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:
Chapter 22 provides an example of variations in local conditions and authorized specifications. The authors present a reclamation case study of an area that was mined 155 years during the gold rush in the state of Victoria, Australia, resulting in significant heavy metal contamination. Using the normal approach of storing the original "natural" vegetation without consideration of ecological differences was not realistic. Measurement of success should cover composition, structure, function and monitoring of invertebrates, because all of these are important components of the ecosystem. This 10 year field trial concluded that (1) only hard seeds survive the pressure of being entombed in stockpiles, so soil should be used soon after stripping to maximize recruitment and diversity; (2) appropriate criteria should be employed for mined sites, especially tailings facilities, with the objective of reverting these to sef-sustaining ecosystems; and (3) future projects should include variables, such as indices of diversity within the ecosystem attributes and at least two reference sites, to suitably portray the ecosystem variation. The authors also discuss how environmental legislation should be based on the ecological settings of the area.
Description:
Chapter 22 provides an example of variations in local conditions and authorized specifications. The authors present a reclamation case study of an area that was mined 155 years during the gold rush in the state of Victoria, Australia, resulting in significant heavy metal contamination. Using the normal approach of storing the original "natural" vegetation without consideration of ecological differences was not realistic. Measurement of success should cover composition, structure, function and monitoring of invertebrates, because all of these are improtant components of the ecosystem. This 10 year field trial concluded that (1) only hard seeds survive the pressure of being entombed in stockpiles, so soil should be used soon after stripping to maximize recruitment and diversity; (2) appropriate criteria should be employed for mined sites, especially tailings facilities, with the objective of reverting these to sef-sustaining ecosystems; and (3) future projects should include variables, such as indices of diversity within the ecosystem attributes and at least two reference sites, to suitably portray the ecosystem variation. The authors also discuss how environmental legislation should be based on the ecological settings of the area.
Description:
In semi-arid north-west Victoria, Slender Cypress-pine (Callitris gracilis) is an important tree hollow forming species for hollow dependent fauna, particularly the Major Mitchell’s Cockatoo (Lophocroa leadbeateri). Long-term management of the Major Mitchell’s Cockatoo must be based on an understanding of the age distribution of Slender Cypress-pine within important habitat areas and the age at which the trees form suitable nesting hollows. This project involved an investigation of the Slender Cypress-pine population within the Pine Plains section of Wyperfeld National Park, north-west Victoria. The objectives of the project were to determine the relationship between stem diameter and age of Slender Cypress-pine, and investigate the age distribution of the Slender Cypress-pine population within Pine Plains. Determination of the relationship between stem diameter and stem age will enable the determination of the number of years trees require to start forming hollows, and to form large hollows suitable for Major Mitchell’s Cockatoo breeding.
Description:
In semi-arid north-west Victoria, Slender Cypress-pine (Callitris gracilis) is an important tree hollow forming species for hollow dependent fauna, particularly the Major Mitchell’s Cockatoo (Lophocroa leadbeateri). Long-term management of the Major Mitchell’s Cockatoo must be based on an understanding of the age distribution of Slender Cypress-pine within important habitat areas and the age at which the trees form suitable nesting hollows. This project involved an investigation of the Slender Cypress-pine population within the Pine Plains section of Wyperfeld National Park, north-west Victoria. The objectives of the project were to determine the relationship between stem diameter and age of Slender Cypress-pine, and investigate the age distribution of the Slender Cypress-pine population within Pine Plains. Determination of the relationship between stem diameter and stem age will enable the determination of the number of years trees require to start forming hollows, and to form large hollows suitable for Major Mitchell’s Cockatoo breeding.
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
Description:
The noxious weed Nassella neesiana is established on a wide range of productive land throughout southeastern Australia. N. neesiana seeds, when mature, are sharp, causing injury to livestock, thus posing a problem in fodder bales. To reduce infestations of agricultural weeds in situ, production of silage from weed-infested pastures is practised as part of integrated weed management (IWM). However, there is little data to demonstrate whether this process is useful to reduce infestations or the harmful properties of N. neesiana. Therefore, the minimum duration of ensilage required to reduce the viability of N. neesiana seeds was investigated, both with and without addition of ensilage inoculants in this process. Also, the decreasing propensity of the seeds to injure livestock, after various times and conditions of ensilage, was assessed. Ensilage inoculant reduced seed germination probability to zero after 35 days. When no inoculant was added, zero viability was achieved after 42 days. A qualitative assessment of the hardness of ensilaged seeds found seed husks were softer (and therefore safer) after 42 days, whether inoculant was used or not. Therefore, we suggest that both the viability of N. neesiana seeds and hardness of seed casings are significantly reduced after 42 days, thereby reducing the risks of seed dispersal and injury to livestock.
