scholarly journals Multivariate drivers of diversity in temperate Australian native grasslands

2019 ◽  
Vol 67 (5) ◽  
pp. 367 ◽  
Author(s):  
Jodi N. Price ◽  
Megan K. Good ◽  
Nick L. Schultz ◽  
Lydia K. Guja ◽  
John W. Morgan
Keyword(s):  
Important Determinant ◽  
Temperate Grassland ◽  
Climatic Variation ◽  
Temperate Grasslands ◽  
Preferred Habitat ◽  
Native Grasslands ◽  
Grassland Diversity ◽  
Key Driver ◽  
Dead Plant ◽  
Univariate Approach

Disturbance has been considered essential for maintaining biodiversity in temperate grassy ecosystems in Australia. This has been particularly well demonstrated for inter-tussock plant species in C4 Themeda-dominated grasslands in mesic environments. Disturbance is also thought crucial to maintain the structure of preferred habitat for some animals. Relationships between disturbance and diversity may be contingent on ecosystem productivity, but little is known about the generality of the disturbance-promoting-diversity paradigm across the range of temperate grasslands. To date, the disturbance-promoting-diversity paradigm has taken a univariate approach to the drivers of biodiversity; rainfall is seen as a key driver of productivity, which then drives diversity, mediated by disturbance. We argue that this framework is too simplistic as biodiversity drivers are multivariate. We suggest that the accumulation of phytomass (live and dead plant material) is an important determinant of diversity in grassy ecosystems and that phytomass accumulation is governed by multiple drivers (of which disturbance is just one). For fauna, it is structure – not biomass – that determines habitat suitability, and this can be moderated by both abiotic and biotic drivers. The assumption that there is a consistent effect of disturbance on diversity through the range of temperate grassland settings in southern Australia ignores the likelihood that biodiversity also responds to other factors such as spatial heterogeneity in the environment, resource availability and climatic variation. We developed a conceptual model of the multivariate drivers of grassland diversity that explores mechanisms underpinning patterns of species richness. Despite four decades of research, it is clear that our understanding of the multivariate drivers of diversity across the range of temperate grasslands in Australia is still incomplete. Further research into the conditions under which disturbance is required to maintain biodiversity in grasslands is integral to conservation planning in these endangered systems.

Home ranges of, and habitat use by, the grassland earless dragon (Tympanocryptis pinguicolla) in remnant native grasslands near Canberra

2010 ◽  
Vol 58 (2) ◽  
pp. 76 ◽  
Author(s):  
Toni A. Stevens ◽  
Murray C. Evans ◽  
William S. Osborne ◽  
Stephen D. Sarre
Keyword(s):  
Habitat Management ◽  
Structural Heterogeneity ◽  
Uniform Structure ◽  
Habitat Requirements ◽  
Home Ranges ◽  
Temperate Grasslands ◽  
South Wales ◽  
Native Grasslands ◽  
Disturbed Areas ◽  
Native Grassland

The grassland earless dragon (Tympanocryptis pinguicolla) is a habitat specialist restricted to the highly fragmented native temperate grasslands of the Australian Capital Territory (ACT) and nearby New South Wales (NSW). These grasslands, which are listed as an endangered ecological community, continue to be affected by a range of processes including development and overgrazing. Although changes to its habitat present a significant threat to the grassland earless dragon, little is known about its spatial and habitat requirements. We used radio-tracking to study the home-range areas and habitat requirements of 10 adult lizards in native grassland adjacent to Canberra, ACT. We found that burrows excavated by arthropods are an important resource for grassland earless dragons, with individuals having one or two home burrows around which they maintained home ranges of between 925 m2 and 4768 m2. Fidelity to these burrows increased with the onset of winter, indicating their importance as over-winter refuge sites. Within the native grasslands, grassland earless dragons were found to use a broad range of grassland structure as habitat. This result contrasts with the prevailing view that these dragons are confined to well drained, minimally disturbed areas, which include large patches of short grass dominated by Austrodanthonia. We conclude that habitat management (i.e. grazing, mowing, burning) for this species should aim to retain structural heterogeneity of native grasslands rather than impose a uniform structure.

