An Assessment of Yourdamung and Nalyerin Lakes in the Jarrah Forest Region of Western Australia

2012·5.3 MB·English

by  Bruce Ward

AN ASSESSMENT OF YOURDAMUNG AND NALYERIN
LAKES IN THE JARRAH FOREST REGION
OF WESTERN AUSTRALIA
By BRUCE WARD* RAY CRANFIELD and GRAEME LIDDELOW
Science Division, Department of Environment and Conservation,
Manjimup 6258, Western Australia
"Corresponding author. Email: [email protected]
ABSTRACT
Surveys of fringing and aquatic plants, birds and aquatic
macro-invertebrate species were carried out at Lake
Yourdamung and Lake Nalyerin during 2002. The purpose
of this survey was to determine whether Lake Yourdamung,
situated on private land, was suitable for inclusion into the
Lane-Poole Reserve. Results provided technical and
scientific support of an application for land acquisition,
which proved to be successful and the 81 ha (182 acres)
property was purchased in 2004. After applying wetland
functional indices to a range of wetland characteristics,
Lake Yourdamung was rated as partially degraded due to
draining and clearing (50%) of its fringing vegetation.
Despite these interventions, it had retained good water
quality and a high diversity of plant, bird and aquatic
invertebrate fauna. Lake Nalyerin in comparison was in
near natural condition but had suffered some degradation
due to vehicle damage of the reed beds. Lake Yourdamung
with some remedial restoration could in time return to a
near-natural condition and form an important wetland
environment, the only one on the Bingham River system.
Lakes Yourdamung and Nalyerin appear to meet criteria for
listing in the Directory of Important Wetlands in Australia.
INTRODUCTION wetlands and their significance
to society (ANCA 1996). Wetlands
Since European settlement
are among the most productive
wetlands have been destroyed at
ecosystems in the world and are a
an alarming rate either filled in
source of substantial biodiversity
or drained and used for other
in supporting numerous species
purposes. It is only in the past
from all of the major groups of
few decades that we have begun
organisms - from microbes to
to understand the many eco¬
mammals. Physical and chemical
logical functions associated with
features such as climate, top-
280
ography, geology, nutrients, and 33°08'S and 116°22’E (Figure 1), is
hydrology help to determine the fully within state forest on the
plants and animals that inhabit Harris River. Lake Nalyerin pro¬
various wetlands. The combi¬ vided a benchmark to compare
nation of shallow water, high against as it was in natural forest
levels of inorganic nutrients, and and has had minimal dis¬
high rates of primary pro¬ turbance. Both Lake Nalyerin
ductivity is ideal for the and Lake Yourdamung are
development of organisms that natural sumpland type wetlands
form the base of a dynamic food and as such have an important
web (US EPA 2010). functional role. Benefits of these
Lake Yourdamung is located on wetlands include water storage,
the head-waters of the Bingham flood control and help with
River at 33°12'S and 116°16'E groundwater recharge. in
situated some 30km north-east addition, many of the aquatic
of Collie, Western Australia, and semi-aquatic plants assist
while Lake Nalyerin, a further 10 with stripping nutrients and
km north east of Yourdamung at harmful contaminants from the
Figure 1. Location of Nalyering and Yourdamung Lakes within the Lane-Poole
Reserve and their proximity to Collie, Western Australia.
281
water improving its quality. The soil, flora and fauna. Both lakes
wetlands also provide habitats are situated within the Jarrah
for many plants and animals, forest biogeographic region,
thereby increasing species di¬ which is defined as: duricrust
versity. Biological monitoring of plateau of Yilgarn Craton
macro-invertebrate fauna is characterised by Jarrah-Marri
often done to assess water forest on laterite gravels and, in
quality and the health of a the eastern part, by Marri-
system. Wandoo woodlands and clayey
soils. Eluvial and alluvial de¬
A drainage channel across the
south west side effectively posits support Agonis shrublands.
In areas of Mesozoic sediments,
drained the majority of Lake
Yourdamung, reducing the lake Jarrah forests occur in a mosaic
with a variety of species-rich
area from 30 hectares down to
shrublands and warm Medi¬
about one hectare. Fringing
vegetation from the original lake terranean climate (ANCA 1996).
Wetlands of the Jarrah forest
level was still evident with a new
biogeographic region are poorly
rim of vegetation developing
around the current high water¬ represented in the Directory of
Important Wetlands in Australia
mark.