Description:
The noxious weed Nassella neesiana is established on a wide range of productive land throughout southeastern Australia. N. neesiana seeds, when mature, are sharp, causing injury to livestock, thus posing a problem in fodder bales. To reduce infestations of agricultural weeds in situ, production of silage from weed-infested pastures is practised as part of integrated weed management (IWM). However, there is little data to demonstrate whether this process is useful to reduce infestations or the harmful properties of N. neesiana. Therefore, the minimum duration of ensilage required to reduce the viability of N. neesiana seeds was investigated, both with and without addition of ensilage inoculants in this process. Also, the decreasing propensity of the seeds to injure livestock, after various times and conditions of ensilage, was assessed. Ensilage inoculant reduced seed germination probability to zero after 35 days. When no inoculant was added, zero viability was achieved after 42 days. A qualitative assessment of the hardness of ensilaged seeds found seed husks were softer (and therefore safer) after 42 days, whether inoculant was used or not. Therefore, we suggest that both the viability of N. neesiana seeds and hardness of seed casings are significantly reduced after 42 days, thereby reducing the risks of seed dispersal and injury to livestock.
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.
Description:
Annual ryegrass is one of the most serious, costly weeds of winter cropping systems in Australia. To determine whether its competition-mediated plant defence mechanisms effect on wheat grain quality, wheat (cv. Yitpi) and annual ryegrass were grown under two levels of CO2 (400 ppm; (a[CO2]) vs 700 ppm; (e[CO2]), two levels of water (well-watered vs drought) and two types of competition (wheat only; (W), and wheatxannual ryegrass; (W x R) with four replicates. The competitionx[CO2] interaction had a significant effect on wheat grain protein content, where it was increased in W x R under both e[CO2] (+ 17%) and a[CO2] (+ 21%). Grain yield, total grain reducing power and phenolic content were significantly affected by [CO2] x drought x competition. In a summary, annual ryegrass competition significantly altered the wheat grain quality under both [CO2] levels (depending on the soil water level), while also decreasing the grain yield.
Description:
Annual ryegrass is one of the most serious, costly weeds of winter cropping systems in Australia. To determine whether its competition-mediated plant defence mechanisms effect on wheat grain quality, wheat (cv. Yitpi) and annual ryegrass were grown under two levels of CO2 (400 ppm; (a[CO2]) vs 700 ppm; (e[CO2]), two levels of water (well-watered vs drought) and two types of competition (wheat only; (W), and wheatxannual ryegrass; (W x R) with four replicates. The competitionx[CO2] interaction had a significant effect on wheat grain protein content, where it was increased in W x R under both e[CO2] (+ 17%) and a[CO2] (+ 21%). Grain yield, total grain reducing power and phenolic content were significantly affected by [CO2] x drought x competition. In a summary, annual ryegrass competition significantly altered the wheat grain quality under both [CO2] levels (depending on the soil water level), while also decreasing the grain yield.
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.
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:
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:
It has been widely observed that recent increases in atmospheric CO2 concentrations have had, so far, a positive effect on the growth of plants. This is not surprising since CO2 is an important nutrient for plant matter, being directly involved in photosynthesis. However, it is also known that the conditions which have accompanied this increase in atmospheric CO2 concentration have also had significant effects on other environmental factors. It is possible that these other effects may emerge as limiting factors which could act to prevent plant growth. This may involve complex interactions between prevailing sunlight and water conditions, variable temperatures, the availability of essential nutrients and the type of synthetic pathway for the plant species. The issue of concern to this investigation is if we should be worried about a possible shift in the C3-C4 paradigm driven by changes in the atmospheric CO2 concentration, or if some other factor, such as water scarcity, is much more relevant within a 30-year time frame. If an opinion is needed on what will have the worst effect on the survival of the planet between the scarcity of water or the reduced efficiency of C3 plants to sequester CO2, the issue of water is the more incisive.
