Disturbance-dependent invasion of the woody weed, Calotropis procera, in Australian rangelands
Enock O. Menge A C , Sean M. Bellairs A and Michael J. Lawes B
+ Author Affiliations
- Author Affiliations
A Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT 0909, Australia.
B Department of Geography, McGill University, 805 Sherbrooke Street West, Montreal, QC H3A 2K6, Canada.
C Corresponding author. Email: Enockondeyo.Menge@cdu.edu.au
The Rangeland Journal 39(2) 201-211 https://doi.org/10.1071/RJ16120
Submitted: 9 November 2016 Accepted: 31 March 2017 Published: 26 April 2017
Abstract
Plant invasions are threats to biodiversity and ecosystem processes that have far reaching ecological and economic impacts. Understanding the mechanisms of invasion essentially helps in developing effective management strategies. Rubber bush (Calotropis procera) is an introduced milkweed that invades Australian beef production rangelands. Its establishment is often associated with disturbances caused by pastoral management practices. We examined whether or not rubber bush (1) outcompetes native grasses, (2) can invade intact rangeland, and (3) if disturbance facilitates rubber bush establishment and spread in grassy rangelands. We measured the competitive response of different densities of Mitchell grass (Astrebla pectinata) individuals and the competitive effects of associate rubber bush seedlings in an additive common garden experiment. Replicated field exclosure experiments, under grass-dominated and tropical savanna woodland conditions examined the effect of increasing levels of disturbance on rubber bush seedling emergence. The dominant native Mitchell grass was a stronger competitor than rubber bush when grown together under greenhouse conditions, whereby root and shoot biomass yields were more restricted in rubber bush compared with Mitchell grass. This finding was corroborated in the field exclosure experiments at both sites, where seedling emergence increased 5-fold in seeded and highly disturbed plots where superficial soils were turned over by treatments simulating heavy grazing and trampling by cattle or machinery. Emergence of rubber bush seedlings in seeded plots that were undisturbed, clipped and grazed was minimal and rubber bush seedlings did not survive the seedling stage in these plots. These results demonstrate that disturbance to the superficial soil stratum affects the ability of rubber bush seeds to successfully establish in a microsite, and high levels of soil disturbance substantially increase establishment. Thus, rubber bush is a poor competitor of Mitchell grass and does not invade intact grassland. Consequently, rubber bush invasion is disturbance-dependent in the vast Australian rangelands. The spread of this weed may be arrested by management practices that minimise disturbances to grass cover.
Additional keywords: barley Mitchell grass, competition, exclosure experiment, grazing, invasion dynamics, rangeland management, rubber bush.
References
Aarssen, L., and Keogh, T. (2002). Conundrums of competitive ability in plants: what to measure? Oikos 96, 531–542.| Conundrums of competitive ability in plants: what to measure?Crossref | GoogleScholarGoogle Scholar |
Andonian, K., and Hierro, J. (2011). Species interactions contribute to the success of a global plant invader. Biological Invasions 13, 2957–2965.
| Species interactions contribute to the success of a global plant invader.Crossref | GoogleScholarGoogle Scholar |
Andrew, M. H. (1988). Grazing impact in relation to livestock watering points. Trends in Ecology & Evolution 3, 336–339.
| Grazing impact in relation to livestock watering points.Crossref | GoogleScholarGoogle Scholar | 1:STN:280:DC%2BC3M7gvFektg%3D%3D&md5=47f4724de6590dd1dbe0a8d454ff61a2CAS |
Bastin, G., Ludwig, J., Eager, R., Liedloff, A., Andison, R., and Cobiac, M. (2003). Vegetation changes in a semiarid tropical savanna, northern Australia: 1973–2002. The Rangeland Journal 25, 3–19.
| Vegetation changes in a semiarid tropical savanna, northern Australia: 1973–2002.Crossref | GoogleScholarGoogle Scholar |
Bebawi, F. F., Campbell, S. D., and Mayer, R. J. (2015). Seed bank longevity and age to reproductive maturity of Calotropis procera (Aiton) W.T. Aiton in the dry tropics of northern Queensland. The Rangeland Journal 37, 239–247.
