A universal model for predicting plant CO2 uptake

New research is set to change the way we predict photosynthesis in plants. Just published in Nature Plants, the research proposes a unified model of CO2 uptake by species and ecosystems that can be used to predict future global terrestrial sinks for anthropogenic CO2.

 

The uptake of CO2 by leaves and its conversion to sugar, called photosynthesis, is the basis of life on land.  We know much about the process; however scientists grapple with the challenge of finding a robust, globally applicable model for predicting photosynthetic CO2 uptake in the face of environmental change.

New research using TERN delivered data has just been published in Nature Plants that fills this information gap and proposes a universal CO2 uptake predictive model that combines light-use efficiency and photosynthesis theory.

The new model is applicable across global biomes and plant functional types, providing a potential basis for the reformulation of current Earth System Models used to predict the future of the terrestrial sink for anthropogenic CO2.

Australia’s “world class observations” and samples key to project success

The international team of researchers has used a worldwide data set of more than 3,500 leaf stable carbon isotope measurements to develop a more accurate method that correctly predicts measured photosynthetic uptake (known as gross primary productivity or GPP) at global Fluxnet sites, including at TERN sites.

“TERN observations, as part of the global Fluxnet dataset, provided a world-class set of measures to develop, test and enhance our new carbon flow model,” says lead researcher, Dr Han Wang of China’s Northwest A&F University and Australia’s Macquarie University.

TERN’s modelling capability, together with the United States Department of Agriculture, also played a significant role in the development of the methods we used to partition the flux data for deriving GPP observations,” adds Han.
TERN is proud to be providing the data and research infrastructure that the international modelling community is demanding.

TERN’s field observatory together with our ecosystem data services and modelling capability were utilised in this global research collaboration. The former collecting the data required to understand ecosystem processes and changes, and the latter processing the data, enabling them to be easily consumed by the international research team.

Earth Systems Models have already played a vital role in greatly improving our ability to understand and predict how plants and ecosystems respond to changes in their environment.  TERN recognises this and we are excited to be contributing to further advancements that lead to improved modelling of climate change and its impacts on the natural world.

 

Data from the global Fluxnet network, captured in part by TERN’s nation-wide network of ecosystem observatories including TERN’s Great Western Woodlands SuperSite in Western Australia (above), provided a world-class set of measures to develop, test and enhance the new plant CO2 uptake model (image courtesy Suzanne Long)

This article has also been published in:

TERN newsletter September 2017

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Assessing Ecological Performance in Fire Prone Kakadu

New research using decades of openly available monitoring data has identified significant problems with historic fire management in one of Australia’s premier National Parks: Kakadu. Despite the data painting a somewhat negative picture of the past, the research proposes economically viable carbon-market based solutions and vindicates recent park management actions that are delivering more sustainable and ecologically appropriate fire management in the reserve.

New research using TERN data indicates that the impact of fire on the ecology in Kakadu National Park was “more dire than previously thought”

New research has evaluated the historic state of fire management for biodiversity conservation in Australia’s premier savanna reserve, Kakadu National Park.

The assessment, just published in Ecosphere, draws on long-term data on fire incidence and severity, and vegetation and fauna collected at the 220 monitoring plots of the Three Parks Savanna Fire Effects Plot Network, part of TERN’s Long Term Ecological Research Network (LTERN).

To assess management effectiveness of historic fire management practices in the National Park, researchers used LTERN data combined with satellite-derived fire and habitat mapping data to model responses of vegetation and fauna.

“We now know that fire regimes up until the end of 2015, especially the high frequency of large, relatively severe late season fires, may have contributed to the declines in small mammals and impacted fire-sensitive flora across Northern Australia,” says Mr Jay Evans of Charles Darwin University’s Darwin Centre for Bushfire Research.

“But the performance metrics we used to quantify this indicate that the impact of fire on the ecology in the reserve was more dire than previously thought.”

Beyond the threshold: quantifying unsustainable fire management

The research team used ecological performance threshold metrics to assess how past fire regimes  impacted on Kakadu’s ecology.  A series of thresholds, or ecological tipping points, relating to fire’s impact on Kakadu’s ecosystems were assigned and the data used to assess their status.  Moving beyond a threshold indicates significant ecological impact.

“Of 14 assessed performance threshold metrics, two were within acceptable thresholds at the end of 2015, and none had improved materially over the decadal assessment period,” report Jay and his co-authors in the paper.

