Interlaken Lakeside Reserve – Wetland Vegetation Survey
Water Assessment Aquatic Ecology Report Series
Interlaken Lakeside Reserve
Wetland Vegetation Survey
August 2010 ISSN: 1835-9523 Report No. WA 10/04
Water Assessment Branch Water and Marine Resources Division 0 Department of Primary Industries, Parks, Water and Environment Interlaken Lakeside Reserve – Wetland Vegetation Survey
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Prepared By: Danielle Hardie, Kate Hoyle and Scott Hardie.
Preferred Citation: DPIPWE. (2010). Interlaken Lakeside Reserve Wetland Vegetation Survey. Water Assessment Aquatic Ecology Report Series, Report No. WA 10/04. Water and Marine Resources Division. Department of Primary Industries, Parks, Water and Environment, Hobart, Tasmania.
Contact Details: Department of Primary Industries, Parks, Water and Environment Water Assessment Branch 13 St Johns Avenue, New Town, Tasmania. Phone: 03 6233 6833 Web: www.dpipwe.tas.gov.au Email: [email protected]
Cover Page Image: Interlaken Lakeside Reserve wetland showing Triglochin procerum in flower (Photo: D. Hardie)
The Department of Primary Industries, Parks, Water and Environment The Department of Primary Industries, Parks, Water and Environment provides leadership in the sustainable management and development of Tasmania’s resources. The Mission of the Department is to advance Tasmania’s prosperity through the sustainable development of our natural resources and the conservation of our natural and cultural heritage for the future. The Water and Marine Resources Division provides a focus for water management and water development in Tasmania through a diverse range of functions including the design of policy and regulatory frameworks to ensure sustainable use of the surface water and groundwater resources; monitoring, assessment and reporting on the condition of the State’s freshwater resources; facilitation of infrastructure development projects to ensure the efficient and sustainable supply of water; and implementation of the Water Management Act 1999 , related legislation and the State Water Development Plan.
i Interlaken Lakeside Reserve – Wetland Vegetation Survey
Summary The Interlaken Lakeside Reserve wetland is one of a number of littoral wetlands associated with Lake Crescent and Lake Sorell, and represents an important component of the Crescent-Sorell ecosystem. The water level regime of the Interlaken Lakeside Reserve wetland (i.e. the temporal pattern and spatial extent of inundation and drying) is closely linked to water levels in Lake Crescent and the interconnecting Lake Sorell. Between 1997 and 2009, an extended period of dry climatic conditions resulted in ongoing low water levels in Lake Crescent and the subsequent absence of full inundation of the Interlaken Lakeside Reserve wetland for more than 12 years. During late 2009 – early 2010, the Interlaken Lakeside Reserve wetland was inundated to the greatest extent since 1996, as a result of higher than average rainfall in 2009. Heffer (2003) undertook a comprehensive study of the wetlands around lakes Crescent and Sorell during 2000-2002. This study recommended a set of operating guidelines for the management of water levels in the lakes, aimed at maintaining or restoring appropriate water regimes for wetland vegetation communities. These guidelines were incorporated into the Lakes Sorell and Crescent Water Management Plan (DPIWE, 2005). Smith and Mendel (2009) surveyed the vegetation within the Interlaken Lakeside Reserve wetland in May 2009 as part of the ecological assessments required for the review of the Lakes Sorell and Crescent Water Management Plan. The Interlaken Lakeside Reserve remained dry at the time of this study, and therefore the survey provided a characterisation and condition assessment of the wetland vegetation community following a prolonged period without full inundation. This present study presents the results of a survey of the Interlaken Lakeside Reserve wetland vegetation undertaken in February 2010. It assesses the response of wetland vegetation to inundation during late 2009 – early 2010 following the extended dry period, and is intended to provide additional information to the review of the Lakes Sorell and Crescent Water Management Plan. Survey results were compared with those of Heffer (2003) and Smith and Mendel (2009). This study found that following inundation, the characteristics of wetland vegetation within the Interlaken Lakeside Reserve indicate a shift from a vegetation community with increased abundance of terrestrial and introduced species (Smith and Mendel, 2009) towards a community dominated by native amphibious species. However, there are still some indicators of the effect of the prolonged dry period on the wetland community, and the potential for a continued transition towards an increasingly terrestrial community will remain in the absence of a more regular pattern of inundation. Short-term colonisation of terrestrial plant species is likely to occur during drying events; however, regular inundation of the wetland is important for the ongoing persistence of amphibious and aquatic species. To encourage and maintain a high diversity of aquatic vegetation within the wetlands associated with the Crescent-Sorell system, this report recommends that an appropriate water regime can be achieved by implementing the operating guidelines related to wetlands in the current Lakes Sorell and Crescent Water Management Plan. Additional recommendations for the management of water levels in lakes Crescent and Sorell are included, and some preferred options regarding future monitoring are discussed.
ii Interlaken Lakeside Reserve – Wetland Vegetation Survey
Contents
Summary ...... ii
1 Introduction ...... 1 1.1 Ecological significance and conservation status ...... 2 1.2 Water level regime ...... 3 1.3 Previous research ...... 5 1.4 Conditions in the Interlaken Lakeside Reserve during late 2009 – early 2010 ...... 5 1.5 Objectives...... 6
2 Methods ...... 7 2.1 Taxonomic notes ...... 7 2.2 Data analysis ...... 9
3 Results and discussion ...... 10 3.1 Species diversity ...... 10 3.2 Species characterisation ...... 11 3.3 Comparisons with previous vegetation studies ...... 14 3.3.1 Water levels ...... 14 3.3.2 Frequency of occurrence ...... 16 3.3.3 Percent cover ...... 18 3.3.4 Plant height ...... 20
4 Conclusions and management recommendations ...... 22
5 References ...... 24
Appendix A – Conservation of Freshwater Ecosystem Values (CFEV) assessment of Lakes Sorell and Crescent, and surrounding areas ...... 25
Appendix B – Location and environment data for quadrats surveyed in February 2010. ... 36
Appendix C – Vegetation data collected for quadrat surveys in February 2010 ...... 38
Appendix D – Species recorded in quadrat surveys in February 2001, February 2002, May 2009 and February 2010 ...... 41
iii Interlaken Lakeside Reserve – Wetland Vegetation Survey
1 Introduction The Interlaken Lakeside Reserve lies between the interconnecting Lake Crescent and Lake Sorell, located in the south-east corner of the Tasmanian Central Plateau. The entire Interlaken Lakeside Reserve covers an area of approximately 520 ha, and contains a wetland along the north-western margin of Lake Crescent with an area of approximately 174 ha. Figure 1 shows the location of the Interlaken Lakeside Reserve wetland in relation to lakes Crescent and Sorell and several other wetlands associated with these lakes.
Figure 1. Location of and Lake Crescent and Lake Sorell, showing the wetland area of the Interlaken Lakeside Reserve. Map data provided by the CFEV Program, DPIPWE.
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1.1 Ecological significance and conservation status The littoral wetlands associated with Lake Crescent and Lake Sorell represent an important component of the Crescent-Sorell ecosystem, providing habitat, refuge and a food source for many plants and animals, including threatened species and other species of significance. When the wetland is full, it provides important habitat for the golden galaxias ( Galaxias auratus ), a native fish which is endemic to the Crescent-Sorell ecosystem and listed as rare under the Tasmanian Threatened Species Protection Act 1995 and endangered under the Commonwealth Environmental Protection and Biodiversity Conservation Act 1999 . The Interlaken Lakeside Reserve has been recognised as a wetland of international and national significance, and is listed under both the Ramsar Convention (Ramsar, 2010) and the Directory of Important Wetlands in Australia (Australian Government, 2010). For the purposes of this report, the ecological values of the lakes, wetlands and surrounding rivers and creeks have been assessed using the Conservation of Freshwater Ecosystem Values (CFEV) database (CFEV 2005; full results are presented in Appendix A, with a glossary of CFEV terminology). Interrogation of the CFEV database indicates that the Interlaken Lakeside Reserve has a very high Integrated Conservation Value. This is due to a high Representative Conservation Value (specifically, a highly representative vegetation assemblage) in combination with the presence of several Special Values. The CFEV database indicates that the Special Values associated with the Interlaken Lakeside Reserve are: platypus (a phylogenetically distinct fauna species), Carex longebrachiata (drooping sedge; a threatened flora species) and Highland grassy sedgeland and Highland Poa grassland (two priority flora communities). The Interlaken Lakeside Reserve receives a CFEV naturalness category of high (0.89 out of a possible score of 1), which indicates that the wetland is considered to be in near-natural condition, although the condition of native riparian vegetation and native wetland vegetation is considered to be moderate. Note that the CFEV assessment for Lake Crescent indicates a naturalness category of medium (0.63), or significantly altered from natural condition. The lower naturalness score for Lake Crescent is partially driven by a moderate condition assessment for hydrology, related to abstraction and water level manipulation. This has the potential to affect the surrounding wetlands, and is discussed further in Section 1.2. Kirkpatrick and Harwood (1981) recorded the presence of Amphibromus neesii and Isolepis montivaga within the Interlaken Lakeside Reserve. Both species are considered rare, and A. neesii is listed as rare under the Tasmanian Threatened Species Protection Act 1995. It is possible that Amphibromus sinuatis was mis-identified as A. neesii in the 1981 survey (Chilcott, 1986), and the presence of A. neesii has not yet been confirmed in any subsequent survey (Chilcott, 1986; Heffer, 2003; Smith and Mendel, 2009). However, Amphibromus sinuatis is also considered to be rare due to its restricted range (Heffer, 2003). Isolepis montivaga has also not been recorded in any subsequent surveys, although it was observed by Heffer (2003) during other field investigations. Smith and Mendel (2009) were not able to identify Isolepis below genus level due to the lack of reproductive material. No other threatened flora species have been detected in the Interlaken Lakeside Reserve during previous surveys, although Glossostigma elatinoides , listed as rare under the Tasmanian Threatened Species Protection Act 1995 , was recorded by Heffer (2003) in the nearby Clyde Marsh. Note that the CFEV database also contains a record for Carex longebrachiata , listed as rare under the Tasmanian Threatened Species Protection Act 1995 , as a Special Value within the Interlaken Lakeside Reserve, although this has not been recorded in any of the previous wetland surveys (Kirkpatrick and Harwood, 1981; Chilcott, 1986; Heffer, 2003; Smith and Mendel, 2009). Smith and Mendel (2009) identified two aquatic vegetation communities within the Interlaken Lakeside Reserve: Freshwater Aquatic Herbland (TASVEG code AHF) and Freshwater Aquatic Sedgeland and Rushland (TASVEG code ASF). Both of these communities are listed as
2 Interlaken Lakeside Reserve – Wetland Vegetation Survey vulnerable vegetation communities under Schedule 3A of the Tasmanian Nature Conservation Act 2002.
