Research

Much of our research falls into four main themes:

1. Invasion ecology
2. Community ecology
3. Hydroecology & ecohydrology
4. Global change & applied ecology

However, our interests are broad and span topics that include species coexistence, community assembly, vegetation management, ecosystem restoration, ecosystem services, biodiversity conservation, functional traits, novel ecosystems, climate change, disturbance and river regulation. More information can be found on the publications and people pages.  

We use various approaches in our research, including field experiments and observational surveys. For example, we maintain a long-term seed addition experiment in grasslands at Cedar Creek Ecosystem Science Reserve in Minnesota, US, and have collected extensive trait for species that occur there, including leaf chemistry (see here and here). We have also trait data for wetland plants in SE Australia (see here, here and here).

Key research themes

1. Invasion ecology: causes and consequences of biological invasions

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Human introduction of species beyond their historical biogeographic boundaries is one of the defining characteristics of the Anthropocene, and the number of alien species introductions is increasing year on year. Alien species that become invasive are considered a top threat to global biodiversity, and alien plants cost the global economy millions of dollars per annum. There is thus a dire need to better understand the causes and consequences of invasions so that we can better predict and manage them.

Focusing mostly on plants, our work in invasions is conceptual, theoretical, empirical and quantitative, and we’re interested in each stage of invasion – from transport and introduction, to colonization and naturalization, to spread and impact. We examine invasions from both a fundamental and applied perspective – and usually link the two.

Examples 

• Palma, E., Vesk, P.A., Baumgartner, J.B., White, M. & Catford, J.A. (2021) Functional trait combinations reflect different demographic dimensions of invasiveness. Ecology.
• Catford, J.A., Smith, A.L., Wragg, P.D., Clark, A.T., Kosmala, M., Cavender-Bares, J., Reich, P.B. & Tilman, D. (2019) Traits linked with species invasiveness and community invasibility vary with time, stage and indicator of invasion in a long-term grassland experiment. Ecology Letters22: 593-604. link accepted author version
• Catford, J.A., Bode, M. & Tilman, D. (2018) Introduced species that overcome life history tradeoffs can cause native extinctions. Nature Communications 9: 2131link pdf 
• Catford, J.A. (2017) Hydrological impacts of biological invasions. Impact of Biological Invasions on Ecosystem Services (eds P.E. Hulme & M. Vilà). Springer, p. 63-80. link author copy (Table 2, Fig. 1)
• Buckley, Y.M. & Catford, J.A. (2016) Does the biogeographical origin of species matter? Ecological effects of native and non-native species and the use of origin to guide management. Journal of Ecology 104: 4-17. abstract pdf
• Catford, J.A., Baumgartner, J.B., Vesk, P.A., White, M., Buckley, Y.M. & McCarthy, M.A. (2016) Disentangling the four demographic dimensions of species invasiveness. Journal of Ecology 104: 1745–1758.abstract pdf
• 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. & Hulme, P.E. (2012) The intermediate disturbance hypothesis and plant invasions: implications for species richness and management. Perspectives in Plant Ecology, Evolution & Systematics 14: 231-241. abstract pdf
• Catford, J.A., Vesk, P.A., Richardson, D.M. & Pyšek, P. (2012) Quantifying levels of biological invasion: towards the objective classification of invaded and invasible ecosystems. Global Change Biology 18: 44-62. abstract pdf
• Catford, J.A., Jansson, R. & Nilsson, C. (2009) Reducing redundancy in invasion ecology by integrating hypotheses into a single theoretical framework. Diversity and Distributions 15: 22‐40. abstract pdf

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2. Community ecology: community assembly, species coexistence and biodiversity

We mostly look at the world through the lens of community ecology, reflecting our interest in what enables many (seemingly very similar) species to coexist in space and time, and the mixtures and abundances of the species that we see. Understanding mechanisms of community assembly and species coexistence is key to understanding – and thus protecting, managing and restoring – biodiversity.

Through the addition of new species into a system, biological invasion effectively acts as a real-life experiment in community assembly (albeit one that lacks controls), so we often use invasions to examine questions related to community ecology (and vice versa). Identifying the mechanisms that drive alien species establishment can therefore increase our understanding of community assembly, a task that is otherwise challenging due to the long temporal and broad spatial scales at which community dynamics typically operate.

Most of our research in this space involves the use of plant functional traits. Species can be characterised based on morphological, physiological, phenological and behavioural traits that affect their growth, reproduction and survival. Based on species characteristics rather than identity, functional traits can act as a universal currency in which the characteristics and responses of myriad species can be compared. Functional traits thus provide a fabulous tool for community ecology. By enabling ready comparison across regions, ecosystems and taxa, functional traits can help us to understand general processes, like mechanisms of species coexistence and characteristics related to species rarity and dominance. Traits have been widely used to characterise species that are invasive and non-invasive too, which has been very useful for biosecurity and species risk assessment.

