Table Of ContentMacrolepidopteran assemblages along an
altitudinal gradient in subtropical rainforest
- exploring indicators of climate change
Louise A. ASHTON
Roger L. KUCHING
Sarah C. MAUNSELL
Darren BITO
Environmental Futures Centre and Griffith School of Environment, Griffith University, Nathan Qld
4111, Australia. Email:[email protected]
David A. PUTLAND
Growcom, PO Box 202, Fortitude Valley Qld 4006, Australia.
Citation: Ashton, L.A., Kitching, R.L., Maunsell, S.C., Bito, D. & Putland, D.A. 2011 12 20:
Macrolepidopteran assemblages along an altitudinal gradient in subtropical rainforest - exploring
indicators of climate change. Memoirs of the Queensland Museum — Nature 55(2) 375-389. Brisbane.
ISSN 0079-8835.
ABSTRACT
Moth assemblages have been widely used to estimate patterns of beta-diversity in forest
ecosystems. As part of the IBISCA-Queensland project we examined patterns of diversity in
a large subset of night-flying moths along an altitudinal gradient in subtropical rainforest.
The permanent IBISCA-Queensland transect located in Lamington National Park, south-east
Queensland, Australia, spans altitudes from 300 metres (m) to 1100 m above sea level
(a.s.l.) within continuous, undisturbed rainforest. We sampled four replicate plots at each
of five altitudes (300, 500, 700, 900, 1100 m a.s.l.). A total of 11379 individual moths
were sampled, belonging to approximately 865 morphospecies. Moth assemblages
displayed a strong altitudinal signal at each of two sampling periods (October 2006 and
March 2007). The results show that cloud forest above 900 m a.s.l. where Nothofagus
moorei becomes dominant, contains a number of moth species that are restricted to the
high elevation forest and these species may be most threatened by climatic change. The
analyses presented here suggest a set of 18 moth species which may be useful as part
of a multi-taxon predictor set for future monitoring of the impact of global warming on
forest biodiversity. (cid:9633) climate change, subtropical, rainforest, IBISCA, Lepidoptera.
lirnate change is having a marked effect on in subtropical rainforest and, by so doing, develop
Oestrial ecosystems, as evidenced by poleward robust measures for future monitoring of climate
nd elevational shifts in the distributions of many change impacts (Kitching et al., 2011). This
T^cies of plants and animals (Bale ct al. 2002;
paper investigates moth assemblages along this
p rabherr ct al 1994; Hickling et al 2006; IPCC 2007;
altitudinal gradient, and suggests a group of moth
aiarmesan 1996). The IBISCA-Queensland project
species that may be used to monitor altitudinal
ate^ t0 clU£mbfy the relationship between clinv
and biodiversity along an altitudinal gradient shifts in distributions.
Me
rr'°'rs of the Queensland Museum | Nature • 2011 • 55(2) • www.qm.qld.gov.au 375
Ashton et al.
It has been predicted that climatic warming A medium-range climate change scenario
over the course of the next century will cause predicts an average global temperature increase
an increase in global average temperature of of 4°C over the next 100 years, which would
between 1.4°C and 5.8°C (IPCC 2007). Changes to push current climate envelopes around 800 m
climatic conditions are likely to result in increased upwards in altitude (Malhi & Phillips 2004). Even
an optimistic climate change scenario predicts
weather variability and extreme weather events
upward shifts in climatic envelopes of up to 450 m
(Easterling et al. 2000), leading to dramatic changes
(Loope & Giambelluca 1998). However, these
in ecosystem dynamics (Weltzin et al. 2003). The
estimates are likely to vary regionally and will
responses of ecosystems to climate change are
also depend on local conditions. Despite this, the
wide and varied, and are confounded by species
estimates are of particular concern because cloud
interactions and feedback relationships. Species
forest ecosystems often encompass rare and
interactions may enable some groups to adapt to
endemic species with limited altitudinal ranges
new conditions, for example, through shifts
(Foster 2001). Some plant species in tropical
in community composition and simplification of
montane forests, for example, display ranges of
food webs (Suttle et al. 2007). However, changed
less than 300 m (Loope & Giambelluca 1998).