1.2 Water level regime The water level regime of the Interlaken Lakeside Reserve wetland is closely related to the water levels in Lake Crescent (and Lake Sorell, which is connected to Lake Crescent via the Interlaken Canal; see Figure 1). Water levels between the two lakes can be manipulated via sluice gates at the southern end of Lake Sorell on the Interlaken Canal, and releases from Lake Crescent can also be regulated via sluice gates on the outflow of Lake Crescent into the upper Clyde River. Preliminary bathymetric surveying conducted by Heffer (2003) demonstrated that small changes in lake water levels can result in large areas of the wetlands being flooded or dewatered. The Interlaken Lakeside Reserve wetland is considered dry at a water level of 802.800 m AHD in Lake Crescent, becomes waterlogged (i.e. inundated to a depth of 10 mm over ~90% of the wetland surface area) when water levels in Lake Crescent rise above 803.000 m AHD, and becomes fully inundated (i.e. inundated to a depth of 300 mm over ~90% of wetland surface area) at 803.300 m AHD (Heffer, 2003). A recent spot elevation survey of the interface between the Interlaken Lakeside Reserve wetland and Lake Crescent (DPIPWE, unpublished data) confirmed the level determined by Heffer (2003) at which the wetland starts to fill from the lake. When water levels within the lake are below 802.800 m AHD, the wetland can receive runoff from its immediate catchment during high rainfall events, however under low water levels, any water which ponds in the wetlands usually drains into the lake or evaporates relatively quickly (Heffer, 2003). The effect of Lake Crescent water levels on the Interlaken Lakeside Reserve are illustrated in Figure 2, which shows that the wetland has not been fully inundated since 1997. Water levels in Lake Crescent are subject to both natural variability, related to rainfall and evaporation, and artificial alterations caused by downstream releases for consumptive water uses in the Clyde Valley, as well as other management objectives. Since 1996 when water levels in Lake Crescent were quite high (Figure 2), there had been a prolonged period of low levels prior to 2009. The significant drawdown in 1996/97 was a result of climatic influences in combination with release of water from the lakes for management purposes. The ongoing low water levels in Lake Crescent during 1997-2009 were primarily related to dry climatic conditions, and to a lesser extent downstream water use. Figure 3 shows annual rainfall totals for the Interlaken area from 1984-2009. Mean annual rainfall over this period was 660.2 mm, while the long-term mean annual rainfall for the region (1900-2003) is 699 mm (Deakin, unpublished data, cited by Heffer (2003)). Between 1997 and 2008, annual rainfall was below average in all but two years. Higher than average rainfall in 2009 (962.4 mm) resulted in Lake Crescent reaching its highest water level since 1997, peaking in November 2009 at 803.290 m AHD. (see Section 1.4).
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804.5
804
803.5
803
802.5 Water level (m AHD) level(m Water
802 Lake Crescent water level Lake Crescent FSL wetland inundated (300mm over ~90%) 801.5 wetland waterlogged (10mm over ~90%) wetland dry 801 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Figure 2. Water levels in Lake Crescent, January 1970 to April 2010 (IFS, unpublished data). Water levels threshold relating to the extent of inundation and the full supply level (FSL) are shown.
1000
900
800
700
600
500
400 Total rainfall (mm) rainfall Total 300
200
100
0
1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 Figure 3. Annual rainfall totals for the Interlaken area between 1984 and 2009. Mean annual rainfall for this period is 660.2 mm (red dashed line). Data are from the Bureau of Meteorology (Interlaken weather station) and the Interlaken Estate property.
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1.3 Previous research Vegetation assessments within the Interlaken Lakeside Reserve were conducted by Kirkpatrick and Harwood (1981) as part of a survey of Tasmanian wetlands, and by Chilcott (1986) as part of an environmental impact study looking at effects of raising water levels in Lake Crescent. The Interlaken Lakeside Reserve wetland was inundated during both these surveys (Figure 2). Heffer (2003) undertook a comprehensive study of the wetlands around lakes Crescent and Sorell, which included extensive vegetation monitoring between August 2000 and February 2002. This study was a part of the Lakes Sorell and Crescent Rehabilitation Project conducted by the Inland Fisheries Service (IFS), which was initiated in response to an observed environmental decline associated with low water levels in the lakes. As shown in Section 1.2, the Interlaken Lakeside Reserve had not been fully inundated since 1997, and the wetland was predominantly dry throughout this study (although at certain times some areas of the wetland contained ‘ponded’ water from rainfall runoff). Heffer (2003) recommended a set of operating guidelines for the management of water levels in Lake Crescent and Lake Sorell aimed at maintaining or restoring appropriate water regimes for wetland vegetation communities. These operating guidelines were incorporated into the Lakes Sorell and Crescent Water Management Plan (DPIWE, 2005), however it has not been possible to implement these guidelines (specifically for the wetlands) due to continued dry climatic conditions in the Clyde River catchment, and hence relatively low water levels in the lakes. Smith and Mendel (2009) surveyed the vegetation within the Interlaken Lakeside Reserve wetland in May 2009 as part of the ecological assessments required for the Lakes Sorell and Crescent Water Management Plan Review. Results of the 2009 study were compared with the May 2001 results of Heffer (2003) to examine changes in species abundance and/or diversity, and investigate the influence of the water level regime within the wetland since 2003. The Interlaken Lakeside Reserve was dry at the time of the Smith and Mendel (2009) study and the wetland had not been fully inundated for over 11 years.
1.4 Conditions in the Interlaken Lakeside Reserve during late 2009 – early 2010 During late 2009 – early 2010, the littoral wetlands in lakes Crescent and Sorell were inundated to the greatest extent since 1996 (DPIPWE, 2010; see Figure 2). This was somewhat remarkable, given the very low water levels that occurred in both lakes in early 2009, and illustrated how quickly the conditions in the Crescent-Sorell system can change due to local climatic conditions. In Lake Crescent, the water level reached the surveyed in-lake edge of the Interlaken Lakeside Reserve wetland (802.800 m AHD; Heffer, 2003) on 15 September 2009 and it remained above edge of wetland until 15 March 2010 (Figure 2; period of 181 days). Based on a survey of the wetted area in the wetland on 9 October 2009 and aerial photographs of the wetland which were taken on 7 November 2009, it estimated that approximately 84% of the surface area of the wetland was inundated during spring 2009 (DPIPWE, 2010). As discussed in Section 1.2, a water level of 803.000 m AHD is likely to inundate ~90% of the surface area of the Interlaken Lakeside Reserve wetland to a depth of 10 mm, while a water level of 803.300 m AHD is likely to inundate ~90% of the surface area of the wetland to a depth of 300 mm. During late 2009 – early 2010, water levels in Lake Crescent did not quite reach 802.300 m AHD (peaking at 803.290 m AHD on 4 November 2009). However, levels did remain above 803.000 m AHD for approximately 109 days, thus providing an extended period of inundated and waterlogged conditions in the Interlaken Lakeside Reserve wetland. These estimates of the depth of inundation in the wetland are supported by the results of a depth survey of the Interlaken Lakeside Reserve wetland on 9 October 2009 when the water level in Lake Crescent was 803.160 m AHD (DPIPWE, 2010). During this survey, depth measurements at
5 Interlaken Lakeside Reserve – Wetland Vegetation Survey
66 points in the wetland showed the mean (± Standard Error) depth in the wetland was 289 ± 11 mm (range = 0-520 mm).
1.5 Objectives The inundation of the Interlaken Lakeside Reserve wetland during late 2009 – early 2010 provided an opportunity to assess the response of vegetation within the wetland to these conditions following an extended dry period. A survey of the Interlaken Lakeside Reserve was undertaken in February 2010, when inundation of the wetland was thought to have been long enough (>4 months) to allow vegetation communities in the wetland to respond in terms of plant growth, and potentially flowering and propagation. This report presents the results of the February 2010 vegetation survey of the Interlaken Lakeside Reserve wetland. It is intended to be an addendum to the assessment of Smith and Mendel (2009), which was conducted under dry conditions, and provide additional information to support the review of the Lakes Sorell and Crescent Water Management Plan.
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2 Methods Vegetation surveys were undertaken in the Interlaken Lakeside Reserve wetland on 1-2 February 2010. Heffer (2003) established 10 quadrats (1 m × 1 m) within each of the two dominant vegetation zones (herb and sedge zones; 20 quadrats in total) in the Interlaken Lakeside Reserve to be used for monitoring temporal changes in vegetation with varying water levels. These quadrats were re-surveyed in May 2009 by Smith and Mendel (2009); in cases where the original quadrat marker could not be relocated, they randomly selected a new position for the quadrat in the vicinity of the original quadrat location, as mapped by Heffer (2003). The current study also attempted to re-survey the 20 quadrats established by Heffer (2003). Seventeen of the original quadrats markers were relocated and for the remaining three, similar to Smith and Mendel (2009), new quadrats were randomly placed in the vicinity of the original quadrats (Figure 4; Appendix B). Where possible, all plant species present within each quadrat were identified in the field. Where field identification was not possible, a sample of the plant was collected for identification in the laboratory. Within each quadrat, abundance of each species was assessed using the Braun-Blanquet percentage cover scale (Table 1; Moore and Chapman, 1986) and mean height for each species was also recorded. Percentage cover of open water and bare ground was also recorded for each quadrat. Other plant species located within the Interlaken Lakeside Reserve wetland, but outside of quadrat locations, were also recorded when observed; however, a comprehensive assessment of all species present within the wetland was not undertaken. Table 1. Braun-Blanquet cover scale (Moore and Chapman, 1986). Class Braun-Blanquet scale Class description + <1% Foliage sparsely or very sparsely present, cover <5% 1 1-5% Plentiful, foliage cover 1-5% 2 6-25% 6-25% foliage cover 3 26-50% 26-50% foliage cover 4 51-75% 51-75% foliage cover 5 76-100% 76-100% foliage cover
2.1 Taxonomic notes Some data amalgamation and name changes have been applied to allow consistent comparison between studies: • Smith and Mendel (2009) used the new taxanomic name Lachnagrostis filiformis for Agrostis avenacea , recorded by Heffer (2003). The current study refers to possible occurrences of Lachnagrostis filiformis and/or Lachnagrostis aemula as Lachnagrostis sp. due to the difficulty in differentiating between the two species. Lachnagrostis aemula was not recorded in the quadrat surveys by Heffer (2003) or Smith and Mendel (2009), however records of L. filiformis from these studies are referred to as Lachnagrostis sp. in this report for the purposes of comparison with the current survey. • Records of the introduced Agrostis species, A. stolonifera and A. capillaris recorded in the Heffer (2003) and Smith and Mendel (2009) surveys were amalgamated and described as Agrostis spp . • The current study and Heffer (2003) identified Isolepis fluitans as present within the quadrats, but Smith and Mendel (2009) were unable to identify small Isolepsis species
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beyond genus level due to a lack of reproductive material. For comparative analyses, Isolepsis records were amalgamated and labelled as Isolepsis spp.
