Competition between two aquatic macrophytes, Lagarosiphon major (Ridley) Moss (Hydrocharitaceae) and Myriophyllum spicatum Linnaeus (Haloragaceae) as influenced by substrate sediment and nutrients
- Martin, Grant D, Coetzee, Julie A
- Authors: Martin, Grant D , Coetzee, Julie A
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76925 , vital:30641 , https://doi.org/10.1016/j.aquabot.2013.11.001
- Description: Competition between two globally economic and ecologically important submerged aquatic macrophytes, Lagarosiphon major (Rid.) Moss ex Wager and Myriophyllum spicatum L., was studied in response to growing in different substrate nutrient and sediment treatments. Addition series experiments were conducted with mixed plantings of L. major and M. spicatum grown under two soil nutrient concentrations (high vs. low) and two sediment treatments (sand vs. loam). Competitive ability of the plants was determined using an inverse linear model of the total dry weights as the yield variable. In high nutrient sediment treatments, L. major was the stronger competitor relative to M. spicatum, with one L. major plant being competitively equivalent to 2.5 M. spicatum plants in terms of their respective ability to reduce L. major biomass. In the loam sediment treatments, L. major was an even stronger competitor relative to M. spicatum with one L. major being equivalent to 10 M. spicatum plants. Additionally, L. major had a faster relative growth rate (RGR) than M. spicatum when grown in mixed cultures, a loam sediment type and at both high and low planting densities. The results indicated that L. major is a superior competitor to M. spicatum and that both nutrient and sediment conditions significantly affect the competitive ability of both species. The results contribute to the understanding of competition between submerged invasive macrophytes, and provide insight into the establishment and spread of invasive submerged macrophytes.
- Full Text:
- Date Issued: 2014
- Authors: Martin, Grant D , Coetzee, Julie A
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76925 , vital:30641 , https://doi.org/10.1016/j.aquabot.2013.11.001
- Description: Competition between two globally economic and ecologically important submerged aquatic macrophytes, Lagarosiphon major (Rid.) Moss ex Wager and Myriophyllum spicatum L., was studied in response to growing in different substrate nutrient and sediment treatments. Addition series experiments were conducted with mixed plantings of L. major and M. spicatum grown under two soil nutrient concentrations (high vs. low) and two sediment treatments (sand vs. loam). Competitive ability of the plants was determined using an inverse linear model of the total dry weights as the yield variable. In high nutrient sediment treatments, L. major was the stronger competitor relative to M. spicatum, with one L. major plant being competitively equivalent to 2.5 M. spicatum plants in terms of their respective ability to reduce L. major biomass. In the loam sediment treatments, L. major was an even stronger competitor relative to M. spicatum with one L. major being equivalent to 10 M. spicatum plants. Additionally, L. major had a faster relative growth rate (RGR) than M. spicatum when grown in mixed cultures, a loam sediment type and at both high and low planting densities. The results indicated that L. major is a superior competitor to M. spicatum and that both nutrient and sediment conditions significantly affect the competitive ability of both species. The results contribute to the understanding of competition between submerged invasive macrophytes, and provide insight into the establishment and spread of invasive submerged macrophytes.
- Full Text:
- Date Issued: 2014
Prioritisation of potential agents for the biological control of the invasive alien weed, Pereskia aculeata (Cactaceae), in South Africa
- Paterson, Iain D, Vitorino, Marcello D, de Cristo, S C, Martin, Grant D, Hill, Martin P
- Authors: Paterson, Iain D , Vitorino, Marcello D , de Cristo, S C , Martin, Grant D , Hill, Martin P
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76946 , vital:30644 , https://doi.org/10.1080/09583157.2013.864382
- Description: Pereskia aculeata Miller (Cactaceae) is an invasive alien species in South Africa that is native in Central and South America. In South Africa, P. aculeata outcompetes native plant species leading to a reduction in biodiversity at infested sites. Herbicidal and mechanical control of the plant is ineffective and unsustainable, so biological control is considered the only potential solution. Climatic matching and genotype matching indicated that the most appropriate regions in which to collect biological control agents were Santa Catarina and Rio de Janeiro provinces in Southern Brazil. Surveys throughout the native distribution resulted in 15 natural enemy species that were associated with the plant. Field host range data, as well as previous host plant records, were used to prioritise which of the species were most likely to be suitably host specific for release in South Africa. The mode of damage was used to determine which species were most likely to be damaging and effective if released. The most promising species prioritised for further study, including host specificity and impact studies, were the stem-wilter Catorhintha schaffneri Brailovsky and Garcia (Coreidae); the stem boring species Acanthodoxus machacalis Martins and Monné (Cerambycidae), Cryptorhynchus sp. (Curculionidae) and Maracayia chlorisalis (Walker) (Crambidae) and the fruit galler Asphondylia sp. (Cecidomyiidae). By prioritising the potential biological control agents that are most likely to be host-specific and damaging, the risk of conducting host specificity testing on unsuitable or ineffective biological control agents is reduced.
- Full Text:
- Date Issued: 2014
- Authors: Paterson, Iain D , Vitorino, Marcello D , de Cristo, S C , Martin, Grant D , Hill, Martin P
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76946 , vital:30644 , https://doi.org/10.1080/09583157.2013.864382
- Description: Pereskia aculeata Miller (Cactaceae) is an invasive alien species in South Africa that is native in Central and South America. In South Africa, P. aculeata outcompetes native plant species leading to a reduction in biodiversity at infested sites. Herbicidal and mechanical control of the plant is ineffective and unsustainable, so biological control is considered the only potential solution. Climatic matching and genotype matching indicated that the most appropriate regions in which to collect biological control agents were Santa Catarina and Rio de Janeiro provinces in Southern Brazil. Surveys throughout the native distribution resulted in 15 natural enemy species that were associated with the plant. Field host range data, as well as previous host plant records, were used to prioritise which of the species were most likely to be suitably host specific for release in South Africa. The mode of damage was used to determine which species were most likely to be damaging and effective if released. The most promising species prioritised for further study, including host specificity and impact studies, were the stem-wilter Catorhintha schaffneri Brailovsky and Garcia (Coreidae); the stem boring species Acanthodoxus machacalis Martins and Monné (Cerambycidae), Cryptorhynchus sp. (Curculionidae) and Maracayia chlorisalis (Walker) (Crambidae) and the fruit galler Asphondylia sp. (Cecidomyiidae). By prioritising the potential biological control agents that are most likely to be host-specific and damaging, the risk of conducting host specificity testing on unsuitable or ineffective biological control agents is reduced.
- Full Text:
- Date Issued: 2014
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