(Environment Australia 2001).
The aim of this investigation was
Only seven wetlands / wetland
to record and measure vegeta¬
systems have been listed in the
tion, birds and aquatic inverte¬
directory as being of national
brates for Lake Yourdamung and
significance. All of these are on
Lake Nalyerin and rate their
the periphery of the region, with
health and condition. The study
five along the southern edge and
further aimed to determine if
two on the northern tip.
Lake Yourdamung would revert
A visit to the lakes was con¬
to natural condition forming a
ducted on the 20 November 2002
worthwhile addition to the
to sample plant material for
State’s conservation areas.
identification and species listing
of fringing and aquatic plants
(See Appendix 1 for plant species,
METHOD
Appendix 3 for cryptogams). The
Australia has an immense array fringing vegetation area sampled
of diversity, both physical and was between the high water mark
biological, and to describe and and the lake edge. Aquatic and
manage this diversity areas of semi-aquatic plants from within
similar ecosystems have been the lake were also included along
divided into biogeographic with cryptogams. Voucher speci¬
regions (ANCA 1996). Biogeo- mens for study were collected
graphical regions are defined from plants flowering at the
according to biological and en¬ time of the survey and returned
vironmental attributes, which to the laboratory, where they
include terrain, climate, geology, were processed and later sent to
282
the Western Australian Herb¬ point transect method (Davies
arium. A rapid assessment tech¬ 1983) and sightings and sounds of
nique rated the condition of the bird species were recorded at
fringing vegetation and pro¬ points around the lake. A bird
vided a comparative species list for Lake Yourdamung is
listing to determine the level of presented in Appendix 2.
degradation and species compo¬
sition for both lake systems
Analysis
Aquatic macro-invertebrate taxa
Data from both lakes (Nalyering
were quantified to determine
and Yourdamung) was applied to
water quality and lake condition
a functional capacity rating
at Yourdamung Lake, whereas
system which assesses each
only a visual inspection was
attribute separately by applying a
done at Lake Nalyerin due to
score based on its condition. All
time constraints. The method
scores are added together to
used a timed survey technique
provide an overall total which is
where sweeps of the water from
compared with a standard. This
surface to lakebed with a fine
produces a functional capacity
mesh net were conducted over a
index derived by the following
20-second period. Ten sweeps
equation for the wetland
placed at random locations
(adapted from Smith et al. 1995)
around the lake produced
(see Table 3).
sample specimens, which were re¬
FCI = Functional capacity
turned to the laboratory, identi¬
measured / Functional capacity
fication of specimens using
standard
available keys provided a list of
species which, together with a
measure of their abundance,
RESULTS
were applied to tables published
by Davis and Christidis (1997) to Vegetation species data collected
determine water quality and the for fringing and aquatic plants
health of the system. are summarised for lakes
Yourdamung and Nalyerin in
Bird counts of fringing and in¬
Table 1.
lake vegetation at Lake
Yourdamung assessed numbers A comparison of the fringing
of bird species. The assessment vegetation for both lakes, shows
used the standard Birds Australia Lake Yourdamung to have
Table 1. Number of fringing and aquatic vegetation species in each lake
Total number Species common Weed
of species to both species
Lake Yourdamung 87 19 28
Lake Nalyerin 50 19 2
283
significantly more weed species pollution and are species
than Lake Nalyerin. This is not consistent with a healthy system.
surprising given that up to 50%
Bird counts using standard bird
of the fringing vegetation was census techniques over two
removed to provide pasture for
mornings at Yourdamung re¬
grazing, allowing 28 exotic grasses
turned a species list of 74 birds
and weeds to become established (See Appendix 3 for complete
compared with only two weeds
list).
at Lake Nalyerin. Once the weed
Water quality was measured
species were deducted from the
twice at Lake Yourdamung
species list there was a similar
during 2002, in July a period of
level of species with Lake
maximum dilution and again in
Yourdamung having slightly
December during the peak of
higher species numbers. How¬
concentration. The results show;
ever, only 19 species are common
pH ranging from 6.0 in July to
to both lakes and this shows that
7.49 in December and con¬
these two lakes have dramati¬
ductivity from 104 to 177 gS/cm
cally different species compo¬
(0.06-0.1ppt) respectively. The
sition even though they are only
dissolved oxygen concentration
10km apart.
