The golf ball method for rapid assessment of grassland structure
- Authors: Schultz, Nick , Keatley, Marie , Antos, Mark , Wong, Nathan , Moxham, Claire , Farmilo, Brad , Morgan, John
- Date: 2017
- Type: Text , Journal article
- Relation: Ecological Management and Restoration Vol. 18, no. 2 (2017), p. 134-140
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- Description: A key task for native grassland managers is to assess when biomass reduction is necessary to maintain plant and animal diversity. This requires managers to monitor grassland structure. Parks Victoria and La Trobe University developed a method for rapid assessment of grassland structure using golf balls. Baker-Gabb et al. (Ecological Management & Restoration, 17, 2016, p235) provide an example of where the method has been used to manage grassland structure to favour an endangered bird, the Plains-wanderer (Pedionomus torquatus). In this study, we provide further critical analysis of the method using three data sets collected across different parts of Victoria that relate golf ball scores to various habitat attributes. We demonstrate how the golf ball score provides a good surrogate for key aspects of grassland structure. We show that the method does not provide a reliable surrogate for above-ground biomass or vegetation cover, although we discuss how biomass and cover are not particularly good indicators of grassland structure. We argue that elements of grassland structure may be better correlated with desired conservation outcomes (e.g. plant species diversity or the presence of a particular species) than biomass or cover alone. We discuss examples of how the golf ball method has been used, and how it can be improved. The method will be particularly useful where a link can be demonstrated between golf ball scores and desired conservation outcomes, such as in the case of the Plains-wanderer. © 2017 Ecological Society of Australia and John Wiley & Sons Australia, Ltd
Effects of grazing exclusion on plant species richness and phytomass accumulation vary across a regional productivity gradient
- Authors: Schultz, Nick , Morgan, John , Lunt, Ian
- Date: 2011
- Type: Text , Journal article
- Relation: Journal of Vegetation Science Vol. 22, no. 1 (2011), p. 130-142
- Full Text: false
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- Description: Question: Does long-term grazing exclusion affect plant species diversity? And does this effect vary with long-term phytomass accumulation across a regional productivity gradient? Location: Lowland grassy ecosystems across the state of Victoria, southeast Australia. Methods: Floristic surveys and phytomass sampling were conducted across a broad-scale productivity gradient in grazing exclusion plots and adjacent grazed areas. Differences in species richness, evenness and life-form evenness between grazed and ungrazed areas were analysed. The environmental drivers of long-term phytomass accumulation were assessed using multiple linear regression analysis. Results: Species richness declined in the absence of grazing only at the high productivity sites (i.e. when phytomass accumulation was >500 gm-2). Species evenness and life-form evenness also showed a negative relationship with increasing phytomass accumulation. Phytomass accumulation was positively associated with both soil nitrogen and rainfall, and negatively associated with tree cover. Conclusions: Competitive dominance is a key factor regulating plant diversity in productive grassy ecosystems, but canopy disturbance is not likely to be necessary to maintain diversity in less productive systems. The results support the predictions of models of the effects of grazing on plant diversity, such as the dynamic equilibrium model, whereby the effects of herbivory are context-dependent and vary according to gradients of rainfall, soil fertility and tree cover. © 2010 International Association for Vegetation Science.
Multivariate drivers of diversity in temperate Australian native grasslands
- Authors: Price, Jodi , Good, Megan , Schultz, Nick , Guja, Lydia , Morgan, John
- Date: 2019
- Type: Text , Journal article , Review
- Relation: Australian Journal of Botany Vol. 67, no. 5 (2019), p. 367-380
- Full Text: false
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- Description: 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 C-4 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.
