The response of Nassella trichotoma (serrated tussock) seeds and seedlings to different levels of fire intensity
- Humphries, Talia, Florentine, Singarayer
- Authors: Humphries, Talia , Florentine, Singarayer
- Date: 2023
- Type: Text , Journal article
- Relation: Australian Journal of Botany Vol. 71, no. 4 (2023), p. 188-198
- Full Text:
- Reviewed:
- Description: Context Fire is an important disturbance regime in grassland communities, since it is responsible for stimulating the regeneration of many species and for maintaining levels of biodiversity. When invasive plants, such as Nassella trichotoma, establish and become widespread in a grassland community, these important fire events can be altered in intensity and frequency, which means that they are able to facilitate the establishment of the exotic species. Therefore, before fire can be recommended as a suitable control technique for invasive species, or alternatively to be integrated into grassland restoration programs, understanding the response of the seeds of exotic species to high temperatures, such as those experienced during a fire, should be well understood. Aims Our aim was to identify their response to a gradient of temperatures associated with different levels of fire intensity. We examined how increased duration of exposure affects their response, and whether seed age or seed moisture content affect the germination response of this species. Methods To gain a fuller understanding of the fire response of N. trichotoma’s seedbank, seeds were collected in 2016, 2017, 2018 and 2019 and then stored until the commencement of the experiments in 2020. Selected seeds were first subjected to an increasing temperature gradient (80°C, 100°C, 120°C, 140°C, and a control), and an increasing duration of exposure (of 1, 3, 6, and 9 min). In the second experiment, one population was selected to test these same temperatures and duration of exposure after the seeds were hydrated to 15%, 50%, or 95%. Last, seedlings were grown for 3 months under glasshouse conditions and then exposed to increasing temperatures (20°C, 60°C, 80°C, 100°C, and 120°C), and an increasing duration of exposure (3, 6, and 9 min). The seedlings were assessed 2 weeks after the heat exposure for signs of damage. Key results It was found that increased temperatures and duration of exposure had a subtle negative effect on germination parameters, including reduced total germination and increased time to 50% germination. The 140°C treatment was seen to be a significant threshold because it killed all the seeds at any duration of exposure. A significant difference among the ages of each seed lot was observed to be a factor on the tested germination metrics, with the oldest tested population (2016) demonstrating the highest germination percentage, uniformity, and rate. Seed germination percentage was significantly reduced for seeds hydrated to 95% compared with the control treatment, whereas no significant difference was observed for the seeds hydrated to 15% and 50%. For the heat treatment of the seedlings, damage to the leaves was observed in the 80°C, 100°C, and 120°C treatments, with some plants in the 120°C treatment experiencing extensive damage prior to resprouting. No seedlings were killed at the tested temperatures. Conclusions Results of this study indicated that fire may be a useful tool for reducing seedbank density by killing a high proportion of the seeds on the soil surface, or located within the top 1 cm of the soil profile, but not for seeds buried more deeply. Efficacy of fire on surface and shallow-buried seeds is improved with high seed moisture content however, these seeds buried below this depth are still protected by the soil from the lethal effects of temperature. Implications Fire implemented before seed set could be used to effectively kill a large proportion of N. trichotoma seeds. However, for more comprehensive control, it is recommended that chemical treatment is integrated with the fire treatment to improve the overall control efficiency.
- Authors: Humphries, Talia , Florentine, Singarayer
- Date: 2023
- Type: Text , Journal article
- Relation: Australian Journal of Botany Vol. 71, no. 4 (2023), p. 188-198
- Full Text:
- Reviewed:
- Description: Context Fire is an important disturbance regime in grassland communities, since it is responsible for stimulating the regeneration of many species and for maintaining levels of biodiversity. When invasive plants, such as Nassella trichotoma, establish and become widespread in a grassland community, these important fire events can be altered in intensity and frequency, which means that they are able to facilitate the establishment of the exotic species. Therefore, before fire can be recommended as a suitable control technique for invasive species, or alternatively to be integrated into grassland restoration programs, understanding the response of the seeds of exotic species to high temperatures, such as those experienced during a fire, should be well understood. Aims Our aim was to identify their response to a gradient of temperatures associated with different levels of fire intensity. We examined how increased duration of exposure affects their response, and whether seed age or seed moisture content affect the germination response of this species. Methods To gain a fuller understanding of the fire response of N. trichotoma’s seedbank, seeds were collected in 2016, 2017, 2018 and 2019 and then stored until the commencement of the experiments in 2020. Selected seeds were first subjected to an increasing temperature gradient (80°C, 100°C, 120°C, 140°C, and a control), and an increasing duration of exposure (of 1, 3, 6, and 9 min). In the second experiment, one population was selected to test these same temperatures and duration of exposure after the seeds were hydrated to 15%, 50%, or 95%. Last, seedlings were grown for 3 months under glasshouse conditions and then exposed to increasing temperatures (20°C, 60°C, 80°C, 100°C, and 120°C), and an increasing duration of exposure (3, 6, and 9 min). The seedlings were assessed 2 weeks after the heat exposure for signs of damage. Key results It was found that increased temperatures and duration of exposure had a subtle negative effect on germination parameters, including reduced total germination and increased time to 50% germination. The 140°C treatment was seen to be a significant threshold because it killed all the seeds at any duration of exposure. A significant difference among the ages of each seed lot was observed to be a factor on the tested germination metrics, with the oldest tested population (2016) demonstrating the highest germination percentage, uniformity, and rate. Seed germination percentage was significantly reduced for seeds hydrated to 95% compared with the control treatment, whereas no significant difference was observed for the seeds hydrated to 15% and 50%. For the heat treatment of the seedlings, damage to the leaves was observed in the 80°C, 100°C, and 120°C treatments, with some plants in the 120°C treatment experiencing extensive damage prior to resprouting. No seedlings were killed at the tested temperatures. Conclusions Results of this study indicated that fire may be a useful tool for reducing seedbank density by killing a high proportion of the seeds on the soil surface, or located within the top 1 cm of the soil profile, but not for seeds buried more deeply. Efficacy of fire on surface and shallow-buried seeds is improved with high seed moisture content however, these seeds buried below this depth are still protected by the soil from the lethal effects of temperature. Implications Fire implemented before seed set could be used to effectively kill a large proportion of N. trichotoma seeds. However, for more comprehensive control, it is recommended that chemical treatment is integrated with the fire treatment to improve the overall control efficiency.
