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Impacts of nutrient additions and digging for human waste disposal
in natural environments, Tasmania, Australia
Kerry L. Bridle, Jamie B. Kirkpatrick*
School of Geography and Environmental Studies, University of Tasmania, Private Bag 78, Hobart, 7001, Tasmania, Australia
Abstract
Very little research has been undertaken on the impacts of human toilet waste disposal in non-serviced sites in the wild. The objective of
the present project was to determine the relative impacts of the mechanical disturbance of digging during the burial of toilet waste (faeces and
toilet paper), and urination, on Tasmanian vegetation types that occur in areas used for wild country camping, in order to develop appropriate
guidelines. The mechanical disturbance of digging cat-holes 15 cm deep, typical of those used for toilet disposal in the Tasmanian wild, had
largely negative effects on the growth of a few native plant species. These effects were of little or no conservation significance. The nutrient
additions simulated by the addition of artificial urine to undug ground and dug ground had largely positive effects on nine distinct types of
native vegetation, encouraging the growth of many plant species at many sites, while discouraging the growth of moss at one site. No weed
species found at any of the sites were significantly affected by the treatments. Thus, it appears that scattered disposal of urine, even combined
with digging, is unlikely to present a major conservation problem in the Tasmania’s wild country, and that present guidelines are appropriate,
where achievable.
q2003 Elsevier Ltd. All rights reserved.
Keywords: Camping impacts; Cat-hole; Urine; Vegetation; Weeds; Tasmania
1. Introduction
The overnight walking experience attracts substantial
numbers of tourists to wild country. Approximately 20,000
people spend at least one night out camping in the Western
Tasmanian Wilderness World Heritage Area per annum
(S. Rundle, pers. comm.). While toilet facilities are provided
at many popular back-country camping sites, a substantial
number of overnight walkers defecate and urinate au
naturel. The research presented here was initiated as the
result of concerns that the processes of disposing of human
wastes outside toilets in the wild might have deleterious
effects on the environment. Most recent research on the
impacts of wilderness users has concentrated on the physical
disturbances caused by trampling and camping (Marion and
Cole, 1996; Leung and Marion, 2000a,b; Sun and Walsh,
1998). Given the lack of research (Cilimburg et al., 2000),
and increasing use of wild places by overnight walkers
(Lachappelle, 2000; Sun and Walsh, 1998; Poll, 2002),
there is an obvious need to determine the nature and
significance of any effects of toilet waste disposal in natural
environments, and the manner in which they vary in
different bushwalking environments.
Minimum impact guidelines for walker behaviour have
been disseminated to those who camp in the wild country of
Tasmania for more than a decade (O’Loughlin, 1988).
These guidelines are believed to have been effective in
changing the behaviour of back-country users in critical
areas, such as avoiding the use of fire and the avoidance of
water pollution. The guidelines for the disposal of toilet
waste (faeces and urine) suggest that disposal sites should be
at least 100 m from lakes or streams and campsites. The
guidelines also state that faeces and toilet paper should be
buried to a depth of at least 15 cm. This depth is not
attainable over most of the glaciated country of Tasmania
(Kirkpatrick and Bridle, 1999), and the excavation process,
to whatever depth is attainable, requires the severance of a
dense mat of roots. Cutting of roots occurs even where
excavation takes place in bare ground, as in many
environments at high altitudes (Kirkpatrick, pers. obs.).
Alpine plants are slow-growing and may have extensive
root systems. Therefore this severance could affect veg-
etation well away from the disposal cat-hole. Digging is also
a form of disturbance that could favour the establishment or
spread of particular species (Pyrke, 1994).
0301-4797/$ - see front matter q2003 Elsevier Ltd. All rights reserved.
doi:10.1016/j.jenvman.2003.09.011
Journal of Environmental Management 69 (2003) 299–306
www.elsevier.com/locate/jenvman
*Corresponding author. Tel.: þ61-3-6226-2463; fax: þ61-3-6226-2989.
E-mail addresses: j.kirkpatrick@utas.edu.au (J.B. Kirkpatrick), kerry.
bridle@utas.edu.au (K.L. Bridle).
The addition of nutrients (via urine and faeces) and the
subsequent impact on exotic plant species has been largely
ignored in the recreational impact literature. Weed cover is
absent or minimal in the low nutrient and relatively
undisturbed environments of western Tasmania. Weeds
are usually present in other Tasmanian environments,
especially where there has been a history of stock grazing.
Urine is rich in nutrients, especially nitrogen. Huts in the
wilderness generally have a ring of introduced herbs around
their doors, possibly largely for this reason (Kirkpatrick,
1997). Faeces are also nutrient rich, in comparison to soils.
