioned that a larger orfaster vehicle would be likely to causemore damage. Weaver et al. (1979) laterundertook a comprehensive review of traildevelopment and recovery in montaneregions in north-west USA. They con-cluded that, in terms of soil bulk density,bare ground, trail depth and trail width,impact generally increases with increaseduser numbers regardless of user identity,but that impact per number of user passesgenerally increases from hiker, motorcycleto horse.Liddle (1997) used these data andseveral other sources of information to cal-culate and compare use-thresholds for different types of users (Table 2). Inthree different environments, toleranceto trampling (indicated by a high use-threshold) was consistently highest forwalkers, followed by motorcycles, horsesand a light van.

The relatively high use-thresholdsshown by grasslands in the Rocky Moun-tains (Table 2) have also been demon-strated in Australian alpine grasslands.In the Central Plateau of Tasmania, forexample, Whinam et al. (1994) showedthat 20–30 horse passes were sufficient tocause changes in shrubland, herbfield andbolster heath, but had little effect on drygrassland.

There are relatively few other data com-paring use-thresholds for horse riding indifferent environments, but Liddle (1997)compiled an extensive set of data compar-ing pedestrian use-thresholds (Table 3).These data indicate that, at least forwalkers, some types of eucalypt woodlandhave an extremely low tolerance of tram-pling.They also illustrate the huge range oftolerances shown by similar vegetationtypes in different environments. Forexample, grasslands on sand dunes in Scot-land have a relatively low use-threshold,but pastures on sand dunes in Wales andsubtropical grasslands near Brisbane havethe highest use-thresholds of any of the

vegetation types compared. There mayalso be seasonal differences. For example,Weaver et al. (1979) found that tramplingthe Rocky Mountains in spring had gener-ally smaller impacts on vegetation.Rates ofrecovery also varied, with montane grass-land recovering more quickly than forest.

Liddle (1997) suggested that the produc-tivity of different environments might be auseful predictor of their tolerance of tram-pling, with vegetation in productive envi-ronments tending to be more tolerant oftrampling. However, this is a generalizationthat needs to be treated with caution;dampareas are frequently very productive butthey are also very vulnerable to tramplingdamage, and fertile areas while productiveare often vulnerable to weed invasion.

Changes in plant composition. Use-thresholds usually indicate gross changesin vegetation cover or structure, but moresubtle changes in plant composition alsooccur. Dale and Weaver (1974) and Weaveret al. (1979) found that, although thebiggest impacts occur on the trail itself,


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Table 2. Comparison of the number of passes required to reach a use-threshold of 50%reduction in vegetation cover for walkers, motorcycles, horses and a light van

Environment User Use-threshold

Rocky Mountain forest Walker 300Motorcycle 80Horse 80

Rocky Mountain grassland Walker 1100Motorcycle 1000Horse 650

Welsh sand dune pasture Walker 1828Light van 203

Source: data compiled by Liddle (1997).

Table 3. Comparison of the number of pedestrian passes required to reach a use-thresholdof 50% reduction in vegetation cover for a range of different communities

Vegetation type Location Use-threshold

Eucalypt woodland Brisbane 12Snow-bank community Rocky Mountains 44Spruce woodland Finland 48Stone stripe community Rocky Mountains 57Grassland on sand dunes Scotland 119Heath on acid soils Scotland 161Heath on sand dunes Denmark 258Forest floor Rocky Mountains 300Subtropical rainforest clearing Brisbane 550Grassland in mountains Rocky Mountains 1000Pasture on sand dune Wales 1445Grassland in subtropics Brisbane 1412

Source: data compiled by Liddle (1997).

changes were also apparent away from itsedges. Not only did some plants commonin forest understorey, particularly shrubsand taller trees,disappear from the edge oftrails, other plants, especially introducedand native grassland species,became morecommon.