Intestinal helminths of man: the interpretation of egg counts

Parasitology ◽  
1982 ◽  
Vol 85 (3) ◽  
pp. 605-613 ◽  
Author(s):  
Andrew Hall
Keyword(s):  
Specific Gravity ◽  
Alimentary Tract ◽  
Important Determinant ◽  
Helminth Parasites ◽  
Intestinal Helminths ◽  
Daily Output ◽  
Infected People ◽  
Helminth Eggs ◽  
Preferred Habitat ◽  
Spherical Diameter

Of the 39 most common helminth parasites of man listed by Peters & Gilles (1977), 30 may be detected and often diagnosed by finding their eggs or larvae in the faeces of infected people. The preferred habitat of many of these helminths is the alimentary tract itself and the continual flow of material through the food tube provides a simple, passive and reliable means of transport and eventual exit from the host for the reproductive stages of a worm. Helminth eggs are generally less than 150 μm in diameter and although individually comprise a small material investment by the adult worm in the propagation of the species, the chances of infecting a host are so slim (though this may be a teleological inference) that adult worms are often highly fecund: a female Ascaris lumbricoides is estimated to release daily into the intestine approximately 200,000 eggs (WHO, 1967). Yet numbers should not always be equated with great substance or bulk – an equally important determinant of the chances of finding an egg in faeces: assuming a spherical diameter of 60 μm and a specific gravity of 1·2 (Sawitz, 1942) then a female Ascaris is estimated to produce only about 25 mg of eggs each day, which is 0·01% of a moderate daily output of 250 g of faeces.

Effect of grazing on photosynthetic carbon allocation in a temperate grassland

2020 ◽  
Author(s):  
Yan Zhao ◽  
Yuqiang Tian
Keyword(s):  
Carbon Allocation ◽  
Grazing Intensity ◽  
C Sequestration ◽  
Intermediate Disturbance Hypothesis ◽  
Temperate Grassland ◽  
Carbon Accumulation ◽  
Temperate Grasslands ◽  
Heavy Grazing ◽  
C Cycle ◽  
C Input

<p>Grazing is an important human activity affecting grassland ecosystems. Many studies have shown that grazing changed the carbon (C) cycle of grasslands, but it is still not clear how grazing will affect the recent photosynthetic C allocation in the temperate grasslands. To clarify this question, a situ field <sup>13</sup>C labeling experiment was carried out in the temperate grasslands of Inner Mongolia, North China, in 2015. In this study. Grazing included 3 intensities of no grazing, medium grazing and heavy grazing. Eighty-one days after the labeling, the plants allocated more recent assimilated<sup> 13</sup>C (6.52% of recovered <sup>13</sup>C) to shoots under medium grazing than that of no grazing (5.60%) and heavy grazing (5.40%). The most <sup>13</sup>C was allocated to the belowground (roots, soil and soil respiration) under no grazing (40.68%). However, within the belowground pools, 1.36% and 17.33% of <sup>13</sup>C were stored in roots and soil under medium grazing which was twice than that under no grazing and heavy grazing, which could be explained by intermediate disturbance hypothesis.<sup> 13</sup>C labeling experiment demonstrated medium grazing increased C assimilates by two processes:(Ⅰ) the highest total C input into plants and soil and (Ⅱ)the least C loss by soil microbial respiration (3.20%) than no grazing grassland (5.19%) and heavy grazing grassland (3.47%). The turnover rate of soil assimilates under the no grazing (0.25 ± 0.07 day<sup>-1</sup>) was higher than that of grazing (medium grazing 0.059 ± 0.01 day<sup>-1</sup>; heavy grazing 0.064 ± 0.02 day<sup>-1</sup>). Overall, the no grazing isn’t the best for carbon accumulation and the medium grazing which promotes C input and C sequestration is the most suitable grazing intensity of temperate grassland in China.</p>

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
Keyword(s):  
Soil Texture ◽  
Spatial Scales ◽  
Temperate Grassland ◽  
Management Tool ◽  
Native Plant ◽  
Temperate Grasslands ◽  
South Eastern ◽  
Eastern Australia ◽  
Fire Exclusion ◽  
South Eastern Australia

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.

scholarly journals Climate change experiments in temperate grasslands: synthesis and future directions

2011 ◽  
Vol 8 (4) ◽  
pp. 484-487 ◽  
Author(s):  
Shannon R. White ◽  
Cameron N. Carlyle ◽  
Lauchlan H. Fraser ◽  
James F. Cahill
Keyword(s):  
Climate Change ◽  
Ecological Integrity ◽  
Temperate Grassland ◽  
Future Climate Change ◽  
Mechanisms Of Change ◽  
Temperate Grasslands ◽  
Future Directions ◽  
Temperature And Precipitation ◽  
Manipulative Experiments ◽  
Broad Understanding