| Seed bank longevity and age to reproductive maturity of Calotropis procera (Aiton) W.T. Aiton in the dry tropics of northern Queensland.Crossref | GoogleScholarGoogle Scholar |
Belote, R. T., Jones, R. H., Hood, S. M., and Wender, B. W. (2008). Diversity-invasibility across an experimental disturbance gradient in Appalachian forests. Ecology 89, 183–192.
| Diversity-invasibility across an experimental disturbance gradient in Appalachian forests.Crossref | GoogleScholarGoogle Scholar |
BOM (2016) ‘Long Term Temperature Statistics.’ (Bureau of Meteorology: Darwin, NT, Australia.)
Bottollier-Curtet, M., Planty-Tabacchi, A.-M., and Tabacchi, E. (2013). Competition between young exotic invasive and native dominant plant species: implications for invasions within riparian areas. Journal of Vegetation Science 24, 1033–1042.
| Competition between young exotic invasive and native dominant plant species: implications for invasions within riparian areas.Crossref | GoogleScholarGoogle Scholar |
Bowman, A. M., Munnich, D. J., Chan, K. Y., and Brockwell, J. (1996). Factors associated with density of Mitchell grass pastures in north-western New South Wales. The Rangeland Journal 19, 40–56.
| Factors associated with density of Mitchell grass pastures in north-western New South Wales.Crossref | GoogleScholarGoogle Scholar |
Brown, J. R., and McIvor, J. G. (1993). Ecology of woody weed invasions in the tropical woodlands of north-eastern Australia: implications for management. In: ‘The 10th Australian Weeds Conference and 14th Conference of the Asian Pacific Weed Society’. (Eds J. Swarbrick, C. Henderson, R. Jettner, L. Streit and S. Walker.) pp. 471–474. (Weed Society of Queensland: Brisbane.)
Brown, J. R., Scanlan, J. C., and McIvor, J. G. (1998). Competition by herbs as a limiting factor in shrub invasion in grassland: a test with different growth forms. Journal of Vegetation Science 9, 829–836.
| Competition by herbs as a limiting factor in shrub invasion in grassland: a test with different growth forms.Crossref | GoogleScholarGoogle Scholar |
Case, T. J. (1990). Invasion resistance arises in strongly interacting species-rich model competition communities. Proceedings of the National Academy of Sciences of the United States of America 87, 9610–9614.
| Invasion resistance arises in strongly interacting species-rich model competition communities.Crossref | GoogleScholarGoogle Scholar | 1:STN:280:DC%2BD3MrmtFSqug%3D%3D&md5=4cb1c8a22bffeadabdd2c10f0b1b9ccdCAS |
Catford, J. A., Daehler, C. C., Murphy, H. T., Sheppard, A. W., Hardesty, B. D., Westcott, D. A., Rejmánek, M., Bellingham, P. J., Pergl, J., Horvitz, C. C., and Hulme, P. E. (2012). The intermediate disturbance hypothesis and plant invasions: Implications for species richness and management. Perspectives in Plant Ecology, Evolution and Systematics 14, 231–241.
| The intermediate disturbance hypothesis and plant invasions: Implications for species richness and management.Crossref | GoogleScholarGoogle Scholar |
Cheam, A. H. (1984). Allelopathy in buffel grass (Cenchrus ciliaris L.) Part 1. Influence of buffel grass association on calotrope (Calotropis procera (Ait.) W.T. Ait.). Australian Weeds 3, 133–136.
Csurhes, S., and Edwards, R. (1998). Potential environmental weeds in Australia. The Director of the National Parks and Wildlife, Canberra.
