Potential contributions of the soil seed bank and seed rain for accelerating the restoration of riparian catchments in Australia
- Authors: Florentine, Singarayer , Milberg, Per , Westbrooke, Martin
- Date: 2023
- Type: Text , Journal article
- Relation: Global Ecology and Conservation Vol. 47, no. (2023), p.
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- Description: The quality and quantity of soil seed bank composition can play a key role in secondary succession restoration efforts such as those involved in this study, which concerned the restoration of damaged native sites in riparian environments in Victoria, Australia. The objective of this study of the restoration work was to determine the role played by naturally existing soil seed bank in the success of natural restoration in these restored and unmanaged riparian areas. In this regard, we sampled the soil seed bank, seed rain, seedlings in the field and vegetation cover from three sub catchments defined by restoration attempts which had been conducted (i) < 3 years, (ii) 4–8 years, and (iii) > 9 years previous to sampling. In addition, (iv) in order to provide comparative data, adjacent sites (iv) chosen for future restoration and (v) with remnant vegetation, were also sampled. From samples, a total of 8858 seedlings were recorded from the seed bank and the vegetation survey showed 170 species, with exotic species being more numerous than native. The seed rain (a total of 1422 seeds) was dominated by exotic species at all sites. When comparing the vegetation distribution and the seed rain composition, it was clear that whilst the seed bank was more promising as a comparative recruitment source of native species, there were still too many sites dominated by exotic species to rely on this as a long-term restoration strategy. However, this study indicated that there were significant variations in restoration potential among the sites, suggesting that some careful prior site selection for investment of restoration efforts is an important issue. As a consequence, we have recommended that a detailed understanding of the soil seed bank and seed rain species composition prior to the restoration is essential, since a positive seed bank composition with a significant relative density of native species seeds, will provide an indication of native species’ resilience and their potential for recovery. We therefore believe that the findings of this study will provide valuable information to natural resource management agencies regarding the strategy for prioritisation of restoration sites, which will be more beneficial than randomly selecting sites for habitat restoration. In addition, with successful sector restoration, it is expected that the increasing usefulness of the seed bank will allow further restoration of adjacent areas with time. © 2023 The Authors
Spatial prioritisation of survey and management efforts for a threatened pygopodid in south-western New South Wales
- Authors: Waudby, Helen , Turak, Eren , Callister, Kate , Florentine, Singarayer , Westbrooke, Martin , Palmer, Grant , Dayman, Ray
- Date: 2023
- Type: Text , Journal article
- Relation: Australian Journal of Zoology Vol. 71, no. 1 (2023), p.
- Full Text: false
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- Description: Determining species’ distributions is challenging for cryptic species that are difficult to detect using standard techniques. The mallee worm-lizard (Aprasia inaurita Kluge, 1974) is a cryptic reptile in the family Pygopodidae, listed as Endangered in New South Wales. We modelled the species’ potential distribution (Maxent) to improve understanding of the species’ distribution and surveyed potential habitat in the Scotia Mallee region (an area with suitable habitat) from 2018 to 2022, with pitfall traps and artificial refuges (terracotta roof tiles). We completed 11 587 pitfall trap-nights and 3200 tile checks over eight monitoring sessions. Over this period, we detected six vertebrate species (all lizards) using roof tiles and 40 species with pitfall traps, but no mallee worm-lizards. Evaluation of existing records of the mallee worm-lizard from NSW suggested that the state constitutes the north-eastern edge of its continental range, with the species apparently present in low numbers across a wide swathe of south-western NSW. Most records were located within or near to spinifex or porcupine grass (Triodia spp.) communities, on private land. Species distribution modelling provided outputs that are useful for spatial prioritisation of conservation efforts for the species, with region-wide maps showing that much of the Scotia Mallee study area contains potentially suitable habitat for the mallee worm-lizard. However, habitat suitability scores for individual cells in this area were low, in some instances, because of high maximum summer temperatures and soil available water capacity. We anticipate that increasing temperatures associated with climate change may further reduce the suitability of habitat in this area in the future. © 2023 The Author(s)