conditions may exceed the environmental
thresholds for many species leading to changes in IBISCA-Queensland was a collaborative, inter¬
distribution or, if this is not possible, local or even
national investigation of patterns of diversity
global extinction (Pounds et al. 1999; Thomas et al.
and ecosystem processes along an altitudinal
2004). Biological responses due to climate change,
gradient. This study investigated which species
such as distribution shifts and phenological
are sensitive to climatic variability associated
changes, have already been measured in a variety
with increasing altitude and therefore most likely
of taxa and ecosystems (Parmesan & Yohe 2003;
to be sensitive to climate change and, by doing so,
Walther et al. 2002).
sought to establish current baseline information,
Studies of altitudinal gradients are an effective
laying the foundation for longer-term monitoring
method of investigating and monitoring the
programs. Study sites for this project are located
impacts of climate change because they allow for
in tire UNESCO World Heritage listed Lamington
a wide range of changing environmental variables
National Park, noted for its isolated patches or
to be observed over small geographical areas.
montane, Antarctic Beech (hlothofagns mooi't’O
They provide ideal situations to explore how
dominated, 'cool temperate' rainforest.
species distributions may be associated with, and
limited by, climatic factors, while minimising The collaborative approach of the 1B1SCA'
confounding historical factors that influence Queensland project involved a broad rang6
species distributions over latitudinal gradients of taxonomic and ecological specialists eac1
(Fiedler & Beck 2008; Shoo et al. 2006). Altitudinal working to a fixed experimental design. This
gradients potentially provide insight into climate helped ensure that a wide range of taxa vvei6
change impacts, because they encompass steep studied, producing a multi-faceted baseliu6
temperature and moisture gradients, leading to dataset describing a range of invertebrate an1
stratified environmental parameters and faunal plant assemblages. The culmination of the study
assemblages (Hodkinson 2005; Shoo et al. 2006). will be a powerful 'predictor set' (Kitching 19CT /
Many studies have shown that montane cloud that can be re-sampled in the future in order 0
forests are highly sensitive to, and threatened by, monitor impacts of climate change. In this paPe
climate change (Foster 2001; Nadkarni & Solano we examine the potential of moths for inclusio
2002; Pounds et al. 1999; Still et al. 1999; Williams in this predictor set. Monitoring protocols sU6
et al. 2003). as those which will be created by this stu )
55(2)
376 Memoirs of the Queensland Museum | Nature • 2011 *
Macrolepidopteran assemblages along an altitudinal gradient
will provide important tools for understanding was formed by a now extinct shield volcano,
biotic responses to climate change, subsequently centred at Mount Warning, in north-eastern
facilitating adaptive management strategies New South Wales (Stevens 1997).
that encompass such responses. Moths are
The altitudinal transect that is the basis of the
potentially particularly useful in this regard
IBISCA-Queensland project was established in
because they are diverse, relatively well-known
continuous rainforest within the Green Mountains
taxonomically and, as herbivores, reflect closely
the vegetational health of the forest (Kitching section of Lamington National Park and en¬
et al 2000; Scoble 1995). They are also sensitive compasses a steep temperature and moisture
to environmental variables, being strongly gradient (Strong et al 2011). The transect encom¬
affected by temperature and precipitation and passes altitudes between 300 and 1100 m a.s.l.
resource limiting factors such as food availability with four replicate plots located within coarse
(Holloway et al 1992). Moths have been used elevational bands centred upon altitudes of 300,
as indicators of environmental change and the
500, 700, 900 and 1100 m a.s.l. Lower elevation
success of restoration in a variety of different
plots (300 and 500 m a.s.l.) are located within the
terrestrial ecosystems, such as rainforests,
valley of West Canungra Creek. Middle and high
temperate forests and agro-ecosystems (Beccaloni
elevation plots (700 m a.s.l. and above) are located
& Gaston 1994; Brown & Freitas 2000, New 1997;
along the western slopes of the same valley, along
Ricketts etal 2001).
the access road to Green Mountains, O'Reilly's
The current study posed the following two Guesthouse and the Border Track leading to
questions by sampling moth assemblages along
Mount Bithongabel. Low altitude plots are
^ altitudinal transect within the subtropical forest
characterised by dryer, hotter conditions and the
°f Tamington National Park.
high altitude sites experience lower temperatures
(1) Ho moth assemblages change with altitude? and higher moisture levels (Strong et al. 2011).
