Fire exclusion and soil texture interact to influence temperate grassland flora in south-eastern Australia

2016 ◽  
Vol 64 (5) ◽  
pp. 417 ◽  
Author(s):  
Claire Moxham ◽  
Josh Dorrough ◽  
Mick Bramwell ◽  
Brad J. Farmilo

Fire has a major influence on the structure and composition of temperate grasslands and woodlands. We investigated whether the impacts of fire exclusion on a temperate grassland plant community varied according to the scale of investigation and soil texture. Ten sites with known fire histories were selected along a soil texture gradient in south-eastern Australia. Floristics and ground layer attributes were investigated at small (0.25 m2) and large (100 m2) spatial scales in regularly burnt and unburnt grasslands. Fire exclusion over a 10 year period led to declines in native species diversity, richness and cover at both spatial scales and in most cases effects were consistent regardless of soil texture. However, the richness of native plant species at small scales and the cover of native plants at large scales were most negatively influenced by fire exclusion on fine textured soils. Conversely, at large scales, exotic plant richness and cover were only weakly increased by fire exclusion. Responses of eight common species were modelled and in seven of these, fire exclusion was a strong predictor of occurrence, although both positive and negative responses were observed. These results reiterate the importance of frequent fire as a management tool in temperate grasslands, but also shed light on how sites may require specific fire management regimes depending on the underlying soil texture.

2016 ◽  
Vol 64 (4) ◽  
pp. 308 ◽  
Author(s):  
Thomas Hurst ◽  
Paul I. Boon

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.


2010 ◽  
Vol 61 (11) ◽  
pp. 1243 ◽  
Author(s):  
Eszter Z. Hidas ◽  
David J. Ayre ◽  
Todd E. Minchinton

The abundant-centre hypothesis predicts that species' abundances peak at the centre of their geographical ranges and decline gradually towards their range limits. We tested predictions of this hypothesis for three rocky-shore, intertidal invertebrates with planktonic larvae (the whelk, Morula marginalba, the snail, Afrolittorina pyramidalis, and the barnacle, Tesseropora rosea) by quantifying their patterns of abundance and size, and inferring pulses of recruitment from size-frequency distributions, at multiple spatial scales spanning a 600-km region in south-eastern Australia and encompassing roughly the southern third of their geographical ranges. At the regional scale, abundances for all species were, as predicted, dramatically lower at their range limits. This decline was not gradual, however, because there were large variations in abundance at smaller spatial scales, and abrupt declines at the south-eastern corner of Australia. Size did not change towards the range limit for any species, but size-frequency distributions suggested a decline in the frequency of recruitment events at the range limit for T. rosea. We conclude that the abundant-centre hypothesis is not an appropriate model for abundance distributions of benthic marine invertebrates with planktonic larvae, because of the vagaries of dispersal and recruitment interacting with complex current patterns along non-uniform coastlines.


1993 ◽  
Vol 44 (6) ◽  
pp. 881 ◽  
Author(s):  
DJ Ferrell ◽  
SE McNeill ◽  
DG Worthington ◽  
JD Bell

A beam trawl was used to sample fish associated with the seagrass Posidonia australis between September 1988 and June 1990. We describe variation in abundance of fish at two spatial scales: among three seagrass beds 1-10 km apart within each of three estuaries, and among the estuaries separated by at least 100 km. Most species had significant differences in abundance among sites and estuaries that changed through time. However, many species also had consistent patterns in abundance among sites and among estuaries. For example, there were large and consistent differences in the abundance of many species among the three estuaries. Widespread changes in abundance (ie: changes that took place at all sites within an estuary or in most estuaries) were not common. The two spatial scales used in this study are also logical scales for management of seagrass habitats. The consistent differences in abundance of some fish found at both spatial scales will complicate management decisions.


2016 ◽  
Vol 67 (10) ◽  
pp. 1410 ◽  
Author(s):  
Jamin Forbes ◽  
Robyn J. Watts ◽  
Wayne A. Robinson ◽  
Lee J. Baumgartner ◽  
Prue McGuffie ◽  
...  