The addition of nutrients to native ecosystems has the
potential to change their nature (Kirkpatrick and Harris,
1999).
The aim of the research reported in this paper was to
determine whether digging for human waste disposal, the
nutrients in human urine and the combination of digging and
nutrient additions, affected attributes of the vegetation at
each of nine sites representing the major bushwalking
environments in Tasmania.
2. Methods
A total of nine sites were chosen on the basis of their
representativeness of environments likely to be used by
overnight walkers. General site conditions were noted,
including variables such as geology, altitude, and climatic
variables such as mean rainfall and mean temperature
(Table 1). Soil depth, texture and nutrient status data were
also collected.
2.1. Site selection and characteristics
Alpine areas have proven particularly sensitive to the
impacts of trampling (Gibson, 1984; Calais and Kirkpatrick,
1986; Whinam and Chilcott, 1999, 2003), and are highly
attractive destinations for overnight walkers. Alpine
environments in Tasmania vary enormously in their soils
and vegetation (Kirkpatrick, 1997; Kirkpatrick and Bridle,
1998, 1999). For this reason, two alpine sites were used in
the project. These exemplified the extremes of the alpine
environments in the State. The first was the western alpine
site at Mount Sprent (western alpine, Fig. 1). The climate,
soils and vegetation of Mt Sprent are well-known
(Kirkpatrick and Brown, 1987; Kirkpatrick et al., 1996;
Bridle and Kirkpatrick, 1997). It typifies the nutrient-poor,
acid, high rainfall (Table 1) extreme of alpine vegetation in
Tasmania. The plant community is Donatia novae-zelan-
diae bolster heath, with high cover of D. novae-zelandiae,
Oreobolus oligocephalus and Dracophyllum milliganii. The
eastern alpine site, on the Central Plateau (eastern alpine),
occurs at the other extreme of alpine vegetation in
Tasmania, with relatively nutrient-rich soils and relatively
low rainfall (Table 1). The vegetation is alpine heath in
which the most abundant taxa are Grevillea australis,
Leucopogon montanus,Pentachondra pumila and Poa spp.
The montane and subalpine zones of Tasmania are also
well-used by overnight walkers. Moorland dominated by
buttongrass (Gymnoschoenus sphaerocephalus) covers
much of these zones in western Tasmania, as well as
extensive areas of lowland (Jarman et al., 1988). A site was
established at Tim Shea (montane moorland, Fig. 1), where
the peat soils are acid and nutrient-poor and the rainfall high
(Table 1). The vegetation is dominated by buttongrass and
shrubs, most notably Leptospermum nitidum and Melaleuca
squamea. Subalpine rainforest is also widespread in western
Tasmania (Jarman et al., 1984). A site was selected at the
Hartz Mountains (subalpine rainforest, Fig. 1). The soils
formed on sandstone at this site are acid and low in the
macro-nutrients, phosphorus and nitrogen, and the precipi-
tation is high (Table 1). The dense canopy of this forest is
underlain by a layer of diffuse shrubs, with a ground stratum
dominated by bryophytes. The third high mountain site was
placed in eucalypt forest on the Central Plateau (montane
eucalypt forest, Fig. 1). The soils are relatively nutrient-rich
and not extremely acid and the precipitation is moderate
(Table 1). The vegetation is Eucalyptus pauciflora-E.
rodwayi open-forest with an understorey in which Leuco-
pogon hookeri and Poa spp. are prominent.
Table 1
Environmental attributes and time of first treatment for each of the study areas
Site Geology Altitude
(m)
Mean annual
rainfall (mm)
Mean annual
temperature
(8C)
Total
nitrogen
(%)
Total
phosphorus
(ppm)
Mean soil
depth (cm)
Soil
texture
Time of first
treatment
Western Alpine Quartzite 950 3222 10.0 0.46 140 30.2 Loamy Sand Mar-00
Eastern Alpine Dolerite 1150 1056 11.6 0.37 760 25.9 Sandy Loam Feb-00
Montane Moorland Quartzite 850 1445 12.4 1.06 160 36.7 Silty Clay Feb-00
Subalpine Rainforest Dolerite 755 900 13.1 0.40 270 29.7 Loam Feb-00
Montane Eucalypt Forest Dolerite 945 854 11.1 0.31 440 17.9 Sandy Loam Feb-00
Lowland Rainforest Quartzite 450 1215 13.2 0.44 260 46.4 Silty Clay Apr-00
Heathy Eucalypt Forest Sandstone 110 677 16.8 0.52 130 33.6 Loamy Sand May-00
Grassy Eucalypt Forest Dolerite 230 619 15.6 0.16 120 13.6 Sandy Clay May-00
Coastal Eucalypt Forest Sandstone 5 507 17.4 0.16 55 65.2 Sand May-00
K.L. Bridle, J.B. Kirkpatrick / Journal of Environmental Management 69 (2003) 299–306300
A lowland rainforest site was selected on the Strathgor-
don Road (lowland rainforest, Fig. 1). Soils are nutrient-
poor and acid and rainfall is high (Table 1). The site is prone
to occasional waterlogging. The rainforest that occupies the
site has an understorey dominated by bryophytes (Table 3).