There are probably multiple causes ofthese differences, including direct effectsof trampling and changes in light, seedsupply, soil water and nutrients followingsoil disturbance. In an English heath,Liddleand Chitty (1981) showed that elevatedsoil nutrients were particularly importantin contributing to changes in the composi-tion of plant species along horse tracks.Although some of the nutrients may havecome from manure, they suggested thatmuch of the increase in nutrients mayhave come from breakdown in soil organicmatter and other soil changes caused bytrampling.

Impacts on existing trails

Existing trails are more robust, and horseriding on them may cause neglibibledamage in some environments. In a studyin the Rocky Mountains of Colorado,Summer (1980, 1986) found that the mostinfluential factors affecting trail degrada-tion were soil parent material, texture andorganic content, grade of trail and side-slope, rockiness, and type of vegetation. Inthe environments she studied, trails weremost resistant to damage by horse trafficwhen they crossed rock outcrops,slopes oftalus (broken fragments of bedrock), andtops of moraines. Trails on level valleyfloors and terraces with well-drained soilswere resistant to erosion,but susceptible totrail widening over time. The trails mostvulnerable to horse traffic were those thatcrossed colluvial slopes (colluvium is rockand soil transported by gravity), morainesideslopes, wet bogs and alpine areas.Gillieson et al. (1987) found similardifferences in vulnerability along anestablished horse trail in subalpinewoodland in Australia, with impacts onplant cover being most marked on thewettest parts of the trail.

One of the most detailed studies ofimpacts on trails constructed to differentstandards (Table 4) was undertaken byUpitis (1980), in eucalypt forest on sand-

stone soils in Ku-ring-gai Chase NationalPark near Sydney. Horses accounted foraround 80% of the trail use during herstudy.In general,trail condition was poorest(in terms of erosional features and sedi-ment movement) on trails in constructionclass 1 (unplanned and unmaintained) andbest on trails constructed to class 3 (con-structed and maintained), even thoughclass 3 trails tended to have the highestlevels of use. In addition, trails on steeperslopes (greater than about 7° in this envi-ronment) were frequently in poor condi-tion, regardless of class of construction.

Differences among users and vegetationtypes. Experimental work by Wilson andSeney (1994) in the Rocky Mountains inMontana compared impacts on establishedtrails from a range of recreational uses.They found that horses and hikerscontributed more to sediment movementthan either motorcycles or off-roadbicycles, and that this effect was mostpronounced when trails were wet. Horsetraffic yielded the most sediment move-ment overall,on both wet and dry tracks. In

a recent study of recreational impacts inthe Wet Tropics World Heritage Area innorth-eastern Queensland, Turton andcolleagues assessed biophysical impacts onboth walking and mountain-bike tracks(Day & Turton 2000; Turton et al. 2000).The relative impacts of the two activitieshave yet to be compared, but indicators ofimpact levels appear similar on both typesof tracks.

Whinam and Comfort (1996) showedthat there were big differences amongvegetation types in the amount of trackdegradation caused by horse riding on pre-existing trails in subalpine environ-ments in Tasmania. The sites they moni-tored were cross-sectional transectslocated across existing commercial horse-riding trails. All were affected by horsetraffic, but those in eucalypt forest andmoorland were affected most and those inrainforest least (Table 5). The highest rateof soil loss occurred from a site in eucalyptforest where there was a log across thetrail, the next highest loss was from a peatymoorland site. Rates of soil loss werelowest from the rainforest sites, possibly


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Table 4. Classes of trails distinguished in Ku-ring-gai Chase National Park

Class Construction Description

1 Unplanned and unmaintained trails Narrow (0.8–2 m), ill-defined, oftenbifurcating trails formed by repeatedtrampling of the vegetation.

2 Constructed but unmaintained trails Wider (2–4 m) trails constructed at sometime by park managers, but no longermaintained.

3 Constructed and maintained trails Wide (5–9 m) trails constructed andcurrently maintained by management. Theyare characterized by a lack of vegetation,presence of drains and culverts and, in somecases, paving materials.