Figure 4. Interlaken Lakeside Reserve wetland, showing sampling quadrat locations. Map data provided by the CFEV Program, DPIPWE.
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2.2 Data analysis Descriptive analyses of vegetation survey data were undertaken using Microsoft Excel. Three measures of relative abundance were calculated for the purpose of characterising the vegetation in the wetland at the time of the current survey. These measures of relative abundance were: • Frequency of occurrence – the number of quadrats within the herb and sedge zones in which each species occurred, calculated as a percentage of total quadrats within each vegetation zone. • Cover – the Braun-Blanquet cover class was converted into a percent cover (% cover) using the mid-range of the class (e.g. class 1 = 3%; class 2 = 15.5%, etc). Using a mid-range % cover for the relevant Braun-Blanquet class helps to minimise the influence of subjective % cover estimations by different observers across studies. For each dominant species (identified as those with a frequency of occurrence of 80% or greater), percent covers for each quadrat were then averaged across all quadrats within either the herb or sedge zone (i.e. across 10 quadrats for each zone, using a % cover of 0% for any quadrats in which the species did not occur). Note that for Baumea arthrophylla , % cover included both green shoots and standing litter. • Plant height – calculated as an average of the plant heights recorded for each dominant species across quadrats within vegetation zones. Note also that for Baumea arthrophylla , only average heights of green shoots were used for plant height analyses.
These measures of abundance were also used to compare the results of the February 2010 survey with those of the previous surveys in February 2001 and February 2002 (Heffer, 2003), and May 2009 (Smith and Mendel, 2009). To ensure consistent data analysis between surveys, the raw data from the February 2001, February 2002 and May 2009 surveys was re-analysed following the methods outlined above. Results presented in this report for the February 2001, February 2002 and May 2009 surveys have been derived from these analyses.
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3 Results and discussion
3.1 Species diversity A total of 22 plant species were recorded from the quadrat surveys in this study, with an additional nine species observed outside the quadrats during field investigations (Table 2). Complete survey data is provided in Appendix C, showing the species present within each quadrat, along with percent cover and mean plant height information. Only two introduced plant species (i.e. not native to Tasmania) were recorded in the quadrat surveys, both of which were terrestrial grasses (Holcus lanatus and Vulpia sp.). Each of these species occurred in low abundance, with Holcus lanatus only being recorded in one quadrat with <1% cover, and Vulpia sp. also being recorded in a single quadrat with 1-5% cover (Appendix C). The high percentage of native species recorded in the survey suggests that native species have responded successfully to the re-inundation of the wetland and are likely to be better suited to these conditions than many introduced species. As observed previously by Heffer (2003) and Smith and Mendel (2009), two distinct vegetation communities were present within the Interlaken Lakeside Reserve wetland: a community dominated by Baumea arthrophylla , termed the “sedgeland” or sedge zone, and a community characterised by aquatic and/or emergent herbaceous vegetation, termed the “herbland” or herb zone. In both the Heffer (2003) and Smith and Mendel (2009) studies, there were 10 quadrats located in each of the main vegetation zones: sedgeland and herbland. Interestingly, in February 2010, two quadrats which occurred within the herb zone during previous surveys (Heffer, 2003; Smith and Mendel, 2009) were found to have undergone a change in dominant vegetation type to a mixed sedge/herb community (Q7 and Q9 in the present study, corresponding to quadrats H4 and H5 in Heffer (2003); Appendix B). However, for the purposes of comparison with previous studies, these quadrats were included in the herbland data set. Species diversity was highest in the herb zone, where a total of 21 species were recorded in the quadrats, compared with seven in the sedge zone (Appendix C; Section 3.3). The sedge zone community was dominated by Baumea arthrophylla , while Triglochin procerum was also common in this zone. The herb zone was dominated by Potamogeton tricarinatus , Triglochin procerum , Villarsia reniformis , Isolepis fluitans and Myriophyllum simulans . The relative abundance of dominant species, in terms of frequency of occurrence, percent cover and plant height, is discussed in further detail in Section 3.3. Renewal of the seed bank is important for ongoing recruitment and survival of many wetland plant species. Some wetland species require inundation for flowering, reproduction and renewal of the seed bank (Smith and Mendel, 2009). During sustained dry conditions, these species will continue to use resources for growth and maintenance, but the seed bank may become depleted if their life cycle is not able to be completed; ultimately, this could cause some species to disappear from the wetland (Heffer, 2003; Smith and Mendel, 2009). During the current survey, eight native species ( Amphibromus recurvatus , Helichrysum bicolor , Brachyscome augustifolia , Juncus bufonius , Poa labilliardieri , Potamogeton tricarinatus , Triglochin procerum and Villarsia reniformis ) and one introduced species ( Holcus lanatus ) were observed to be in flower. This indicates that the duration of the recent inundation within the wetland was long enough to enable certain species to undertake reproduction, potentially adding to the seed bank.
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Table 2. Species recorded in February 2010 in the Interlaken Lakeside Reserve wetland, separated into functional groups based on habitat type and growth characteristics. Functional group classifications follow that of Heffer (2003) and Smith and Mendel (2009), which used information provided by Smith (2002), Brock et al., (2000) and Brock and Cassanova (2000). (i) = introduced species, (o) = only observed outside quadrats. Functional group Growth/habitat type Species Terrestrial Dry Eucalyptus sp. (o) Hakea sp. (o) Holcus lanatus (i) Vulpia sp. (myuros or bromoides )(i) Damp Brachyscome augustifolia Galium gaudichaudii Juncus spp. (o) Poa labilliardieri Amphibious Low growing/saturated/edge Hydrocotyle hirta (o) Isolepis montivaga (o) Juncus bufonius (o) Leptinella reptans Emergent/tolerator Lachnagrostis sp. (filiformis or aemula) Amphibromus recurvatus Baumea arthrophylla Carex gaudichaudiana Eleocharis acuta Helichrysum bicolor (o) Juncus holoschoenus Juncus sp. Responder Hydrocotyle muscosa Isolepis fluitans Lilaeopsis polyantha Limosella australis Myriophyllum simulans Neopaxia australasica Potamogeton tricarinatus Ranunculus amphitrihcus (o) Triglochin procerum Utricularia dichtoma (o) Villarsia reniformis
3.2 Species characterisation Wetland species are usually represented by three broad functional groups: terrestrial, amphibious and submerged. Terrestrial species do not tolerate inundation, while submerged species require inundation and do not tolerate dry conditions. Amphibious species are characterised by their ability to adapt to changes in water level (Smith and Mendel, 2009). Amphibious species can be further divided based on growth form into low growing species that prefer saturated conditions, emergent species that tolerate fluctuations in water level without a major change in morphology or growth, and responding species that change their growth or morphology in response to inundation or drying (Heffer 2003; Smith and Mendel, 2009).
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The majority of species (74%) recorded in the current survey were amphibious (Table 2). All of the dominant species identified in the herb zone are amphibious responders, which respond well to inundation. The dominant species in the sedge zone, Baumea arthrophylla , is an amphibious emergent species, which tends to grow taller as water levels increase, and will usually remain in the wetland (with some die back, called standing litter) after it dries out (Heffer, 2003). All of the seven terrestrial species recorded inside quadrats were present in low abundance (Appendix C; or see Figure 8 in Section 3.3). Five terrestrial species were recorded in a single herb zone quadrat, and only one terrestrial species (the introduced Holcus lanatus ) was recorded in the sedge zone, in a single quadrat. Outside of the quadrats, the presence of a considerable number of Eucalypt trees (1-4 m tall) was observed, both concentrated on the outer edges of a section of the wetland and scattered within sections of the sedge zone. Numerous terrestrial shrubs ( Hakea sp., identified as Hakea macrocarpa by Smith and Mendel (2009)) were also observed within sections of the sedge zone (Figure 5). Smith and Mendel (2009) noted that this invasion of shrubs and trees, which appears to have been occurring for about 10 years, may represent the beginning of a successional process towards a terrestrial vegetation community, which is indicative of the prolonged period of quite dry conditions in the wetland (i.e. minimal inundation from Lake Crescent and limited periods of soil saturation). This successional process may continue under ongoing dry conditions, however these species would be unlikely to persist if the wetland receives a more regular pattern of inundation (as occurred between 1970 and 1997; Figure 2) in the future. No submerged species were identified in the current quadrat surveys. The only submerged species recorded in previous vegetation surveys of the Interlaken Lakeside Reserve wetland have been charophyte species (or stoneworts) and they were found in low abundance (Chilcott, 1986; Heffer, 2003; Smith and Mendel, 2009).
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(a)
(b)
(c)
Figure 5. Interlaken Lakeside Reserve wetland showing (a) encroachment of Eucalyptus sp. on the western edge of the wetland; and both (b) Eucalyptus sp. and (c) Hakea sp. scattered within the sedge zone.