(2) If so, which moth species show the strongest The cloud cap, the lower limit of which sits
altitudinal signal thus making them poten¬ between 800 and 900 m a.s.l depending on
tially appropriate indicators of future climate season and weather conditions, is likely to have a
change within Lamington National Park? strong influence on local climate.
The rationale for the overall project and the
METHODS
locations of study plots are presented by Kitching
Stud et al (2011). Strong et al (2011) describe the
y site
climate and soil conditions prevailing across the
Tamington National Park is a protected area selected altitudes. Laidlaw et al (2011) describe
^ forests covering 206 km2 and includes the vegetation changes along the transect. The low
amington Plateau, which is located across the elevation plots at 300 m a.s.l. are classified as
vUeensland-New South Wales border, a part
complex notophyll vine forest (sensu Webb
20n e ,arSer Tweed Caldera region (Willmont and Tracey 1978) dominated by Hoop Pine
u4). Lamington National Park is part of the
(Araucaria cunninghamii). The mid-elevation
^ °udwana Rainforests of Australia, a group of
plots, 500, 700 and 900 m a.s.l., are also complex
a national parks in south-east Queensland
notophyll vine forest (McDonald & Hunter 2008).
Yy n°rth-east New South Wales, and has been
The highest altitude plots at 1100 m a.s.l. are simple
]je°r T Heritage listed since 1994. The area mainly
fr S uP°u Cainozoic igneous rock, derived microphyll fern forest dominated by Antarctic
ni volcanic eruptions. Lamington Plateau Beech (Nothofagus moorei).
Me
moirs °f the Queensland Museum | Nature • 2011 • 55(2) 377
Ashton et al.
Moth collection and identification targeted in addition to the macrolepidoptera
because of the relatively good resources available
Trap design. Moths were sampled using modified for the identification of many subgroups within
Pennsylvania light traps (Frost 1957; Kitching et al. the Pyraloidea (Common 1990).
2005) fitted with 12 volt gel-cell batteries. Traps Based on external characteristics, moths
employed a vertical actinic tube, producing short were sorted to species, hereafter referred to as
wavelength blue light. This tube was surrounded 'morphospecies' and each morphospecies was
by three transparent vanes that intercepted and assigned a unique code number. As sorting
knocked down insects attracted to the light into a proceeded, a reference collection including at
feast one representative of each morphospecies
bucket below. The bucket contained a Sureguard®
resin strip impregnated with Dicholorvos(cid:8482) was assembled. Individuals in a given sample
that could be readily identified as belonging
insecticide which killed moths in situ. Traps were
to an existing, numbered morphospecies were
set daily and ran for 12 hours from 6 pm to 6 am.
recorded and discarded. Identification to generic
Two Pennsylvania light traps were run and species level was carried out principally
by comparison with the reference collections
simultaneously on a plot on each trapping night,
available in the Queensland Museum, Brisbane,
with one trap at ground level and one in the forest
Australia. Identified material from previous
canopy Canopy traps were raised to a height of
surveys in the Lamington region held by the
approximately 35 metres, depending on the height
Arthropod Biodiversity Laboratory at Griffith
of the canopy, and ground traps were raised a few University was also used in addition to printed
metres above the ground and hung from a low and electronic resources (Common 1990; wwW.
branch. The light traps were placed at both ground ento.csiro.au / anic/ mo ths .html).
and canopy level to ensure a broader sampling
of moth diversity (Brehm 2007; Beck et al 2002; ANALYSIS.
Schulze et al. 2001).
