Amaranthus retroflexus L (redroot pigweed) : effects of elevated CO2 and soil moisture on growth and biomass and the effect of radiant heat on seed germination
- Weller, Sandra, Florentine, Singarayer, Welgama, Amali, Chadha, Aakansha, Turville, Christopher
- Authors: Weller, Sandra , Florentine, Singarayer , Welgama, Amali , Chadha, Aakansha , Turville, Christopher
- Date: 2021
- Type: Text , Journal article
- Relation: Agronomy Vol. 11, no. 4 (2021), p.
- Full Text:
- Reviewed:
- Description: Amaranthus retroflexus L. (Amaranthaceae), Redroot pigweed, is native to North America, but has become a weed of agriculture worldwide. Previous research into competition with food crops found it significantly reduces yields. Additionally, taxonomy, biomass allocation, physiological responses to light intensity, water stress, elevated CO2, and herbicide resistance have been inves-tigated. To extend other research findings, we investigated growth and biomass yield in response to (i) soil moisture stress, and (ii) drought and elevated CO2. Additionally, we investigated seed germination rates following exposure to three elevated temperatures for two different time periods. Overall, moisture stress reduced plant height, stem diameter, and number of leaves. Elevated CO2 (700 ppm) appeared to reduce negative impacts of drought on biomass productivity. Heating seeds at 120◦C and above for either 180 or 300 s significantly reduced germination rate. These results inform an understanding of potential responses of A. retroflexus to future climate change and will be used to predict future occurrence of this weed. The finding that exposing seeds to high temperatures retards germination suggests fire could be used to prevent seed germination from soil seed banks, particularly in no-till situations, and therefore may be used to address infestations or prevent further spread of this weed. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. **Please note that there are multiple authors for this article therefore only the name of the first 5 including Federation University Australia affiliates “Sandra Weller, Singarayer Florentine, Amali Welgama, Aakansha Chadha, Chrisopher Turville" are provided in this record**
- Authors: Weller, Sandra , Florentine, Singarayer , Welgama, Amali , Chadha, Aakansha , Turville, Christopher
- Date: 2021
- Type: Text , Journal article
- Relation: Agronomy Vol. 11, no. 4 (2021), p.
- Full Text:
- Reviewed:
- Description: Amaranthus retroflexus L. (Amaranthaceae), Redroot pigweed, is native to North America, but has become a weed of agriculture worldwide. Previous research into competition with food crops found it significantly reduces yields. Additionally, taxonomy, biomass allocation, physiological responses to light intensity, water stress, elevated CO2, and herbicide resistance have been inves-tigated. To extend other research findings, we investigated growth and biomass yield in response to (i) soil moisture stress, and (ii) drought and elevated CO2. Additionally, we investigated seed germination rates following exposure to three elevated temperatures for two different time periods. Overall, moisture stress reduced plant height, stem diameter, and number of leaves. Elevated CO2 (700 ppm) appeared to reduce negative impacts of drought on biomass productivity. Heating seeds at 120◦C and above for either 180 or 300 s significantly reduced germination rate. These results inform an understanding of potential responses of A. retroflexus to future climate change and will be used to predict future occurrence of this weed. The finding that exposing seeds to high temperatures retards germination suggests fire could be used to prevent seed germination from soil seed banks, particularly in no-till situations, and therefore may be used to address infestations or prevent further spread of this weed. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. **Please note that there are multiple authors for this article therefore only the name of the first 5 including Federation University Australia affiliates “Sandra Weller, Singarayer Florentine, Amali Welgama, Aakansha Chadha, Chrisopher Turville" are provided in this record**
Characterizing selected soil attributes of different land-use management to assess reforestation benefits of deforested riparian buffers