Source: Upitis (1980).

Table 5. Vegetation types, drainage, track width and soil erosion from monitoring sitesacross pre-existing trails used by horse riders in subalpine Tasmania

Site Vegetation Drainage Track width Soil loss or gain after 24 monthstype (cm) (cm2 per 1 m width)

1 Rainforest Well drained 80 +92 Rainforest Well drained 220 –353 Eucalypt forest Well drained 115 –1084 Eucalypt forest Well drained 140 –3975 Moorland Poorly drained 210 –236

Source: Whinam and Comfort (1996)

Note: the gain in soil recorded at one site was due to the shoulders of the track collapsing in acrossthe monitoring transect.

because of churning and re-working of thehumus soil between tree roots.

Impacts on formed roads

With the exception of the study by Upitis(1980), most of the research that has beendone on the impacts of horse riding ontrails has not described how the trailswere constructed. However, the usualinference is that the trails have mainlydeveloped through repeated use. In manyconservation areas in Australia (e.g. manyVictorian national parks), horse ridingoccurs on vehicular roads constructed forpurposes such as management access andbushfire management. Provided trails suchas this are maintained and do not traversesteep slopes, they may be capable ofsustaining relatively high levels of use byhorses and vehicles (Upitis 1980).

Trail proliferation

Recreational users do not always stay onestablished trails. In a general discussion ofeffects of hikers and horses on mountaintrails, McQuaid-Cook (1978) noted thattrail proliferation is one of the biggestenvironmental issues associated withtrails. For example, trails making longstretches of switchbacks up a steep slopeare frequently disregarded in favour offaster,but much more damaging,short-cutsstraight up the hill.Also, if the surface of anexisting trail becomes untrafficable due todamage or tree fall, riders bypass thedamaged section by riding around it. Trailbraiding of this sort has beendemonstrated in subalpine environmentsin Tasmania (Whinam & Comfort 1996)and in lowland eucalypt forests nearSydney (Upitis 1980). Upitis estimated therate of proliferation of trails in Ku-ring-gaiChase National Park to have been about0.6 km/year during the 30 years prior toher 1980 study.

McQuaid-Cook (1978) suggested thathorses, especially when shod, cause moredamage than hikers on steep short-cuts.Healso suggested that equestrian trails gener-ally have a less compacted and often moreincised path than pedestrian trails, particu-larly in areas of moderate slope. This heattributed to shod hooves tending toloosen and move soil rather than flatten

and harden it. However, these suggestionsneed to be treated with some caution,since no scientific evidence is cited intheir support.

Contr ibut ion of horses tothe spread of weeds

The contribution of horses to the spreadof weeds is one of the key environmentalconcerns raised by members of the com-munity concerned about horse riding inCNP (Standing Committee on Urban Ser-vices 1998).

Horses as agents of weed spread. There ispotential for horses to act as agents ofspread of the plants they eat,because seedsof many plant species pass uninjuredthrough the digestive tracts of horses.Smallseeds or seeds with hard seed coats havethe highest levels of survival, with highestrates of transmission 2 and 3 days afteringestion. However, a small number ofseeds may be passed up to 13 days afteringestion (St John-Sweeting & Morris1991).Weaver and Adams (1996) recorded29 plant species germinating from horsemanure samples collected from horse trailsin three national parks in Victoria.The mostwidespread and abundant species wereWinter Grass (Poa annua) and Hare’s-footClover (Trifolium arvense).

Sources of potential weed seed in horsediets include both local pastures and driedstock feeds, which may be rich in weedseed. For example, hay and grain importedfor feeding livestock during the 1980–1981 drought in southern New SouthWales contained viable seeds of manyweedy species. The most common werePaterson’s Curse (Echium plantagineum),Wild Radish (Raphanus raphanistrum),Sorrel (Acetosella vulgaris), Swamp Dock(Rumex brownii), Buchan Weed (Hirshfel-dia incana), Knotweed (Polygonum avic-ulare) and Onion Grass (Romulea rosea)(Thomas et al. 1984).