An investigation of the soil seedbank and seed germination of perennial species in Belah (Casuarina pauper)woodlands in north-west Victoria
- Authors: Callister, Kate , Florentine, Singarayer , Westbrooke, Martin
- Date: 2018
- Type: Text , Journal article
- Relation: Australian Journal of Botany Vol. 66, no. 3 (2018), p. 202-212
- Full Text: false
- Reviewed:
- Description: Semiarid and arid woodlands across much of southern Australia have been subject to prolonged high total grazing pressure leading to loss of species diversity and a lack of recruitment of long-lived perennial species. Regeneration of perennial species requires grazing pressure to be maintained at low levels, but gaps remain in our ecological understanding of regeneration potential. The present study investigated the abundance of germinable seed in the soil seedbank in high quality remnants of Casuarina pauper F.Muell. ex L.A.S.Johnson (Belah) woodlands in north-west Victoria. Seed viability and response to six seed pretreatments including dry heat, wet heat, smoky water, soaking in distilled water, cold stratification and sand scarification were also tested to determine whether seed factors may be limiting regeneration. Results suggest that seed viability was not a limiting regeneration factor for nine out of the 10 perennial species tested with the exception of Alectryon oleifolius S.T. Reynolds. Only small amounts of seed from perennial species, largely Chenopodiaceae species and C. pauper, were found in the soil seedbanks of intact sites, suggesting component perennial species do not maintain long-term soil seedbanks. Results suggest that natural recovery of perennial species diversity in depauperate sites will depend on seed dispersal.
Seed germination response of a noxious agricultural weed Echium plantagineum to temperature, light, pH, drought stress, salinity, heat and smoke
- Authors: Florentine, Singarayer , Weller, Sandra , King, Alannah , Florentine, Arunthathy , Dowling, Kim , Westbrooke, Martin , Chauhan, Bhagirath
- Date: 2018
- Type: Text , Journal article
- Relation: Crop and Pasture Science Vol. 69, no. 3 (2018), p. 326-333
- Full Text: false
- Reviewed:
- Description: Echium plantagineum is a significant pasture weed in the Mediterranean climatic zone of several countries, including Australia. This invasive weed, introduced as an ornamental into Australia (where it is known as Paterson's curse), quickly became established and is now a significant weed of agriculture. Although E. plantagineum is a well-established, highly competitive weed that thrives under disturbance and is tolerant of a wide variety of conditions, including varying soil moisture and drought, and some aspects of its ecology remain unknown. This study investigated germination response to temperature and light, pH, soil moisture, salinity, and pre-germination exposure of seed to heat and smoke. Temperature was found to be more influential on germination than light and the species is tolerant to a wide range of pH. However, available moisture may limit germination, as may elevated salinity. Management of this weed requires approaches that minimise soil seedbank input or prevent germination of soil seedbanks.
Rainfall and grazing : Not the only barriers to arid-zone conifer recruitment
- Authors: Zimmer, Heidi , Florentine, Singarayer , Enke, Rita , Westbrooke, Martin
- Date: 2017
- Type: Text , Journal article
- Relation: Australian Journal of Botany Vol. 65, no. 2 (2017), p. 109-119
- Full Text: false
- Reviewed:
- Description: An understanding of the drivers of infrequent recruitment is fundamental in managing for species persistence. Callitris glaucophylla Joy Thomps. & L.A.S. Johnson (white cypress-pine) is a slow-growing, long-lived conifer, with a distribution that extends across arid Australia. Arid populations of C. glaucophylla are endangered in New South Wales, and are characterised by infrequent recruitment. We examined recruitment patterns of C. glaucophylla in differential grazing exclosures (excluding rabbits, excluding large herbivores or excluding both) and in unfenced areas. More recruitment occurred in rabbit-proof exclosures, compared with nearby large herbivore and control exclosures, although some rabbit-proof exclosures recorded no recruitment. Increases in recruitment at several long-term exclosures were associated with wet periods, as was recruitment at some unfenced sites. Apart from grazing and rainfall, recruitment was related to mature tree size and stand density (probably because of their influence on seed availability). These endangered arid C. glaucophylla woodlands are all that remains of a once extensive distribution, and are habitat for a suite of threatened species. Reduction in grazing pressure, particularly from rabbits, is clearly critical to maintain recruitment in these remnant populations. Chances of recruitment appear to be enhanced in low-density stands, around large trees, and in dune blow outs - fencing should focus on these areas. © 2017 CSIRO.