13 Interlaken Lakeside Reserve – Wetland Vegetation Survey
3.3 Comparisons with previous vegetation studies 3.3.1 Water levels In the February 2010 survey, eleven of the twenty quadrats contained standing water and in these quadrats water depths ranged from 10-150 mm (see Figure 6; Appendix B). The water level in Lake Crescent at the time of the survey was 802.940 m AHD, having dropped from a peak of 803.290 m AHD in November 2009 which provided conditions that approximated a full inundation of the wetland (i.e. inundated to a depth of 300 mm over ~90% of its area). In both the February 2001 and 2002 (Heffer, 2003) and May 2009 (Smith and Mendel, 2009) surveys, all quadrats were dry, and the wetland had not been fully inundated since January 1997 (see Figure 6). As shown in Figure 2 (Section 1.2), water levels in Lake Crescent at the time of these previous surveys were well below 802.800 m AHD. This water level threshold was established by Heffer (2003) as the level below which the Interlaken Lakeside Reserve receives no input of water from Lake Crescent and the wetland is considered “dry”. However, during the dry period between 1997 and 2009, aquatic wetland vegetation is likely to have been maintained by direct rainfall over the wetland resulting in periodic soil saturation, combined with partial inundation or “waterlogging” of the wetland during brief periods when water levels rose just above 802.800 m AHD in spring 2003, 2004 and 2005. This theory is supported by the observations of researchers while working in the wetlands of the Crescent-Sorell system. Smith and Mendel (2009) reported that while there was no standing water in the wetland during May 2009, the water table was high and soils were saturated throughout the Interlaken Lakeside Reserve wetland. Similarly, Heffer (2003) also observed similar conditions in this wetland and other littoral wetland of lakes Crescent and Sorell during the 2000-2003 study period. This partial wetting of the wetland during prolonged periods of low water levels in the main basin of Lake Crescent is likely to be important for its vegetation communities, especially maintenance of the amphibious plant species.
14 Interlaken Lakeside Reserve – Wetland Vegetation Survey
Figure 6. Interlaken Lakeside Reserve wetland towards the end of an inundation period (February 2010; time of survey during the present study).
Figure 7. Interlaken Lakeside Reserve wetland during a dry period (September 2002). (D. Hardie, unpublished observation).
15 Interlaken Lakeside Reserve – Wetland Vegetation Survey
3.3.2 Frequency of occurrence The influence of inundation on the vegetation in the Interlaken Lakeside Reserve wetland is evident in Figure 8 (also see Appendix D), which compares the frequency of occurrence of plant species (expressed as the percentage of quadrats in which each species was recorded) during February 2010 (the current survey), May 2009 (Smith and Mendel, 2009) and February 2001 and February 2002 (Heffer, 2003). It should be kept in mind however, that while the results may reflect the influence of changing water levels within the wetland, comparisons between surveys in February and May may be influenced by seasonal differences in the presence and/or abundance of some species. While the total number of plant species recorded in February 2010 was less than those found the three previous surveys, the most notable difference between the surveys is the greater proportion of amphibious species in the 2010 survey (Figure 8). Similarly, fewer species, with greater relative proportions of amphibious species, were recorded in the surveys conducted by Kirkpatrick and Harwood (1981) and Chilcott (1986) when the wetland was inundated (cited by Smith and Mendel, 2009). In February 2010, 23% of all species recorded in quadrats were terrestrial, compared with 39%, 52% and 51% in February 2001 and 2002 and May 2009 respectively. The total number of quadrats in which terrestrial species occurred was also much lower in 2010 compared with previous studies, especially in the sedge zone (Figure 8). In May 2009, the plant community of Interlaken Lakeside Reserve wetland had become characteristic of a wetland that had been dry for several years (Smith and Mendel, 2009). In particular, the presence of introduced Agrostis spp. were noted by Smith and Mendel (2009) as having increased in abundance since 2003 with the potential to out-compete the native Isolepis species. While not as prevalent in the sedge zone as it was in 2001 and 2002, the occurrence of Isolepis spp. increased following inundation of the wetland in winter-spring 2009, and no introduced Agrostis spp. were detected in February 2010. Following inundation in late 2009, several other amphibious species had either increased in frequency of occurrence or reappeared in the wetland since the 2001 and 2002 surveys, including Amphibromus recurvatus , Leptinella reptans , Myriophyllum simulans , Neopaxia australisica , Potamogeton tricarinatus and Triglochin procerum (Figure 8). The presence of these species, having not been detected in May 2009, demonstrates the capacity for these plants to persist in the soil, either in the seed bank or as vegetative propagules (e.g. rhizomes), and regenerate when conditions are suitable. While these amphibious species are more prevalent in the herb zone, the return of several amphibious species to the sedge zone is also noticeable in February 2010 (compared with May 2009), particularly T. procerum . The frequency of occurrence of the amphibious species Villarsia reniformis has been consistently high in the herb zone in all surveys (80-100% of herb zone quadrats), however this species has not been recorded in the sedge zone quadrats since the February 2002 survey. Three amphibious species, Hydrocotyle muscosa , Lilaeopsis polyantha and Lachnagrostis sp . were recorded in fewer quadrats in 2010 than in 2001, 2002 or 2009 (Figure 8). This is most likely due to the increase in water depth during the 2009-2010 inundation and the relatively long period of this inundation. While these species do respond to changes in water level, they are known to be more prevalent under waterlogged conditions, and hence under wetter conditions these species would be dominated by aquatic macrophytes such as Triglochin procerum and Potamogeton tricarinatus , which thrive with the increased inundation.
16 Interlaken Lakeside Reserve – Wetland Vegetation Survey
100
90 Feb 2001 Total species = 28 80
70
60
50
40
30
20
10 Percentage of quadrats in which species occurred species which in Percentagequadrats of
0
100
90 Feb 2002 Total species = 36 80
70
60
50
40
30
20
10 Percentage of quadrats in which species occurred species which in Percentagequadrats of
0
100 May 2009 90 Total species = 27 80
70
60
50
40
30
20
10 Percentage of quadrats in which species occurred Percentagespecies which in quadrats of
0
100
90 Feb 2010 Total species = 22 80
70 Herb zone 60 Sedge zone 50
40
30
20
10 Percentage of quadrats in which species occurred species which in Percentagequadrats of
0 … zelandiae Juncussp. - Openwater Isolepisspp. Vulpia(i) sp. Bareground Junusbufonis Elocharisacuta Aira praecoxAira (i) Agrostis (i) spp. Crassula Crassula helmsii Pratiasurrepens Vulpiamyuros (i) Lachnagrostissp. Holcuslanatus (i) Poa labillardiereiPoa Euchitoncollinus Violahederaceae Hydrocotylehirta Myosotis australis Leptinellareptans Limosellaaustralis Cirsiumarvense(i) Seneciovulgaris(i) Villarsiareniformis Pseudognaphalium Trifoliumdubium (i) Lilaeopsispolyantha Triglochinprocerum Galiumgaudichaudii Baumea arthrophylla Baumea Juncusholoschoenus Hydrocotylemuscosa Neopaxiaaustralasica Carexgaudichaudiana Juncusratkowskyanus Hypericumjaponicum Rorippadictyosperma Epilobiumtasmanicum Taraxacum officinale(i) Myriophyllumsimulans Schoenustesquorum (i) Acaena novae Acaena Ranunculusamphitrichus Amphibromusrecurvatus Brachyscomeangustifolia Potamogetontricarinatus Onopordumacanthium (i) Leuconthemumvulgare (i) Leontodontaraxaciudes (i) UnidentifiedPoaceae (i) sp. Anthoxanthumodoratum (i) UnidentifiedCharophyte sp.
Submerged Amphibious Terrestrial Figure 8. Frequency of occurrence of species in February 2001, February 2002, May 2009 and February 2010, expressed as the percentage of quadrats in which each species was recorded.
17 Interlaken Lakeside Reserve – Wetland Vegetation Survey
In the sedge zone, the amphibious emergent species Baumea arthrophylla has been recorded in 100% of sedge zone quadrats consistently, and it has also re-emerged in the herb zone in the 2010 survey. Smith and Mendel (2009) observed that B. arthrophylla may be increasingly encroaching into the herb zone (although it was not recorded in herb zone quadrats in the 2009 survey) and that the area of sedge zone dominated by with B. arthrophylla may have increased in recent years. While the current survey did not conduct an assessment of the extent of distribution of vegetation zones (this would involve considerably more field work), the increased presence of B. arthrophylla in the herb zone quadrats may support this observation. Generally, the number of plant species in the sedge zone decreased between the 2001-2002 and 2009-2010 surveys, and this reduction has included both amphibious and terrestrial species (Figure 8). However, the results from February 2010 suggest that since May 2009 – following significant inundation of the wetland – there has been some recovery of native amphibious species in the sedge zone, while numbers of terrestrial species in the sedge zone decreased further. As noted previously, the recently inundated sedge zone may not be suitable habitat for the majority of terrestrial species, including the introduced species recorded in May 2009. However, as pointed out by Smith and Mendel (2009), many of the invasive terrestrial species recorded in the wetlands during previous surveys will still be present in the surrounding environment. As such, the potential for these terrestrial species to re-establish during dry conditions remains, highlighting the importance of regular inundation of the wetlands of the Crescent-Sorell system.
3.3.3 Percent cover In 2010, mean percent plant cover in herb zone quadrats was dominated by amphibious responder species including Isolepis spp., Potamogeton tricarinatus , Triglochin procerum and Villarsia reniformis (Figure 9a). In the earlier surveys, terrestrial or amphibious emergent grasses ( Agrostis spp and Lachnagrostis sp.) comprised the greatest proportion of quadrat plant cover, although some amphibious species such as Isolepis sp. and V. reniformis also had reasonable cover in 2001 and 2002. The mean percent cover of bare ground in the herb zone had also decreased substantially in 2010 (at 6.6%) when compared with previous surveys, particularly since 2001 (when bare ground mean percent cover was 42.5%). Increased cover by amphibious species is the likely reason for this. These observations reflect the pattern of increased prevalence of amphibious species in response to inundated conditions in 2010, as opposed to the dominance of bare ground and/or species better suited to drier conditions in 2001, 2002 and 2009. In the sedge zone, mean percent cover of the amphibious emergent sedge species Baumea arthrophylla has been very high across all four surveys (Figure 9b). The cover estimate for B. arthrophylla includes both standing litter and green shoots, so these results will not reflect any differences in the amount of new growth between surveys. Nevertheless it is evident that this species dominates the sedge zone in the Interlaken Lakeside Reserve wetland in both inundated and dry conditions. A reduction in the mean percent cover of bare ground is also evident since 2001, which is likely explained by an increase in Lachnagrostis sp. and Lilaeopsis polyantha in 2002, an increase in B. arthrophylla in 2009 and an increase in both B. arthrophylla and the aquatic species Triglochin procerum in 2010.