Conservation challenges for Victorian banksias: Workshop May 2020
- Authors: Muir, Annette , Heyes, Simon , Morgan, John , Hoebee, Susan , Enright, Neal , Whelan, Robert , Geschke, Andrew , Bennett, Andrew , Walsh, Sean , Weatherly, William , Milne, Robert
- Date: 2022
- Type: Text , Journal article
- Relation: Ecological management & restoration Vol. 23, no. 2 (2022), p. 199-202
- Full Text: false
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- Description: Banksias are iconic Australian plants, with a Gondwanan origin. Their specialised roots help survival on low-phosphorus soils, and many species have reproductive cycles adapted to fire. They are trophically important in many of Australia’s native forests, woodlands and heathlands, providing nectar, pollen and seeds for many species of birds, mammals and invertebrates. While legacies of land use have reduced the historic extent of some Banksia species, more recent declines have raised additional concerns about their persistence in some landscapes. A range of factors are considered to be impacting Banksia persistence (Lamont et al. 2007), including habitat loss and fragmentation (e.g. Miller et al. 2020), increased fire frequency (e.g. Bradstock et al. 1997) and climate change (e.g. Steel et al. 2019), but there is no consensus about how these interacting factors may be driving declines, and how widespread these declines may be. The challenges facing Banksia species conservation in the south-eastern state of Victoria were the focus of an online workshop in May 2020. The workshop brought together researchers and land managers from Victorian and interstate universities, Victorian government agencies and volunteer land management groups to share their knowledge of the threats facing banksias, and document ideas to reverse declines. It was organised by Arthur Rylah Institute for Environmental Research (Department Environment, Land, Water and Planning), La Trobe University (Department of Ecology, Environment and Evolution) and Federation University (Centre for eResearch and Digital Innovation). "From introduction"
Change in dominance determines herbivore effects on plant biodiversity
- Authors: Koerner, Sally , Smith, Melinda , Burkepile, Deron , Hanan, Niall , Avolio, Meghan , Collins, Scott , Knapp, Alan , Lemoine, Nathan , Forrestel, Elizabeth , Eby, Stephanie , Thompson, Dave , Aguado-Santacruz, Gerardo , Anderson, John , Anderson, Michael , Angassa, Ayana , Bagchi, Sumanta , Bakker, Elisabeth , Bastin, Gary , Baur, Lauren , Beard, Karen , Beever, Erik , Bohlen, Patrick , Boughton, Elizabeth , Canestro, Don , Cesa, Ariela , Chaneton, Enrique , Cheng, Jimin , D'Antonio, Carla , Deleglise, Claire , Dembele, Fadiala , Dorrough, Josh , Eldridge, David , Fernandez-Going, Barbara , Fernandez-Lugo, Silvia , Fraser, Lauchlan , Freedman, Bill , Garcia-Salgado, Gonzalo , Goheen, Jacob , Guo, Liang , Husheer, Sean , Karembe, Moussa , Knops, Johannes , Kraaij, Tineke , Kulmatiski, Andrew , Kytoviita, Minna-Maarit , Lezama, Felipe , Loucougaray, Gregory , Loydi, Alejandro , Milchunas, Dan , Milton, Suzanne , Morgan, John , Moxham, Claire , Nehring, Kyle , Olff, Han , Palmer, Todd , Rebollo, Salvador , Riginos, Corinna , Risch, Anita , Rueda, Marta , Sankaran, Mahesh , Sasaki, Takehiro , Schoenecker, Kathryn , Schultz, Nick , Schutz, Martin , Schwabe, Angelika , Siebert, Frances , Smit, Christian , Stahlheber, Karen , Storm, Christian , Strong, Dustin , Su, Jishuai , Tiruvaimozhi, Yadugiri , Tyler, Claudia , Val, James , Vandegehuchte, Martijn , Veblen, Kari , Vermeire, Lance , Ward, David , Wu, Jianshuang , Young, Truman , Yu, Qiang , Zelikova, Tamara
- Date: 2018
- Type: Text , Journal article
- Relation: Nature Ecology & Evolution Vol. 2, no. 12 (2018), p. 1925-1932
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- Description: Herbivores alter plant biodiversity (species richness) in many of the world’s ecosystems, but the magnitude and the direction of herbivore effects on biodiversity vary widely within and among ecosystems. One current theory predicts that herbivores enhance plant biodiversity at high productivity but have the opposite effect at low productivity. Yet, empirical support for the importance of site productivity as a mediator of these herbivore impacts is equivocal. Here, we synthesize data from 252 large-herbivore exclusion studies, spanning a 20-fold range in site productivity, to test an alternative hypothesis—that herbivore-induced changes in the competitive environment determine the response of plant biodiversity to herbivory irrespective of productivity. Under this hypothesis, when herbivores reduce the abundance (biomass, cover) of dominant species (for example, because the dominant plant is palatable), additional resources become available to support new species, thereby increasing biodiversity. By contrast, if herbivores promote high dominance by increasing the abundance of herbivory-resistant, unpalatable species, then resource availability for other species decreases reducing biodiversity. We show that herbivore-induced change in dominance, independent of site productivity or precipitation (a proxy for productivity), is the best predictor of herbivore effects on biodiversity in grassland and savannah sites. Given that most herbaceous ecosystems are dominated by one or a few species, altering the competitive environment via herbivores or by other means may be an effective strategy for conserving biodiversity in grasslands and savannahs globally.