Davis, M. A., Grime, P. J., and Thompson, K. (2000). Fluctuating resources in plant communities: a general theory of invasibility. Journal of Ecology 88, 528–534.
| Fluctuating resources in plant communities: a general theory of invasibility.Crossref | GoogleScholarGoogle Scholar |
DeWalt, S. J., Denslow, J. S., and Ickes, K. (2004). Natural-enemy release facilitates habitat expansion of the invasive tropical shrub Clidemia hirta. Ecology 85, 471–483.
| Natural-enemy release facilitates habitat expansion of the invasive tropical shrub Clidemia hirta.Crossref | GoogleScholarGoogle Scholar |
Duggin, J. A., and Gentle, C. B. (1998). Experimental evidence on the importance of disturbance intensity for invasion of Lantana camara L. in dry rainforest–open forest ecotones in north-eastern NSW, Australia. Forest Ecology and Management 109, 279–292.
| Experimental evidence on the importance of disturbance intensity for invasion of Lantana camara L. in dry rainforest–open forest ecotones in north-eastern NSW, Australia.Crossref | GoogleScholarGoogle Scholar |
Elton, C. S. (1958) ‘Ecology of Invasiveness by Animals and Plants.’ 1st edn. (Springer: London, UK.)
Ens, E., Hutley, L. B., Rossiter-Rachor, N. A., Douglas, M. M., and Setterfield, S. A. (2015). Resource-use efficiency explains grassy weed invasion in a low-resource savanna in north Australia. Frontiers in Plant Science 6, 1–10.
| Resource-use efficiency explains grassy weed invasion in a low-resource savanna in north Australia.Crossref | GoogleScholarGoogle Scholar |
Eriksson, O., and Ehrlén, J. (1992). Seed and microsite limitation of recruitment in plant populations. Oecologia 91, 360–364.
| Seed and microsite limitation of recruitment in plant populations.Crossref | GoogleScholarGoogle Scholar | 1:STN:280:DC%2BC1czot1SmsA%3D%3D&md5=d6217986de79ba4ccb2e45aa05343390CAS |
Fargione, J. E., and Tilman, D. (2005). Diversity decreases invasion via both sampling and complementarity effects. Ecology Letters 8, 604–611.
| Diversity decreases invasion via both sampling and complementarity effects.Crossref | GoogleScholarGoogle Scholar |
Fisher, A. (2001). ‘Biogeography and Conservation of Mitchell Grasslands in Northern Australia.’ (Northern Territory University: Darwin.)
Fisher, A., Baker, B., and Woinarski, J. (2002). Mitchell Grass Downs, Northern Territory – Bioregional case study. Parks and Wildlife Commission of the Northern Territory Department of Infrastructure, Planning and Environment, Darwin.
Foran, B. D., Bastin, G., and Hill, B. (1985). The pasture dynamics and management of two rangeland communities in the Victoria River District of the Northern Territory. Australian Rangeland Journal 7, 107–113.
| The pasture dynamics and management of two rangeland communities in the Victoria River District of the Northern Territory.Crossref | GoogleScholarGoogle Scholar |
Francis, J. K. (2004). Wildland shrubs of the United States and its territories: thamnic descriptions. International Institute of Tropical Forestry and Fort Collins, Co. Rocky Mountain Research Station, No. Rep. IITF-6TR-26, San Juan, PR.
French, K. (2012). Competition strength of two significant invasive species in coastal dunes. Plant Ecology 213, 1667–1673.
| Competition strength of two significant invasive species in coastal dunes.Crossref | GoogleScholarGoogle Scholar |
García-Meza, D., and Martorell, C. (2016). A trade off in the absolute magnitudes of seed and microsite limitations and their effects on population regulation. Oikos 125, 308–314.
| A trade off in the absolute magnitudes of seed and microsite limitations and their effects on population regulation.Crossref | GoogleScholarGoogle Scholar |
Gelbard, J. L., and Belnap, J. (2003). Roads as conduits for exotic plant invasions in a semiarid landscape. Conservation Biology 17, 420–432.
| Roads as conduits for exotic plant invasions in a semiarid landscape.Crossref | GoogleScholarGoogle Scholar |
Gioria, M., and Osborne, B. A. (2014). Resource competition in plant invasions: emerging patterns and research needs. Frontiers in Plant Science 5, 501.
| Resource competition in plant invasions: emerging patterns and research needs.Crossref | GoogleScholarGoogle Scholar |
Goldberg, D. E., and Scheiner, S. M. (Eds) (2001). ANOVA and ANCOVA: Field Competition Experiments. In: ‘Design and Analysis of Ecological Experiments’. pp. 77–98. (Oxford University Press: Oxford, UK.)