Effect of slope position on soil properties and soil moisture regime of Stagnosol in the vineyard
- Magdić, Ivan, Safner, Toni, Rubinić, Vedran, Rutić, Filip, Husnjak, Stjepan, Filipović, Vilim
- Authors: Magdić, Ivan , Safner, Toni , Rubinić, Vedran , Rutić, Filip , Husnjak, Stjepan , Filipović, Vilim
- Date: 2022
- Type: Text , Journal article
- Relation: Journal of Hydrology and Hydromechanics Vol. 70, no. 1 (2022), p. 62-73
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- Reviewed:
- Description: Hillslope hydrology in agricultural landscapes is complex due to a variety of hydropedological processes and field management possibilities. The aim was to test if there are any differences in soil properties and water regime along the hillslope and to compare vineyard rows (vine) with inter-rows (grass) area for those properties. The study determined that there are significant differences in the contents of soil particle fractions, pH, and humus content along the slope ( < 0.0001), with lower confidence level in bulk density < 0.05). Differences between row and inter-row space were significant for the pH, humus, and silt content, but for sand and clay content, and bulk density differences were not determined. The study determined differences in soil water content among five slope positions ( < 0.0001), and between row and inter-row vineyard space (all with < 0.05). Where in the upper slope positions (e. g., P1) soil water content was higher than on lower slope positions. Higher soil water content was observed at higher slope positions, associated with clay content. However, it can be concluded that the retention of moisture on the slope is more influenced by local-scale soil properties (primarily soil texture) and variability of the crop (row/inter-row) than the position on the slope.
- Authors: Magdić, Ivan , Safner, Toni , Rubinić, Vedran , Rutić, Filip , Husnjak, Stjepan , Filipović, Vilim
- Date: 2022
- Type: Text , Journal article
- Relation: Journal of Hydrology and Hydromechanics Vol. 70, no. 1 (2022), p. 62-73
- Full Text:
- Reviewed:
- Description: Hillslope hydrology in agricultural landscapes is complex due to a variety of hydropedological processes and field management possibilities. The aim was to test if there are any differences in soil properties and water regime along the hillslope and to compare vineyard rows (vine) with inter-rows (grass) area for those properties. The study determined that there are significant differences in the contents of soil particle fractions, pH, and humus content along the slope ( < 0.0001), with lower confidence level in bulk density < 0.05). Differences between row and inter-row space were significant for the pH, humus, and silt content, but for sand and clay content, and bulk density differences were not determined. The study determined differences in soil water content among five slope positions ( < 0.0001), and between row and inter-row vineyard space (all with < 0.05). Where in the upper slope positions (e. g., P1) soil water content was higher than on lower slope positions. Higher soil water content was observed at higher slope positions, associated with clay content. However, it can be concluded that the retention of moisture on the slope is more influenced by local-scale soil properties (primarily soil texture) and variability of the crop (row/inter-row) than the position on the slope.
Controlling Lachnagrostis filiformis (Fairy grass) on dry lake beds in western Victoria, Australia
- Authors: Warnock, Andrew
- Date: 2009
- Type: Text , Thesis , PhD
- Full Text:
- Description: The indigenous grass Lachnagrostis filiformis (Fairy grass) has colonised extensive areas of dry lakebeds in western Victoria, Australia during the current (1997-) drought. Large numbers of the plants' detached seed heads disperse in the wind and lodge against housing, fences, railway lines and other obstacles ... In this study, late season application of Glyphosate based herbicide, slashing, seed broadcasting of Atriplex australasica and Puccinellia perlaxa, grazing and burning were examined ... The results highlight how weed management aimed at achieving short-term goals, without controlling the ecological processes that promote weeds establishment and persistence, can be counter productive in the long-term.
- Description: Doctorate of Philosophy
- Authors: Warnock, Andrew
- Date: 2009
- Type: Text , Thesis , PhD
- Full Text:
- Description: The indigenous grass Lachnagrostis filiformis (Fairy grass) has colonised extensive areas of dry lakebeds in western Victoria, Australia during the current (1997-) drought. Large numbers of the plants' detached seed heads disperse in the wind and lodge against housing, fences, railway lines and other obstacles ... In this study, late season application of Glyphosate based herbicide, slashing, seed broadcasting of Atriplex australasica and Puccinellia perlaxa, grazing and burning were examined ... The results highlight how weed management aimed at achieving short-term goals, without controlling the ecological processes that promote weeds establishment and persistence, can be counter productive in the long-term.
- Description: Doctorate of Philosophy
Controlling wind blown Lachnagrostis filiformis (fairy grass) seed heads in western Victoria
- Warnock, Andrew, Florentine, Singarayer, Graz, Patrick, Westbrooke, Martin
- 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
- Full Text:
- Description: 2003007372
- 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
- Full Text:
- Description: 2003007372
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