Effects of environmental conditions on the production of hypocotyl hairs in seedlings of Melaleuca ericifolia (swamp paperbark)

2008 ◽  
Vol 56 (7) ◽  
pp. 564 ◽  
Author(s):  
Randall W. Robinson ◽  
Paul I. Boon ◽  
Nina Sawtell ◽  
Elizabeth A. James ◽  
Robert Cross
Keyword(s):  
Environmental Conditions ◽  
Water Availability ◽  
Coastal Wetlands ◽  
Root Hairs ◽  
Harsh Environments ◽  
Low Salinity ◽  
South Eastern ◽  
Eastern Australia ◽  
Small Wetland ◽  
South Eastern Australia

The production of hypocotyl hairs in the early stages of seedling development can strongly influence the success with which plants recruit sexually in harsh environments. Although wetlands are one type of environment in which seedlings might be expected to develop hypocotyl hairs, there have been few studies of these structures in the woody aquatic plants. We investigated the production of hypocotyl hairs in Melaleuca ericifolia Sm., a small wetland tree widely distributed across swampy coastal areas of south-eastern Australia, in relation to water availability, salinity, temperature and light regime. Hypocotyl hairs were ~20 mm long × 30 μm wide; in contrast, root hairs were generally less than 5 mm long and 15 μm wide. Hypocotyl hairs were produced only under a narrow range of environmental conditions—low salinity, low water availability, moderate temperature, and darkness—and seedlings that failed to produce hypocotyl hairs did not survive. Since the conditions under which hypocotyl hairs were produced were at least as, and possibly even more, restricted than those required for successful germination of seeds, it is likely that the successful sexual recruitment of M. ericifolia would be rare and episodic under conditions existing in most coastal wetlands in south-eastern Australia.

Agricultural weeds and coastal saltmarsh in south-eastern Australia: an insurmountable problem?

2016 ◽  
Vol 64 (4) ◽  
pp. 308 ◽  
Author(s):  
Thomas Hurst ◽  
Paul I. Boon
Keyword(s):  
Plant Species ◽  
Coastal Wetlands ◽  
Land Reclamation ◽  
Vascular Plant ◽  
Control Measures ◽  
Native Plant ◽  
Pasture Grass ◽  
South Eastern ◽  
Eastern Australia ◽  
South Eastern Australia

It is often assumed that saline coastal wetlands experience environmental conditions so severe that they are largely immune to invasion by exotic plant species. The belief is implicit in many older reviews of threats to mangroves and coastal saltmarshes, where a limited range of vascular plant taxa, often focussing on *Spartina, (throughout the paper an asterisk denotes an introduced (exotic) species as per Carr 2012) have been invoked as the major species of concern. Even though the weed flora of southern Australia is derived largely from agriculture and horticulture, neither of which includes many species tolerant of waterlogged, variably saline environments, a recent assessment of Victorian saline coastal wetlands indicated that exotic plants were the third-most pervasive threat, after land ‘reclamation’ and grazing. Tall wheat grass, *Lophopyrum ponticum (Podp.) A.Love., is one of the most severe and widely distributed weeds of saline coastal wetlands in south-eastern Australia. It is promoted by the agricultural extension arm of the Victorian government as a salt-tolerant pasture grass; however, its broad ecological amplitude and robust life form make it a most serious invader of upper saltmarsh in Victoria. We assessed the effectiveness of different control measures, including slashing and herbicides, for the management of *L. ponticum infestations (and their side effects on saltmarsh communities) in the Western Port region of Victoria. A nominally monocot-specific herbicide widely used to control *Spartina, Fluazifop-P, was ineffective in controlling *L. ponticum. The broad-spectrum systemic herbicide glyphosate was more effective in controlling *L. ponticum, but had undesirable impacts on native plant species. Controlling weeds in coastal wetlands using available herbicides for use near coastal waterways would seem to remain problematic.