- Rasiah, Velu, Florentine, Singarayer
- Authors: Rasiah, Velu , Florentine, Singarayer
- Date: 2018
- Type: Text , Journal article
- Relation: Ecological Processes Vol. 7, no. 1 (2018), p. 1-12
- Full Text:
- Reviewed:
- Description: Introduction: The information available on the sensitivity of soil biotic and abiotic attributes, which can be used to track the impact of reforestation in riparian buffers, is often insufficient to refine management practices and convince stakeholders of the benefits of reforestation. Methods: In this study, conducted in Victoria, Australia, the changes in soil biotic and abiotic attributes, organic carbon (OC), mineral nitrogen (MN), total dissolved solutes (TDS) and pH were characterised to assess the impact of land-use change from bare riparian (BR) to reforested riparian (RR). Additionally, the benefits of revegetating a deforested creek bank with regard to salinity abatement and C-sequestration potentials were assessed. Results: The TDS depletion in the RR strips varied spatiotemporally from 65 to 169 mg/L, the net OC deposition from 16 to 19 g C/kg soil and MN deposition from 1.2 to 2.1 g N/kg soil, respectively. Additionally, the net changes in pH from alkaline to near neutral condition varied by 0.4 to 1.0 pH units. Approximately 30% to 60% of the net OC depletion after deforestation was redeposited under RR over 3 to 6 years. The TDS depletion after land-use changed from BR to RR ranged from 15 to 32% over 3 to 6 years. Conclusion: The soil attributes OC, MN and TDS characteristics under different land-use practices varied spatiotemporally. This information may be useful to convince stakeholders to undertake reforestation of creek banks for salinity abatement, and that change in land-use has the potential to increase C sequestration at a farm scale.
- Authors: Rasiah, Velu , Florentine, Singarayer
- Date: 2018
- Type: Text , Journal article
- Relation: Ecological Processes Vol. 7, no. 1 (2018), p. 1-12
- Full Text:
- Reviewed:
- Description: Introduction: The information available on the sensitivity of soil biotic and abiotic attributes, which can be used to track the impact of reforestation in riparian buffers, is often insufficient to refine management practices and convince stakeholders of the benefits of reforestation. Methods: In this study, conducted in Victoria, Australia, the changes in soil biotic and abiotic attributes, organic carbon (OC), mineral nitrogen (MN), total dissolved solutes (TDS) and pH were characterised to assess the impact of land-use change from bare riparian (BR) to reforested riparian (RR). Additionally, the benefits of revegetating a deforested creek bank with regard to salinity abatement and C-sequestration potentials were assessed. Results: The TDS depletion in the RR strips varied spatiotemporally from 65 to 169 mg/L, the net OC deposition from 16 to 19 g C/kg soil and MN deposition from 1.2 to 2.1 g N/kg soil, respectively. Additionally, the net changes in pH from alkaline to near neutral condition varied by 0.4 to 1.0 pH units. Approximately 30% to 60% of the net OC depletion after deforestation was redeposited under RR over 3 to 6 years. The TDS depletion after land-use changed from BR to RR ranged from 15 to 32% over 3 to 6 years. Conclusion: The soil attributes OC, MN and TDS characteristics under different land-use practices varied spatiotemporally. This information may be useful to convince stakeholders to undertake reforestation of creek banks for salinity abatement, and that change in land-use has the potential to increase C sequestration at a farm scale.
- Dunstan, Heath, Florentine, Singarayer, Calvino-Cancela, Maria, Westbrooke, Martin, Palmer, Grant
- 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
Does Geijera parviflora Lindl. (Rutaceae) facilitate understorey species in semi-arid Australia?
- Warnock, Andrew, Westbrooke, Martin, Florentine, Singarayer, Hurst, Cameron
- 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
- Full Text:
- Reviewed:
- 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
- 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
- Full Text:
- Reviewed:
- 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
- Florentine, Singarayer, Westbrooke, Martin, Gosney, Kathleen, Ambrose, Graeme, O’Keefe, M.