Examples 

• O’Reilly-Nugent, A., Wandrag, E., Catford, J.A., Gruber, B., Driscoll, D. & Duncan, R. (2020) Measuring competitive impact: joint-species modelling of invaded plant communities. Journal of Ecology 108: 449-459. link
• Pinto-Ledezma, J.N., Villalobos, F., Reich, P.B., Catford, J.A., Larkin, D.J. & Cavender-Bares, J. (2020) Testing Darwin’s Naturalization Conundrum based on taxonomic, phylogenetic and functional dimensions of vascular plants. Ecological Monographs 4: e01420. link 
• Wandrag, E.M., Catford, J.A. & Duncan, R.P. (2019) Quantifying niche availability, niche overlap and competition for recruitment sites in plant populations without explicit knowledge of niche axes. Journal of Ecology 107: 1791-1803. link
• Catford, J.A., Bode, M. & Tilman, D. (2018) Introduced species that overcome life history tradeoffs can cause native extinctions. Nature Communications 9: 2131link pdf 
• Palma, E., Catford, J.A., Corlett, R., Duncan, R., Hahs, A., McCarthy, M., McDonnell, M., Thompson, K., Williams, N. & Vesk, P.A. (2017) Functional trait changes in the floras of 11 cities across the globe in response to urbanization. Ecography 40: 875-886. link
• Catford, J.A. & Jansson, R. (2014) Drowned, buried and carried away: effects of plant traits on the distribution of native and alien species in riparian ecosystems (Tansley Review). New Phytologist 204: 19-36. abstract pdf

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3. Hydroecology & ecohydrology: links between hydrology and vegetation

River regulation, water extraction, climate change, and land use and land cover change (including changes in vegetation) can all affect the hydrology of rivers and other freshwater ecosystems. By altering the amount of water available to natural ecosystems, and the distribution of water in space and time, humans directly and indirectly alter the hydrological regime of these systems. Hydrology is the key structuring force in freshwater and riparian ecosystems – shaping ecosystem structure and function and the composition of biotic assemblages, including plants – so hydrological change typically prompts ecological change, including the loss of native species and increase in alien ones.

We seek to understand the links between flow and ecology, with the aim of reducing the ecological impacts of hydrological change. Our work has shown, for example, that maintaining flood magnitude (rather than e.g. flood frequency or duration) is key for maintaining native-dominated wetland plant assemblages (pdf, pdf), and restoring “natural” floods can restore floodplain vegetation even after decades of agricultural land use (link, link).

Our work in this space covers wetland and river health, impacts of flow regulation, impacts of species invasions on hydrology and associated ecosystem services, environmental flows.

Examples 

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4. Global change & applied ecology: human-induced environmental change, ecological management and biodiversity conservation

As captured by the name of the current geological era – the Anthropocene – all taxa and ecosystems are affected by human-induced environmental change, so this theme intersects all of the other ones and is integral to the work that we do.

We examine ecological impacts of different types of environmental change, including climate change, species invasions, flow regulation, fire regime change, nitrogen deposition, herbivore exclusion and land use change. Increased understanding of these impacts, and the processes through which they occur, can help inform environmental policy and management.

We design, undertake and communicate our research to try to maximize the value of our work for ecological management, restoration and environmental policy. We often work with practitioners to help us achieve that goal.

Examples 

• Jane contributed to a project that developed and trialed a river health monitoring strategy and an environmental flows assessment protocol for three major rivers in China (the Gui, Taizi and Yellow). Funded by AusAid’s Australia-China Environment Development Program, the project was led by the International Water Centre in conjunction with the Chinese Ministry of Water Resources and Ministry of Environmental Protection.
• Turbelin, A. & Catford, J.A. (2021) Invasive species under climate change. Climate Change: Observed Impacts on Planet Earth (ed T. Letcher). Elsevier.
• Binder, S., Isbell, F., Polasky, S., Catford, J.A. & Tilman, D. (2018) Grassland biodiversity can pay. Proceedings of the National Academy of Sciences115: 3876-3881. link
• Buckley, Y.M. & Catford, J.A. (2016) Does the biogeographical origin of species matter? Ecological effects of native and non-native species and the use of origin to guide management. Journal of Ecology 104: 4-17. abstract pdf
• Catford, J.A. (2016) Using management to determine drivers of alien plant invasion and limits to native restoration. Applied Vegetation Science 19: 5-6. abstract pdf
• Johnson, D.P., Catford, J.A., Driscoll, D.A. & Gibbons, P. (2018) Seed addition and biomass removal key to restoring native forbs in degraded temperate grassland. Applied Vegetation Science 21: 219-228. link
• Lindenmayer, D.B., Wood, J., MacGregor, C., Hobbs, R.J. & Catford, J.A. (2017) Non-target impacts of weed control on birds, mammals and reptiles. Ecosphere8: e01804. link pdf
• Driscoll, D.A., Catford, J.A., et al. (2014) New pasture plants intensify invasive species risk. Proceedings of the National Academy of Sciences of the USA 111: 16622-16627. abstract pdf video Featured in Nature as a Research Highlight.
• Catford et al. (2012) The intermediate disturbance hypothesis and plant invasions: implications for species richness and management. Perspectives in Plant Ecology, Evolution & Systematics 14: 231-241. pdf (more about this paper here)

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