Goldberg, D. E., Rajaniemi, T., Gurevitch, J., and Stewart-Oaten, A. (1999). Empirical approaches to quantifying interaction intensity: competition and facilitation along productivity gradients. Ecology 80, 1118–1131.
| Empirical approaches to quantifying interaction intensity: competition and facilitation along productivity gradients.Crossref | GoogleScholarGoogle Scholar |
Grace, J. B. (1995). On the measurement of plant competition intensity. Ecology 76, 305–308.
| On the measurement of plant competition intensity.Crossref | GoogleScholarGoogle Scholar |
Grace, B. S. (2006). The biology of Australian weeds 45. Calotropis procera (Aiton) W.T.Aiton. Plant Protection Quarterly 21, 152–160.
Hobbs, R. J., and Huenneke, L. F. (1992). Disturbance, diversity, and invasion: implications for conservation. Conservation Biology 6, 324–337.
| Disturbance, diversity, and invasion: implications for conservation.Crossref | GoogleScholarGoogle Scholar |
Holle, B. V., and Simberloff, D. (2005). Ecological resistance to biological invasion overwhelmed by propagule pressure. Ecology 86, 3212–3218.
| Ecological resistance to biological invasion overwhelmed by propagule pressure.Crossref | GoogleScholarGoogle Scholar |
Hulme, P. E. (2009). Trade, transport and trouble: managing invasive species pathways in an era of globalization. Journal of Applied Ecology 46, 10–18.
| Trade, transport and trouble: managing invasive species pathways in an era of globalization.Crossref | GoogleScholarGoogle Scholar |
Huston, M. A. (2004). Management strategies for plant invasions: manipulating productivity, disturbance, and competition. Diversity & Distributions 10, 167–178.
| Management strategies for plant invasions: manipulating productivity, disturbance, and competition.Crossref | GoogleScholarGoogle Scholar |
Iacarella, J. C., Mankiewicz, P. S., and Ricciardi, A. (2015). Negative competitive effects of invasive plants change with time since invasion. Ecosphere 6, art123.
| Negative competitive effects of invasive plants change with time since invasion.Crossref | GoogleScholarGoogle Scholar |
International, V. S. N. (2015). ‘Genstat for Windows.’ 18th edn. (VSN International: Hemel Hempstead, UK.) Available at: www.vsbi.co.uk (accessed 5 November 2016).
ISTA (2016). International rules for seed testing. Vol. 2016, Ch 2. pp. i-2-40 (46). (International Seed Testing Association: Bassersdorf, Zürich.)
Jauni, M., Gripenberg, S., and Ramula, S. (2015). Non-native plant species benefit from disturbance: a meta-analysis. Oikos 124, 122–129.
| Non-native plant species benefit from disturbance: a meta-analysis.Crossref | GoogleScholarGoogle Scholar |
Joshi, S., Gruntman, M., Bilton, M., Seifan, M., and Tielborger, K. (2014). A comprehensive test of evolutionarily increased competitive ability in a highly invasive plant species. Annals of Botany 114, 1761–1768.
| A comprehensive test of evolutionarily increased competitive ability in a highly invasive plant species.Crossref | GoogleScholarGoogle Scholar |
Kennedy, T. A., Naeem, S., Howe, K. M., Knops, J. M. H., Tilman, D., and Reich, P. (2002). Biodiversity as a barrier to ecological invasion. Nature 417, 636–638.
| Biodiversity as a barrier to ecological invasion.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD38Xkt1eksbc%3D&md5=eb55636c46eced32b2afe50884b4bd09CAS |
King, V. M., and Sargent, R. D. (2012). Presence of an invasive plant species alters pollinator visitation to a native. Biological Invasions 14, 1809–1818.
| Presence of an invasive plant species alters pollinator visitation to a native.Crossref | GoogleScholarGoogle Scholar |
Komac, B., Alados, C. L., Bueno, C. G., and Gómez, D. (2011). Spatial patterns of species distributions in grazed subalpine grasslands. Plant Ecology 212, 519–529.