Weed establishment in disturbed areas.Horse trails may also provide environ-ments suitable for establishment of manyspecies of weeds,regardless of the primaryagent of transport of the seed. Manyintroduced herbs (grasses and forbs) seedprolifically, and opportunistically occupy

disturbed spaces. They also tend to havehigh relative growth rates and competevigorously for available moisture, therebyinhibiting recruitment of native species;tendencies that are exacerbatedin nutrient-enriched sites. Thus, disturbedsites within any environment are veryvulnerable to invasions by many species ofintroduced grasses and forbs; and sitessuch as watercourses are particularlyvulnerable because they also represent themesic end of local moisture gradients(Humphries et al. 1991). The extent towhich horse trails provide conditions forweed establishment therefore depends onthe degree of disturbance associated withthem, and their moisture and nutrientstatus. Logically, the potential for weedestablishment on horse trails is likely to begreatest on softened tracks in damp areas,particularly if soils are also fertile. Manuredeposited in disturbed, damp sites couldpose a particular risk.

Horses and weed spread in conservationareas. Despite the clear potential for weedsto be spread by horses and/or establishalong horse trails, there have been relativelyfew scientific studies of this issue. Gibbs(1993) cites unpublished work by Ziegelersuggesting that there are greater levels ofweed infestation in Tasmanian wildernessareas along tracks frequented by ridingparties when compared with walkingtracks. In experiments with horse manurein alpine environments in Tasmania,Whinam et al. (1994) showed that thehighest rates of weed establishmentoccurred at shrubland sites where the soilhad been disturbed and grazing by rabbitsand native marsupials was experimentallyexcluded. However, few weeds establishedin open plots that were not protected fromgrazing by wild animals, particularly ingrassland. Nor were any weeds observedduring a study of the impacts of horseriding on pre-existing trails in the CentralPlateau Conservation Area of Tasmania(Whinam & Comfort 1996). Similarly,Gillieson et al. (1987) did not record anyweed establishment during their study ofhorse-riding impacts in tussock grassland inKosciusko National Park.

The most comprehensive study under-taken of horse and weed association in


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Australian conservation areas is that ofWeaver and Adams (1996) in Kinglake,Otway and Alpine National Parks inVictoria. They found there was substantialoverlap in the weed species germinatedfrom horse manure and the weeds presentalong trails used by horses, indicating thathorses were probable agents of spread ofat least some of the weeds establishedalong trails. However, they also cautionedthat many of the species that can ger-minate from manure were not present ontrack verges, presumably because trackconditions did not favour their establish-ment. There are several possible reasons.For example, Liddle and Chitty (1981) sug-gested that lack of water may inhibit somespecies from establishing on trails in dryenvironments, while Whinam and Comfort(1996) suggested that continued churningby horses may also inhibit successfulestablishment of some species that germi-nate from manure. Weaver and Adams(1996) cautioned that many of the weedspecies associated with horse trails mayalso be introduced by vectors such as vehi-cles and birds. For example, Hatton (1989)showed that Sweet Briar (Rosa rubigi-nosa) can be spread by both horses andbirds together, or by either in isolation ifthe other is not present; and Wace (1979)showed that there is considerable poten-tial for weeds to be spread by vehicles.

Weaver and Adams (1996) concludedthat,while banning horse riding would notnecessarily prevent weeds from spreadingto nature reserves, concerns about disper-sal of weeds by horses are legitimate.Theyalso found that when horses were closelyconfined to a track, weed establishmentwas much reduced. They sampled weeddistribution away from seven tracks, fiveof which had no physical constraints onoff-track riding and two of which wereconstrained by very steep slopes on eitherside of the track. Near the tracks wherehorses were not constrained, numbers ofweed species showed a clear pattern ofdecline with distance from track, withsome weed species still apparent 20 mfrom the track margin. However, onlyone species, Winter Grass, establishednear the two tracks where horses wereconstrained, and it was restricted to thetrack margins.