“For example, by the end of 2015 it was observed that just 6% of woodland habitat in lowland and 23% in upland situations had remained unburnt for longer than three years and 98% of mapped fires in lowland and 87% in upland habitats were >1 km2 in extent.”

Essential research for sustainable fire management

Despite the data painting a somewhat negative picture of the past, the research vindicates park management actions over the past two years that are delivering more sustainable and ecologically appropriate fire management in the reserve.

“Our research has shown that areas which experience low intensity fires earlier in the dry season are more ecologically healthy than those impacted by late season severe fires,” says Professor Jeremy Russell-Smith, also of the Darwin Centre for Bushfire Research and Co-Leader of the Three Parks Savanna Fire-Effects Plot Network within LTERN.

“By prescribed burning areas of the parks early in the dry season, park managers are already reducing the extent of fires later in the season,” says Jeremy.

“Park managers are working closely with the scientists, statisticians, rangers, Aboriginal custodians, school and university students, and agronomists conducting research across the Three Parks Savanna Fire Effects Plot Network.

“There are cost savings for management agencies, but more importantly this inclusiveness means that park managers understand fires in savannas and how they affect biodiversity, and are better placed to implement appropriate management in policy and practice.”

 

Low intensity fires earlier in the dry season (centre and right) are more ecologically healthy than late season severe fires (left) (images courtesy Jay Evans)

 

Savanna burning greenhouse gas emissions abatement projects need to be further explored

But, such seasonally intensive, fine-grained adaptive fire management for biodiversity conservation is incredibly difficult and expensive.  So, in addition to creating a more environmentally sustainable fire management program, the research also recommends landscape-scale carbon sequestration and savanna burning emissions abatement projects as an additional management tool.

“We are very keen to further promote formal carbon-market savanna burning approaches in the Northern Territory, similar to those undertaken in Western Arnhem Land through the West Arnhem Land Fire Abatement [WALFA] project, which have proven very successful environmentally, economically and culturally,” says Jeremy.

Under WAFMA ConocoPhillips pays around $1million a year to Indigenous ranger groups to undertake savanna fire management to offset the carbon emissions from its liquefied natural gas plant in Darwin Harbour. Since 2006 the project has abated over 100,000 tonnes of CO2 annually—equivalent to around 14,000 homes’ electricity use for a year.

“Projects like this, and indeed the ones currently being established by Kakadu’s traditional Aboriginal landowners and the park management agency, provide traditional custodians and knowledge-holders with a very viable means to stay on the land they care for and earn an income from it in the new carbon economy,” says Jeremy.

The ongoing challenge of managing Australia’s fire-prone Top End

As the researchers point out in their paper, “the substantial technical and operational fire management challenges identified here are not unique to Kakadu.”

More than 50% of substantial areas of north Australia’s 460,000-km2 mesic savannas (>1000 mm mean annual rainfall) are currently burnt annually, mostly in extensive late dry season fires.

Considering this, and the fact that extreme fires are likely to become more frequent in Australia, it is essential that the long-term collection of fire ecology data within Northern Australia is continued. Without the appropriate resourcing that will ensure the continuity and availability of long-term biodiversity and vegetation data the potential for ongoing collaboration of scientists and conservation and research agencies is severely undermined.

 

The plots in the Three Parks Savanna Fire Effects Plot Network, which forms part of TERN’s Long Term Ecological Research Network (LTERN)

 

Kakadu’s sandstone country illustrating prescribed protective burning early in the dry season using creeklines to help break up the country (image courtesy of Jeremy Russel-Smith)

 

Kakadu’s striking sandstone country with endemic Allosyncarpia monsoon forest (dark green) and sandstone heath (short vegetation on sides of rock formation), which is listed as an endangered vegetation community due to ecologically unsustainable contemporary fires regimes (image courtesy of Jeremy Russell-Smith)

 

 

This article has also been published in:

TERN newsletter August 2017

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Mapping Australia’s orchards for improved industry biosecurity and natural disaster recovery

Calling all citizen scientists, growers and horticulture industry experts. Your knowledge is required to improve a new map of Australia’s avocado, macadamia and mango orchards. The map delivers vital information to industry bodies to aid in more informed responses to biosecurity outbreaks and post natural disaster recovery and monitoring. So grab your smart phone, get out into your orchard and become part of this collaborative land-use mapping project.