Data from the paired canopy and ground'
Sampling regime. Sampling took place in October
level traps across three trap nights were pooled
2006 and March 2007. Two traps (ground and
into one dataset for each plot. Quantitative
canopy) were set simultaneously for three nights
samples of insects are often characterised by
at each plot. Traps were emptied daily and all
zero-inflated data with a small number of very
arthropods caught were transferred to sample
containers and taken to a field laboratory. In total, abundant species and tills was found to be the case
120 samples were collected in the first sampling in our samples. Multivariate analyses were based
period, from 14th to 31st October 2006, and 108 on the proportion of species within samples and
samples were collected in the second sampling these were log transformed in order to reduce
period, from 10th March to 2nd April 2007. Two the impact of highly dominant species. Ihe
of the four 500 m a.s.l. plots were not sampled multivariate analysis package Plymouth Routines
in March 2007 due to time constraints. In order in Multivariate Ecological Research [PRIMER 6r I
to minimise the negative effect of moonlight
(Clarke & Gorley 2006) was used to investigate
on catches (Muirhead-Thomson 1991; Yela &
patterns of moth assemblages across altitudina
Holyoak 1997; Nowinszky 2004) no trapping was
zones.
carried out five days either side of the full moon.
Permutational multivariate analysis of variance
Processing catches. Moths with a wing length of
(PERMANOVA) was conducted in PRIMER
1 cm or more were processed, thus representing
with PERMANOVA+ add-on software (Anderson
the macrolepidoptera. In addition, all moths
et al. 2008), testing for significant differences
belonging to the superfamily Pyraloidea (i.e. the
in the moth assemblage composition among
families Crambidae and Pyralidae), regardless
of their size, were also processed. This group was a number of a priori groups, in this case the five
55(2)
378 Memoirs of the Queensland Museum 1 Nature • 2011 •
A
Macrolepidopteran assemblages along an altitudinal gradient
altitudinal bands. This analysis was run with 9999 of this environmental data are summarised by
permutations, using the Bray-Curtis dissimilarity Strong et al and Laidlaw et al. (2011). A metric
measure (Bray & Curtis 1957). The pair-wise called Tog events' was also used, indicating
post-hoc comparisons of each altitudinal group days when weather data recorders showed
were used here to explore differences between
periods of 100% atmospheric humidity, thought
altitudinal bands. Owing to time constraints, in
to reflect fog events, although some inaccurate
the October 2006 sampling session, only three
readings may result from the data loggers
°f the 300 m a.s.l. sites were sampled, and in
being wet from rainfall.
March 2007 only two of tine 500 m a.s.l. sites were
sampled. Because of this discrepancy pair-wise We also investigated the extent of variation
comparisons between altitudes for tlie 500 m sites in moth assemblage explained by spatial-auto
in the March 2007 have been excluded to avoid correlation, in comparison to altitudinal differenc¬
unbalanced replication. es. To this end, latitudes and longitudes of the
site locations were first centred and rotated using
The Bray-Curtis dissimilarity measure (Bray
PCA ordination with PRIMER 6, and the resultant
& Curtis 1957) was also used to create a distance
x and y coordinates were used to generate a
matrix. From this matrix, non-metric multi¬
between-site distance matrix based on Euclidean
dimensional scaling (NMDS), set to 100 random
distance measures. Similarly, another distance
starts, was used to produce ordination plots
matrix (based on Euclidean distance measures)
illustrating the relationship of moth assemblages
among sampling sites. The NMDS approach to was generated using altitudinal differences
analysis has been adopted successfully in similar between sites. Two separate Mantel tests (available
studies of moths, and is useful in detecting from the RELATE routine within PRIMER 6) were
patterns in assemblages that tend toward high conducted to calculate correlation coefficients and
diversity and low evenness (Beck & Chey 2008; associated P values between distance matrices of
rehm & Fiedler 2004; Fielder et al 2008). moth assemblages and site locations, and moth
assemblages and altitudinal differences.
Relationships between environmental variables
I IT
>a overall moth assemblage composition were
RESULTS
investigated using the Distance-based Linear
Model (DistLM) function in PERMANOVA+.
A total of 11 379 moths belonging to 865
arginal tests available within the DistLM
morphospecies was sampled in this study;
Pr°cedure investigate which environmental 3490 individuals in October 2006 and 7889 in
vatiables are significantly correlated to the March 2007. Samples collected in October 2006
variation in moth assemblage composition. The showed a mid-elevation peak in species richness
Vectors of significant environmental variables which was highest at 500 m a.s.l. No such peak
were then superimposed on NMDS ordinations of was apparent in the March 2007 data, although it
tL°th assemblages. The length of vectors indicates should be noted that sampling effort at 500 m a.s.l.