Socioeconomic issues

Management objectives

There are agreed national standards formanagement of protected areas when theprimary purpose is nature conservation(Australian Nature Conservancy Agencyand New South Wales National Parks andWildlife Service 1995).Two points are par-ticularly relevant when a specified, legallydefined State or Federal managementobjective is oriented to protection andmaintenance of biodiversity. The first isabout the concept of ‘natural’ in the Aus-tralian context:

. . . ecosystems presumed to be present at

the time of European settlement (1788)

represent natural ecosystems; and ‘natural’

areas are those which largely retain the

landscape character that existed prior to

European settlement. (p. 6)

The second point of agreement is aboutland allocation when there are conflictingland uses:

At least three-quarters and preferably more of

the area must be managed for the primary

purpose of biological conservation; and the

management of the remaining area must not

conflict with that primary purpose. (p.10)

Since horses are not native animalsthere is usually legislation governingwhether, and if so where and when,horses may be taken into public landmanaged for nature conservation. Theremay also be legislative restrictions on thetype of building and other works permit-ted on public conservation land. Thiscould constrain the construction or main-tenance of roads, tracks, fences, gates orother infrastructure or amenities providedfor equestrian use.

Most urban conservation areas are alsomanaged to provide for some level of recre-ational use, as is the case in CNP (LandPlanning and Environment Act 1991).

Provision for recreation

The challenge for management is toprovide a balance between allowingpeople to visit and experienceconservation areas without causing theareas to become so degraded that they lose

their conservation value. Furthermore,because different sections of the Australiancommunity enjoy different recreationalactivities, potential exists for someactivities to reduce the spectrum ofrecreational opportunities available forothers. While various models (reviewedby McArthur 2000) have been used todetermine appropriate management pro-vision for recreation, one of the mostwidely applied to natural areas in Australiais the Recreational Opportunity Spectrum(ROS) (van Oosterzee 1984; McArthur2000). Under this model, each recreationopportunity is seen as having naturaldimensions such as landscape andvegetation, recreational dimensions suchas the level and nature of use, andmanagement dimensions such as facilitiesand regulations. The management dimen-sions seen as appropriate for providingnatural recreational opportunities includesemi-natural access and non-mechanicalforms of conveyance (feet mainly), limitedand natural-appearing onsite management,infrequent social interactions, limitedregimentation of visitors, and limitedevidence of visitor impact (Clark &Stankey 1979, cited in van Oosterzee1984).

Popularity of horse riding

Horse riding is a popular recreationalactivity in Australia, receiving variouslevels of government recognition andsupport. The Bicentennial National Trail, ajoint project between governmentagencies and equestrian associations,provides a continuous route for ridinghorses from Cooktown in Queensland toMelbourne in Victoria, passing through theACT en route. Some sections of theBicentennial National Trail pass throughconservation areas. Independently of theBicentennial National Trail, urbanconservation areas in several Statesexperience high levels of equestrianactivity, reflecting the popularity of horseriding among suburban residents. Fewdetailed data are available, however,numbers of horse riders using several ofSydney’s suburban National Parks wereestimated at more than 1000 during1995–1996 (Harden 1996).


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Potential for conflict between users

As with many other aspects of thecontroversy surrounding horse riding inconservation areas, there is surprisinglylittle documentation about how it isperceived by other users. Australianreviews generally cite American work. Forexample, Harden (1996) cites work byWatson et al. (1994) in the John MuirWilderness, USA, that found about one-third of walkers who met horse ridersdisliked the encounter, although theirreasons were not stated.Gibbs (1993) citeswork by Stankey (1973) in wildernessareas in Wyoming, where user perceptionsof conflict varied with environment andlevel of use. In one area where back-packing was the norm, 59% of partiespreferred not to meet horse riders, whilein a second area where stock use wascommon only 21% of walkers preferrednot to meet horse riders.