Arid land invasive weed Salvia verbenaca L. (wild sage) : Investigation into seedling emergence, soil seedbank, allelopathic effects, and germination
- Authors: Fisher, R. , Florentine, Singarayer , Westbrooke, Martin
- Date: 2016
- Type: Text , Conference paper
- Relation: Twentieth Australian Weeds Conference
- Full Text: false
- Reviewed:
- Description: y Salvia verbenaca L., wild sage (Lamiaceae) is native to western and southern Europe. In Australia S. verbenaca is considered an environmental weed with high invasiveness often growing on disturbed sites: tracks, roadsides and around earth tanks. Little is known about the ecology of this invasive species in Australia. Therefore, our objectives in this study were to determine: (i) seedling emergence in relation to sowing depth, (ii) density ofsoilseed bank, (iii) allelopathic effects, (iv) favourable conditions for seed germination of three month old and nine years old seeds, and (v) seed longevity. Of four burial depths, only surface sown seeds germinated and survived. From the soil seedbank, S. verbenaca density was 343 ± 198 m−2. For the allelopathic effects of S. verbenaca, neither the extract nor the leachate inhibited germination of L. sativa; however, the growth of the radicle of seedlings was shown to decrease. Germination was highest at 20°C under 12 h light/12 h dark. Burial of seeds in the field prior to germination reduced viability over time. Germination of three month old seed wassignificantly less than nine year old seed. In conclusion, it is clear that S. verbenaca functions as a casual weed in arid and semi-arid environments of Australia. Understanding the plants’ ecological characteristics in this study will help us take appropriate control measures for this species.
Influence of selected environmental factors on seed germination and seedling survival of the arid zone invasive species tobacco bush (Nicotiana glauca R. Graham)
- Authors: Florentine, Singarayer , Weller, Sandra , Graz, Patrick , Westbrooke, Martin , Florentine, Arunthathy , Javaid, Muhammad , Fernando, Nimesha , Chauhan, Bhagirath , Dowling, Kim
- Date: 2016
- Type: Text , Journal article
- Relation: Rangeland Journal Vol. 38, no. 4 (2016), p. 417-425
- Full Text: false
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- Description: Tobacco bush (Nicotiana glauca R. Graham) is an aggressive invading species, which is active after disturbances such as high rainfall events and flooding. Past studies have focussed on population dynamics and allelopathic effects associated with the species, but little is known about its seed ecology. To address this dearth of information, this study aimed to investigate: (i) the effect of various stress factors (temperature, light, osmotic potential, salt stress, heat-shock, a combination of heat-shock and smoke, pH buffer, and burial depth of seed) on seed germination and seedling emergence, and (ii) factors affecting the fate of seedlings. The results show that N. glauca was able to germinate over a broad range of temperatures with highest seed germination occurring at 30/20°C with 12h of light and 12h of dark conditions. Seed germination was greatest (89%) when seeds were placed on the soil surface and emergence decreased considerably as planting depth increased from 0.5 to 1.5cm. Water stress greatly reduced seed germination (58% germination at osmotic potentials below -0.2 MPa) and germination was completely inhibited at water potentials of -0.4 to -0.6 MPa. Although increasing salinity reduced the seed germination of this invasive species, N. glauca seed was able to germinate in both alkaline (81% at pH 10) and acidic (80% at pH 4) conditions. The trial on the effect of seed age and field seed burial on seed germination showed a slight decline in seed germination after 120 days of burial compared with non-buried seeds. Further, the combined effect of heat-shock and smoke effectively inhibited the germination of N. glauca seeds; however, our study shows that seedlings of N. glauca can withstand heat-shock of up to 130°C. Studies such as this will assist in the development of control strategies to prevent the spread of this invasive species into arid landscapes. © 2016 Australian Rangeland Society.