_le length of the correlation and their direction in March 2007 was restricted to two sites.
Kates whether the environmental variables
Ordination plots of moth assemblages sampled
positively or negatively correlated with the in October 2006 (Fig. 2a) and March 2007 (Fig.
pnSeiVec^ patterns of assemblage composition. 2b) show a clear altitudinal signal in assemblage
Vl,°nmental vectors which were measured structure between 300 and 1100 m a.s.l. The
^ Part of the IBISCA-Qld project included soil PERMANOVA analysis indicated a highly
^ ^re' so^ organics, tree species richness and significant relationship between altitude and moth
lan temperature. The methods of collection assemblages for both the October 2006 (pseudo-F
Mei
rn°irs of the Queensland Museum | Nature • 2011 • 55(2) 379
Ashton et al.
160
300 500 700 900 1100
Altitude (m a.s.l.)
FIG. 1. Mean moth species richness (+1 x standard deviation) at each sampled elevation in October 2006
(black bars) and March 2007 (open bars). In March 2007, only two of the four 500 m a.s.l plots were sampled,
therefore the complete range is shown for this sampling occasion.
A B
FIG. 2. NMDS ordination plots of moth assemblages, based on log transformed proportion of morpj1^
species, collected in (a) October 2006 and (b) March 2007. Only three of the 300 m a.s.l. plots were samp
in October 2006, and only two of the 500 m a.s.l. plots during March due to time constraints. Superimp°s
vectors are environmental parameters significantly correlated to the assemblage composition.
55(2)
380 Memoirs of the Queensland Museum | Nature • 2011 •
Macrolepidopteran assemblages along an altitudinal gradient
TABLE l. Results of pair-wise post-hoc comparisons of moth assemblages
between altitudinal (m a.s.l.) groups for October 2006 and March 2007
(500 m sites have been excluded from March 2007 analysis due to low
replication), showing degrees of freedom (df), t and P values. Analyses
were based on log transformed proportions of morphospecies.
October 2006 March 2007
[Comparison df t P df t P
poo and 500 m 5 1.85 0.030 - - -
300 and 700 m 5 1.83 0.029 6 2.32 0.028
300 and 900 m 5 2.02 0.028 6 2.35 0.029
300 and 1100 m 5 2.02 0.026 6 3.55 0.031
500 and 700 m 6 1.28 0.057 - - -
300 and 900 m 6 1.69 0.030 - - -
500 and 1100 m 6 2.02 0.029 - - -
700 and 900 m 6 1.26 0.062 6 1.60 0.028
700 and 1100 m 6 1.69 0.030 6 2.86 0.028
900 and 1100 m 6 1.39 0.025 6 2.05 0.026
= 2.95, P = 0.001) and March 2007 datasets
(pseudo-F = 5.13, P = 0.0001). Pair-wise post-
ABLE 2. Average similarities between and within hoc comparisons, testing between each of the
a btudinal (m a.s.l.) groups, based on log transformed altitudinal groups (Table 1), showed that most
Proportions of morphospecies, from four plots at each altitudinal groups were significantly different
a htudinal band collected in (a) October 2006 and (b) from each other, with the exception of 500 and
March 2007.
700 m, and 700 and 900 m, but only in the October
2006 results, when fewer moths were collected.
a) Collection from October 2006
Marginal tests within the DistLM routine
300 m 500 m 700 m 900 m 1100 m
showed the same six environmental variables
300 m
44.89
significantly correlated with moth assemblages
500 m 24.23 40.16 collected in both October 2006 and March 2007.