Description:
It has been widely observed that recent increases in atmospheric CO2 concentrations have had, so far, a positive effect on the growth of plants. This is not surprising since CO2 is an important nutrient for plant matter, being directly involved in photosynthesis. However, it is also known that the conditions which have accompanied this increase in atmospheric CO2 concentration have also had significant effects on other environmental factors. It is possible that these other effects may emerge as limiting factors which could act to prevent plant growth. This may involve complex interactions between prevailing sunlight and water conditions, variable temperatures, the availability of essential nutrients and the type of synthetic pathway for the plant species. The issue of concern to this investigation is if we should be worried about a possible shift in the C3-C4 paradigm driven by changes in the atmospheric CO2 concentration, or if some other factor, such as water scarcity, is much more relevant within a 30-year time frame. If an opinion is needed on what will have the worst effect on the survival of the planet between the scarcity of water or the reduced efficiency of C3 plants to sequester CO2, the issue of water is the more incisive.
Description:
Major government funds have been allocated to revegetation of degraded catchments in Australia in order to enhance biodiversity, protect stock and improve water quality. However, the success or otherwise of the different restoration practices used has not been assessed. To redress this deficiency we audited these practices by measuring biotic and abiotic variables in two field surveys, one at a landscape scale and the second at a local scale. The landscape survey comprised 21 sites in western Victoria, a third of the sites were revegetated and were between 8 and 12 years old, a third carried remnant native vegetation and a third were degraded and not revegetated. In the local survey the results of the landscape survey were tested by sampling sites within a small area using the same methods but including pine plantations as an untreated site. Here we report on density and species composition of soil and surface active fauna. native and exotic Collembola and decomposition rates as measured with bait laminae. Fifty seven species of Collembola were found on the landscape survey and 47 on the local survey. Densities ranged from 17,000 to 45,000 m-2 in soil. In both the surveys we found decomposition was directly related to soil moisture and in the landscape survey exotic Collembola (Hypogastrura and Ceratophysella spp) to abundance of exotic grass species. MDS analysis of soil Collembola in the landscape survey placed remnant sites separate from the revegetated sites and untreated sites. which tended to cluster together. A suite of nine native Collembola species were found exclusively on remnant sites in the landscape survey. In the local survey, the revegetated sites. here with a ground cover of native not exotic grasses, were found to have nine characterising species, four of which were the same indicators as in the landscape survey. The pine plantations were dominated by acidophil exotic Collembola species. MDS analysis of pitfall data in local survey placed all sites in the same space, except for one remnant because of domination by the same exotic species as in the landscape survey. In contrast. MDS of the soil-core data separated all three treatments with the revegetated sites occupying the space between the remnants and the pines as in the landscape survey. When exotic species were removed. there was spatial separation of each treatment. We conclude that. in some circumstances, soil fauna of revegetated sites can develop characteristics of remnant sites in terms of native Collembola even after only 8 to 12 years. The bait lamina method must be used with caution as it is strongly influenced by soil moisture.
Description:
Major government funds have been allocated to revegetation of degraded catchments in Australia in order to enhance biodiversity, protect stock and improve water quality. However, the success or otherwise of the different restoration practices used has not been assessed. To redress this deficiency we audited these practices by measuring biotic and abiotic variables in two field surveys, one at a landscape scale and the second at a local scale. The landscape survey comprised 21 sites in western Victoria, a third of the sites were revegetated and were between 8 and 12 years old, a third carried remnant native vegetation and a third were degraded and not revegetated. In the local survey the results of the landscape survey were tested by sampling sites within a small area using the same methods but including pine plantations as an untreated site. Here we report on density and species composition of soil and surface active fauna. native and exotic Collembola and decomposition rates as measured with bait laminae. Fifty seven species of Collembola were found on the landscape survey and 47 on the local survey. Densities ranged from 17,000 to 45,000 m
Biology, distribution and management of the globally invasive weed Solanum elaeagnifolium Cav (silverleaf nightshade): A global review of current and future management challenges