| Spatial patterns of species distributions in grazed subalpine grasslands.Crossref | GoogleScholarGoogle Scholar |
Lake, J. C., and Leishman, M. R. (2004). Invasion success of exotic plants in natural ecosystems: the role of disturbance, plant attributes and freedom from herbivores. Biological Conservation 117, 215–226.
| Invasion success of exotic plants in natural ecosystems: the role of disturbance, plant attributes and freedom from herbivores.Crossref | GoogleScholarGoogle Scholar |
Lambert, F., Bower, M., Whalley, R., Andrews, A., and Bellotti, W. (1990). The effects of soil moisture and planting depth on emergence and seedling morphology of Astrebla lappacea (Lindl.) Domin. Australian Journal of Agricultural Research 41, 367–376.
| The effects of soil moisture and planting depth on emergence and seedling morphology of Astrebla lappacea (Lindl.) Domin.Crossref | GoogleScholarGoogle Scholar |
Lawes, M., and Clarke, P. (2011). Ecology of plant resprouting: populations to community responses in fire-prone ecosystems. Plant Ecology 212, 1937–1943.
| Ecology of plant resprouting: populations to community responses in fire-prone ecosystems.Crossref | GoogleScholarGoogle Scholar |
Leal, L. C., Maiado, M. V., Lopes, A. V., and Leal, I. R. (2013). Germination responses of the invasive Calotropis procera (Ait.) R.Br. (Apocynaceae): comparisons with seeds from two ecosystems in northeastern Brazil. Annals of the Brazilian Academy of Sciences 85, 1025–1034.
| Germination responses of the invasive Calotropis procera (Ait.) R.Br. (Apocynaceae): comparisons with seeds from two ecosystems in northeastern Brazil.Crossref | GoogleScholarGoogle Scholar |
Leishman, M. R., Cooke, J., and Richardson, D. M. (2014). Evidence for shifts to faster growth strategies in the new ranges of invasive alien plants. Journal of Ecology 102, 1451–1461.
| Evidence for shifts to faster growth strategies in the new ranges of invasive alien plants.Crossref | GoogleScholarGoogle Scholar |
Levine, J., and D’Antonio, C. M. (1999). Elton revisited: a review of evidence linking diversity and invasibility. Oikos 87, 15–26.
| Elton revisited: a review of evidence linking diversity and invasibility.Crossref | GoogleScholarGoogle Scholar |
Lockwood, J. L., Cassey, P., and Blackburn, T. (2005). The role of propagule pressure in explaining species invasions. Trends in Ecology & Evolution 20, 223–228.
| The role of propagule pressure in explaining species invasions.Crossref | GoogleScholarGoogle Scholar |
Lozon, J. D., and McIsaac, H. J. (1997). Biological invasions: are they dependent on disturbance? Environmental Review 5, 131–144.
| Biological invasions: are they dependent on disturbance?Crossref | GoogleScholarGoogle Scholar |
Ludwig, J. A., Coughenour, M. B., Liedloff, A. C., and Dyerc, R. (2001). Modelling the resilience of Australian savanna systems to grazing impacts. Environment International 27, 167–172.
| Modelling the resilience of Australian savanna systems to grazing impacts.Crossref | GoogleScholarGoogle Scholar | 1:STN:280:DC%2BD3MnksVynsg%3D%3D&md5=6a1f52f7df726ed66581ae47f29f3b66CAS |
MacDougall, A. S., Gilbert, B., and Levine, J. M. (2009). Plant invasions and the niche. Journal of Ecology 97, 609–615.
| Plant invasions and the niche.Crossref | GoogleScholarGoogle Scholar |
Mack, R. N., Simberloff, D., Lonsdale, W. M., Evans, H., Clout, M., and Bazzaz, F. A. (2000). Biotic invasions: causes, epidemiology, global consequences and control. Ecological Applications 10, 689–710.
| Biotic invasions: causes, epidemiology, global consequences and control.Crossref | GoogleScholarGoogle Scholar |
Menge, E. O., Bellairs, S. M., and Lawes, M. J. (2016a). Seed-germination responses of Calotropis procera (Asclepiadaceae) to temperature and water stress in northern Australia. Australian Journal of Botany 64, 441–450.
| Seed-germination responses of Calotropis procera (Asclepiadaceae) to temperature and water stress in northern Australia.Crossref | GoogleScholarGoogle Scholar |
Menge, E. O., Stobo-Wilson, A., Oliveira, S. L. J., and Lawes, M. J. (2016b). The potential distribution of the woody weed Calotropis procera (Aiton) W.T. Aiton (Asclepiadaceae) in Australia. The Rangeland Journal 38, 35–46.