- 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
- 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
- Westbrooke, Martin, Florentine, Singarayer, Milberg, Per
- 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
- 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
Invasion of the noxious weed Nicotiana glauca R. Graham after an episodic flooding event in the arid zone of Australia
- Florentine, Singarayer, Westbrooke, Martin
- Authors: Florentine, Singarayer , Westbrooke, Martin
- Date: 2005
- Type: Text , Journal article
- Relation: Journal of Arid Environments Vol. 60, no. 4 (Mar 2005), p. 531-545
- Full Text:
- Reviewed:
- Description: During November 1997, an extreme rainfall event caused flooding in the Olary Creek and created a terminal lake within mallee vegetation on Nagaela Station, far western New South Wales. To assess the effect of this rare event on native flora, six 25×25 m2 grazing exclusion plots were established on flooded (4), and un-flooded control (2) areas. We investigated (i) the distribution of Nicotiana glauca in relation to the 1997 flooding event (ii) the variation in density of N. glauca soil-stored seed between soil in control and exclosure plots (iii) the allelopathic effects of N. glauca on germination of Lactuca sativa seeds. Analysis of N. glauca stem sections revealed a maximum of five growth rings, confirming an origin following the 1997 flood event. At a September 1998 assessment, no N. glauca were found across flooded and control plots. In October 2000 N. glauca occurred at densities of 24 and 12 N. glauca seedlings ha−1 in the flooded unfenced and fenced plots respectively. No N. glauca individuals were recorded either from control fenced or unfenced plots. The soil-stored seed study revealed that larger numbers of N. glauca seeds were recovered from the flooded open plot (1936±968) than in flooded fenced plots (856±428.12) but none was found in the control plots. Leachates obtained from dry leaves and twigs had a significantly greater negative impact (p>0.001) on germination of L. sativa seeds than leachates obtained from fresh leaves and bark. This study showed that the density of N. glauca is high in areas where grazing had eliminated competition from native shrubs and grasses. N. glauca is potentially a serious weed along the Olary Creek and ephemeral lake boundaries. Management strategies such as reducing grazing pressure from native and introduced animals and/or effective eradication programs should be adopted, to minimize further infestation.
- Description: C1
- Description: 2003001049
- Authors: Florentine, Singarayer , Westbrooke, Martin
- Date: 2005
- Type: Text , Journal article
- Relation: Journal of Arid Environments Vol. 60, no. 4 (Mar 2005), p. 531-545
- Full Text:
- Reviewed:
- Description: During November 1997, an extreme rainfall event caused flooding in the Olary Creek and created a terminal lake within mallee vegetation on Nagaela Station, far western New South Wales. To assess the effect of this rare event on native flora, six 25×25 m2 grazing exclusion plots were established on flooded (4), and un-flooded control (2) areas. We investigated (i) the distribution of Nicotiana glauca in relation to the 1997 flooding event (ii) the variation in density of N. glauca soil-stored seed between soil in control and exclosure plots (iii) the allelopathic effects of N. glauca on germination of Lactuca sativa seeds. Analysis of N. glauca stem sections revealed a maximum of five growth rings, confirming an origin following the 1997 flood event. At a September 1998 assessment, no N. glauca were found across flooded and control plots. In October 2000 N. glauca occurred at densities of 24 and 12 N. glauca seedlings ha−1 in the flooded unfenced and fenced plots respectively. No N. glauca individuals were recorded either from control fenced or unfenced plots. The soil-stored seed study revealed that larger numbers of N. glauca seeds were recovered from the flooded open plot (1936±968) than in flooded fenced plots (856±428.12) but none was found in the control plots. Leachates obtained from dry leaves and twigs had a significantly greater negative impact (p>0.001) on germination of L. sativa seeds than leachates obtained from fresh leaves and bark. This study showed that the density of N. glauca is high in areas where grazing had eliminated competition from native shrubs and grasses. N. glauca is potentially a serious weed along the Olary Creek and ephemeral lake boundaries. Management strategies such as reducing grazing pressure from native and introduced animals and/or effective eradication programs should be adopted, to minimize further infestation.