700 m
21.89 33.36 36.34 Changes in moth assemblages with increasing
90u m 16.18 25.60 32.24 37.27 altitude were positvely correlated to soil moisture
(October, F = 3.6, P = 0.0001; March, F = 6.4, P =
12.96 14.45 19.95 27.23 32.03
0.0001), soil organic content (October, F = 3.2, P
= 0.0001; March, F = 5.5, P = 0.0001) (presumably
reflecting slower breakdown processes induced
by lower temperatures) as well as fog events
(October, F = 2.6, P = 0.0004; March, F = 5.2, P =
0.0001) (100% atmospheric humidity, from which
we may infer a higher frequency of fog events
and rainfall), whereas reverse trends were
found for median temperature (October, F = 3.7,
P = 0.0001; March, F = 6.5, P = 0.0001), soil pH
^moirs of the Queensland Museum | Nature • 2011 • 55(2) 381
Ashton et al.
TABLE 3. Altitudinally restricted moth species collected along the IBISCA-Queensland transect in Lamington
National Park based on combined data from samples taken in October 2006 and March 2007. Only species
that were represented by 30 or more individuals included. The black bars indicate the altitude or range of
altitudes at which at least 80% of the total number of individuals were restricted.
Altitude (m a.s.l.)
Species Family Subfamily Fig. 300 500 700 900 1100
Termessa grcitiosa Arctiidae Lithosiinae 3A
Rhimphalea sceletalis Crambidae Pyraustinae 3B
Lyclene structa Arctiidae Lithosiinae 3C
Asura cervicalis Arctiidae Lithosiinae 3D
Eustixis laetifera Lacturidae 3E
Palaeosia bicosta Arctiidae Lithosiinae 3F
Ectropis bispinaria Geometridae Ennominae 3G
Hesychopa chionora Arctiidae Lithosiinae 3H
Xylodryas leptoxantha Geometridae Ennominae 31
Aboetheta pteridonoma Crambidae Pyraustinae 3J
Eurychoria fictilis Geometridae Ennominae 3K
Lyelliana dryophiki Geometridae Ennominae 3L
Larophylla amimeta Geometridae Ennominae 3M
'Dyscheraids' crimnodes Geometridae Ennominae 3N
Heterochasla conglobata Geometridae Larentiinae 30
Lychnographa heroica Geometridae Ennominae 3P
Thalatha trichroma Noctuidae Amphipyrinae 3Q
Middleton ia hemi chroma Geometridae Ennominae 3R
(October, F = 3.4, P = 0.0001; March, F= 5.0, P = 2, demonstrates decreasing assemblage similarity
0.0001) and tree species richness (October, F = with increasing distance between altitudinal
1.7, P = 0.027; March, F = 2.8, P = 0.007) (Figures groups, indicating strong altitudinal turnover or
2a and 2b). modi assemblages with altitude.
Mantel tests showed a high correlation between Species with altitude-restricted distributions
moth assemblages and altitude (correlation
As a first step towards nominating which
coefficient (Rho) of 0.84, P < 0.002 in March, and
species might be useful as indicators of climate
Rho = 0.73, P < 0.001 in October). However, moth
change at particular elevations, or ranges of
assemblages were also equally highly correlated
vations, and hence promising candidates f°r
with the geographic arrangement of the sites (Rho
future monitoring, we identified species wit1
= 0.85, P < 0.001 in March, and Rho = 0.728, P <
restricted altitudinal distributions (Table 3)-
0.001 in October).
For this we selected species represented by a
The moth assemblages of plots at 1100 m a.s.l. least 30 specimens with at least 80% of the catc1
were clearly differentiated from those at other restricted to one or a small range of altitudes. 1
elevations, particularly in the March sample (Fig. total there were 28 such taxa, 18 of which we have
2b), and featured a number of moth species not thus far been able to identify with confidence t°
found at lower elevations. The average similarity species level. Of these 18 species (and usinb
between altitudinal groups, summarised in Table the 80% criterion mentioned above) nine wde
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382 Memoirs of the Queensland Museum | Nature • 2011 •
Macrolepidopteran assemblages along an altitudinal gradient
(cid:9632)pTo
Nar ^ ^titudinally restricted moth species collected along the IBISCA-Queensland transect in Lamington
Park (see Table 3 for family and subfamily placements). A, Termessa gratiosa (Walker); B, Rhimphalea
bico h'S ^ederer/ Q Lydene structa (Walker); D, Asura cenncalis Walker; E, Eustixis laetifera (Walker); F, Palaeosia
},Ah ^a^er)/ G, Ectropis bispinaria (Guenee); H, Hesychopa chionora (Meyrick); I, Xylodryas leptoxantha (Turner);
Tur 0et^a PteridonomaTurner; K, Eurychoriafictilis (Turner); L, Lyelliana dryophila Turner; M, Larophylla amimeta
Turn^' ‘tyfsdtefcilcis' crimnodes (Turner); O, Heterochasta conglobata (Walker); P, Lydinographa heroica
er; Q/ Thalalha trichroma (Meyrick); R, Middletonia hemichroma. (Turner).
