Delivering data for climate research and decision-making on Perth's water resources

To help celebrate the 20^th anniversary of OzFlux—the TERN-supported Australian and New Zealand eddy-covariance flux research community—a regular "site of the month" series is being launched that will visit a new flux site each month to celebrate recent achievements, the people who work there and the uniqueness of the environment measured.

To kick off this new series let's journey to Gingin, located in the Swan Coastal Plain of Western Australia on land traditionally owned by the Yued group of the Noongar people.

Gingin Banksia Woodland is both an OzFlux site and a TERN SuperSite , with its research activities and infrastructure supported by a collaboration between NCRIS-enabled TERN, the Centre for Ecosystem Management at Edith Cowen University (ECU), the Government of Western Australia, CSIRO and the University of Western Australia (UWA). It is managed by Associate Professor Richard Silberstein from ECU.

Banksia heath woodland (left, credit: Richard Silberstein) and the flux tower at Gingin (right, credit: Richard Silberstein).

Sensors deliver data to understand natural capital change

As extreme events such as droughts, floods and fires become more commonplace, understanding and predicting the response of Australia’s ecosystems and their services becomes more important. TERN and its operating partners and user communities are committed to collecting the data underpinning research and modelling related to a potentially hotter future with more extreme weather-related events.

To this end, the national research infrastructure at Gingin, including the 15 m tall eddy covariance flux tower, was installed in 2011 with the aim of determining recharge rates to the Gnangara groundwater mound—a crucial water resource for Perth—and to understand how vegetation changes accompany groundwater changes.

TERN, with initial support from CSIRO and now ECU, maintains the flux tower instrumentation that continuously measures exchanges of carbon dioxide, water vapour and energy between the terrestrial ecosystem and atmosphere.  The data these sensors collect are used by researchers to assess inter-annual variability in ecosystem fluxes from this important coastal Banksia heath woodland - the most prominent natural vegetation around Perth. Additional regular assessment of flora, fauna, microbial biodiversity, soils and hydrology complement these ecosystem scale flux measurements to provide a more complete picture of ecosystem processes.

Annual cumulative net ecosystem exchange (NEE), gross primary productivity (GPP), ecosystem respiration (ER), evapotranspiration (ET) and precipitation collected by the flux tower at Gingin for each year from October 2011 to 2020. Figures produced by Richard Silberstein using PyFluxPro outlined in Isaac et al. 2017 .

Documenting ecosystem threats

The Gingin site is characterised by seasonal drying and drought which, along with ecosystem water use, human consumption and a decline in annual rainfall, has led to falling watertables as Perth's population grows.

'There are many former wetlands dotted around the woodland, most of which were inundated all winter and some had permanent water 30 years ago. The watertable has now fallen below the base of these systems and they are disconnected and are no longer permanently wet.

The fine sediments, sometimes diatomaceous, hold water and they have a perched watertable each winter. There is a natural progression of species accompanying this process as they gradually become increasingly dominated by more dry-adapted (xeric) species.

Added to this is the ever-present threat of fire and feral species encroachment, which threaten the species richness and long-term ecological functioning of the site.' - Richard Silberstein

This blend of threats to ecosystem functioning is not unique to Gingin. Rather, they represent the situation in many ecosystems around Australia that are subject to a drying climate, falling watertables, fire and encroachment of feral species.

Therefore, the data collected at the site provide a fantastic resource for studies of such ecosystems across the nation. If these data are scaled-up and used alongside data from other OzFlux, TERN and Fluxnet sites, the national and global research possibilities are astounding.

Richard working on the Gingin flux tower (left, credit: Mirko Karan) and the TERN Advisory Board visiting the site in March 2020 (right, credit: Peter Brady).

How to use Gingin's equipment and data

All the data collected at Gingin are accessible via the TERN Data Discovery Portal and the OzFlux data portal .  If you have any questions about these data please email the TERN data help desk *.

The Gingin site is 2 km from the UWA International Gravity Wave Observatory and accommodation, storage and other facilities for wider use by educators and researchers can be arranged.

We're sure you don't need much motivation to get out and visit this beautiful part of the world but, just in case, Richard's spring invitation sounds very enticing!

'We have over 100 different species within our 1 ha flux site, most of them with beautiful flowers. There's something in flower throughout the year; in spring, it's a dream.

To be able to study the hydrological connections with the ecosystem, while enjoying the stunning flora is a wonderful combination; I never get tired of site visits.'

If you are interested in using TERN ecosystem research infrastructure please contact the TERN Project Office in the first instance. We'll connect you with the relevant TERN members to progress your request. This process is streamlined and potential users of the field based research infrastructure should know within 1-2 weeks (as long as there are no ethical issues) if their proposed activities are approved.

Once researchers have completed their studies and journal publications have been completed, TERN encourages publication of the data through TERN's data repository, under a Creative Common licence. The centralised storage of monitoring and independent research data adds value to Australia's long-term monitoring data and provides valuable temporal context for future studies.

* As COVID-19 restrictions are eased, TERN welcomes co-use of all its sites, including Gingin, by researchers.