- Description: C1
- Description: 2003001049
- Fox, John, Florentine, Singarayer, Westbrooke, Martin, Hurst, Cameron
- Authors: Fox, John , Florentine, Singarayer , Westbrooke, Martin , Hurst, Cameron
- Date: 2004
- Type: Text , Journal article
- Relation: Rangeland Journal Vol. 26, no. 2 (2004), p. 150-160
- Full Text: false
- Reviewed:
- Description: Observations are presented on the natural regeneration of Eucalyptus victrix L. Johnson and K. Hill (coolibah), the dominant tree species of grassy woodlands on the floodplain of the Fortescue River, north of Newman in the Pilbara district of Western Australia. The main objectives of this study were to examine: (i) survival of newly recruited E. victrix seedlings on flooded and burnt sites, and (ii) growth and survival of established plants in a gilgaied landscape. Populations of newly-recruited seedlings following flooding or fire were monitored opportunistically at 'Marillana' and 'Ethel Creek' stations, for up to two years from tagging. A population of saplings at 'Roy Hill' station was observed over eight years. Seedling densities of E. victrix in flooded sites were 0.32 and 1.03 plants/m2 in 1995 and 1997 respectively. Locally high densities reached from 1.2 to 17.7 plants/m2 on areas of 28 and 6 m2 respectively. At the burnt site at 'Ethel Creek', 1.30 plants/m2 were observed where 58 seedlings were recorded on an area of 445 m2 a year after a natural fire. Many of these persisted well into their second year, whereas seedlings recruited in the flooded sites generally lasted less than a year (250-376 days). In contrast, persistence of a cohort of 100 established saplings <2 m tall in a gilgaied landscape at 'Roy Hill' was high. During 8 years of observations, only one sapling was lost. Those found at the edges of gilgais had attained greater heights (3.91 ± 1.14 m) than saplings located inside (3.16 ± 0.95 m) or on top (3.12 ± 0.93 m) of the gilgais. This study demonstrates that the seedling stage in E. victrix is critical, in that once newly recruited individuals reach the sapling stage (0.6-1 m), mortality rates are much reduced. Unfortunately, it was not possible during the course of this study to locate a cohort of young seedlings that did survive and so any consideration of the conditions necessary for their survival is speculative.
- Description: C1
- Description: 2003000725
Restoration on abandoned tropical pasturelands - Do we know enough?
- Florentine, Singarayer, Westbrooke, Martin
- Authors: Florentine, Singarayer , Westbrooke, Martin
- Date: 2004
- Type: Text , Journal article
- Relation: Journal for Nature Conservation Vol. 12, no. (2004), p. 85-94
- Full Text:
- Reviewed:
- Description: Tropical rainforests have been disappearing at an alarming rate. In addition to preserving remaining tropical rainforests, we need to convert degraded and abandoned pasturelands into secondary forests. To accelerate this, human intervention in the recovery process is essential. In this review paper we (i) encapsulate some of the problems, which might surface when converting abandoned land to secondary forest. (ii) Look at some of the restoration techniques used in restoration programs and propose additional techniques for consideration. Major barriers to natural regeneration on abandoned and degraded pasturelands are: weed infestation, lack of indigenous soil seed bank, lack of seed supply/movement, soil compaction, depletion of soil nutrients and unsuitable microclimate and microhabitat. Although several restoration techniques have been recommended, most restoration programs have been carried out using native seedling transplants to accelerate natural recruitment. Most restoration groups in the tropics are still in the initial stages of determining which species or species combination to chose to gain maximum benefit. On the other hand restoration ecologists are struggling to detect which techniques are most appropriate to restore degraded and abandoned pasturelands. Our review shows that there is immediate need for further research and development on restoration techniques by examining the ecological and economic effectiveness of: direct seeding, stem cuttings using native pioneer or climax species and simple manipulation such as displacing branches of pioneer species with mature seeds on abandoned and degraded pasturelands and artificial perching to accelerate natural regeneration. These techniques are essential to successfully heal the wound humans have inflicted on the most spectacular and species-rich ecosystems on earth.