Timing of snowmelt affects species composition via plant strategy filtering
- Authors: Good, Megan , Morgan, John , Venn, Susanna , Green, Peter
- Date: 2019
- Type: Text , Journal article
- Relation: Basic and Applied Ecology Vol. 35, no. (2019), p. 54-62
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- Description: Plant strategy schemes aim to classify plants according to measurable traits and group species according to their shared evolutionary responses to selective pressures. In this way, it becomes possible to make meaningful comparisons among ecosystems and communities and to predict how plant communities might respond to changes in their environment. Here, we classified common alpine plants which occur in snowpatches (Early and Late snowmelt sites) and in adjacent vegetation (Snow-free sites which melt early in the growing season) using Grime's CSR plant strategy scheme. Alpine plant communities are largely driven by environmental filters associated with a relatively constant gradient of snowmelt timing. Since snow persistence influences the abiotic environment and plant assemblages alike, we hypothesised that these patterns would be reflected in community CSR scores. Weighted community CSR scores were clustered towards the stress-tolerator (S) corner of the triangular CSR space, and Snow-free communities were significantly more stress-tolerant than Early and Late snowmelt communities. This suggests that snowpatch communities are functionally distinct from surrounding vegetation when considering the major axes of plant variation identified by CSR theory. These results lend further support to the importance of the timing of snowmelt as a key filter, influencing how species and plant strategy types distribute themselves across the alpine landscape.
Relative contribution of photodegradation to litter breakdown in Australian grasslands
- Authors: Butler, Freja , Good, Megan , Morgan, John , Schultz, Nick
- Date: 2023
- Type: Text , Journal article
- Relation: Ecology and Evolution Vol. 13, no. 12 (2023), p.
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- Description: Grassy ecosystems cover ~40% of the global land surface and are an integral component of the global carbon (C) cycle. Grass litter decomposes via a combination of photodegradation (which returns C to the atmosphere rapidly) and biological decomposition (a slower C pathway). As such, decomposition and C storage in grasslands may vary with climate and exposure to solar radiation. We investigated rates of grass litter decomposition in Australian temperate grasslands along a climate gradient to uncouple the relative importance of photodegradation and climate on decomposition. Litterbags containing leaf litter from two common native grass species (Poa labillardierei, Themeda triandra) were deployed at six grassland sites across a precipitation gradient (380–890 mm) in south-eastern Australia. Bags were retrieved over 39 weeks to measure mass loss from decomposition. We used shade treatments on the litter of one species (T. triandra) to partition photodegradation from biological decomposition. The shade treatment reduced the rate of decomposition of T. triandra relative to the full-sun treatment at all sites, by an average of 38% at 39 weeks; the effect size of the shade treatment was not correlated with site productivity. The rate of decomposition in both species was positively correlated with rainfall midway through the experiment, but there were no significant differences in total decomposition among sites after 39 weeks. By week 39, total decomposition of T. triandra was significantly greater than for P. labillardierei. In general, we observed relatively linear decomposition rather than the strong negative exponential decay observed in many global litter decomposition studies. Synthesis: We found that solar radiation exposure was a strong contributor to litter decomposition in temperate Australian grasslands across a broad climate gradient, which may be related to a period of photopriming prior to further biotic decomposition. This study highlights the importance of litter composition and solar radiation exposure in our understanding of how decomposition patterns contribute to global C cycling. © 2023 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.