The effectiveness of different planting frameworks for recruitment of tropical rainforest species on ex-rainforest land
- Authors: Florentine, Singarayer , Pohlman, Catherine , Westbrooke, Martin
- Date: 2016
- Type: Text , Journal article
- Relation: Restoration Ecology Vol. 24, no. 3 (2016), p. 364-372
- Full Text: false
- Reviewed:
- Description: A long-term rainforest restoration experiment was established on abandoned pasture in northeastern Queensland in 1993 to examine the effectiveness of five different restoration planting methods: (T1) control (no plantings); (T2) pioneer monoculture (planting seedlings of one pioneer species, Homalanthus novoguineensis, Euphorbiaceae); (T3) Homalanthus group framework method (H. novoguineensis and eight other pioneer species); (T4) Alphitonia group framework method (Alphitonia petriei, Rhamnaceae, with eight other pioneer species); and (T5) maximum diversity method (planting pioneers, middle-phase species, and mature-phase species). We investigated temporal patterns in the (1) fate of seedlings originally planted in 1993; (2) natural recruitment of native plant species; and (3) current habitat structure (canopy cover and ground cover of grasses and invasive plants) within each restoration treatment. A total of 97% of seedlings planted in T2 died within the first 13 years and all had died by 2014. A total of 72% of seedlings planted in T3, 55.5% of seedlings planted in T4, and 55% of seedlings planted in T5 also died by 2014. By 2014, 42 species from 21 families had recruited across the experimental site, and the abundance of recruits was almost twice that recorded in 2001 and 2006. Overall, T3, T4, and T5 had the greatest diversity and abundance of recruits. By 2014, canopy cover was greatest in T3, T4, and T5 but grass cover was least in T5. It is concluded that some restoration success measures increase with planting diversity, but overall the rate of recovery is similar in framework species and maximum diversity method. © 2016 Society for Ecological Restoration.
Decade-long response of arid-land mallee vegetation to fire, flooding and grazing in south-eastern Australia
- Authors: Florentine, Singarayer , Milberg, Per , Di Stefano, Julian , Westbrooke, Martin , Graz, Patrick
- Date: 2015
- Type: Text , Journal article
- Relation: Journal of Arid Environments Vol. 121, no. October (2015), p. 7-14
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- Description: Australian arid vegetation has evolved within highly variable environments characterised by low rainfall and sporadic fire events. Episodic high rainfall events are a significant factor in plant species recruitment, but their unpredictability makes them difficult to study. We report on the response of vascular plants to a major rainfall event and flood in an arid region of south-eastern Australia. Fire that occurred two months before the flood was incorporated into the study. Paired fenced and unfenced plots were established at control locations and also in areas that had been either flooded, burnt, or flooded and burnt. Objectives were to quantify the long-term effects of fire, flood and vertebrate herbivory, and their interactions, on vegetation composition, plant life forms and species diversity. We found that relative to controls (i) there was a significant effect of flooding on vegetation composition, (ii) changes in life form abundance were driven by flooding and grazing, (iii) there was a strong positive relationship between grazer exclusion and species diversity that was maintained over time and (iv) there was little effect of fire. Understanding the long-term effects of both natural disturbances and vertebrate herbivory will benefit plant conservation in the arid zone. © 2015 Elsevier Ltd.