- Description: C1
- Description: 2003000720
- Authors: Florentine, Singarayer , Westbrooke, Martin
- Date: 2004
- Type: Text , Journal article
- Relation: Journal for Nature Conservation Vol. 12, no. (2004), p. 85-94
- Full Text:
- Reviewed:
- Description: Tropical rainforests have been disappearing at an alarming rate. In addition to preserving remaining tropical rainforests, we need to convert degraded and abandoned pasturelands into secondary forests. To accelerate this, human intervention in the recovery process is essential. In this review paper we (i) encapsulate some of the problems, which might surface when converting abandoned land to secondary forest. (ii) Look at some of the restoration techniques used in restoration programs and propose additional techniques for consideration. Major barriers to natural regeneration on abandoned and degraded pasturelands are: weed infestation, lack of indigenous soil seed bank, lack of seed supply/movement, soil compaction, depletion of soil nutrients and unsuitable microclimate and microhabitat. Although several restoration techniques have been recommended, most restoration programs have been carried out using native seedling transplants to accelerate natural recruitment. Most restoration groups in the tropics are still in the initial stages of determining which species or species combination to chose to gain maximum benefit. On the other hand restoration ecologists are struggling to detect which techniques are most appropriate to restore degraded and abandoned pasturelands. Our review shows that there is immediate need for further research and development on restoration techniques by examining the ecological and economic effectiveness of: direct seeding, stem cuttings using native pioneer or climax species and simple manipulation such as displacing branches of pioneer species with mature seeds on abandoned and degraded pasturelands and artificial perching to accelerate natural regeneration. These techniques are essential to successfully heal the wound humans have inflicted on the most spectacular and species-rich ecosystems on earth.
- Description: C1
- Description: 2003000720
- Graham, R.A., Florentine, Singarayer, Fox, John, Luong, T. M.
- Authors: Graham, R.A. , Florentine, Singarayer , Fox, John , Luong, T. M.
- Date: 2004
- Type: Text , Journal article
- Relation: Rangeland Journal Vol. 26, no. 1 (2004), p. 17-33
- Full Text: false
- Reviewed:
- Description: The paper reports soil seedbank species composition, of Eucalyptus victrix grassy woodlands, of the upper Fortescue River in the Pilbara District, Western Australia. In this study, our objectives were to investigate germinable soil seedbanks and species composition in response to three simulated seasons, using emergence. Variation in seed density from three depths was tested. Four field sites were sampled. Thirty samples were collected in late spring, after seed rain and prior to summer rainfall. From each sample spot, three soil depths (surface, 1-5, and 6-10 cm) were segregated from beneath surface areas of 100 cm(2). Samples were later incubated in a glasshouse to simulate three different seasonal conditions (autumn, winter and spring). Germinating seedlings were recorded on emergence and grown until identified. Forty-one species germinated, comprising 11 grasses (7 annuals and 4 perennials), 25 annual herbs and 5 perennial herbs. Distribution patterns of germinable seed in both the important annual grass Eragrostis japonica and the perennial Eragrostis setifolia (a preferred cattle fodder species), suggest that seedbank accumulation differs among species and between sites. In part, this may be associated with the absence of grazing. Species with most total germinable seed were E. japonica (Poaceae; 603/m(2)), and the annual herbs Calotis multicaulis (Asteraceae; 346/m(2)), and Mimulus gracilis (Scrophulariaceae; 168/m(2)). Perennial grass seed was sparse. Spring simulation gave most germination (1059), followed by autumn (892) and winter (376) sets. Greatest species diversity was produced from the spring simulation (33 species), followed by autumn (26), and winter (22). Of the total germination, 92% came from 17 species that were represented in all three simulations. Of the 1227 grass seedlings counted, most were recruited from the surface soil (735), followed by the 5 (310) and 10 (182) cm depths. Marginally more grass seedlings germinated from the spring simulation (558) than the autumn set (523). Only 11.9% of grass germinants came from the winter simulation. All grass species recruited from the soil seedbanks had a C-4 photosynthetic pathway. Except for Cenchrus ciliaris all grass species are native to Australia. Of the four sites sampled, one fenced to exclude cattle five years earlier had significantly more germination than the three unfenced sites. Seedbank sampling produced several new records for plants in the areas sampled.
- Description: C1
- Description: 2003000711
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