The immediate need to understand the complex responses of grasslands to climate change, to ensure food supplies and to mitigate future climate change through carbon sequestration, necessitate a global, synthesized approach. Numerous manipulative experiments have altered temperature or precipitation, often in conjunction with other interacting factors such as grazing, to understand potential effects of climate change on the ecological integrity of temperate grasslands and understand the mechanisms of change. Although the different ways in which temperature and precipitation may change to effect grasslands were well represented, variability in methodology limited generalizations. Results from these experiments were also largely mixed and complex; thus, a broad understanding of temperate grassland responses to these factors remains elusive. A collaboration based on a set of globally dispersed, inexpensive experiments with consistent methodology would provide the data needed to better understand responses of temperate grassland to climate change.

Subtropical native grasslands may not require fire, mowing or grazing to maintain native-plant diversity

2017 ◽  
Vol 65 (2) ◽  
pp. 95 ◽  
Author(s):  
Roderick J. Fensham ◽  
Donald W. Butler ◽  
Boris Laffineur ◽  
Harry J. MacDermott ◽  
John W. Morgan ◽  
...  
Keyword(s):  
Species Diversity ◽  
Plant Diversity ◽  
Perennial Grass ◽  
Soil Disturbance ◽  
Temperate Grassland ◽  
Response To Treatment ◽  
Native Plant ◽  
Widespread Species ◽  
Native Grasslands ◽  
Initial Sampling

The rarity of native grasslands in agricultural districts heightens the requirement for optimal management to maintain diversity. Previous studies have suggested that disturbance is required to maintain species diversity in temperate Australian grasslands, but grasslands in semiarid environments do not have the same disturbance requirement. The current study examines the short-term responses to disturbance of subtropical grassland of the Darling Downs, south-eastern Queensland. We also compare temperate and subtropical grasslands in terms of biomass and rainfall. A field experiment was established with treatments, including burning in 2013, burning in 2014, burning in both years, mowing in both years, mowing and raking in both years, and an undisturbed control. Treatments were replicated at each of seven sampling stations in similar environments. The initial sampling after 2013 followed a wet summer and the final sampling was in 2015 after a dry summer. Non-metric multi-dimensional scaling showed that environmental differences, including silt content, soil pH, waterlogging and rainfall history, had more effect on the variation in species composition than did the treatments. The treatments engendered no significant response in species diversity. Of 51 widespread species, only four had a significant change in abundance in response to treatment. Herbaceous biomass was higher in temperate than subtropical grassland after a dry period. The grassland sward may be more open in the subtropics than in temperate grassland because of higher decomposition rates. A comparison of rainfall distribution between subtropical grassland and temperate grassland indicated that droughts are much more frequent in the former environments. These occasional droughts may provide a stress that reduces perennial grass cover, supplanting the requirement for grazing or fire to maintain plant diversity in grasslands. The management of grassland remnants in the subtropics, therefore, seems straightforward because there is little response in species richness or composition to disturbance. However, soil disturbance should be avoided to ensure that exotic species do not proliferate.

SGC-CK2-1: The First Selective Chemical Probe for the Pleiotropic Kinase CK2

2020 ◽  
Author(s):  
Carrow Wells ◽  
David Drewry ◽  
Julie E. Pickett ◽  
Alison D. Axtman
Keyword(s):  
Cell Lines ◽  
Small Molecule ◽  
Chemical Probe ◽  
High Quality ◽  
Extensive Evaluation ◽  
Key Driver ◽  
Selective Chemical ◽  
Kinase Ck2 ◽  
Ck2 Inhibitors

Building upon a wealth of published knowledge surrounding the pyrazolopyrimidine scaffold, we designed a small library around the most selective small molecule CK2 inhibitors reported. Through extensive evaluation of this library we identified inhibitor 24 (SGC-CK2-1) as a potent, selective, and cell-active CK2 chemical probe. Remarkably, despite years of research pointing to CK2 as a key driver in cancer, our probe did not elicit an antiproliferative phenotype in cell lines tested. While many publications have attempted tocharacterize CK2 function, CK2 biology is complex and a high-quality chemical tool like SGC-CK2-1 will aid in connecting CK2 functions to phenotypes.

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