The dry eucalypt forests that occupy most of eastern
Tasmania (Duncan and Brown, 1985), have understories
that vary from heathy to grassy as soils become less acid,
more nutrient-rich and, with a greater proportion of clay in
the profile. A grassy eucalypt forest on dolerite in the
University of Tasmania Reserve (grassy eucalypt forest,
Fig. 1) was selected to represent one of these extremes. The
soils are only mildly acid and are nutrient rich (Table 1), and
rainfall is low (Table 2). Eucalyptus pulchella and E. ovata
dominate the tree layer. The understorey has a dense cover
of native tussock grasses, most notably Themeda triandra
and Poa rodwayi (Table 3). This site was burned last in
1995. A heathy forest on sandstone at Huntingfield (heathy
eucalypt forest, Fig. 1) was selected to represent the other
extreme of dry eucalypt forest. The soils are acid and
nutrient-poor and rainfall low (Table 1). The tree canopy is
dominated by Eucalyptus amygdalina. The understorey is
dominated by scleromorphic (small and hard-leaved) shrubs
and bracken (Pteridium esculentum). Bracken, Bossiaea
cinerea and Leucopogon collinus have the greatest covers in
this layer. The site was burned in 1998.
The coast is one of the most attractive places for
bushwalking and coastal sand dunes are one of the easiest
places to dig a hole for defecation in the wild. A coastal
eucalypt forest on Holocene beach ridges at Seven Mile
Beach (coastal eucalypt forest, Fig. 1) was selected. The
sandy soils are only mildly acid and moderately nutrient-
rich, and the precipitation low (Table 1). The forest is
dominated by Eucalyptus viminalis. The understorey is a
mixture of sagg (Lomandra longifolia), tussock grasses,
shrubs and succulent creepers. The species with the most
cover in this layer are the sedge, Lepidosperma concavum,
sagg and the succulent, Carpobrotus rossii.
2.2. Site environmental data
Soil chemical properties have an impact on vegetation
dynamics at each site. Any addition of nutrients is likely to
change nutrient balances. For example, low fertility soils
may show an increase in plant productivity after the addition
of artificial urine, which is rich in the macro-nutrients
Fig. 1. Location of all sites mentioned in the text.
K.L. Bridle, J.B. Kirkpatrick / Journal of Environmental Management 69 (2003) 299–306 301
nitrogen and phosphorus. Therefore, the surface 5 cm of the
soil below the litter layer was collected for chemical
analysis. The sample was bulked from five subsamples. The
nutrients nitrogen and phosphorus were determined in the
laboratory. Total phosphorus (P) was determined using a
nitric/perchloric digest and I.C.P. analysis, while % nitrogen
(N) was determined by methods outlined in (Rayment and
Higginson, 1992), semi-micro Kjeldahl with steam distilla-
tion (7A1). Particle size analysis was undertaken on the soil
samples (McDonald et al., 1984). Soil depth was determined
by probing each of 10 soil sample locations along a transect
between the 2 treatment transects.
2.3. Sampling and experimental design
At each site two parallel transects, each approximately
20 m in length were laid out along the contour. Within
each transect 20 quadrats (50 £50 cm) were located in
areas that would be attractive as a toilet spot for
bushwalkers, that is, the area was free from prickly
shrubs, and the soil depth was a minimum of 15 cm.
Quadrats were marked by steel roof spikes in each corner
and the distance along the transect, and distance and
direction of offset from the transect line was recorded.
Quadrats were located at least 50 cm from each other in
all directions to avoid overlap.
Quadrats were randomly allocated to four treatments: (1)
control; (2) 250 ml of artificial urine, formulated according
to the recipe of Gotaas (1956), added to the centre of the
quadrat at each visit; (3) 10 cm diameter hole dug in centre
of the quadrat to 15 cm depth and refilled; (4) hole dug and
filled as previously and 250 ml of artificial urine added at
each visit. Visits took place at 0, 6, 12, 18 and 24 months.
