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
The germination success of Acacia longifolia subsp. longifolia (Fabaceae) : A comparison between its native and exotic ranges
- Authors: Welgama, Amali , Florentine, Singarayer , Marchante, Hélia , Javaid, Muhammad , Turville, Christopher
- Date: 2019
- Type: Text , Journal article
- Relation: Australian Journal of Botany Vol. 67, no. 5 (2019), p. 414-424
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- Description: Acacia longifolia subsp. longifolia is native to South-eastern Australia and has naturalised in many regions across the globe, including in Portugal, Spain, and South Africa invading extensive areas. Prolific seed production and a long-lived seedbank are considered key factors that enhance its invasiveness. Yet, the effects of different factors on germination are still underexplored. Seeds were collected from Portuguese and Australian populations, and germination was evaluated under different temperature regimes, photoperiods, pH levels, salt stress, osmotic potential and burial depths. Findings show both populations share some similar patterns but also reveal important differences related to their germination. Higher temperatures induce increased germination rates while the photoperiod has no effect on germination. Both populations had quicker seed emergence under dark conditions. Seeds from both populations decrease germination rate under increasing salt-stress and show a wide range of pH tolerance, but Australians seeds are more tolerant to increase of both parameters. Seeds from the Portuguese population are bigger and germinated from deeper depths than the Australian. Our results may provide information to improve management of this species seedbank. Germination can prevent by, tillage or other interventions that help to increase burial depths; adding lime (to increase the soil alkalinity) can reduce its germination rate in both geographical ranges.
Effects of Tetranychus lintearius (Acari : Tetranychidae) on the structure and water potential in the foliage of the invasive Ulex europaeus (Fabaceae) in Australia
- Authors: Marriott, Jeremy , Florentine, Singarayer , Raman, Anantanarayanan
- Date: 2013
- Type: Text , Journal article
- Relation: International Journal of Acarology Vol. 39, no. 4 (2013), p. 275-284
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- Description: Ulex europaeus, a native of Western Europe and the Mediterranean coast, is a serious agricultural and environmental weed in many parts of the earth, including Australia. Tetranychus lintearius attacks U. europaeus in its natural range and is one of the four biological control agents introduced into Australia to regulate populations of U. europaeus. Tetranychus lintearius is specific to different species of Ulex, which enhances its status as a key biological control agent. Little is known on the physiological effects and structural changes induced by T. lintearius on U. europaeus. This article describes anatomical changes and evaluates the physiological effects in U. europaeus consequent to feeding by T. lintearius for more than 100 d. This study demonstrates that feeding by T. lintearius reduces the quantity of photosynthetic tissue in U. europaeus, as a result of feeding on mesophyll parenchyma by inserting its stylets through the stomatal aperture. Unfed parenchyma cells display signs of stress, either exhibiting deformed cell organelles aligned along the walls of vacant cells or with cells with no well-defined cell organelles. Subsequent to T. lintearius feeding, leaves externally manifest bleaching. After feeding by a population of T. lintearius, leaf water potential is decreased by 30% and tender shoots lose their turgor, indicating water-related stress. Tetranychus lintearius has the potential to decelerate vigour and retard the competitiveness of U. europaeus by inflicting stress. Our findings reinforce the use of T. lintearius in the biological management of populations of U. europaeus in temperate Australia.
Hydraulic heterogeneity in a highly weathered basaltic regolith : Impact on lateral-flow and solute transport
- Authors: Rasiah, Velu , Armour, John , Florentine, Singarayer
- Date: 2012
- Type: Text , Journal article
- Relation: Journal of Environmental Hydrology Vol. 20, no. 13 (2012), p.
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- Description: Reliable on-ground information on groundwater (GW) hydraulic heterogeneity is required to determine flow direction and quantities, but its experimental characterization is difficult because of the complexities associated with the interaction involving the temporal changes in space modified by regolith stratigraphy. The impact of the aforementioned variables, particularly stratigraphy in a 51 m thick highly weathered basaltic regolith in the northeast humid tropics of Queensland, Australia, on flow gradients and directions was investigated in this study. Regolith cores at 1 m increments indicated that there were 3 different major strata. The temporal changes in water table, hydraulic- and pressure- heads, and solute concentrations in space indicated the top 51 m aquifer was contiguous, dynamic and hydraulically differentiated into three segments which approximately corresponded with the regolith strata. The lateralflow and solute transport from each aquifer segment was controlled by depth to water table, the number of regolith layers the segment covered, and the solute concentration.
- Description: 2003010399
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
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- 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