 In collaboration with Avocados Australia, Australian Macadamia Society and Australian Mango Industry Association, a collaborative team from four universities, government agencies, industry partners, grower groups and commercial providers have developed a new interactive web map of selected horticulture tree crops across Australia. The draft mapping integrates satellite imagery with industry and government land cover data, regional surveys and on-ground evaluations to map the location and area of every commercial (>2ha) avocado, macadamia and mango orchard across Australia.

Launched in May 2017 and now open for review, the Industry Engagement Web Map provides stakeholders, growers and experts from the avocado, macadamia and mango industries an opportunity to review and improve the draft map.

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The Web Map and its associated data will be used by industry to develop a better understanding of growing area and underpin improved biosecurity and post natural disaster response and monitoring.

For example, in the event of a disease outbreak industry groups can access the map and know exactly where surrounding crops are and quickly develop management strategies. The product can also be used to map disasters like floods, fires and cyclones and speed up applications for recovery assistance. In fact, the map is already providing critical information to the natural disaster response and recovery effort in the wake of the devastating Category 4 Tropical Cyclone Debbie which crossed the Queensland coast in March 2017.

The Web Map—accessible from any desktop or mobile device web browser and no user account or subscription is required—uses coloured polygons to identify horticultural land-use classes (avocados, macadamias, mangoes) on the base satellite imagery.

Stakeholders are invited to view this draft mapping, compare it with their own local knowledge and provide comments and feedback. Comments can be submitted if the information is missing, incorrect or misclassified using an easy pop-up window with predefined options in drop down menus live within the Web Map. Once the comment window is completed it will be synchronised for other users to see. Search www.arcgis.com for ‘”Industry Engagement Web Map”, open the web map and add your comments!

Stakeholders can also use the free Land Use Survey app (iOS and Android) to inform the classification of tree crops by capturing GPS-coded point observations and photos. Comments and data collected via the map and app will be interpreted before the final mapping products are compiled and released in September 2017.

Australia’s National Tree Project

The Web Map is the first component of Australia’s National Tree Project, an ambitious project that combines innovative technologies such as satellite mapping, laser scanning and on ground robotics with citizen science apps to deliver improved industry information and methods of monitoring tree health, productivity and quality.

The National Tree Project is funded through the Australian Government’s Rural Research and Development (R&D) for Profit Grants Programme, managed by Horticulture Innovation Australia Ltd and coordinated by the University of New England. The success of the project can be attributed to the multi-disciplinary team from industry, research/academia and government, including The University of Queensland, University of Sydney, Central Queensland University, Agtrix Pty Ltd, the Queensland Department of Agriculture and Fisheries, Queensland Department of Science, Information Technology and Innovation, and Simpson Farms Pty Ltd.

This article has also been published by:

Australian Mangoes:

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Avocados Australia:

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Australia’s first state-wide ecosystem map

Assisted by TERN data infrastructure, the Queensland government has released Australia’s first comprehensive state-wide regional ecosystem maps, providing unparalleled detailed online information on the status of Queensland’s diverse native vegetation.

The Queensland government is a valued partner and user of TERN.  Thanks to long standing collaborations with the Queensland Department of Science, Information Technology and Innovation (DSITI) and the Queensland Herbarium, TERN is providing the state government with the data infrastructure necessary for them to house, update and re-use detailed data on remnant vegetation in Queensland.

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The Queensland Regional Ecosystems (RE) mapping includes both mapping of pre-clearing regional ecosystems and remnant ecosystems present in 2015, documenting ecosystem change caused by vegetation clearing (images courtesy DSITI)

This valuable dataset, known as CORVEG, is a major contributor to the first state-wide regional ecosystem maps in Australia, launched on 30 May by two Queensland State Government Ministers.

The Queensland Regional Ecosystems (RE) mapping includes both mapping of pre-clearing regional ecosystems and remnant ecosystems present in 2015, documenting ecosystem change caused by vegetation clearing.

“Accurate mapping of our changing landscape makes it easier to avoid some of the impacts of clearing, for example, by preserving wildlife corridors between similar habitats,” said Queensland Environment Minister Steven Miles at the launch of the new maps.

 

High-value Queensland vegetation data now openly available via TERN

Over 10,000 study locations across Queensland have been visited since 1982 to collect data on physical and vegetation features, including structural and floristic attributes well as descriptions of landscape, soil and geologic features.

The resulting CORVEG database is a key data source for defining, describing and classifying regional ecosystems, and ground truthing the RE mapping says Dr John Neldner the Science Leader of DSITI’s Queensland Herbarium.