2.3.1. Data collection
The first data collection took place in summer to autumn
2000. Data collection was repeated at approximately the
same time in the year for each site in 2001 and 2002. The
first data collection occurred before the excavation of holes
and the pouring of artificial urine. The periodic removal and
replacement of bags containing toilet paper, tissues and
tampons for a related study led to redisturbance of
Table 2
Percentage covers by time and treatment for the herbs Leptorhynchos
squamatus and Senecio lautus at the eastern alpine site
Leptorhynchos Control Urine Dig Dig and urine
2000 3.1 3.0 1.5 1.5
2001 3.7 4.9 1.8 2.6
2002 5.4 12.6 3.3 3.5
Senecio
2000 0.28 0.97 1.77 0.83
2001 0.39 3.20 0.96 2.00
2002 0.66 6.80 1.66 4.60
Table 3
Significant cover changes through time at each site (ANOVA)
Site and element 2000 2001 2002 FP
Western Alpine
Lichen 5.62 4.15 3.04 5.19 0.007
Litter 4.85 7.40 9.55 8.11 0.001
Montane Moorland
Epacris lanuginosa 3.28 5.31 5.75 3.60 0.031
Dillwynia glaberrima 0.00 0.34 0.61 5.07 0.008
Boronia parviflora 0.06 0.30 0.09 3.45 0.035
Bare 0.35 1.32 0.55 5.51 0.005
Eastern Alpine
Oreomyrrhis ciliata 0.26 0.26 0.66 4.34 0.015
Leptorhynchos squamatus 2.25 3.24 6.36 8.84 0.000
Senecio lautus 0.98 1.66 3.52 10.08 0.000
Asperula gunnii 0.07 0.18 0.52 6.20 0.003
Luzula spp. 0.55 0.71 1.73 13.9 0.000
Agrostis spp. 0.00 0.43 0.67 6.88 0.002
Aira spp. 0.15 0.38 1.20 3.93 0.022
Exotic grass 0.15 0.38 1.48 4.75 0.011
Lowland Rainforest
Bryophyta cover 69.5 65.6 57.8 3.26 0.042
Lichen 0.81 0.15 0.25 6.29 0.003
Fungi 0.04 0.58 0.26 8.87 0.000
Litter 22.55 25.83 34.45 6.63 0.002
Subalpine Rainforest
Lichen 1.04 1.48 1.06 5.01 0.008
Seedlings 0.27 0.37 1.07 6.42 0.002
Montane Eucalypt Forest
Hydrocotyle sibthorpioides 1.50 1.51 4.35 6.51 0.002
Poa hiemata 1.05 1.62 4.58 14.04 0.000
Heathy Eucalypt Forest
Epacris impressa 0.32 0.55 2.07 9.69 0.000
Leucopogon collinus 0.68 2.61 14.87 46.52 0.000
Styphelia adscendens 0.01 0.05 0.13 3.93 0.023
Aotus ericoides 1.24 2.26 6.19 11.00 0.000
Bossiaea cinerea 5.90 7.46 10.15 4.24 0.017
Baeckea ramosissima 0.47 0.86 2.10 4.09 0.019
Stylidium graminifolium 0.05 0.12 0.23 4.11 0.019
Hypolaena fastigiata 6.40 1.47 1.90 7.29 0.000
Pteridium esculentum 1.30 4.75 13.85 10.97 0.000
Bryophyta 0.00 8.08 7.90 6.88 0.002
Bare 53.05 22.79 8.25 87.74 0.000
Litter 22.27 55.25 28.12 4.82 0.010
MDS cover 1 20.43 20.01 0.46 70.90 0.000
MDS height 1 20.17 20.04 0.21 11.02 0.000
MDS height 2 0.16 0.05 20.22 13.72 0.000
MDS height 3 20.13 20.06 0.19 11.11 0.000
Grassy Eucalypt Forest
Astroloma humifusum 0.20 0.66 0.93 6.17 0.003
Epacris impressa 0.00 0.04 0.49 9.02 0.000
Gonocarpus tetragynus 1.11 4.06 5.09 8.63 0.000
Carex breviculmis 2.43 2.62 4.62 8.84 0.000
Schoenus apogon 5.25 4.85 8.95 8.28 0.000
Bryophyta 0.02 1.85 0.00 20.47 0.000
Bare 0.10 0.75 0.00 3.17 0.046
MDS height 1 20.08 20.04 0.12 4.99 0.008
MDS height 2 20.17 20.05 0.22 22.11 0.000
MDS height 3 0.09 0.05 20.13 7.00 0.001
(continued on next page)
K.L. Bridle, J.B. Kirkpatrick / Journal of Environmental Management 69 (2003) 299–306302
a proportion of the dug quadrats between 2000 and 2001 and
2001 and 2002.