was 83% in July. The pH of Lake
At sweep sites ‘Yourdamung’, 10
Yourdamung is slightly acidic
aquatic invertebrate taxa were
but well within the range of
present in low numbers and of a
values reported for other lakes in
type consistent with good water South-Western Australia (Lane et
quality (Davis and Christidis
al. 2004, 2011), most of which are
1997) (Table 2). Time allowed for
more alkaline, probably due to
only a visual inspection of Lake differences in soils and vege¬
Nalyerin, which showed a high
tation. Salinity values are very
abundance of shrimp and other
low compared with those of
crustaceans that are sensitive to most South West Wetland
Monitoring Program (SWWMP)
Table 2. Macro-invertebrate taxa and wetlands, as is typical in the
abundance at Yourdamung Lake. Jarrah forest. Lake Yourdamung
had a maximum depth in its
Taxa Abundance current state of about lm, which
is lower than that of most
Caddis fly Trichoptera 1
SWWMP wetlands.
Clam shrimp Mollusca 40
Mites Arichnida 15 A functional capacity index of
Backswimmer Hemiptera 10 each lake was calculated from
Beetle Coleoptera Spl 5 wetland attributes that rated the
Beetle Coleoptera Sp2 3 level of degradation and com¬
Dragonfly Odonata 2
pared against a standard value
Midges Diptera 6
(Table 3). The functional capacity
Worms Oligochaeta 20
index was determined by enter¬
Mosquitoes Diptera 2
ing the total of all ratings into
284
Table 3. Showing functional capacity index for both lakes compared with the
standard for each function
Function standard Yourdamung Nalyerin Comments
index index
Water storage 1.0 0.5 1.0 Yourdamung drained
Nutrient cycling 1.0 0.8 1.0 Intact aquatic
vegetation
Removal of compounds 1.0 0.6 1.0 Area at Yourdamung
reduced
Organic carbon 1.0 0.6 1.0 Area of Yourdamung
reduced
Maintain plant community 1.0 0.9 0.9
Maintain detrital biomass 1.0 0.9 1.0
Spatial structure of habitat 1.0 0.6 1.0
Connectivity 1.0 0.3 1.0
Abundance of invertebrates 1.0 0.9 0.9
Abundance of vertebrates 1.0 0.9 0.9
Water quality 1.0 0.9 0.9
Total 11.0 7.9 10.6
the equation from Smith et al. river system. Comparison of
(1995). plant diversity for both lakes
show the numbers of species to
FCI = Functional capacity
be similar but they have
measured / Functional capacity
distinctly different species
standard
composition and this highlights
Lake Yourdamung = 7.9/11 gives a
the spatial differences between
FCI of 0.71
the two catchments. Lake
Lake Nalyering = 10.6/11 gives a Yourdamung has more species
FCI of 0.96 with higher levels of grasses and
A wetland in pristine condition weeds, which has resulted from
disturbance associated with
would have a score of 1.0 and
clearing to produce pastured
both lakes rated highly.
land. This lake although cleared
of some of its fringing vegetation
has maintained good water
DISCUSSION
quality and a high diversity of
The fringing vegetation is plant, bird and aquatic in¬
subject to inundation annually vertebrate species. The land
and forms a natural filtration surrounding the lake is mostly
system that strips and retains pastured farmland with a narrow
nutrients and harmful pollut¬ strip of vegetation upstream that
ants from the water improving provides some connectivity to
water quality discharged into the the natural forest to the north.
285
The areas cleared would easily and animal species; it can be
revert to natural vegetation and restored back to a natural state; it
already show some evidence of is within the boundaries of the
sedges and reed beds becoming Lane-Poole Reserve; and it
established, an observation noted contains habitat suitable for the
during the initial visit and a reintroduction of rare fauna
subsequent visit during 2010. such as Tammar, Woylie and
Lake Nalyerin in comparison is Chuditch also lakes listed in the
in near-natural condition but Directory of Important Wetlands
has some damage due to vehicle in Australia are poorly repre¬
traffic crossing reed beds. Some sented in the Jarrah forest bio-
remedial action could rectify this geographical region. Combined,
area by resiting tracks and access these reasons provided com¬
points. pelling biological evidence to
support the application for land
Lake Yourdamung appears to
acquisition which was finally
meet Criteria for listing in the
achieved in 2004.