In the United Kingdom, Banister et al.(1992) surveyed the attitudes of walkers,anglers and cyclists to other users alongcanal-side towing paths popular for arange of recreational activities. The usersreported as being most likely to affectrespondents’ enjoyment if their numbersincreased were motorcyclists (who werealmost universally disliked) and horseriders (disliked by about half of respon-dents). Cyclists were disliked by about athird of respondents, anglers by about 20%and walkers by about 10%.

Conversely, other recreational activitiesmay cause problems for horse riders.Horses may be frightened by loud noises,sudden movements and unfamiliar objectsand may therefore be startled or becomeuncontrollable if suddenly confronted withother trail users, particularly cyclists anddogs (Manning 1993). Because of the sizeand nature of horses, they may pose risksto the safety of riders or other recreationalusers of public conservation areas.There isanecdotal evidence that potentially riskyencounters with other users occur, butthere is little evidence of horse-relatedinjuries occurring in conservation areas.

Financial costs

The financial costs associated withmanaging facilities for horse riding can besubstantial. Gibbs (1993) reported that the

North Metropolitan District of the NewSouth Wales National Parks and WildlifeService allocated $80 000 from its annualbudget to maintain a network of bridletracks in Ku-ring-gai Chase National Parkand other north metropolitan parks.Harden(1996) cited an unpublished report byDavidson et al. (1994) that estimated itwould cost $325 000 to repair and upgrade33 km of horse tracks in Ku-ring-gai Chase(excluding supervision costs), and a further$34 000 per annum for maintenance. Thusthe estimated cost of repairing and up-grading tracks in this dry eucalypt forestwas approximately $10 000 per km initially,plus an extra annual expenditure of $1000per km for maintenance. Similar costs wereestimated for track works in subalpineenvironments in Tasmania (Whinam &Comfort 1996). The cost of rehabilitating2 km of four-wheel-drive track used byriders was estimated to be of the order of$17 000, while the cost of basic hardeningof 900 m of track was estimated at $26 000.Track drainage, realignments to avoidproblem areas and track hardening arethe main forms of track remediationrecommended by Harris (1993) for thehorse tracks in the Victorian Alps.

Policing and enforcing compliancewith restrictions on access can also becostly in terms of staff time and provisionof infrastructure such as signs, fences andaccess points. Current estimates of costsfor infrastructure used to manage horseriding in CNP include: $100–200 per sign,$4500 per km for fencing and $1500 percavaletti crossing. (Cavalettis are specialbarriers that can be crossed by horses butnot wheeled vehicles.) Signs are requiredfor most recreational activities, but theother requirements are either specific tohorse riding (fencing and cavalettis) ormuch higher for horse riding than forother recreational activities (trail mainte-nance and hardening). Fencing is used tocreate laneways that constrain riders toauthorized trails; this cost could beavoided if riders complied with regula-tions restricting them to authorized trails.

Social equity

On grounds of social equity, allrecreational activities in publicly ownedconservation areas should be treated

equivalently, to the extent they do notcompromise the primary objective ofmanagement for nature conservation(Vollbon 1996) and do not imposeconditions (such as noise pollution,dangeror physical competition) which competi-tively exclude other recreational users(McArthur 2000).Thus, equity also impliesequal responsibility to conform to rulesestablished to minimize impacts andconflicts between users. Equity in terms ofnot compromising nature conservationvalues is not the same as treating eachperson equally, regardless of activity. Asingle horse rider generally has a greaternegative impact on conservation valuesthan a single dog walker or hiker.Furthermore, the management resourcesrequired to provide for a single rider arefrequently greater than the resourcesrequired to provide for a single participantin many of the other recreational activitiesthat occur in conservation areas. Vollbon(1996) argued that it is therefore sociallyequitable for more walkers than riders touse conservation areas, on the groundsthat walkers individually do less damage,and cost less to manage.