The outline covers of all discernible vascular plant taxa,
cryptogam groups, bare soil, litter and rock were measured
using a gridded quadrat frame. Bare soil, litter and rock
were not counted if beneath vegetation cover. Overlapping
cover was used for plant taxa. The maximum height of each
taxon was also measured. Vegetation taller than 2 m was not
included for either cover or height.
2.3.2. Data analysis
All analyses were undertaken for each of the sites.
Global non-metric multidimensional scaling, following
the default options in DECODA (Minchin, 1990) was
used to ordinate the taxon cover data and the taxon
height data. The ordination scores provide a measure of
overall similarity. Generalized linear modelling was used
to test for significant interactions between time and
treatment. Only the most abundant taxa, the ordination
scores and the cover of bare ground, litter and rock could
be analysed in this manner. One way analysis of variance
(ANOVA) was used to test for significant changes in
values for variables over time. ANOVA was also used to
test for significant treatment effects on the difference in
cover between 2000 and 2002. In this case, the data for
each individual analysis were reduced to those quadrats
with a cover value in either or both of 2000 and 2002. In
Table 3 (continued)
Site and element 2000 2001 2002 FP
Coastal Eucalypt Forest
Carpobrotus rossii 1.0 2.3 7.2 5.32 0.006
Lepidosperma concavum 6.3 6.6 11.0 5.13 0.007
Pteridum esculentum 1.9 0.4 11.8 20.12 0.000
Bare 0.0 1.8 0.6 4.68 0.011
Litter 84 81 59 39.97 0.000
Seedlings 0.1 0.5 0.0 4.87 0.031
MDS cover 2 0.16 0.22 20.39 23.50 0.000
MDS height 2 20.05 0.16 20.10 4.87 0.010
MDS height 3 0.07 0.07 20.01 3.78 0.026
Table 4
Significant effects of treatment on changes in vegetation cover by site from 2000–2002
Site and element Control Urine Dig Dig and urine FP
Western Alpine
Monotoca submutica 20.1a 0.7ab 20.3ab 2.2b 3.87 0.045
Bryophyta 1.0a 22.2b 20.6ab 22.6b 2.95 0.046
Eastern Alpine
Leptorhynchos squamatus 3.3a 9.2b 2.4a 2.6a 5.55 0.004
Senecio lautus 0.5a 6.3b 20.2a 5.3b 9.12 0.000
Asperula gunnii 0.6a 2.4b 0.0a 0.9ab 4.54 0.015
Luzula spp. 1.2ab 2.7a 0.7b 0.6b 3.96 0.017
Poa hiemata 0.2a 10.4b 20.3a 0.4a 4.53 0.014
Native grass 23.9a 4.4b 0.0ab 4.2b 3.09 0.041
MDS cover 2 0.03b 20.25a 0.05b 0.01b 5.62 0.003
Montane Moorland
Melaleuca squamea 21.2ab 20.1ab 21.9a 5.8b 3.11 0.038
Epacris lanuginosa 0.0a 8.1b 2.4a 2.0a 5.19 0.005
Eurychorda complanata 1.7a 12.0b 1.9a 11.5b 3.45 0.029
Bare 20.3a 20.4a 1.3b 0.2ab 3.89 0.017
Litter 2.4a 24.9b 3.4a 24.6b 3.64 0.022
MDS cover 2 0.00a 0.16b 0.04ab 0.12ab 2.97 0.045
Montane Eucalypt Forest
Native grass 20.1a 5.7b 20.7a 3.9ab 4.67 0.007
Grassy Eucalypt Forest
Native grass 211.7ab 4.5b 220.7a 22.1b 5.48 0.003
Litter 20.7a 213.2b 4.0a 27.5b 5.32 0.004
MDS cover 1 0.12ab 20.01a 0.28b 0.00a 3.56 0.024
MDS cover 2 0.02ab 0.16a 20.02b 0.11ab 3.33 0.030
Heathy Eucalypt Forest
Litter 24.2a 23.0b 10.4ab 28.2b 9.87 0.000
MDS cover 2 0.03a 20.42b 20.16ab 20.29ab 3.42 0.028
Coastal Eucalypt Forest
Lepidosperma concavum 1.0a 9.3b 3.5a 6.6ab 4.81 0.007
Note that there were no significant treatment effects at either of the rainforest sites.
