Transient shifts in composition of degraded temperate native grassland following grazing exclusion
- Farmilo, Brad, Duncan, David, Moxham, Claire, Buchan, Anne, Turner, Vivienne, Ballentine, Michelle, White, Matt, Schultz, Nick
- Authors: Farmilo, Brad , Duncan, David , Moxham, Claire , Buchan, Anne , Turner, Vivienne , Ballentine, Michelle , White, Matt , Schultz, Nick
- Date: 2023
- Type: Text , Journal article
- Relation: Applied Vegetation Science Vol. 26, no. 2 (2023), p.
- Full Text: false
- Reviewed:
- Description: Questions Globally, grassy ecosystems are threatened and are still declining in extent in many areas. Improving the management of degraded native temperate grasslands that are grazed by livestock is important to the conservation of this critically endangered ecosystem. Questions remain about the role of grazing in the management of such grasslands, particularly in the face of climate change and given the sensitivity of these systems to inter‐annual rainfall variability. Here, we investigate the effect of livestock exclusion on grassland composition. Location Temperate grassland, Victoria, Australia. Methods Over 9 years (2009–2017), we monitored plant functional groups in plots open‐to‐grazing or ungrazed exclusion plots within five fields of degraded native temperate grassland on private land. Results In the years after grazing had been excluded, we found significant differences in cover between grazed and ungrazed plots for some functional groups (e.g. native perennial graminoids) in some years, but we did not observe long‐term divergence in cover or composition of the treatments. At the final monitoring point there were no significant differences in native or exotic species richness between the grazed and ungrazed plots. We show that the years in which differences were observed correspond with the 2010–2011 La Niña high‐rainfall event, suggesting that grazing exclusion effects are mediated by rainfall, and are likely to be evident only under certain conditions. Conclusion In grassy ecosystems already degraded by long‐term grazing, excluding grazing has limited potential to shift plant species composition in favour of native dominance. Such grasslands may persist in the medium term in a stable but degraded state with or without continued light to moderate livestock grazing pressure. Hence, managed livestock grazing need not be incompatible with the conservation of degraded temperate grasslands particularly where biomass management is important for the maintenance of faunal habitat. However, improving the function and diversity of these degraded grasslands will seemingly require additional management, including seed addition and experimentation with alternative disturbance regimes. We investigated the effect of livestock exclusion on degraded native temperate grasslands. We found that climate events caused short‐term differences in cover between grazed and ungrazed plots, but grazing exclusion had little potential to shift plant species composition. This highlights how additional management (e.g. seed addition, alternative disturbance regimes) is required to improve their function and diversity.
Change in dominance determines herbivore effects on plant biodiversity
- 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
- 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
- Full Text:
- Reviewed:
- 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.
- 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
- Full Text:
- Reviewed:
- 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.
The golf ball method for rapid assessment of grassland structure
- Schultz, Nick, Keatley, Marie, Antos, Mark, Wong, Nathan, Moxham, Claire, Farmilo, Brad, Morgan, John
- 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
- Full Text: false
- Reviewed:
- 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
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