Tree water sources over shallow, saline groundwater in the lower River Murray, south-eastern Australia: implications for groundwater recharge mechanisms

2006 ◽  
Vol 54 (2) ◽  
pp. 193 ◽  
Author(s):  
K. L. Holland ◽  
S. D. Tyerman ◽  
L. J. Mensforth ◽  
G. R. Walker
Keyword(s):  
Soil Water ◽  
Riparian Vegetation ◽  
Water Sources ◽  
Plant Water ◽  
Deep Soil ◽  
Saline Groundwater ◽  
Low Salinity ◽  
South Eastern ◽  
Eastern Australia ◽  
South Eastern Australia

The decline of riparian vegetation in the lower River Murray, south-eastern Australia, is associated with a reduction in flooding frequency, extent and duration, and increased salt accumulation. The plant water sources of healthy Eucalyptus largiflorens trees growing over highly saline (>40 dS m–1) groundwater were investigated during summer when water deficit is greatest. The study found low-salinity soil water overlying highly saline groundwater at most sites. This deep soil water, rather than the saline groundwater, was identified as the plant water source at most sites. Stable isotopes of water and water potential measurements were used to infer how the deep soil water was recharged. The low-salinity, deep soil water was recharged in the following two ways: (1) vertically through the soil profile or via preferential flow paths by rainfall or flood waters or (2) horizontally by bank recharge from surface water on top of the saline groundwater. Vertical infiltration of rainfall and floodwaters through cracking clays was important for trees growing in small depressions, whereas infiltration of rainfall through sandy soils was important for trees growing at the break of slope. Bank recharge was important for trees growing within ∼50 m of permanent and ephemeral water bodies. The study has provided a better understanding of the spatial patterns of recharge at a scale relevant to riparian vegetation. This understanding is important for the management of floodplain vegetation growing in a saline, semi-arid environment.

scholarly journals Mangrove and Saltmarsh Distribution Mapping and Land Cover Change Assessment for South-Eastern Australia from 1991 to 2015

2021 ◽  
Vol 13 (8) ◽  
pp. 1450
Author(s):  
Alejandro Navarro ◽  
Mary Young ◽  
Peter I. Macreadie ◽  
Emily Nicholson ◽  
Daniel Ierodiaconou
Keyword(s):  
Coastal Wetlands ◽  
Coastal Wetland ◽  
Temporal Distribution ◽  
Random Forest Classification ◽  
South Eastern ◽  
Shuttle Radar Topographic Mission ◽  
Eastern Australia ◽  
Wide Range ◽  
Conservation Projects ◽  
South Eastern Australia

Coastal wetland ecosystems, such as saltmarsh and mangroves, provide a wide range of important ecological and socio-economic services. A good understanding of the spatial and temporal distribution of these ecosystems is critical to maximising the benefits from restoration and conservation projects. We mapped mangrove and saltmarsh ecosystem transitions from 1991 to 2015 in south-eastern Australia, using remotely sensed Landsat data and a Random Forest classification. Our classification results were improved by the addition of two physical variables (Shuttle Radar Topographic Mission (SRTM), and Distance to Water). We also provide evidence that the addition of post-classification, spatial and temporal, filters improve overall accuracy of coastal wetlands detection by up to 16%. Mangrove and saltmarsh maps produced in this study had an overall User Accuracy of 0.82–0.95 and 0.81–0.87 and an overall Producer Accuracy of 0.71–0.88 and 0.24–0.87 for mangrove and saltmarsh, respectively. We found that mangrove ecosystems in south-eastern Australia have lost an area of 1148 ha (7.6%), whilst saltmarsh experienced an overall increase in coverage of 4157 ha (20.3%) over this 24-year period. The maps developed in this study allow local managers to quantify persistence, gains, and losses of coastal wetlands in south-eastern Australia.

Two new species of Dacrydium (Podocarpaceae) based on vegetative fossils from middle eocene sediments at Nelly Creek, South Australia

2001 ◽  
Vol 14 (2) ◽  
pp. 193 ◽  
Author(s):  
Robert S. Hill ◽  
David C. Christophel
Keyword(s):  
New Species ◽  
Water Availability ◽  
Middle Eocene ◽  
South Australia ◽  
South Eastern ◽  
Early Oligocene ◽  
Eastern Australia ◽  
Two New Species ◽  
Central Australia ◽  
South Eastern Australia

Two new macrofossil species of Dacrydium (Podocarpaceae), D. fimbriatus (with dimorphic foliage) and D. mucronatus, are described from Middle Eocene sediments at Nelly Creek just south of Lake Eyre South. These species extend the number of Dacrydium macrofossil species from four to six, the macrofossil range from south-eastern to central Australia and the earliest macrofossil record of the genus from the Early Oligocene to Middle Eocene. On the basis of the low numbers and poor development of epiphyllous germlings, these species were probably growing in a region where water availability was reduced compared with Paleogene sites in south-eastern Australia, but the morphology of the foliage does not reflect that.

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