Winter diet of introduced red deer (Cervus elaphus) in woodland vegetation in Grampians National Park, western Victoria
- Authors: Roberts, Cathryn , Westbrooke, Martin , Florentine, Singarayer , Cook, Simon
- Date: 2015
- Type: Text , Journal article
- Relation: Australian Mammalogy Vol. 37, no. 1 (2015), p. 107-112
- Full Text: false
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- Description: Although red deer (Cervus elaphus) have the potential to play a major role in influencing the structure and composition of vegetation, little is known about the dietary preferences of red deer in Australia. In the Grampians National Park, Victoria, where there is a large, established red deer population, there has been concern over the condition of woodlands, with lack of perennial seedling recruitment observed. We estimated the diets of 12 red deer using macroscopic sorting techniques. We examined rumen contents of seven male and five female red deer from four woodland Ecological Vegetation Classes, which indicate that they act as intermediate feeders. A wide variety of plants were ingested, with evergreen tree species, small trees and woody shrubs making up a large proportion of the diet, along with grasses. This study found that red deer show significantly different dietary intake due to sex, with females consuming a diet much higher in grasses, while males consume more trees and shrubs. These findings have implications for the management of red deer populations within the park and broader implications for their effects on Australian ecosystems.
Dietary characteristics of Emus (Dromaius novaehollandiae) in semi-arid New South Wales, Australia, and dispersal and germination of ingested seeds
- Authors: Dunstan, Heath , Florentine, Singarayer , Calvino-Cancela, Maria , Westbrooke, Martin , Palmer, Grant
- Date: 2013
- Type: Text , Journal article
- Relation: Emu Vol. 113, no. 2 (2013), p. 168-176
- Full Text: false
- Reviewed:
- Description: The Emu (Dromaius novaehollandiae) eats a wide range of seeds and other plant material but little is known of the seeds eaten and dispersed in arid Australia. This study aimed to determine the species of seed and fruits eaten by Emus through the year and investigate the effect of the passage of seeds through the Emu gut on seed germination. Emu scats were opportunistically collected in all seasons of 2005 at Nanya Research Station, western New South Wales. Seeds of 29 plant species were retrieved, identified and counted from 221 scats. Seeds of perennial species, such as Belah (Casuarina pauper), Ruby Saltbush (Enchylaena tomentosa), Common Emu-bush (Eremophila glabra) and Nitre-bush (Nitraria billardierei), predominated. Seed composition of scats was more diverse in summer than in winter, autumn and spring. Seeds of Common Emu-bush, Berrigan (Eremophila longifolia) and Sweet Quandong (Santalum acuminatum) showed no germination after passage through the gut. Ruby Saltbush and Nitre-bush showed very low germination rates. The Emu is a generalist feeder, capable of ingesting and dispersing large numbers of plant species. Through high seed consumption and long gut-retention time, Emus could potentially play a significant role in long-distance dispersal of seeds and, through such dispersal, in the vegetation dynamics of arid Australia. © 2013 Bird Life Australia.
- Description: 2003011097
Modelling the effects of water-point closure and fencing removal : A GIS approach
- Authors: Graz, Patrick , Westbrooke, Martin , Florentine, Singarayer
- Date: 2012
- Type: Text , Journal article
- Relation: Journal of Environmental Management Vol. 104, no. (2012), p. 186-194
- Full Text: false
- Reviewed:
- Description: Artificial water-points in the form of troughs or ground tanks are used to augment natural water supplies within rangelands in many parts of the world. Access to such water-points leads to the development of a distinct ecological sub-system, the piosphere, where trampling and grazing impact modify the vegetation. This study aims to consolidate existing information in a GIS based model to investigate grazing patterns within the landscape. The model focuses on the closure of water-points and removal of fences on Nanya Station, New South Wales, Australia. We found that the manipulation of water-points and fences in one management intervention may change grazing activity in a way different to that which would be experienced if each had been modified separately. Such effects are further modified by the spatial distribution of the water-points and the underlying vegetation. © 2012 Elsevier Ltd.