Stock enhancement is a management tool used for fishery recovery worldwide, yet the success of many stocking programs remains unquantified. Murray cod (Maccullochella peelii) and golden perch (Macquaria ambigua) are important Australian recreational target species that have experienced widespread decline. Stocking of these species has been undertaken for decades, with limited assessment of effectiveness. A batch marking and recapture approach was applied to assess stocked Murray cod and golden perch survival, contributions to wild fisheries, and condition in rivers and impoundments. Stocked fish were marked with calcein. Marked fish were detected during surveys undertaken 3 years and 10 months from initial marking, and it is probable that marks will persist beyond this time. The proportion of calcein marked fish in the population sub-sample whose age was equal to, or less than, the number of years since release, varied by 7–94% for Murray cod, and 9–98% for golden perch. Higher proportions of marked fish were found in impoundments than rivers. Marked Murray cod had significantly steeper length–weight relationships (i.e. higher weight at a given length) to unmarked fish. Our results show that application of methods for discriminating stocked and wild fish provides critical information for the development of adaptive, location-specific stocking strategies.


1999 ◽  
Vol 47 (4) ◽  
pp. 537 ◽  
Author(s):  
Ian D. Lunt ◽  
John W. Morgan

Changes in the vegetation composition of a remnant Themeda triandra Forsskal grassland in south-eastern Australia were documented following the replacement of stock grazing with intermittent burning at 3–11-year intervals. The vegetation was initially sampled in 1986, 1 year after stock were removed, and then 10 years later in 1996. Most frequently encountered grassland species were abundant in both surveys, although there was little correspondence between species richness at the quadrat scale in 1986 and 1996. Total floristic richness increased slightly over the 10-year period, owing to the proliferation of tall forbs with wind-blown seeds, including exotic thistles and colonising native forbs. Unfortunately, most native ‘increasers’ were ‘weedy’ species which are not typical or common components of species-rich temperate grassland remnants in southern Victoria. Thus, replacing grazing with intermittent burning has not resulted in the flora becoming more similar to that of high-quality, species-rich grassland remnants, but instead, has promoted a group of ruderal colonisers. The ability to identify factors contributing to particular botanical changes was hampered by the design of the management regimes implemented over the past decade. Suggestions are provided to overcome these difficulties, incorporating principles from adaptive management.


2009 ◽  
Vol 36 (3) ◽  
pp. 231 ◽  
Author(s):  
David M. Forsyth ◽  
Steve R. McLeod ◽  
Michael P. Scroggie ◽  
Matthew D. White

Combining abundance data collected in designed field surveys with biophysical data derived from geographic information systems is a powerful way to investigate predictors of spatial variation in the abundance of wildlife. We used such an approach to evaluate hypotheses about factors influencing the abundance of sambar deer (Cervus unicolour Kerr, 1792), a large non-native herbivore, in south-eastern Australia. We developed a spatial model for the abundance of sambar deer faecal pellets in a 3650-ha area in the Upper Yarra Ranges, Victoria. We counted the number of sambar deer faecal pellets along 100 randomly located transects and used a geographic information system to estimate biophysical variables around each transect. We formulated our hypotheses about how those variables might affect the abundance of sambar deer pellets into 22 candidate models and used the deviance information criterion to identify the ‘best’ model(s). Because five models had strong support we used model averaging to generate a predictive model. The three variables included in the predictive model were aspect (abundance of pellets declined with increasing ‘northerliness’ and increased with increasing ‘easterliness’), distance to water and elevation; the latter two variables were positively correlated and had a negative effect on the abundance of pellets. In contrast to previous models of sambar deer abundance in south-eastern Australia, our spatial predictions of the abundance of faecal pellets can be easily tested and updated. Our approach would be useful for modelling the abundances of other wildlife species at a range of spatial scales.


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