Menge, E. O., Greenfield, M. L., McConchie, C. A., Bellairs, S. M., and Lawes, M. J. (2017). Density-dependent reproduction and pollen limitation in an invasive milkweed, Calotropis procera (Ait.) R.Br. Apocynaceae. Austral Ecology 42, 61–71.
| Density-dependent reproduction and pollen limitation in an invasive milkweed, Calotropis procera (Ait.) R.Br. Apocynaceae.Crossref | GoogleScholarGoogle Scholar |
Milchunas, D. G., Sala, O. E., and Lauenroth, W. K. (1988). A generalized model of the effects of grazing by large herbivores on grassland community structure. American Naturalist 132, 87–106.
| A generalized model of the effects of grazing by large herbivores on grassland community structure.Crossref | GoogleScholarGoogle Scholar |
Miller, J. T., Murphy, D. J., Brown, G. K., Richardson, D. M., and González-Orozco, C. E. (2011). The evolution and phylogenetic placement of invasive Australian Acacia species. Diversity & Distributions 17, 848–860.
| The evolution and phylogenetic placement of invasive Australian Acacia species.Crossref | GoogleScholarGoogle Scholar |
Mott, J. J., and McDonald, C. K. (1981). Vegetation survey – Manbulloo grazing experiment site. In: ‘Tropical Agronomy Technical Memorandum’. Vol. 12. (Eds J. Mott and C. McDonald.) pp. 1–3. (CSIRO Division of Tropical Crops and Pastures: Brisbane.)
Mott, J. J., Williams, J., Andrew, M. H., and Gillison, A. N. (1985). Australian savanna ecosystems. In: ‘Ecology and Management of the World’s Savannas’. (Eds J. Tothill and J. Mott.) pp. 56–82. (Australian Academy of Sciences: Canberra, ACT.)
Müller, J., Heinze, J., Joshi, J., Boch, S., Klaus, V. H., Fischer, M., and Prati, D. (2014). Influence of experimental soil disturbances on the diversity of plants in agricultural grasslands. Journal of Plant Ecology 7, 509–517.
| Influence of experimental soil disturbances on the diversity of plants in agricultural grasslands.Crossref | GoogleScholarGoogle Scholar |
Myers, B., Allan, G., Bradstock, R., Dias, L., Duff, G., Jacklyn, P., Landsberg, J., Morrison, D. J., Russell-Smith, J., and Williams, R. (2004). ‘Fire Management in the Rangelands.’ (Tropical Savannas CRC: Darwin.)
Naeem, S. (2000). Plant diversity increases resistance to invasion in the absence of covarying extrinsic factors. Oikos 91, 97–108.
| Plant diversity increases resistance to invasion in the absence of covarying extrinsic factors.Crossref | GoogleScholarGoogle Scholar |
Namba, T., and Takahashi, S. (1993). Competitive coexistence in a seasonally fluctuating environment II. multiple stable states and invasion success. Theoretical Population Biology 44, 374–402.
| Competitive coexistence in a seasonally fluctuating environment II. multiple stable states and invasion success.Crossref | GoogleScholarGoogle Scholar |
NTG (2016). Rubber bush (Calotropis procera). Available at: www.lrm.nt.gov.au/weeds/find/rubberbush (accessed 19 April 2016).
Orr, D. M. (1975). A review of Astrebla (Mitchell Grass) pastures in Australia. Tropical Grasslands 9, 21–36.