“We [DSITI] make the CORVEG data openly available via TERN’s AEKOS data portal, using a TERN-developed API data transfer tool embedded behind our firewalls to feed monthly CORVEG updates to AEKOS.”

“TERN provides the conduit for national and global access to this high-value vegetation data so we are highly appreciative of the TERN infrastructure and services.”

Publishing via TERN protects government data and meets open data goals

The other thing about TERN’s data infrastructure that suited Queensland Government needs is the fact that data can be accessed under a Creative Commons International 4.0 licence, says Steve Jones, Director of Science Information Services for DSITI.

“As well as protecting the data and their authors by law, publishing under Creative Commons is in line with the Australian and Queensland Government’s move towards greater open access to its information,” said Steve.

“Working with TERN has been great in focussing our attention on data management and strengthening our internal processes regarding data publishing and licensing.  The services TERN provides have also helped DSITI meet our open data goals.”

TERN exposes government vegetation data and facilitates new science

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Queensland’s CORVEG data, openly available via TERN’s AEKOS data portal, is being downloaded by a diverse range of users representing a wide range of sectors including industry (environmental services, agriculture and mining) and state and federal governments 

TERN’s data infrastructure, as ‘the conduit for national and global access’ to CORVEG data, not only gives this state government dataset widespread exposure, but also allows people to use the data without having to invest new funds to re-collect that information—saving huge amounts of time and money.

CORVEG data and RE mapping is widely used for environmental research and management, such as assessments of vegetation change and estimates of plant abundances, and for modelling of species and ecosystem distributions.  Business, government, NGOs and landholders are also users of the information.

Ecologist Dr Steve Murphy of Adaptive NRM is just one of the many researchers using the Regional Ecosystems mapping derived from CORVEG. Dr Murphy says that the mapping has been hugely valuable in efforts to protect and research one of Australia’s most endangered birds, the night parrot.

“A fundamental aspect of our research program has been to identify and describe night parrot habitats.  Queensland regional ecosystems mapping is the main tool we use to define habitats at a regional level in western Queensland, where the elusive bird is found.”

 

Discovering Qld CORVEG Data in TERN AEKOS: Viewing a Location of Interest by IBRA from TERN Australia on Vimeo.

 

Discovering Qld CORVEG Data in TERN AEKOS: Find, View & Download Values per Species from TERN Australia on Vimeo.

 

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This article has also been published in:

TERN newsletter June 2017

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Australian Bureau of Meteorology eXchange Magazine:

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Finding the lost forests of the drylands

A new global analysis of the distribution of forests and woodlands across dryland ecosystems using TERN data has increased current estimates of global forest cover by nearly 10%. The work, just published in Science, is a direct result of TERN’s on-going collaborations with the United Nation’s Food and Agriculture Organization through their Global Forest Survey, which uses TERN data for crucial on-ground verification of satellite-based analyses.

Finding these lost dryland forests increases current estimates of global forest cover by almost 10%, and by approximately 45% for dryland forest types. An innovative new analysis of global drylands using high-resolution satellite imagery has ‘found’ 467 million hectares of previously unreported forest—an area equivalent to 60% of the size of Australia.

These results, just published in Science, are set to drastically improve the accuracy of global models of terrestrial carbon sinks and carbon inventories submitted under international climate conventions including the UNFCCC and the Kyoto Protocol.

Moreover, by revealing that drylands—which make up about 40% of Earth’s land surface—have a greater capacity to support trees and forest than previously perceived and understood, a unique chance to mitigate climate change impacts through large-scale dryland conservation and afforestation actions is presented.

 

A Baobab forest in Senegal, a few kilometers away from Dakar (image courtesy of FAO/Faidutti)

The research, conducted by an international team of scientists from The Food and Agriculture Organization of the United Nations (FAO), the University of Adelaide, TERN and a dozen other public and private institutions from all continents, stems from the FAO’s Global Drylands Assessment phase of the Global Forest Survey.

The team analysed very high spatial and temporal resolution satellite imagery of more than 210,000 dryland monitoring plots to calculate global forest cover and its change over time. TERN’s national network of over 500 ecosystem observation plots and the field data collected at them were used to complete the Oceania component of the study.

The resources provided by TERN are the only global plot-based data source readily available and accurate enough to validate satellite imagery, verify the observed density of trees, and assess observer accuracy. In fact, TERN ecosystem observation plots are so vital to the project that the FAO is working on permanently incorporating them into their global forest-monitoring network.