Directory of Important Wetlands
in Australia. Such as, It is a good
Restoration of Lake Yourdamung
example of a wetland type occurring
within a biogeographic region in A priority following land acqui¬
Australia but, due to a lack of sition was to destock the
data demonstrating national sig¬ property of cattle and sheep. This
nificance at the time of assess¬ significantly reduced grazing
ment of wetlands in this region pressure allowing natural vege¬
(J. Lane, pers. comm., 3 March tation to re-establish. As part of
2011), has not been listed. Lake the farming activities, a drain cut
Yourdamung is also not included on the south-eastern edge
among the 152 wetlands of the effectively lowered the lake by
Department of Environment 0.8-1.0m altering the entire
and Conservation’s ‘South West hydrology of the lake. The lake
Wetlands Monitoring Program’ originally covered about 36
which, for historical reasons, has hectares and because of drainage,
an emphasis on wetlands of the only about one hectare holds
wheatbelt and the coastal plains. water and actively functions as a
Most lakes in this monitoring sump. To restore this lake to its
program are within national natural level, forms the next
parks or nature reserves estab¬ priority and can be achieved by
lished prior to 2000 (Lane et al. filling in or blocking the drain.
2004, 2011). The Lake Restoration of the damaged
Yourdamung property was with¬ fringing vegetation would de¬
in, but not part of, the Lane- velop naturally but intervention
Poole Reserve and had many in the form of replanting and
reasons why it should be added infilling of the vegetation would
to the reserve. These include: it speed this process. The cost of
has a high diversity of plant, bird this type of intervention often
286
prohibits this work. important habitat and its
ecological diversity.
There was evidence of water
birds nesting and foraging in the
water during our visit and
CONCLUSION
suggests that this is an important
site for many of these species. Lake Yourdamung showed
Lane-Poole Reserve has 120 partial impact from farming and
species of birds and this survey has a high diversity of plant, bird
has captured over 60% from this and aquatic animals with
one site, which emphasises its fringing vegetation forming an
importance. Increasing the area important habitat which would
of the lake back to its original regenerate over time. The prop¬
size would benefit these species erty containing the majority of
providing increased habitat and the lake was purchased and
maintenance of diversity. incorporated into the Lane-
Despite the draining and clearing Poole Reserve and will form an
of the lake, the health of this important natural wetland for
system is in good order. Evidence this area.
of this was shown by the cover of
aquatic and semi-aquatic plants,
with good water quality capable ACKNOWLEDGEMENTS
of supporting growth and a suite
We thank Department of
of macroinvertebrate fauna
Environment and Conservation,
recognised for their capacity to
District and Regional officers for
only survive in good quality
assistance. Special thanks to Matt
water. The water was clear and
Williams for advice with data
contained no evidence of algal
analysis and to Dr Lachie McCaw
blooms.
and Jim Lane for reading the
Lake Yourdamung drains into draft and providing invaluable
the Bingham River through a
comment.
broad valley flat that is subject to
inundation. The lake forms a
natural sump and experiences a REFERENCES
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the long-term viability of this Royal Australasian Ornithologists
287
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288
.
APPENDIX 1 (Vegetation species from Lakes Yourdamung and Nalyering in
2002). Genus marked with an asterisk is a weed species
Lake Lake
Yourdamung Nalyering
Amaranthaceae *
Alternanthera nodi flora
Apiaceae
Daucus glochidiatus * *
Homalosciadium homalocarpum * *
Araliaceae
Trachymene pilosa * *
Asparagaceae
Chamaescilla corymbosa * *
Sowerbaea laxiflora *
Thysanotus tenellus *
Asteraceae
*Arctotheca calendula *
*Cotula coronopifolia *
Helichrysum luteoalbum *
*Hypochaeris glabra * *
Lagenophora huegelii *
Senecio quadridentatus *
Siloxerus humifusus * *
*Sonchus asper *
*Sonchus oleraceus *
Campanulaceae
Lobelia anceps * *
*Monopsis debilis *
Wahlenbergia gracilenta * *
Centrolepidaceae
Aphelia cyperoides *
Centrolepis aristata *
Characeae
Chara sp. algae
Crassulaceae
*Crassula natans *
Cyperaceae
B aumea articulata *
Baumea juncea *
Isolepis cyperoides *
*Isolepis marginata *
Isolepis stellata *
Dilleniaceae
Hibbertia amplexicaulis *
Hibbertia racemosa * *
Hibbertia stellaris *
Elaeocarpaceae
Platytheca galioides *
289