REVITALISING AUSTRALIA'S FRESHWATER WETLANDS
Freshwater wetlands perform many functions and are vital for environmental, economic, social, and cultural reasons. They have among the highest carbon sequestration rates in the world (3 to 5 times greater than terrestrial forests), they provide habitat for native wildlife, protect against flooding and erosion, and act as biofilters to improve the water quality of rivers. Wetlands are also of cultural significance for Indigenous Australians as they represent sites for ceremonies, initiations, hunting, and gathering.
However, many natural wetlands are drying out as irrigation canals and levees associated with modern agricultural methods are diverting water to crops.
Dry wetlands are of lower natural capital, with lower water holding capacities, higher risks of fires, and are generally colonised by invasive plant species
With climate change rapidly intensifying, restoring freshwater wetlands is therefore crucial to improve soil fertility, enhance carbon sequestration, reduce flooding risks, and boost biodiversity.
Background
Natural wetlands in Australia sequester up to 6.93 Mg C ha-1 year-1. However, disturbances from human practices (e.g., cropping and grazing, drainage, and reclaiming) are turning wetlands into carbon sources, releasing previously stored soil carbon in the form of GHGs (e.g., CO2, CH4) into the atmosphere. Similarly, the use of fertilisers can promote the production of nitrous oxide (N2O), a potent greenhouse gas with a global warming potential 273 times that of CO2 on a 100-year timescale.
Our work
Our work aims to restore and revitalise freshwater wetlands by reinstating their natural hydrology and returning the land to its natural condition.
- We engage with farmers and landowners to identify degraded wetlands
- We use rewetting techniques to bring them back to their original condition.
- We work with indigenous rangers to combine traditional knowledge with conservation training to protect restored sites.
- We engage with stakeholders to discuss incentives for restoration practices, such as generating Australian Carbon Credit Units (ACCUs) by restoring wetlands.
Our partners include the Wetland Revival Trust, the Arthur Rylah Institute for Environmental Research, the Dja Dja Wurrung Aboriginal Corporation, and several management authorities (see below).
The Blue Carbon Lab is at the forefront of international efforts to understand the value of natural wetlands. We published the first large-scale estimates of carbon sequestration from natural wetlands in the southeast of Australia (Carnell et al. 2018). We also showed that excluding grazing from wetlands by installing fences can increase soil carbon concentration by up to 30%, while reducing greenhouse gas (GHG) emissions by 30% (Limpert et al. 2021). Similarly, excluding livestock from natural wetlands using fences can boost plant biomass and primary production (Treby et al. 2020), whereas active restoration efforts such as environmental watering can reduce GHG emissions by 28-84% (Limpert et al. 2020).
Carbon and nitrogen cycles in freshwater wetlands (from Bonetti et al. 2022, Environmental Pollution). Green arrows represent N-cycle processes, blue arrows represent C-cycle processes.
The benefits of revitalising degraded freshwater wetlands
The benefits of restoring natural wetlands include:
- Increased carbon storage, with an estimated 28-84% reduction in GHG emissions (Limpert et al. 2020)
- Provision of habitat for native and endangered species
- Increased water security for agriculture and drought resilience due to increased water holding capacity
- Protection from flooding
- Cultural significance for indigenous people
Selected Publications
- Bonetti, G., Limpert, K. E., Brodersen, K. E., Trevathan-Tackett, S. M., Carnell, P. E., & Macreadie, P. I. (2022). The combined effect of short-term hydrological and N-fertilization manipulation of wetlands on CO2, CH4, and N2O emissions. Environmental Pollution. https://doi.org/10.1016/j.envpol.2021.118637
- Limpert, K. E., Carnell, P. E., & Macreadie, P. I. (2021). Managing agricultural grazing to enhance the carbon sequestration capacity of freshwater wetlands. Wetlands Ecology and Management. https://doi.org/10.1007/s11273-020-09780-7
- Limpert, K. E., Carnell, P. E., Trevathan-Tackett, S. M., & Macreadie, P. I. (2020). Reducing emissions from degraded floodplain wetlands. Frontiers in Environmental Science. https://doi.org/10.3389/fenvs.2020.00008
- Treby, S., Carnell, P. E., Trevathan-Tackett, S. M., Bonetti, G., & Macreadie, P. I. (2020). Assessing passive rehabilitation for carbon gains in rain-filled agricultural wetlands. Journal of environmental management. https://doi.org/10.1016/j.jenvman.2019.109971
- Carnell, P. E., Windecker, S. M., Brenker, M., Baldock, J., Masque, P., Brunt, K., & Macreadie, P. I. (2018). Carbon stocks, sequestration, and emissions of wetlands in south eastern Australia. Global Change Biology. https://doi.org/10.1111/gcb.14319
Funding & Program Partners
This program is managed by Dr Lukas Schuster, Dr Martino Malerba, Dr Paul Carnell, and Dr Stacey Trevathan-Tackett from Deakin University’s Blue Carbon Lab.
The Australian Research Council funded this project through a DECRA fellowship awarded to Dr Malerba. Other partners include the Wetland Revival Trust; Arthur Rylah Institute for Environmental Research; Department of Environment, Land, Water and Planning (DELWP); Murray Darling Wetlands Working Group (MDWWG); North Central Catchment Management Authority (NCCMA).