K.L. Bridle, J.B. Kirkpatrick / Journal of Environmental Management 69 (2003) 299–306 303
all cases results are regarded as not significant if P.
0:05:
3. Results
The only significant interactive effects between treatment
and time were for Leptorhynchos squamatus (F¼2:24;
P¼0:044) and Senecio lautus (F¼3:2;P¼0:006) at the
Eastern Alpine site (Table 2). The treatments that involved
urine additions resulted in accelerated increases in the cover
of both species.
Across all sites, 29 species significantly increased in
cover over time, while 2 species showed a significant
decrease in cover and 8 others showed no consistent
tendency (Table 3). The increasers were concentrated in the
eastern alpine (8), heathy eucalypt forest (9) and grassy
eucalypt forest (4) environments. The lowland rainforest
was the only site where increasers equalled decreasers (1 cf.
1). It was also the only site where increasers were
outnumbered by species with no consistent tendency (1 cf
2). The two cases of significant decreases were lichen in the
western alpine and bryophytes in the lowland rainforest
environments (Table 3).
The control treatment had significantly higher values
than one or more of the other treatments in 8 cases, and
significantly less in 10 cases (Table 4). The urine treatment
had significantly higher values than one or more of the other
treatments in 14 cases and significantly less in 7 cases
(Table 4). The dig treatment showed the reverse pattern with
3 and 14, respectively, while the dig and urine treatment had
8 in each class (Table 4). This differentiation by treatment is
significant (Chi-square ¼9.2, d.f. ¼3, P,0:01), with the
urine treatment having more positive outcomes than
expected and the dig treatment having more negative
outcomes than expected.
There were no significant treatment effects in either of
the rainforest sites. Both alpine sites showed some effects.
In the western alpine environment the shrub, Monotoca
submutica, was positively affected by the dig and urine
treatment whereas bryophytes were negatively affected by
the treatments involving urine. In the eastern alpine
environment 6 non-woody taxa were favoured by urine
additions, and the scores on the second axis of the cover
ordination were significantly different between the urine
treatment and the rest (Table 4).
At the montane moorland site, the dominant shrub,
Melaleuca squamea, was favoured by the combination of
digging and urine, the shrub, Epacris lanuginosa, was
favoured by urine without digging, and the restiad,
Eurychorda complanata, was favoured by both the urine
treatments (Table 4). Bare ground was significantly greater
in the digging treatment than in the urine or control
treatments, litter cover decreased in quadrats where urine
was added and the scores on the second axis of the cover
ordination differentiated between the urine treatment and
the rest (Table 4).
The eucalypt forest sites did not individually exhibit as
many significant treatment effects as the montane moorland
and eastern alpine sites. At the montane eucalypt site urine
additions promoted native grass cover (Table 4). In the
grassy eucalypt forest urine also promoted native grass
cover, while it decreased litter cover (Table 4). The cover
ordination scores also indicated a strong effect of urine
additions (Table 4). At the heathy eucalypt site urine also
decreased litter cover, and on cover ordination axis 2 the
scores were significantly different between the control and
the urine treatment (Table 4). At the coastal eucalypt forest
urine increased the cover of the rhizomatous sedge,
Lepidosperma concavum(Table 4).
4. Discussion
Relatively few taxa exhibited significant impacts from
digging, urine application or their combination. Significant
effects on the vegetation as a whole were only evident at the
eastern alpine, montane moorland, grassy eucalypt and
heathy eucalypt sites, which between them accounted for 17
of the 21 significant treatment effects. It is tempting to
attribute this pattern to the successional status of the
vegetation at these four sites, in comparison to the rest. The
eastern alpine site is in process of recovery from a regime of
burning and grazing by sheep, the latter of which only
ceased in the early 1990s (Bridle et al., 2001). The montane
moorland, grassy eucalypt forest and heathy eucalypt forest
were all burned in the 1990s. In comparison, the rainforest
sites were last burned many centuries ago, the western
alpine site was likely to have been burned in the 1890s
(Marsden-Smedley, 1999) and both the montane eucalypt
forest and the coastal eucalypt forest exhibit no signs of
burning in the last few decades. However, there is no
relationship between the number of significant changes
through time and the number of significant treatment effects
on changes in values between 2000 and 2002, indicating that
vegetation dynamism was not related to treatment impact.