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Recent advances in satellite imagery, as well as new data collected and made available by TERN, have enabled researchers to greatly improve our mapping of drylands forest ecosystems, like the Coolabah forest (Eucalyptus victrix) in the Pilbara region of Western Australia shown above (image courtesy TERN)

Project member Danilo Mollicone of the FAO said the decision to use TERN infrastructure and expertise was made thanks to TERN’s proven expertise and research infrastructure in Australia’s arid ecosystems.

“TERN’s infrastructure and expertise is vital to the FAO and the successful completion of our Global Drylands Assessment,” says Danilo.

“The data we collect via TERN fills an important information gap that ensures the project has worldwide coverage.  With such global coverage we were able to accurately obtain estimates on tree cover, forest extension and land use in the drylands.”

“Over time, our ongoing partnership with TERN, will also help the project identify spatial and temporal changes and trends within ecosystems and between continents as biological and non-biological influences come into play.”

Associate Professor Ben Sparrow of the University of Adelaide and TERN AusPlots, led Australia’s involvement in the project and seconds Danillo’s call for ongoing monitoring.

“Dryland forests play an increasingly important role in preventing desertification, maintaining livelihoods and mitigating the impacts of climate change at regional and global scales, so it’s vital that we continue to monitor the long-term trends in dryland forest cover and quality,” says Ben.

TERN looks forward to further strengthening our relationship with the FAO and continuing to provide the infrastructure, data and expertise required to complete this ongoing study that has already delivered such positive and timely global outcomes for our ecosystems.

This article has also been published in:

TERN newsletter May 2017

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And, used in this Conversation article:

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Conserving blink-and-you’ll-miss-it biodiversity

New research has revealed the conservation and management implications of rapid changes in species composition between Western Australia’s sandplain ecosystems.

Researchers from Western Australia’s Department of Parks and Wildlife, the University of Western Australia and the CSIRO have found that the vegetation of southern WA’s sandplains is not only very diverse but also highly variable between locations.

In their paper just published in the journal PLOS One, the team report rapid and significant changes in botanical composition between locations—known as species turnover or beta diversity—resulting in remarkably diverse sandplain ecosystems.

Species composition between locations along the SWATT changes so quickly that sites with similar soils less than 10km apart have almost completely different plant communities.

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New research using TERN’s South West Australian Transitional Transect research infrastructure (right) has revealed the conservation and management implications of highly variable biodiversity across Western Australia’s sandplain ecosystems (left) 

Conservation of these diverse environments is challenging

Parks and Wildlife senior principal research scientist Neil Gibson said the findings were consistent with earlier work in sandplain and mallee vegetation in WA’s south-west and suggest that conservation strategies need to encompass this variability.

“When biodiversity changes significantly over short distances, as we found in WA’s sandplains, all areas make a significant contribution to regional diversity and it’s logistically difficult and expensive to capture this diversity in a reserve system,” says Neil.

“So biodiversity conservation approaches need to include off-reserve management through protecting remnant vegetation and minimising human disturbance, and this approach is already happening in areas under traditional land ownership or joint management agreements.”

Implications of climate driven species turnover

So what’s causing this high species turnover? Co-author Suzanne Prober of CSIRO Land and Water said at smaller scales, distance between locations and natural barriers that limit species distribution appear to be key factors.  At broader scales, climate and geography, or a combination of both, are the biggest drivers.

“Changes in soil along the 870 km transect partly explain the broader-scale turnover, but of particular interest is the role climate is playing,” says Suzanne. “We found that the most important climatic factor was the amount of rain during the driest time of the year, effectively an aridity gradient.”

“Whilst this is not unexpected, it’s very important because rainfall patterns are expected to dramatically change with climate change,” Suzanne explains.

“It’s hard to predict just how these projected climatic changes will impact sandplain biodiversity so ongoing monitoring and adaptive management is essential.”

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Reserves are conservation jewels but by themselves are unlikely to fully represent the diversity across such variable sandplain ecosystems

The extensive data on WA’s sandplain ecosystems, compiled with TERN support and now openly available via TERN data infrastructure, is already playing an integral role in monitoring and management.

Parks and Wildlife Assistant Director of Science Stephen van Leeuwen said that land managers and policy makers could now use the TERN-delivered SWATT data to make informed decisions on how to best manage these ecosystems for economic and environmental sustainability.