18 Interlaken Lakeside Reserve – Wetland Vegetation Survey
(a) Herb zone
45.0 Feb -01 Feb -02 May -09 Feb -10 40.0
35.0
30.0
25.0
20.0 Mean % cover % Mean 15.0
10.0
5.0
0.0 Triglochin Triglochin procerum muscosa simulans Hydrocotyle Hydrocotyle Isolepis spp. Isolepis Bare ground Bare tricarinatus Potamogeton Potamogeton Myriophyllum Myriophyllum luteoalbum Lachnagrostissp. Villarsia reniformis Villarsia Pseudognaphalium Pseudognaphalium
(b) Sedge zone
100.0 Feb -01 Feb -02 May -09 Feb -10 90.0
80.0
70.0
60.0
50.0
40.0 Mean % cover % Mean
30.0
20.0
10.0
0.0 Triglochin Triglochin procerum Lilaeopsis polyantha Baumea filiformis arthrophylla Bare ground Bare Lachnagrostis
Figure 9. Mean percent cover of bare ground and dominant plant species recorded within the (a) herb and (b) sedge zones of the Interlaken Lakeside Reserve wetland in February 2001, February 2002, May 2009 and February 2010. Within each vegetation zone, dominant species were identified as those with a frequency of occurrence of 80% or greater in one or more of the wetland surveys.
19 Interlaken Lakeside Reserve – Wetland Vegetation Survey
3.3.4 Plant height For dominant plant species that were recorded in both 2010 and in earlier surveys, mean plant heights were considerably greater in both vegetation zones in February 2010 (Figure 10). These differences were notable for both amphibious species and species which also tolerate drier conditions (such as Lachnagrostis sp. in the herb zone). Furthermore, it appears that the differences in plant heights between the 2001, 2002 and 2009 surveys ( in “dry” conditions) and the 2010 survey (in “wet” conditions) are generally much greater than any differences between the February and May sampling periods (which are potentially influenced by seasonal variation in growth patterns between February and May). Therefore, it is likely that the substantial increase in heights observed in February 2010 were primarily related to the greater water depths in the wetland prior to and during the current survey. An interesting exception was the mean plant height for the amphibious responder Lilaeopsis polyantha , which was highest in the sedge zone during the 2002 survey. Similarly, the highest frequency of occurrence and mean percent cover values for this species were recorded in 2002 (Figure 8 and Figure 9). Although mean cover is still relatively low when compared with more dominant species such as B. arthrophylla , the reason for this apparent “spike” in prevalence during the 2002 survey, undertaken during dry conditions, is unknown. Smith and Mendel (2009) also observed that some amphibious responder species, such as Villarsia reniformis , Hydrocotyle muscosa and Triglochin procerum occurred as small rosettes and/or with small leaves and at ground level in May 2009. This was noted as a response to drier conditions, with these species persisting in a morphology more suited to a mudflat environment. In February 2010, the morphology of these species had responded to inundation by growing in height with an increase in water level (as reflected by mean plant heights in Figure 10). With inundation, the plants also became more upright ( cf. a prostrate form under waterlogged conditions) and less rigid in structure.
20 Interlaken Lakeside Reserve – Wetland Vegetation Survey
(a) Herb zone
600 Feb -01 Feb -02 May -09 Feb -10
500
400
300
200 Mean plant height (mm) heightplant Mean
100
0 sp. Villarsia Triglochin Triglochin procerum reniformis muscosa simulans Hydrocotyle Hydrocotyle Isolepis spp. Isolepis tricarinatus Agrostis spp. Agrostis Potamogeton Potamogeton Lachnagrostis Myriophyllum Myriophyllum um luteoalbum um Pseudognaphali
(b) Sedge zone
800 Feb -01 Feb -02 May -09 Feb -10
700
600
500
400
300 Mean plant height (mm) heightplant Mean 200
100
0 Triglochin Triglochin procerum Lilaeopsis polyantha Baumea filiformis arthrophylla Lachnagrostis
Figure 10. Mean height of dominant plant species recorded within the (a) herb and (b) sedge zones of the Interlaken Lakeside Reserve wetland February 2001, February 2002, May 2009 and February 2010. Within each vegetation zone, dominant species were identified as those with a frequency of occurrence of 80% or greater in one or more of the wetland surveys.
21 Interlaken Lakeside Reserve – Wetland Vegetation Survey
4 Conclusions and management recommendations The main observations and conclusions that can be made from this study (and comparisons with previous surveys) are: • Fewer total species, but a greater occurrence and cover of amphibious species compared with terrestrial species, were recorded following inundation of the wetland during winter- spring 2009. • The height of plants increased with an increase in water depths within the wetland. • Many of the species present within the Interlaken Lakeside Reserve wetland have survival mechanisms (including vegetative, seed bank, or underground rhizomes and tubers) to persist through extended dry periods. • The sedge zone appears to have increased in size (i.e. surface area) in some areas (i.e. a transition from herb to sedge zone), most likely due to a lack of regular inundation. • Prolonged dry periods experienced by the wetland have resulted in the increased abundance of terrestrial species, including many introduced species (as found in the May 2009 survey). Some species of shrubs and trees have also begun to invade the wetland from the western shoreline, due to a lack of full inundation in recent years. • Short-term colonisation of terrestrial plant species is likely to occur during drying events, however regular inundation of the wetland will assist the aquatic species to persist. • While the current study showed reasonable recovery of some of the aquatic plant species following inundation, longer-term impacts of extended drying events may not be evident without a more comprehensive survey of the wetland vegetation. It is difficult to assess if changes in species composition are due to the water regime of the wetland in recent years or an artefact of the sampling regime.
A key assumption of this study, and that conducted by Heffer (2003), is that management recommendations applicable to the Interlaken Lakeside Reserve wetland would also benefit the other littoral wetlands which are connected hydrologically to lakes Crescent and Sorell (i.e. Clyde Marsh, Kemps/Kermodes Marsh, Silver Plains Marsh and Robertsons Marsh). Therefore, to encourage and maintain a high diversity of aquatic vegetation within the wetlands associated with the Crescent-Sorell system, it is recommended that an appropriate water regime be employed. This can be achieved by implementing the operating guidelines in the current Lakes Sorell and Crescent Water Management Plan (DPIWE, 2005) in conjunction with recommendations made by Heffer (2003). Additionally, as recommended by Heffer (2003), to ensure inundation events in spring-summer are of sufficient duration to allow for vegetation reproduction and recruitment in Lake Crescent and Lake Sorell, drawdowns in water levels in both lakes during summer should follow natural patterns (i.e. decreases in water levels approximate natural rates and magnitudes). For example, it is recommended than when full inundation of the wetlands occurs in either lake and this extends into late summer, the wetlands should still be inundated by at least 10 mm (water levels of 803.900 m AHD and 803.000 m AHD in Lake Sorell and Lake Crescent, respectively) at the end of February. To assist the implementation of an appropriate water regime, the Water Availability Model for lakes Crescent and Sorell (DPIPWE, unpubl. data) should be executed annually (at approximately the beginning of September) to predict the probability of wetland inundation for
22 Interlaken Lakeside Reserve – Wetland Vegetation Survey the upcoming season (spring-summer). The outputs from the model should be considered in light of the preferred operating rules for the wetlands. Consideration of natural climatic conditions being experienced at the time the modelling is undertaken should also be reflected in water level management decisions for the lakes. For example, if water levels in lakes Sorell and Crescent are reasonably high at the beginning of winter and the region experiences higher than average rainfall during winter, then it would be reasonable to expect that under natural conditions, the wetlands would be inundated during the following spring-summer (and therefore that management of the water levels in the lakes would allow this to occur). Conversely, if water levels in the lakes are low at the onset of winter and the catchment experiences below average winter rainfall, then the wetlands might be expected to have lower water levels or be dry. To monitor the effect of the water regime, it is recommended that vegetation and water level monitoring should be carried out in at least one littoral wetland of Lake Crescent and one of Lake Sorell (most likely the public wetlands, Interlaken Lakeside Reserve and Robertsons Marsh, respectively). The installation of a water level gauge (surveyed to m AHD) to record water level changes over a minimum 12-month period in each of the chosen wetlands would help further explore seasonal water level patterns in the wetlands, especially when they are not inundated by water from the main basins of the lakes. This monitoring would also help to determine the relationship between water levels in the wetlands and in lakes Crescent and Sorell. Monitoring of the vegetation should be undertaken following the guidelines in the current Lakes Sorell and Crescent Water Management Plan (DPIWE, 2005) to assess any long- term changes in plant species presence and community composition. Given that a requirement within the Water Management Plan is to assess the effects of inundation on wetland vegetation only once every 5 years, it is recommended that future monitoring consists of the following elements: • That vegetation within a wetland associated with both Lake Crescent (Interlaken Lakeside Reserve wetland) and Lake Sorell (e.g. Robertsons Marsh) be surveyed to account for differences in water level regimes of the two lakes. • That the vegetation surveys are more extensive in their design (i.e. sample more than the 20 quadrats used by previous studies) to encompass a greater area across each of the wetlands. This increase in sampling effort would aim to detect greater numbers of plant species (therefore improving the ability to detect a greater proportion of all plant species present) and improve the ability of the monitoring strategy to detect long-term changes in the vegetation communities within the wetlands.
23 Interlaken Lakeside Reserve – Wetland Vegetation Survey
5 References Australian Government (2010) Australian Wetlands Database . Department of the Environment, Water, Heritage and the Arts. http://www.environment.gov.au/water/topics/wetlands/database/index.html. Viewed 11 July, 2010. Brock M.A. and Casanova, M.T. (2000) Are there plants in your wetland? Revegetating wetlands. LWRRDC, UNE, DLWC and EA. Brock, M.A., Casanova, M.T. and Berridge, S.M. (2000) Does your wetland flood and dry? LWRRDC, UNE, DLWC and EA. CFEV (2005). Conservation of Freshwater Ecosystem Values Project Database. v. 1.0 (periodic updating). Chilcott, S.J. (1986) Lake Crescent Environmental Impact Statement. The effects of a 0.5m water level increase of Lake Crescent. Inland Fisheries Commission. Commissioned by the Rivers and Water Supply Commission and the Clyde Water Trust, Hobart. DPIWE( 2005) Lakes Sorell and Crescent Water Management Plan . Department of Primary Industries, Water and Environment, Hobart. DPIPWE (2010). Response of the Crescent-Sorell system and golden galaxias ( Galaxias auratus ) populations to water level variability during 2009: a period of drought and post-drought recovery. Water Assessment Aquatic Ecology Report Series, No. WA 10/01 . Water and Marine Resources Division. Department of Primary Industries, Parks, Water and Environment, Hobart, Tasmania. Heffer, D.K. (2003) Wetlands of Lakes Sorell and Crescent: Conservation and Management. Rehabilitation of Lakes Sorell and Crescent Report Series No. 6/1 .Inland Fisheries Service, Hobart. Kirkpatrick, J.B. and Harwood, C.E. (1981) The conservation of Tasmanian wetland macrophytic vegetation and communities. Tasmanian Conservation Trust Inc, Hobart. Moore, P.D. and Chapman, S.B. (1986) Methods in plant ecology . Blackwell Scientific Publications, Oxford, UK. Ramsar (2010) The Ramsar Convention on Wetlands . Ramsar Convention Bureau. http://www.ramsar.org. Viewed 11 July, 2010. Smith, J.A. (2002) Seed Banks, Community Dynamics and Species Persistence in Tasmanian Temporary Wetlands. PhD Thesis, University of Tasmania, Hobart. Smith, J. and Mendel, L. (2009) An assessment of the effectiveness of the inundation regime on wetland plant species at Lake Crescent. A report to the Department of Primary Industries and Water, Hobart.