Orr, D. M., and Evenson, C. J. (1991). Effects of sheep grazing Astrebla grasslands in central western Queensland III. Dynamics of Astrebla spp. under grazing and exclosure between 1975 and 1986. The Rangeland Journal 13, 36–46.
| Effects of sheep grazing Astrebla grasslands in central western Queensland III. Dynamics of Astrebla spp. under grazing and exclosure between 1975 and 1986.Crossref | GoogleScholarGoogle Scholar |
Orr, D., and Evenson, C. (1993). A glasshouse study of competition between Astrebla lappacea (Curly Mitchell Grass) and two associated species. The Rangeland Journal 15, 298–301.
| A glasshouse study of competition between Astrebla lappacea (Curly Mitchell Grass) and two associated species.Crossref | GoogleScholarGoogle Scholar |
Orr, D. M., and Phelps, D. G. (2014). Corrigendum to: Impacts of level of utilisation by grazing on an Astrebla (Mitchell grass) grassland in north-western Queensland between 1984 and 2010. 2. Plant species richness and abundance. The Rangeland Journal 36, 309.
Orr, D. M., and Silcock, R. (2010). The occurrence and causes of episodic recruitment of Astrebla spp. In: ‘16th Biennial Conference of the Australian Rangeland Society’. 2010, Bourke. (Eds D. J. Eldridge and C. Waters.) (Australian Rangeland Society: Perth.)
Panetta, D. F. (2009). ‘The Biology of Australian Weeds.’ (R. G. and F. J. Richardson: Frankston, Vic.)
Powell, K. I., Chase, J. M., and Knight, T. M. (2011). A synthesis of plant invasion effects on biodiversity across spatial scales. American Journal of Botany 98, 539–548.
| A synthesis of plant invasion effects on biodiversity across spatial scales.Crossref | GoogleScholarGoogle Scholar |
Pyšek, P., Jarošík, V., Chytrý, M., Danihelka, J., Kühn, I., Pergl, J., Tichý, L., Biesmeijer, J. C., Ellis, W. N., Kunin, W. E., and Settele, J. (2011). Successful invaders co-opt pollinators of native flora and accumulate insect pollinators with increasing residence time. Ecological Monographs 81, 277–293.
| Successful invaders co-opt pollinators of native flora and accumulate insect pollinators with increasing residence time.Crossref | GoogleScholarGoogle Scholar |
Radunz, B. L., Wilson, G., and Beere, G. (1983). Toxicity experiments of rubberbush to cattle and sheep. Department of Regional Development, Primary Industry, Fisheries and Resources, Katherine, NT.
Ramos, D. M., Liaffa, A. B. S., Diniz, P., Munhoz, C. B. R., Ooi, M. K. J., Borghetti, F., and Valls, J. F. M. (2016). Seed tolerance to heating is better predicted by seed dormancy than by habitat type in Neotropical savanna grasses. International Journal of Wildland Fire 25, 1273–1280.
| Seed tolerance to heating is better predicted by seed dormancy than by habitat type in Neotropical savanna grasses.Crossref | GoogleScholarGoogle Scholar |
Renne, I. J., and Tracy, B. F. (2013). Disturbance intensity, timing and history interact to affect pasture weed invasion. Basic and Applied Ecology 14, 44–53.
| Disturbance intensity, timing and history interact to affect pasture weed invasion.Crossref | GoogleScholarGoogle Scholar |
Richardson, D. M., and Rejmánek, M. (2011). Trees and shrubs as invasive alien species-a global view. Diversity & Distributions 17, 788–809.
| Trees and shrubs as invasive alien species-a global view.Crossref | GoogleScholarGoogle Scholar |
Riginos, C. (2009). Grass competition suppresses savanna tree growth across multiple demographic stages. Ecology 90, 335–340.
| Grass competition suppresses savanna tree growth across multiple demographic stages.Crossref | GoogleScholarGoogle Scholar |
Sattler, P. S., and Williams, R. D. (Eds) (1999). ‘The Conservation Status of Queensland’s Bioregional Ecosystems.’ (Environmental Protection Agency: Brisbane.)