The generally positive effect of urine additions on the
cover of taxa is consistent with the roles of P and N in plant
growth. It is notable that the only taxon to respond
negatively to urine additions was the Bryophyta at the
western alpine site. The addition of nutrients to native
vegetation has been long recognized to have negative
outcomes in terms of exotic invasion and reduction of native
species richness (e.g. Specht, 1963; Connor and Wilson,
1968). However, our experiment does not indicate any effect
of urine addition on exotic invasion at the sites where
exotics occurred, and the local impact of urine addition in
the quadrats in which it occurred would mitigate against
reductions in species richness. Digging had a predominantly
depressive effect on native plant taxa that is revealed both
K.L. Bridle, J.B. Kirkpatrick / Journal of Environmental Management 69 (2003) 299–306304
directly through the effects of urine without digging, and in
the depressive effect of digging on the positive effects of
urine addition (Table 4). The only positive effect of digging
on a plant taxon was for Melaleuca squamea, and then only
when combined with urine addition. Previous work in
lowland Tasmania has indicated that physical disturbance,
in the absence of nutrient additions, favours rare or
threatened species and increases species richness (Pyrke,
1994; Kirkpatrick and Gilfedder, 1995, 1998; Gilfedder and
Kirkpatrick, 1998). These tendencies have not been
manifest in the present study.
5. Conclusions
We conclude that scattered disposal of urine, even
combined with digging, is unlikely to present a major
conservation problem in Tasmanian bush. The rings of
exotics around hut doors represent an extreme situation with
frequent, sustained urination. Therefore, there is no need for
amendment of the minimum impact guidelines as a result of
impacts of nutrient additions or mechanical disturbance by
digging.
Acknowledgements
We would like to thank the CRC for Sustainable Tourism
for funding this project. Thanks to the many field assistants
and technical officers with special mention to Denis
Charlesworth, Margaret Gill, Paul Smart, Mona Loofs,
Nick Fitzgerald, Micah Visiou and Bonnie Wintle. The
Tasmanian Parks and Wildlife Service, the Forestry
Commission, the University of Tasmania and Jennie
Whinam of the Nature Conservation Branch, Department
of Primary Industry, Water and Environment, facilitated
access to the study sites.
References
Bridle, K.L., Kirkpatrick, J.B., 1997. Local environmental correlates of
variability in the organic soils of moorland and alpine vegetation, Mt
Sprent, Tasmania. Australian Journal of Ecology 22, 196 – 205.
Bridle, K.L., Kirkpatrick, J.B., Cullen, P., Shepherd, R.R., 2001. Recovery
in alpine heath and grassland following burning and grazing, eastern
Central Plateau, Tasmania. Arctic, Antarctic and Alpine Research 33,
348– 356.
Calais, S.S., Kirkpatrick, J.B., 1986. The impact of trampling on the natural
ecosystems of the Cradle Mt- Lake St. Clair National Park. Australian
Geographer 17, 6–15.
Cilimburg, A., Monz, C., Kehoe, S., 2000. Wildland recreation and human
waste: A review of problems, practices and concerns. Environmental
Management 25, 587– 598.
Connor, D.J., Wilson, G.L., 1968. Response of a coastal Queensland heath
community to fertilizer application. Australian Journal of Botany 16,
117– 123.
Duncan, F., Brown, M.J., 1985. Dry sclerophyll vegetation in Tasmania:
Extent and conservation status of the communities. Wildlife Division
Technical Report. 85(1). National Parks and Wildlife Service,
Tasmania.
Gibson, N., 1984. Impact of trampling on bolster heath communities of Mt
Field National Park. Papers and Proceedings of the Royal Society of
Tasmania 118, 47–52.
Gilfedder, L., Kirkpatrick, J.B., 1998. Factors influencing the integrity of
remnants in subhumid Tasmania. Biological Conservation 84, 89 – 96.
Gotaas, H.B., 1956. Composting: Sanitary disposal and reclamation of
organic wastes. 31, World Health Organisation, Geneva.
Jarman, S.J., Brown, M.J., Kantvilas, G., 1984. Rainforest in Tasmania,
National Parks and Wildlife Service, Tasmania.
Jarman, S.J., Kantvilas, G., Brown, M.J., 1988. Buttongrass moorland in
Tasmania. Research Report 2. Tasmanian Forest Research Council Inc.,
Hobart.
Kirkpatrick, J.B., 1997. Alpine Tasmania: An Illustrated Guide to the Flora
and Vegetation, Oxford University Press, Melbourne.
Kirkpatrick, J.B., Bridle, K.L., 1998. Environmental relationships of
floristic variation in the alpine vegetation of south-east Australia.
Journal of Vegetation Science 9, 251– 260.