24 Interlaken Lakeside Reserve – Wetland Vegetation Survey
Appendix A – Conservation of Freshwater Ecosystem Values (CFEV) assessment of Lakes Sorell and Crescent, and surrounding areas Data sourced from the CFEV database (CFEV database, v1.0), Conservation of Freshwater Ecosystem Values Project, Water and Marine Resources Division, Department of Primary Industries, Parks, Water and Environment, Tasmania, accessed 18 May 2010). Refer to Figure 1 of the main report for ecosystem locations. See following glossary for an explanation of CFEV terminology and assessment framework. CFEV data ICV SV name SV type RCV Important biophysical class Naturalness LAKES Lake Crescent Very High Platypus Phylogenetically Distinct A Tree assemblage (T35) - A mosaic Medium (0.63) (Ornithorynchus anatinus ) Fauna Species of dry sclerophyll, highland Waterbody eucalypt, alpine herbfield and significantly altered Golden galaxias Threatened Fauna Species highland grasslands on the south from natural condition. (Galaxias auratus ) eastern Central Plateau from Bradys Lake to Lakes Sorell and Key drivers of Great crested grebe Threatened Fauna Species Crescent ( Acacia dealbata, condition include poor (Podiceps cristatus ) Eucalyptus dalrympleana, condition for fish Eucalyptus delegatensis, Eucalyptus condition (native fish gunnii, Eucalyptus pauciflora, Sedge/rush wetland Priority Flora Communities and exotic fish) and Eucalyptus rodwayi, Eucalyptus moderate condition for rubida, Notelaea ligustrina) hydrology (abstraction Highland grassy sedgeland Priority Flora Communities and lake level
manipulation). Highland Poa grassland Priority Flora Communities
25 Interlaken Lakeside Reserve – Wetland Vegetation Survey
CFEV data ICV SV name SV type RCV Important biophysical class Naturalness Lake Sorell Very High Platypus Phylogenetically Distinct A Tyler (biogeochemical) Medium (0.85) (Ornithorynchus anatinus ) Fauna Species classification (TY4) – Mesotrophic Waterbody upland lakes - Shallow, productive significantly altered Golden galaxias Threatened Fauna Species lakes often with dense from natural condition. (Galaxias auratus ) macrophytes and/or fringing Key drivers of wetlands; e.g. Lakes Sorell and condition include poor Sedge/rush wetland Priority Flora Communities Crescent. condition for fish condition (native fish and exotic fish) and Freshwater snail Priority Fauna Species moderate to high (Austropyrgus pagodoides ) condition for lake level
manipulation and Highland Poa grassland Priority Flora Communities catchment disturbance. WETLANDS Interlaken Very High Platypus Phylogenetically Distinct A Tree assemblage (T35) - A mosaic High (0.89) Wetland in Lakeside (Ornithorynchus anatinus ) Fauna Species of dry sclerophyll, highland natural or near-natural Reserve eucalypt, alpine herbfield and condition. Drooping sedge Threatened Flora Species highland grasslands on the south Key drivers of (Carex longebrachiata ) eastern Central Plateau from condition include Bradys Lake to Lakes Sorell and moderate condition for Highland grassy sedgeland Priority Flora Communities Crescent ( Acacia dealbata, native riparian Eucalyptus dalrympleana, vegetation and native Eucalyptus delegatensis, Eucalyptus Highland Poa grassland Priority Flora Communities wetland vegetation. gunnii, Eucalyptus pauciflora, Eucalyptus rodwayi, Eucalyptus rubida, Notelaea ligustrina)
26 Interlaken Lakeside Reserve – Wetland Vegetation Survey
CFEV data ICV SV name SV type RCV Important biophysical class Naturalness Clyde Marsh Very High Platypus Phylogenetically Distinct A Dominant wetland vegetation (Dv- High (1.00) Wetland in (Ornithorynchus anatinus ) Fauna Species Ws) – Sedge rush wetland. natural or near-natural condition. Sedge/rush wetland Priority Flora Communities
Highland grassy sedgeland Priority Flora Communities
Highland Poa grassland Priority Flora Communities
Eucalyptus rodwayi forest Threatened Flora Communities
Great crested grebe Threatened Fauna Species (Podiceps cristatus) Bullies Marsh Very High Platypus Phylogenetically Distinct B Tree assemblage (T35) - A mosaic High (1.00) Wetland in (Ornithorynchus anatinus ) Fauna Species of dry sclerophyll, highland natural or near-natural eucalypt, alpine herbfield and condition. Sedge/rush wetland Priority Flora Communities highland grasslands on the south eastern Central Plateau from Eucalyptus rodwayi forest Threatened Flora Bradys Lake to Lakes Sorell and Communities Crescent ( Acacia dealbata, Eucalyptus dalrympleana, Eucalyptus delegatensis, Eucalyptus gunnii, Eucalyptus pauciflora, Eucalyptus rodwayi, Eucalyptus rubida, Notelaea ligustrina)
27 Interlaken Lakeside Reserve – Wetland Vegetation Survey
CFEV data ICV SV name SV type RCV Important biophysical class Naturalness Agnews High Platypus Phylogenetically Distinct B Wetland physical classification High (1.00) Wetland in Marsh (Ornithorynchus anatinus ) Fauna Species (WLP30) Wetland located east of natural or near-natural Tyler corridor, in non-responsive condition. Highland Poa grassland Priority Flora Communities geomorphology, 10-100 ha area, at >800 m elevation. Eucalyptus rodwayi forest Threatened Flora Communities Wetlands High Platypus Phylogenetically Distinct B Wetland physical classification High (1.00) Wetland in behind (Ornithorynchus anatinus ) Fauna Species (WLP30) Wetland located east of natural or near-natural Boathouse Tyler corridor, in non-responsive condition. shore Eucalyptus rodwayi forest Threatened Flora geomorphology, 10-100 ha area, at Communities >800 m elevation. Kemps/ Very High Platypus Phylogenetically Distinct A Tree assemblage (T35) - A mosaic Medium (0.63) Kermodes (Ornithorynchus anatinus ) Fauna Species of dry sclerophyll, highland Wetland significantly Marsh eucalypt, alpine herbfield and altered from natural Sedge/rush wetland Priority Flora Communities highland grasslands on the south condition. eastern Central Plateau from Key drivers of Bradys Lake to Lakes Sorell and condition include: poor Crescent ( Acacia dealbata, condition for Eucalyptus dalrympleana, hydrology (abstraction) Eucalyptus delegatensis, Eucalyptus and moderate gunnii, Eucalyptus pauciflora, condition for native Eucalyptus rodwayi, Eucalyptus vegetation (riparian rubida, Notelaea ligustrina) vegetation and native wetland vegetation), and catchment disturbance.