Implications for managinghorse riding in CanberraNature Park

Probable high risk of environmentaldamage in some areas

There is a large body of scientific evidenceindicating that environmental damage isvery likely to occur when horses areridden off established trails, on poorly con-structed or maintained trails, and on trailsacross steep, wet or boggy terrain. Environ-mental damage is most likely to haveserious consequences for nature conserva-tion when it affects areas that have highnatural integrity or provide habitat forthreatened flora and fauna. Objectivecriteria can be constructed for assessingdifferent areas according to level of riskposed by horse riding. Since nature conser-vation is the paramount managementobjective of the CNP, it is reasonable thathorse riders should be denied access toareas of the Park where there are high risksof damage to nature conservation values.


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Apparently low risk of environmentaldamage in other areas

There are few studies and no scientificevidence of environmental damagecaused specifically by horses when theyare ridden along well-constructed and -maintained trails across gently sloping,well-drained terrain. There are, instead,rational grounds for suspecting that horsesmay cause negligible damage under thesecircumstances. However, this conclusion isbased on an absence of reports of damage,rather than any positive evidence thatdamage does not occur. In particular, therehave been few studies of weed spreadassociated with horse use of such trails.There is therefore an urgent need forundertaking a carefully designed monitor-ing study that will allow a more informeddecision to be made. Management policiesshould be sufficiently flexible to allowappropriate adaptive responses to theresults of monitoring.

Need for equity in providingopportunities for natural recreation

If the precautionary principle were to bestrictly applied, most recreation activitiescould be banned from all Australian con-servation areas including CNP, on thegrounds that they undoubtedly pose aninherent risk of causing environmentaldamage. It would not be equitable to singleout horse riding on these grounds only.However, levels of environmental impactvary, as do levels of impact on otherpeople’s experience. The balance of evi-dence suggests that, per user, horse ridingis probably associated with higher envi-ronmental impacts than any of the otherrecreational activities permitted in CNP.Management costs are also higher. Further-more, although the effect of low levels ofhorse riding on the recreational experi-ence of other users may not be high, thereis sufficient potential for conflict to justifylimiting the level of horse-riding activity.Thus, while it would not be equitable toban horse riding altogether, it would beequitable to restrict it to a greater extentthan other less damaging and/or conflict-ing recreational activities.

Princip les to guidemanagement of horser id ing in Canberra NaturePark

The following principles for the provisionof recreational horse riding opportunitiesin CNP were developed within the con-straint that horse riding in the Park mustnot compromise primary managementobjectives for conservation of the naturalenvironment.They reflect the potential forhorses to impact mechanically upon vege-tation and ground surfaces and to intro-duce weeds to natural areas.They also takeaccount of the historical development of ahorse-trail network that links governmenthorse paddocks, provides the ACT compo-nent of the bicentennial horse trail andcurrently is dependent upon access toparts of CNP for continuity. Safety andconflict issues associated with usingand sharing multi-purpose facilities arealso recognized.

11. The activity being provided for isrecreational trail riding. More spe-cialized activities that involve off-trailor fast riding, such as training for orconducting cross-country or endur-ance events, are not appropriate andwill not be provided for. Commercialhorse riding will be subject to thesame management principles, in addi-tion to any applicable concessionspolicy.

12. Dogs will not be allowed toaccompany horses and riders inCNP, because of the potential foraccident, injury and disturbance.

13. Horse riding will be confined tospecified trails that form part ofthe ACT horse-trail network. Prior-ity will be given to maintaining traillinks that service government horsepaddocks and the bicentennial trail.Trails will be identified by appropri-ate signage.