Short-term gain and long-term pain: Lessons learnt from the control of Lachnagrostis filiformis (fairy grass) in Victoria, Australia
- Authors: Warnock, Andrew , Florentine, Singarayer , Graz, Patrick , Westbrooke, Martin
- Date: 2012
- Type: Text , Journal article
- Relation: Weed Biology and Management Vol. 12, no. 4 (December 2012), p. 156-167
- Full Text: false
- Reviewed:
- Description: The indigenous Lachnagrostis filiformis colonized extensive areas of dry lake beds in Victoria, Australia, during the drought from 1997 to 2009. Large numbers of the plants' detached seed heads disperse in the wind, lodging against nearby housing, fences and other obstacles. This accumulation of material creates a fire hazard, degrades townships' aesthetics and presents a nuisance to the communities of lake-side towns. This study aimed to examine the effects of various control methods on L.?filiformis in the short and long term. Although herbicide applications, slashing, grazing and burning were found to be effective in controlling the blown L.?filiformis seed heads in the short term, they failed to prevent subsequent reinvasion and can increase its abundance in the long term. The late application of herbicide resulted in an increase in the foliage cover and seed-head biomass of L.?filiformis by up to 37% and 150%, respectively, in the year following the treatment application. The results from this study highlight how management focused on achieving short-term goals, without consideration of the successional trajectory after implementation, can not only fail but be counter-productive in the long term. In order to achieve sustainable management, the fundamental ecological processes that promote the establishment and persistence of the weed need to be addressed.
Controlling wind blown Lachnagrostis filiformis (fairy grass) seed heads in western Victoria
- Authors: Warnock, Andrew , Florentine, Singarayer , Graz, Patrick , Westbrooke, Martin
- Date: 2009
- Type: Text , Conference paper
- Relation: Paper presented at Fourth Victorian Weed Conference : Plants behaving badly - in agriculture and the environment, Mercure Hotel, Geelong, Victoria : 7th-8th October 2009
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- Description: 2003007372
A unique weed problem — the control of fairy grass Lachnagrostis filiformis seedheads on Lake Learmonth in western Victoria
- Authors: Warnock, Andrew , Florentine, Singarayer , Graz, Patrick , Westbrooke, Martin
- Date: 2008
- Type: Text , Conference paper
- Relation: Paper presented at 16th Australian Weeds Conference: Weed management 2008 hot topics in the tropics, Cairns, Queensland : May 18th-22nd, 2008 p. 165-167
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- Description: The native fairy grass (Lachnagrostis filiformis (G. Forst.) Trin.) has colonised extensive areas of dry lake beds in western Victoria during the current drought. Large numbers of the plants’ detached mature panicles (seed heads) lodge against housing, fences, railway lines and other obstacles. This can be a fire hazard, degrades township aesthetics and creates a general nuisance to communities of lakeside towns. Current control measures are costly and only provide short-term solutions. A three-year study commencing in 2006 was designed to assess current and innovative control measures and develop a potential long-term management solution to the problem. Treatments applied to the bed of Lake Learmonth during the first year of the study included late-season glyphosate herbicide at two concentrations, late-season slashing, and seed broadcasting of two native species to reduce L. filiformis inflorescence biomass through competition. Slashing reduced L. filiformis inflorescence biomass and herbicide treatments successfully killed L. filiformis plants, while having no effect on germination of seed collected from sprayed plants. Although these treatments successfully limited the impact of L. filiformis on lakeside towns during the first year, the longer term efficiency is doubted. Treatment effects will be monitored over a further two years.