28 Interlaken Lakeside Reserve – Wetland Vegetation Survey
CFEV data ICV SV name SV type RCV Important biophysical class Naturalness Silverplains High Platypus Phylogenetically Distinct B Tree assemblage (T35) - A mosaic High (1.00) Wetland in Marsh (Ornithorynchus anatinus ) Fauna Species of dry sclerophyll, highland natural or near-natural eucalypt, alpine herbfield and condition. Eucalyptus rodwayi forest Threatened Flora highland grasslands on the south Communities eastern Central Plateau from Bradys Lake to Lakes Sorell and Crescent ( Acacia dealbata, Eucalyptus dalrympleana, Eucalyptus delegatensis, Eucalyptus gunnii, Eucalyptus pauciflora, Eucalyptus rodwayi, Eucalyptus rubida, Notelaea ligustrina) Robertsons Very High Platypus Phylogenetically Distinct B Tree assemblage (T35) - A mosaic High (1.00) Wetland in Marsh (Ornithorynchus anatinus ) Fauna Species of dry sclerophyll, highland natural or near-natural eucalypt, alpine herbfield and condition. Sedge/rush wetland Priority Flora Communities highland grasslands on the south eastern Central Plateau from Short paperbark swamp Priority Flora Communities Bradys Lake to Lakes Sorell and Crescent ( Acacia dealbata, Eucalyptus dalrympleana, Eucalyptus rodwayi forest Threatened Flora Eucalyptus delegatensis, Eucalyptus Communities gunnii, Eucalyptus pauciflora, Eucalyptus rodwayi, Eucalyptus rubida, Notelaea ligustrina)
29 Interlaken Lakeside Reserve – Wetland Vegetation Survey
CFEV data ICV SV name SV type RCV Important biophysical class Naturalness Hazelwoods High Platypus Phylogenetically Distinct C Tree assemblage (T35) - A mosaic High (0.97) Wetland in Lagoon (Ornithorynchus anatinus ) Fauna Species of dry sclerophyll, highland natural or near-natural eucalypt, alpine herbfield and condition. Highland grassy sedgeland Priority Flora Communities highland grasslands on the south Key drivers of eastern Central Plateau from condition include Highland Poa grassland Priority Flora Communities Bradys Lake to Lakes Sorell and moderate condition for Crescent ( Acacia dealbata, catchment Eucalyptus dalrympleana, Eucalyptus rodwayi forest Threatened Flora disturbance. Eucalyptus delegatensis, Eucalyptus Communities gunnii, Eucalyptus pauciflora, Eucalyptus rodwayi, Eucalyptus rubida, Notelaea ligustrina) Tea-tree High Platypus Phylogenetically Distinct C Tree assemblage (T35) - A mosaic High (1.00) Wetland in Swamp (Ornithorynchus anatinus ) Fauna Species of dry sclerophyll, highland natural or near-natural eucalypt, alpine herbfield and condition. Highland grassy sedgeland Priority Flora Communities highland grasslands on the south eastern Central Plateau from Highland Poa grassland Priority Flora Communities Bradys Lake to Lakes Sorell and Crescent ( Acacia dealbata, Eucalyptus dalrympleana, Eucalyptus rodwayi forest Threatened Flora Eucalyptus delegatensis, Eucalyptus Communities gunnii, Eucalyptus pauciflora, Eucalyptus rodwayi, Eucalyptus rubida, Notelaea ligustrina)
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CFEV data ICV SV name SV type RCV Important biophysical class Naturalness RIVERS Clyde River High Platypus Phylogenetically Distinct C (100%) Tree assemblage (T35) - A mosaic High (94%); Medium (summary of (75%); (Ornithorynchus anatinus ) Fauna Species of dry sclerophyll, highland (6%) 16 river Moderate eucalypt, alpine herbfield and Key drivers of sections (25%) Golden galaxias (Galaxias Threatened Fauna Species highland grasslands on the south condition include poor immediately auratus ) eastern Central Plateau from condition for exotic downstream Bradys Lake to Lakes Sorell and fish and moderate of Lake Highland grassy sedgeland Priority Flora Communities Crescent ( Acacia dealbata, condition for Crescent) Eucalyptus dalrympleana, macroinvertebrate Eucalyptus delegatensis, Eucalyptus Highland Poa grassland Priority Flora Communities condition (flow gunnii, Eucalyptus pauciflora, variability), and
Eucalyptus rodwayi, Eucalyptus sediment input. Eucalyptus rodwayi forest Threatened Flora rubida, Notelaea ligustrina) Communities Agnews Creek Very High Platypus Phylogenetically Distinct A (100%) Tree assemblage (T35) - A mosaic High (100%) (summary of (75%); (Ornithorynchus anatinus ) Fauna Species of dry sclerophyll, highland Key drivers of 4 river High (25%) eucalypt, alpine herbfield and condition include poor sections Highland Poa grassland Priority Flora Communities highland grasslands on the south condition for exotic immediately eastern Central Plateau from fish and moderate upstream of Eucalyptus rodwayi forest Threatened Flora Bradys Lake to Lakes Sorell and condition for Lake Communities Crescent ( Acacia dealbata, catchment Crescent) Eucalyptus dalrympleana, disturbance. Eucalyptus delegatensis, Eucalyptus gunnii, Eucalyptus pauciflora, Eucalyptus rodwayi, Eucalyptus rubida, Notelaea ligustrina)
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CFEV data ICV SV name SV type RCV Important biophysical class Naturalness Mountain High Platypus Phylogenetically Distinct B (100%) Fluvial geomorphic river type (G22) High (100%) Creek (67%); (Ornithorynchus anatinus ) Fauna Species – Southern Midlands - Dolerite Key drivers of (summary of Moderate plateau in headwaters of western condition include poor 6 river (33%) Highland grassy sedgeland Priority Flora Communities rivers; Predominantly dolerite, condition for exotic sections rounded interfluves and broad fish. immediately Long-nosed swamp wallaby Threatened Flora Species alluvial valleys; Dry hills increase in upstream of grass East (70%). Lake Sorell) (Amphibromus macrorhinus ) Tree assemblage (T36) - Upland rainforest wet eucalypt forest, woodland and sedgy grasslands of the Southern Central Plateau. There is also an outlying occurrence of this community on the south eastern side of the Ben Lomond massif. ( Cenarrhenes nitida, Eucalyptus coccifera, Eucalyptus dalrympleana, Eucalyptus delegatensis, Eucalyptus gunnii, Eucalyptus pauciflora, Eucalyptus rodwayi, Eucalyptus subcrenulata, Leptospermum lanigerum, Nothofagus cunninghamii, Phebalium squameum, Phyllocladus aspleniifolius, Pittosporum bicolor, Richea scoparia, Tasmannia lanceolata ) (30%)
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CFEV data ICV SV name SV type RCV Important biophysical class Naturalness Silverplains Very High Platypus Phylogenetically Distinct B (100%) Tree assemblage (T35) - A mosaic High (100%) Creek (13%); (Ornithorynchus anatinus ) Fauna Species of dry sclerophyll, highland Key drivers of (summary of High eucalypt, alpine herbfield and condition include poor 8 river (50%); Highland grassy sedgeland Priority Flora Communities highland grasslands on the south condition for exotic sections Moderate eastern Central Plateau from fish and moderate immediately (38%) Highland Poa grassland Priority Flora Communities Bradys Lake to Lakes Sorell and condition for upstream of Crescent ( Acacia dealbata, catchment Lake Sorell) Eucalyptus dalrympleana, Mountain shrimp Phylogenetically Distinct disturbance. Eucalyptus delegatensis, Eucalyptus (Anaspides tasmaniae ) Fauna Species gunnii, Eucalyptus pauciflora,
Eucalyptus rodwayi, Eucalyptus Eucalyptus rodwayi forest Threatened Flora rubida, Notelaea ligustrina) Communities
33 Interlaken Lakeside Reserve – Wetland Vegetation Survey
CFEV Glossary Biophysical class: An individual classification group for each ecosystem component (geomorphic, hydrological, biological) that are used to characterise each of the ecosystem spatial units. Each ecosystem spatial unit (a river section, for example) is characterised by the set of individual biophysical classes from each of the ecosystem components . Condition: The degree of change from the ‘natural’ or pre-European state (also see Naturalness) Integrated Conservation Value (ICV): The conservation value of an ecosystem spatial unit expressed as the relative importance of that unit where Representative Conservation Value has been combined with its Special Value rating. An ecosystem can be ranked as having Very High, High, Moderate or Lower Integrated Conservation Value. Naturalness score/N-score: The final naturalness score attributed to an ecosystem spatial unit derived from the aggregated condition scores of individual condition variables for a particular ecosystem theme. The Naturalness score for each ecosystem ranges continuously between 1 ('best case' or equivalent to natural reference) and 0 ('worst case' i.e. very altered from natural reference) without distinct internal thresholds in condition. These descriptors and ranges are provided for guidance only (i.e. there are no sharp boundaries between condition descriptor states). Naturalness: A measure of the departure from pre-European natural reference condition. This was derived for each ecosystem unit within the audit process as a single score based on a variety of sources of biophysical information. Representative Conservation Value (RCV): The conservation value of an ecosystem spatial unit expressed as the relative importance of that example of the particular representative component with a priority on spatial units of high naturalness. An ecosystem can be rated as A, B or C class for Representative Conservation Value, where A is the first group of sites selected (highly representative), B is the second (moderately representative) and C is the remainder of sites selected (least representative). River section: The section of river in the drainage network between confluences. Special Value (SV)s: Unique or ‘distinctive’ conservation values other than those captured by the representativeness assessment process. These include values such as threatened flora and fauna species, threatened flora and fauna communities, priority geomorphic and limnological features and important bird sites. Outstanding Special Values have higher conservation significance than undifferentiated and non-outstanding ones.
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CFEV Assessment Framework
Ecosystem Type Other Groundwater Dependent Ecosystems Rivers, Estuaries, Wetlands, Waterbodies, Saltmarshes and Karst (locations only)
Classification Condition assessment Statewide audit
Physical and Biological classes (R) Naturalness score (N)
Attributed spatial units
Spatial selection
Representative Conservation Value
Special Values (D) Conservation evaluation Integrated Conservation Value
Land Tenure Security
Conservation Management Priorities i) Priority to improve current management of freshwater ecosystem values (CMP-Immediate) ii) Priority to maintain freshwater ecosystem values (CMP-Potential)
Flowchart showing steps in the CFEV framework (statewide audit and conservation evaluation) for assessing freshwater dependent ecosystems.
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Appendix B – Location and environment data for quadrats surveyed in February 2010. Note: all map coordinates are in AGD 66. Quadrat Heffer Wind Wind Cloud Water level number (2003) Zone Easting Northing direction speed cover (%) (mm) Comments 1 S1 Sedgeland 512249 5332006 SW Light 98 0 2 H1 Herbland 512210 5331993 SW Light 95 75 3 H2 Herbland 512277 5332510 SE Light 65 0 4 S2 Sedgeland 512080 5332501 SE Light 25 15 New waypoint. Original stake not located. 5 H3 Herbland 512270 5332998 SE Light 15 0 6 S3 Sedgeland 512077 5333053 SE Light 15 0 Light- Originally a herbland quadrat but was mixed 7 H4 Herbland 512408 5333437 E-SE Moderate 15 150 herbland/sedgeland in 2010. 8 S4 Sedgeland 512204 5333503 E-SE Light 15 0 Originally a herbland quadrat but was mixed 9 H5 Herbland 512594 5333611 SE Moderate 5 0 herbland/sedgeland in 2010. Light- 10 H6 Herbland 512561 5333813 SE Moderate 5 100 New waypoint. Original stake not located. Light- 11 S5 Sedgeland 512529 5334003 SE Moderate 5 50 Light- 12 S6 Sedgeland 512516 5334166 SE Moderate 5 30 13 H8 Herbland 512784 5333752 E-SE Moderate 5 40 Animal/swan has been lying/nesting in 14 S8 Sedgeland 512810 5333943 N Light 2 10 quadrat. New location. Original stake not located. Forgot to take waypoint but approx. 2m from 15 H7 Herbland ? ? N Light 0 80 original location.