Shea, K., and Chesson, P. (2002). Community ecology theory as a framework for biological invasions. Trends in Ecology & Evolution 17, 170–176.
| Community ecology theory as a framework for biological invasions.Crossref | GoogleScholarGoogle Scholar |
Smith, M. D., and Knapp, A. K. (1999). Exotic plant species in a C4-dominated grassland: invasibility, disturbance, and community structure. Oecologia 120, 605–612.
| Exotic plant species in a C4-dominated grassland: invasibility, disturbance, and community structure.Crossref | GoogleScholarGoogle Scholar |
Sousa, W. P. (1984). The role of disturbance in natural communities. Annual Review of Ecology and Systematics 15, 353–391.
| The role of disturbance in natural communities.Crossref | GoogleScholarGoogle Scholar |
Spence, L. A., Ross, J. V., Wiser, S. K., Allen, R. B., and Coomes, D. A. (2011). Disturbance affects short-term facilitation, but not long-term saturation, of exotic plant invasion in New Zealand forest. Proceedings. Biological Sciences 278, 1457–1466.
| Disturbance affects short-term facilitation, but not long-term saturation, of exotic plant invasion in New Zealand forest.Crossref | GoogleScholarGoogle Scholar |
Stafford Smith, D. M., McKeon, G. M., Watson, I. W., Henry, B. K., Stone, G. S., Hall, W. B., and Howden, S. M. (2007). Learning from episodes of degradation and recovery in variable Australian rangelands. Proceedings of the National Academy of Sciences of the United States of America 104, 20690–20695.
| Learning from episodes of degradation and recovery in variable Australian rangelands.Crossref | GoogleScholarGoogle Scholar |
Stohlgren, T. J., Binkley, D., Chong, G. W., Kalkhan, M. A., Schell, L. D., Bull, K. A., Otsuki, Y., Newman, G., Bashkin, M., and Son, Y. (1999). Exotic plant species invade hot spots of native plant diversity. Ecological Monographs 69, 25–46.
| Exotic plant species invade hot spots of native plant diversity.Crossref | GoogleScholarGoogle Scholar |
Tilman, D. (1994). Competition and biodiversity in spatially structured habitats. Ecology 75, 2–16.
| Competition and biodiversity in spatially structured habitats.Crossref | GoogleScholarGoogle Scholar |
Tothill, J. C., and Gillies, C. (1992). The pasture lands of northern Australia: their condition, productivity and sustainability. Meat Research Corporation, Brisbane.
Tsvuura, Z., and Lawes, M. J. (2016). Light availability drives tree seedling success in a subtropical coastal dune forest in South Africa. South African Journal of Botany 104, 91–97.
| Light availability drives tree seedling success in a subtropical coastal dune forest in South Africa.Crossref | GoogleScholarGoogle Scholar |
Vilà, M., and Weiner, J. (2004). Are invasive plant species better competitors than native plant species? – evidence from pairwise experiments. Oikos 105, 229–238.
| Are invasive plant species better competitors than native plant species? – evidence from pairwise experiments.Crossref | GoogleScholarGoogle Scholar |
Vincke, C., Diedhiou, I., and Grouzis, M. (2010). Long term dynamics and structure of woody vegetation in the Ferlo (Senegal). Journal of Arid Environments 74, 268–276.
| Long term dynamics and structure of woody vegetation in the Ferlo (Senegal).Crossref | GoogleScholarGoogle Scholar |
Weber, J., Panetta, D. F., Virtue, J., and Pheloung, P. (2009). An analysis of assessment outcomes from eight years’ operation of the Australian border weed risk assessment system. Environmental Management 90, 798–807.
Weigelt, A., and Jolliffe, P. (2003). Indices of plant competition. Journal of Ecology 91, 707–720.
| Indices of plant competition.Crossref | GoogleScholarGoogle Scholar |
Williams, O. B., and Roe, R. (1975). Management of arid grasslands for sheep: plant demography of six grasses in relation to climate and grazing. Proceedings of the Ecological Society of Australia 9, 142–156.
Winter, W. H. (1990). Australia’s northern savannas: a time for change in management philosophy. Journal of Biogeography 17, 525–529.
| Australia’s northern savannas: a time for change in management philosophy.Crossref | GoogleScholarGoogle Scholar |