- Description: 2003006269
Post-wildfire seedling colonisation patterns in a Eucalyptus delegatemsis (Myrtaceae) windthrow site at Snowy Rover National Park, Victoria
- Authors: Florentine, Singarayer , Westbrooke, Martin , Milberg, Per , Gibson, Matthew
- Date: 2008
- Type: Text , Journal article
- Relation: Australian Forestry Vol. 71, no. 1 (2008), p. 48-53
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- Reviewed:
- Description: During June 1998, a severe windstorm caused significant damage to a sub-alpine stand of Eucalyptus delegatensis (Myrtaceae) at the Snowy River National Park. In 2002, about 4.5 y after the windstorm, a study documented the effects on E. delegatensis and early understorey succession. In February 2003, wildfire burnt across the windthrow site and we examined the seedling recruitment patterns at windthrow–burn and burn-only sites. Our aim was to document the regeneration of the canopy-dominant E. delegatensis and to confirm that Acacia dealbata is a pioneer species that potentially interferes with or prevents regeneration of E. delegatensis. Permanent transects were established within the windthrow–burn and burn-only sites. The data suggest that the heavily disturbed (mounded) soil at the windthrow site had a strong positive influence on regeneration of both species. By providing favourable growing conditions, the disturbed soil appears to have assisted seedling survival and subsequent growth of the E. delegatensis, despite competition from dense, concurrently established A. dealbata.
- Description: C1
Does Geijera parviflora Lindl. (Rutaceae) facilitate understorey species in semi-arid Australia?
- Authors: Warnock, Andrew , Westbrooke, Martin , Florentine, Singarayer , Hurst, Cameron
- Date: 2007
- Type: Text , Journal article
- Relation: Rangeland Journal Vol. 29, no. 2 (2007), p. 207-216
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- Description: Species composition under tree canopies often differs from that of surrounding micro-environments. In arid and semi-arid zones, trees can be beneficial to understorey vegetation. This study examined zones of vegetation composition and soil physiochemical parameters associated with Geijera parviflora Lindl. The importance of shade, rainfall redistribution, seed bank and soil moisture were examined. Species abundance, soil moisture, seed bank composition, rainfall redistribution and soil nutrient concentration were measured under five randomly selected mature G. parviflora trees in south-western New South Wales, Australia. To complement the findings from this study, artificial shade plots were constructed in a canopy-free area and species abundance measured seven months after shade construction. The study demonstrated that G. parviflora was associated with zonation of understorey vegetation. Two zones of understorey vegetation were found in relation to G. parviflora: (i) under the tree canopy with high species diversity, and (ii) beyond the canopy, this community being dominated by Dissocarpus paradoxus throughout the year with Crassula colorata appearing after rainfall. The zone beyond the canopy also had lower soil nutrient concentrations. Soil moisture, nutrient concentration and the seed bank density were significantly higher under the canopy. However, the canopy reduced precipitation reaching the soil surface. The effects of the canopy on understorey species composition and soil moisture were enhanced after winter rainfall. Artificial shade increased species abundance and richness under a 90%-shading treatment. The results indicated that G. parviflora generated spatial heterogeneity over the broader plant community increasing species richness, abundance and diversity under the canopy. This emphasises the importance of arid zone trees in conserving understorey plant diversity. Shading, soil nutrient concentration and increased seed bank density and soil moisture appeared to be key influences on the plant communities under the canopy. © Australian Rangeland Society 2007.
- Description: C1
- Description: 2003004817
The arid land invasive weed Nicotiana glauca R. Graham (Solanaceae) : Population and soil seed bank dynamics, seed germination patterns and seedling response to flood and drought
- Authors: Florentine, Singarayer , Westbrooke, Martin , Gosney, Kathleen , Ambrose, Graeme , O’Keefe, M.