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Quadrat Heffer Wind Wind Cloud Water level number (2003) Zone Easting Northing direction speed cover (%) (mm) Comments 16 S7 Sedgeland 512877 5334330 NE Very light 0 20 17 H9 Herbland 513033 5333815 N Moderate 3 0 Light- 18 S9 Sedgeland 513139 5333977 N Moderate 5 70 Animal track through quadrat. Light- 19 S10 Sedgeland 513272 5334114 N Moderate 6 100 Light- 20 H10 Herbland 513400 5334266 N Moderate 10 0
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Appendix C – Vegetation data collected for quadrat surveys in February 2010
% Cover Quadrat Water level (Braun- Plant height number (mm) Species name Blanquet) (mm) 1 0 Bare ground 4 1 0 Baumea arthrophylla 3 350 1 0 Isolepis fluitans 1 20 1 0 Lilaeopsis polyantha + 30 1 0 Triglochin procerum + 300 2 75 Amphibromus recurvatus 1 400 2 75 Isolepis fluitans 2 200 2 75 Myriophyllum simulans + 20 2 75 Open water 2 2 75 Potamogeton tricarinatus 2 300 2 75 Triglochin procerum 4 650 2 75 Villarsia reniformis 1 300 3 0 Amphibromus recurvatus 1 50 3 0 Bare ground 3 0 3 0 Baumea arthrophylla + 200 3 0 Carex gaudichaudiana 1 200 3 0 Isolepis fluitans 2 30 3 0 Leptinella reptans 1 20 3 0 Limosella australis + 40 3 0 Myriophyllum simulans + 30 3 0 Potamogeton tricarinatus + 30 3 0 Triglochin procerum 4 600 3 0 Villarsia reniformis 2 200 4 0 Baumea arthrophylla 5 600 4 0 Hydrocotyle muscosa + 10 5 0 Lachnagrostis sp. (filiformis or aemula) 4 500 5 0 Bare ground 1 5 0 Galium gaudichaudii 2 150 5 0 Hydrocotyle muscosa 1 20 5 0 Leptinella reptans + 15 5 0 Myriophyllum simulans + 50 5 0 Neopaxia australasica 2 100 5 0 Potamogeton tricarinatus 1 150 5 0 Triglochin procerum 3 500 5 0 Villarsia reniformis 2 200 6 0 Bare ground 1 6 0 Baumea arthrophylla 5 900 6 0 Isolepis fluitans + 250 6 0 Potamogeton tricarinatus + 150 6 0 Triglochin procerum 2 600
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% Cover Quadrat Water level (Braun- Plant height number (mm) Species name Blanquet) (mm) 7 150 Baumea arthrophylla 5 900 7 150 Hydrocotyle muscosa + 120 7 150 Isolepis fluitans 2 300 7 150 Open water 2 7 150 Potamogeton tricarinatus 2 300 7 150 Villarsia reniformis 2 300 8 0 Baumea arthrophylla 5 700 8 0 Triglochin procerum 2 600 9 0 Bare ground 1 9 0 Baumea arthrophylla 5 700 9 0 Hydrocotyle muscosa + 50 9 0 Isolepis fluitans + 250 9 0 Leptinella reptans 1 60 9 0 Potamogeton tricarinatus + 100 9 0 Triglochin procerum 2 500 9 0 Villarsia reniformis + 150 10 100 Lachnagrostis sp. (filiformis or aemula) 1 300 10 100 Galium gaudichaudii + 250 10 100 Hydrocotyle muscosa + 150 10 100 Isolepis fluitans 5 300 10 100 Juncus holoschoenus + 250 10 100 Leptinella reptans + 150 10 100 Myriophyllum simulans + 150 10 100 Open water 1 10 100 Potamogeton tricarinatus 1 200 10 100 Triglochin procerum 2 500 10 100 Villarsia reniformis 3 300 11 50 Baumea arthrophylla 5 700 11 50 Holcus lanatus + 700 11 50 Triglochin procerum 2 800 12 30 Baumea arthrophylla 5 800 12 30 Triglochin procerum 1 700 13 40 Lachnagrostis sp. (filiformis or aemula) 1 250 13 40 Bare ground 1 13 40 Baumea arthrophylla + 400 13 40 Brachyscome augustifolia 2 200 13 40 Hydrocotyle muscosa 1 50 13 40 Isolepis fluitans 3 200 13 40 Juncus holoschoenus 1 100 13 40 Leptinella reptans 1 30 13 40 Lilaeopsis polyantha + 70 13 40 Myriophyllum simulans 1 100 13 40 Potamogeton tricarinatus 3 200 13 40 Triglochin procerum + 300
39 Interlaken Lakeside Reserve – Wetland Vegetation Survey
% Cover Quadrat Water level (Braun- Plant height number (mm) Species name Blanquet) (mm) 13 40 Villarsia reniformis 1 200 14 10 Baumea arthrophylla 5 500 14 10 Potamogeton tricarinatus + 150 14 10 Triglochin procerum 2 600 15 80 Lachnagrostis sp. (filiformis or aemula) + 200 15 80 Isolepis fluitans 5 200 15 80 Lilaeopsis polyantha + 100 15 80 Myriophyllum simulans + 150 15 80 Potamogeton tricarinatus 4 200 15 80 Triglochin procerum 2 600 15 80 Villarsia reniformis 2 300 16 20 Baumea arthrophylla 5 800 16 20 Triglochin procerum 1 600 17 0 Lachnagrostis sp. (filiformis or aemula) 1 350 17 0 Bare ground 2 17 0 Baumea arthrophylla + 650 17 0 Hydrocotyle muscosa + 20 17 0 Isolepis fluitans 3 50 17 0 Leptinella reptans + 70 17 0 Lilaeopsis polyantha + 100 17 0 Limosella australis + 60 17 0 Myriophyllum simulans 2 70 17 0 Neopaxia australasica 2 100 17 0 Potamogeton tricarinatus 1 100 17 0 Triglochin procerum 3 500 17 0 Vulpia sp .(myuros or bromoides) 1 500 17 0 Villarsia reniformis 2 250 18 70 Baumea arthrophylla 5 600 18 70 Triglochin procerum + 200 19 100 Baumea arthrophylla 5 800 19 100 Triglochin procerum 1 700 20 0 Lachnagrostis sp. (filiformis or aemula) 1 100 20 0 Bare ground 1 20 0 Eleocharis acuta 1 300 20 0 Isolepis fluitans 4 50 20 0 Juncus sp. 2 600 20 0 Juncus holoschoenus 1 200 20 0 Myriophyllum simulans + 20 20 0 Neopaxia australasica 2 70 20 0 Poa labilliardieri 2 600 20 0 Potamogeton tricarinatus 2 150 20 0 Triglochin procerum 2 400
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Appendix D – Species recorded in quadrat surveys in February 2001, February 2002, May 2009 and February 2010 Frequency of occurrence of species, expressed as the number of quadrats in which species was recorded, in February 2010 (current survey), May 2009 (Smith and Mendel, 2009), and February 2001 and 2002 (Heffer, 2003). FG (broad functional group): S = submerged; A = amphibious; T = terrestrial. Status: n = native; i= introduced. Species FG Status Herb zone Sedge zone Combined zones Feb Feb May Feb Feb Feb May Feb Feb Feb May Feb 2001 2002 2009 2010 2001 2002 2009 2010 2001 2002 2009 2010 Total number of quadrats 10 10 10 10 10 10 10 10 20 20 20 20 Bare ground 10 7 10 6 10 8 2 19 15 10 8 Open water 3 3 Unidentified Charophyte sp. S n 1 1 Amphibromus recurvatus A n 2 1 2 2 1 2 Baumea arthrophylla A n 1 3 5 10 10 10 10 11 13 10 15 Carex gaudichaudiana A n 1 1 Crassula helmsii A n 1 1 1 1 Elocharis acuta A n 1 1 1 1 Hydrocotyle hirta A n 1 3 1 3 Hydrocotyle muscosa A n 5 7 8 6 2 7 1 7 14 8 7 Hypericum japonicum A n 2 2 2 1 1 3 3 2 Isolepis spp . A n 10 9 4 9 4 8 2 14 17 4 11 Junus bufonis A n 1 1 Juncus holoschoenus A n 3 3 Juncus ratkowskyanus A n 1 1 Juncus sp. A n? 1 1 Lachnagrostis sp. A n 10 10 10 6 6 9 4 16 19 14 6 Leptinella reptans A n 3 4 4 6 3 4 4 6 Lilaeopsis polyantha A n 6 7 4 3 3 10 1 9 17 4 4
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Species FG Status Herb zone Sedge zone Combined zones Feb Feb May Feb Feb Feb May Feb Feb Feb May Feb 2001 2002 2009 2010 2001 2002 2009 2010 2001 2002 2009 2010 Limosella australis A n 2 1 2 1 3 1 2 Myriophyllum simulans A n 4 8 5 9 8 Neopaxia australasica A n 1 3 1 1 1 3 Potamogeton tricarinatus A n 10 1 2 1 12 Pratia surrepens A n 1 1 1 1 Ranunculus amphitrichus A n 1 1 Triglochin procerum A n 6 7 6 9 5 2 9 11 9 6 18 Villarsia reniformis A n 8 8 10 9 5 7 13 15 10 9 Schoenus tesquorum A i 1 1 Acaena novae-zelandiae T n 3 1 3 1 Brachyscome angustifolia T n 2 2 1 1 2 2 1 1 Epilobium tasmanicum T n 1 1 Euchiton collinus T n 1 2 1 4 2 6 Galium gaudichaudii T n 2 5 2 2 2 5 2 2 Myosotis australis T n 1 1 Poa labillardierei T n 1 1 1 1 1 1 1 2 1 Pseudognaphalium luteoalbum T n 6 8 3 3 6 9 14 3 Rorippa dictyosperma T n 1 1 2 Viola hederaceae T n 1 1 1 1 Agrostis spp. ( stolonifera & capillaris ) T i 2 1 8 1 1 2 2 9 Aira praecox T i 3 3 Anthoxanthum odoratum T i 5 4 2 1 1 6 5 2 Cirsium arvense T i 1 1 Holcus lanatus T i 2 4 3 1 2 4 3 1 Leontodon taraxaciudes T i 2 3 5 Leuconthemum vulgare T i 1 1
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Species FG Status Herb zone Sedge zone Combined zones Feb Feb May Feb Feb Feb May Feb Feb Feb May Feb 2001 2002 2009 2010 2001 2002 2009 2010 2001 2002 2009 2010 Onopordum acanthium T i 1 1 2 1 3 2 Senecio vulgaris T i 1 1 2 Taraxacum officinale T i 3 6 1 1 3 4 9 1 Trifolium dubium T i 1 1 2 Unidentified Poaceae sp. T i 1 1 Vulpia myuros T i 3 5 1 4 5 Vulpia sp . T i 1 1 Total (50 species) 26 34 24 21 16 21 7 6 28 36 27 22
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Contact details Water and Marine Resources Division Department of Primary Industries, Parks, Water and Environment GPO Box 44 Hobart Tas 7001 Telephone: (03) 6233 6328 Facsimile: (03) 6233 8749 Email: [email protected]