Kirkpatrick, J.B., Bridle, K.L., 1999. Environment and floristics of ten
Australian alpine vegetation formations. Australian Journal of Botany
47, 1–21.
Kirkpatrick, J.B., Brown, M.J., 1987. The nature of the transition from
sedgeland to alpine vegetation in South West Tasmania: I. Altitudinal
vegetation change on four mountains. Journal of Biogeography 14,
539– 550.
Kirkpatrick, J.B., Gilfedder, L., 1995. Maintaining integrity compared with
maintaining rare and threatened taxa in remnant bushland in subhumid
Tasmania. Biological Conservation 74, 1 – 8.
Kirkpatrick, J.B., Gilfedder, L., 1998. Conserving weedy natives: Two
Tasmanian endangered herbs in the Brassicaceae. Australian Journal of
Ecology 23, 466–473.
Kirkpatrick, J.B., Harris, S., 1999. The Disappearing Heath Revisited,
Tasmanian Environment Centre, Hobart.
Kirkpatrick, J.B., Nunez, M., Bridle, K.L., Chladil, M., 1996. Explaining a
sharp transition from sedgeland to alpine vegetation on Mount Sprent,
south-west Tasmania. Journal of Vegetation Science 7, 763 – 768.
Lachapelle, P.R., 2000. Sanitation in wilderness: Balancing minimum tool
policies and wilderness values. In: Cole, D.N., McCool, S.F., Borrie,
W.T., O’Loughlin, J. (Eds.), Wilderness ecosystems, threats and
management, Proceedings of the Wilderness Science in a Time of
Change Conference, vol. 5. USDA Forest Service, Rocky Mountain
Research Station.
Leung, Y.-F., Marion, J.L., 2000a. Characterizing backcountry camping
impacts in Great Smokey Mountains National Park, USA. Journal of
Environmental Management 57, 193– 203.
Leung, Y.-F., Marion, J.L., 2000b. Recreation impacts and management in
wilderness: A state of knowledge review. In: Cole, D.N., McCool, S.F.,
Borrie, W.F., O’Loughlin, J. (Eds.), Wilderness ecosystems, threats and
management, Proceedings of the Wilderness Science in a Time of
Change Conference, vol. 5. USDA Forest Service, Rocky Mountain
Research Station.
Marion, J.L., Cole, D.N., 1996. Spatial and temporal variation in soils and
vegetation impacts on campsites. Ecological Applications 6, 520–530.
Marsden-Smedley, J.B., 1999. Changes in southwestern Tasmanian fire
regimes since the early 1800s. Papers and Proceedings of the Royal
Society of Tasmania 132, 15.
McDonald, R.C., Isbell, R.F., Speight, J.G., Walker, J., Hopkins, M.S.,
1984. Australian soil and land survey—field handbook, Inkata Press,
Melbourne.
Minchin, P.R., 1990. DECODA user’s manual, Research School of Pacific
Studies, ANU, Canberra.
O’Loughlin, T., 1988. Evaluating the effectiveness of a minimal impact
bushwalking campaign. Wilderness Education Project Report to the
Tasmanian Parks and Wildlife Service and the Australian Parks and
Wildlife Service.
Poll, M., 2002. World Heritage walking: Overnight bushwalking
opportunities in the Tasmanian wilderness, Parks and Wildlife Service,
Hobart.
K.L. Bridle, J.B. Kirkpatrick / Journal of Environmental Management 69 (2003) 299–306 305
Pyrke, A., 1994. Soil disturbance by native mammals and the germination
and establishment of plant species. PhD Thesis. University of
Tasmania, Hobart.
Rayment, G.E., Higginson, F.R., 1992. Australian Laboratory
Handbook of Soil and Water Chemical Methods, Inkata Press,
Melbourne.
Specht, R.L., 1963. Dark Island heath (Ninety-Mile Plain, South Australia).
Vll. The effect of fertilizers on composition and growth, 1950 – 60.
Australian Journal of Botany. 11, 67 –94.
Sun, D., Walsh, D., 1998. Review of studies on environmental impacts of
recreation and tourism in Australia. Journal of Environmental Manage-
ment 53, 323–338.
Whinam, J., Chilcott, M., 1999. Impacts of trampling on alpine
environments in central Tasmania. Journal of Environmental Manage-
ment 57, 205–220.
Whinam, J., Chilcott, M., 2003. Impacts after four years of experimental
trampling on alpine/sub-alpine environments in western Tasmania.
Journal of Environmental Management 67, 1– 13.
K.L. Bridle, J.B. Kirkpatrick / Journal of Environmental Management 69 (2003) 299–306306