- Date: 2006
- Type: Text , Journal article
- Relation: Journal of Arid Environments Vol. 66, no. (2006), p. 218-230
- Full Text:
- Reviewed:
- Description: Disturbances in plant communities provide opportunities for weed germination, propagation, spread, and invasion. When the population density of a weed increases, fast-tracked and appropriate control management strategies are required. The objectives of this study were to: (i) examine the population and soil seed bank dynamics of Nicotiana glauca; (ii) compare the germination patterns of invasive N. glauca seeds collected from two states in Australia, and (iii) investigate the impact of a flood in September 1997 and subsequent drought on N. glauca seedlings. The density of N. glauca followed a steep positive increment during the sampling time (September 1999 to October 2004). The increment pattern was similar in flooded fenced and unfenced plots. Plant density increased over much of the observation period, but had declined to 80 and 432 stems ha−1, respectively, by October 2004. Stem density recorded in October 2004 along two transects radiating from the central point of the newly created lake demonstrated that a significant number of stems appeared to be dead. A soil seed bank study revealed that seed density varied significantly (p=0.0001) between flooded fenced (598.75±71) and flooded unfenced (327.5±66) plots. In contrast, no N. glauca seedlings were recruited from the soil collected from the control plots. Germination trials were undertaken on N. glauca seed collected from New South Wales. There was no significance difference detected between treatments light and temperature. Similarly, no interaction was found between light and temperature. A comparative study on seed germination patterns of N. glauca seeds collected from Ivanhoe, New South Wales, and the Flinders Ranges, South Australia, showed that temperature had a significant effect on N. glauca seed germination. The effect varied significantly with main variables (state, length and time) and also with different interactions, except state×light (p=0.3840). N. glauca seedlings exposed to flood were found to withstand partial flooding for at least 58 days. Under waterlogged conditions, the seedlings showed stem hypertrophy and produced adventitious roots. Only one seedling was found dead in the drought treatment. In conclusion, it is clear that N. glauca invaded the area after a rare flood event and began to function as a casual weed. Established seedlings in the field can withstand extreme ecological events such as flood and drought. Understanding the plants’ ecological characteristics through a study such as this at an early rather than late stage in the invasion will help us to take appropriate control measures for this species.
- Description: C1
- Description: 2003001616
Arid land vegetation dynamics after a rare flooding event : influence of fire and grazing
- Authors: Westbrooke, Martin , Florentine, Singarayer , Milberg, Per
- Date: 2005
- Type: Text , Journal article
- Relation: Journal of Arid Environments Vol. 61, no. 2 (Apr 2005), p. 249-260
- Full Text:
- Reviewed:
- Description: Arid vegetation is subjected to more or less frequent fire, drought, and sporadic flooding events and grazing. Whilst fire, drought and grazing have been the subject of considerable research, little is known of the impact of flooding in arid environments. In this study we examined opportunistically the effects of a flooding event, and its interaction with fire and grazing on moulding arid vegetation in New South Wales, Australia. We assessed vegetation approximately 2 and 5 years after recession of the water in fenced and unfenced plots subjected to different combinations of flooding and fire. Number of species per area dropped from 11.8 to 5.7 per 625 m(2). Vegetation in plots left open to grazing by vertebrates differed from fenced plots, but the amount of variation explained was small compared with flooding and the change over time. The taxa mostly associated with flooding were Eragrostis spp., Pseudognaphalium luteoalbum and the exotic Nicotiana glauca. Major flooding events not only trigger native species' germination and recruitment but may also create an avenue for exotic species to invade. (C) 2004 Elsevier Ltd. All rights reserved.
- Description: C1
- Description: 2003001050
Exotic plant species invasion in south west New South Wales : Influence of a rare flooding event and grazing
- Authors: Florentine, Singarayer , Westbrooke, Martin
- Date: 2005
- Type: Text , Journal article
- Relation: Plant Protection Quarterly Vol. 20, no. 2 (2005), p. 42-45
- Full Text: false
- Reviewed:
- Description: The main objectives of this study were to investigate: (i) the distribution of exotic plant species in flooded and control (unflooded) areas in relation to a 1997 episodic flooding event and (ii) the influence of grazing in flooded and unflooded open and fenced plots on wed colonization.
- Description: 2003001069