Me
m°irs of the Queensland Museum | Nature • 2011 • 55(2) 383
Ashton et al.
characteristic of a single altitude; three to 300 m, moonlight undoubtedly adversely affects catches
one to 700 m and five to 1100 m a.s.l. A further on clear nights (Nowinszky 2004). Any moth
six species were commonly spread over two trapping programme must be flexible enough to
substitute additional sampling nights in response
altitudes; one from 700 - 900 m and five from 900
- 1100 m a.s.l. Finally, three species occupied less to the occasionally unsuccessful trap night. A
more serious issue concerning the repeatability
restricted altitude ranges; one from 300 - 700 m
and representativeness of light-trap samples
and two from 700 -1100 m a.s.l. These altitudinally
is that of seasonality. There are undoubtedly
restricted species represented five families. The
different assemblages of moth species flying
Tower elevation species', those characteristic
at different times of the year. Further, even for
of plots from 300 to 700 m a.s.l., comprised three
a particular species, there will be a peak time
lithosiine arctiids and a single pyraustine crambid.
of flight activity and the first emergents or last
In contrast, species characteristic of higher
survivors of a species, appearing in trap catches,
elevations (900 -1100 m a.s.l.) were principally
may give a false impression of rarity. We have
geometrids (nine ennomines and one larentiine)
partly addressed this problem by sampling on
with one amphipyrine noctuid and a pyraustine
two different occasions (and a third not reported
crambid. Species restricted to mid-elevations
on here). Nevertheless, any comparisons using
(500-700 m a.s.l.) were, in general, scarce. The two
results of the kind we have reported must arm to
species we identified in this category comprised a
target a comparable season. Of course, year-long
lithosiine arctiid and the lacturid, Eustixis Icietifera.
sequences of catches would be useful in resolving
the issue of seasonality across species. There are,
DISCUSSION however, no such datasets available for any
subtropical Australian location. Even where such
The main objective of this study was to docu¬
datasets available, the highly variable Australia*1
ment changes in moth assemblages along an
climate would, quite possibly, prevent the
altitudinal gradient within continuous rainforest.
drawing of general conclusions concerning
We have demonstrated that there are characteristic
species diversity from a single year's data. We
assemblages of species at each elevation in two suggest the large sample sizes and the fact that
seasons and have identified particular species rather similar patterns emerged from two quite
with indicator potential. In this discussion we different sampling periods lends a good dea
examine potential explanations for these patterns of credibility to the conclusions. We note als°
and the potential impacts of climate change upon that singletons or doubletons (i.e. species tha
them. We discuss the likely generality of our appear only once or twice within our sample^
results and avenues for further research. had little impact on the results of multivariate
ordinations (results not presented here).
The occurrence of a species in a particular
sample results from a multiplicity of factors. Ecologically, the presence or absence of a p<*r"
These may be methodological or biological. ticular species at a particular elevation will °
Methodologically we acknowledge that we are determined by the limiting dimensions of ^
sampling only night-flying, light-attracted moths. niche of each species. These may be physic0'
This is a subset of all moths but, nevertheless, chemical dimensions such as temperature, m01'
is sufficiently large to provide a degree of sture and soil chemistry, or biological variabl
confidence to identify community patterns from based on interactions with food-plants, compet
which usable management tools can be derived. itors and natural predators. The physico-cherrhc
Light traps are relatively easy to use and produce variables are dimensions of the fundamental ni°1
large samples. Poor catches can result from their of the species and reflect the evolved physiology
use on cold and/or windy nights and bright tolerances of the species concerned. BioIoglCc
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384 Memoirs of the Queensland Museum | Nature • 2011 •