14. Trails will be located near theperimeter of reserves and in zonesthat have already been extensivelymodified, as far as possible, so thatpotential for undesirable impact onnature conservation values can be

either avoided or subject to low risk.Gentle grades will be preferred.

15. Trails will be constructed andmaintained to a standard that ischaracterized by: adequate drainage inwet areas; a hard or stable surface sothat erosion potential is minimized;few opportunities for weed establish-ment by having a hard surface, orbeing located in a disturbed area thatalready is dominated by exotic species;and adequate visibility and passingwidth for riders and other users.

16. Where discrete sites of scientific,ecological or cultural significancemay be subject to, or at risk of,damage, horse riding will beexcluded or physically separatedfrom these sites by trail location orbarriers.

17. Rationalization of horse trails willbe necessary where pre-existinghorse-riding activities are in con-flict with conservation require-ments. Where a trail forms animportant link in the horse-trailnetwork and there is no readily avail-able alternative route, horse ridingmay be allowed to continue if the trailis of satisfactory construction andmaintenance standard, and impactcan be confined to the trail. Changesmay need to be staged (e.g. to allowan alternative route to be developedbefore closing a trail segment).

18. A high degree of rider compliancewill be required if horse riding onunfenced trails is to continue in CNP.A code of conduct for equestrian useof CNP will be developed in collabo-ration with the equestrian community.

19. A programme for monitoring willbe developed for levels of use ofhorse trails, compliance with useconstraints (including any code ofconduct) and the impact of horse-riding activities on nature conserva-tion values, and the experience ofother park users.

10. These principles may be modifiedif the results of the monitoring pro-gramme indicate that the impacts ofhorse-riding activities are unaccept-ably high.


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Assessing r isk atindiv idual s i tes wi th in CNP

Individual areas of CNP were evaluated to

determine their suitability or otherwise for

horse riding according to these principles,

using a proforma for recording objective

assessment of risk (available on request

from Bill Logan or David Shorthouse).This

procedure was applied to all areas with

established patterns of equestrian use, and

to other areas where horse riding was a

subject of contention. Of the 13 separate

reserves that were evaluated, 12 were

found suitable for some level of horse-

riding activity. In many cases the existing

horse trails were in highly modified areas

and of satisfactory standard. Some other-

wise satisfactory trails were identified as

needing drainage works, and several short

steep sections were also identified for

upgrading or re-routing. Several possibili-

ties for new perimeter trails to provide

circuit loops were identified for explo-

ration. Several trails that crossed reserves

or did not meet safety or construction

standards were deemed unsuitable and

will be closed. Several other long-estab-

lished trails across reserves were identified

as potentially suitable, providing that

riders exhibit very high levels of compli-

ance in using only designated trails. The

amended horse-riding policy for CNP has

established a framework for management

of a recreational activity that has been

dogged by controversy for several years.

While some criticism is still in evidence,

the process has advanced to a stage where

management decisions can be taken in an

open, consistent and justifiable manner. All

sides have increased certainty as to where

horse riding is or is not permitted. Imple-

mentation of horse-riding policy will be a

continuing activity involving consultation

with both proponents and protagonists.

The monitoring programme will be crucial

for showing whether it is also compatible

with CNP’s paramount management objec-

tive of nature conservation. In the absence

of local data, the policy is necessarily

based on reasonable hypotheses. Future

management will need to embrace an

adaptive approach that ensures new

knowledge, including the results of moni-

toring studies, is used to modify manage-

ment practices as necessary to achieve

primary conservation outcomes.

Acknowledgements

We thank Mark Dunford,Environment ACTfor drafting the figure, Frank Ingwerson,Environment ACT, for his extensive searchof the literature, Alison Ramsey, NSWNational Parks and Wildlife Service foraccess to the unpublished report byR. Harden (1996), and Odile Arman, Parksand Conservation Service ACT, for allow-ing us to use unpublished survey data.

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horse riding in urban conservation areas: reviewing scientific evidence to guide management

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