“Department vegetation and soil monitoring programs are specifically aligned with TERN’s surveying and monitoring protocols (TERN’s AusPlots protocol), which streamlines the use of TERN data in state management approaches” he said.

“For example, the data collected by our recent study indicates that the State’s sandplains are of similar biological significance as its woodlands,” reports Stephen. “The integration of this information on diversity with ongoing fire ecology research is expected to better inform the way we manage sandplain environments, especially with regards to fire management and prescribed burning programs.”

“TERN provides the research infrastructure and data at the scales we need to understand and manage these vast, but fragile and highly variable sandplain ecosystems.”

With pressures on these ecosystems increasing, the ongoing role of TERN in providing researchers, policy makers and environmental managers with a better footing on which to make informed decisions, including threat abatement and adaptation to climatic changes, is more important than ever.

  • The SWATT is part of TERN’s Australian Transect Network and is one of several major environmental monitoring transects within the Australian continent.  It extends about 1200 km, from Walpole on the southern coast, north-east into the Little Sandy Desert and traverse eight bioregions and various land uses from tall southern forests, through agricultural land with fragmented vegetation and across northern rangelands where pastoralism and mining are dominant land uses. It also takes in the Great Western Woodland, and Credo station—where TERN operates the Great Western Woodlands Supersite and OzFlux monitoring tower.
  • Data from SWATT are openly available via TERN’s AEKOS Data Portal.
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“TERN provides the research infrastructure and data at the scales we need to understand and manage these vast, but fragile and highly variable sandplain ecosystems.” – WA Parks and Wildlife Assistant Director of Science Stephen van Leeuwen (left)

 

This article has also been published in:

The TERN newsletter March 2017

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Raincoat for a rainforest: Simulating drought in the Daintree

How might the world’s rainforests respond if droughts become more frequent in the future? This question is behind a unique experiment in the world-famous Daintree Rainforest in Far North Queensland, Australia.
Susan Laurance installing a dendrometer band on a Daintree rainforest tree (Photo courtesy of Dr Alex Cheesman)

A team of scientists led by Associate Professor Susan Laurance of James Cook University are studying how trees and other plant life-forms of a rainforest respond to a prolonged, experimentally induced drought at plots where tree growth, composition, soil water and atmospheric exchange have been monitored with TERN support since 1999.

“Major drought events are known to cause widespread tree and seedling death, reduced plant growth, and increased flammability, but just how quickly this happens is relatively unknown,” says Susan.

To investigate these mechanisms, the Daintree Drought Experiment is simulating drought conditions by excluding rainfall using clear-panel roofing structures, or raincoats, that capture rain and remove it from two sites of 50 x 40 m.

“We’ve successfully lowered soil water to at least 50 cm from the surface and reduced tree water use at the sites from 40-60%.”

The study is collecting data on tree demography, plant functional traits and water use, and overall tree health at both ‘drought’ and control plots to investigate changes in three main mechanisms that cause tree death during droughts: hydraulic failure, gradual carbon starvation, and insect and/or pathogen attack.

Data collected and made available by TERN’s plot network and flux monitoring tower at the site are providing the information necessary for comparison between control and drought plots.

“The data we are getting from TERN is really crucial comparative information on tree growth and survival; forest productivity with respect to coarse woody debris and leaf litter; and climate data from the TERN towers,” says Susan. “The data enables our experimental comparison to happen easily and efficiently.”

“So far, we have observed increased leaf fall and decreased growth rates of drought-affected trees at the site. We are also excited about the signs of elevated herbivory and disease on leaves and increased wood boring of drought-affected plant stems.”

Susan emphasises that these preliminary findings are a global first as most drought investigations have, until now, focussed on plant physiology and largely ignored factors such as herbivory and disease that are known to be pervasive and often powerful in tropical rainforests.

The Daintree Drought Experiment is an ambitious project that will address one of the most important potential threats to tropical forests. This is a vital undertaking, given that droughts could imperil the capacity of rainforests to store carbon and sustain biodiversity.

 

The construction (above and below) and design (map below) of the Daintree Drought Experiment includes 2 x 0.2 ha plots adjacent to a Control plot 1 (0.5 ha) under the canopy crane, and a nearby topographically matched Control plot 2 (1 ha) (photo courtesy of Mirko Karan and Yoav Daniel Bar-Ness.)

 

Control versus drought leaves illustrate signs of elevate herbivory and disease (centre) and recent wood boring signs in a drought-stressed sapling (right) (Photos courtesy of D. Tng and S. Laurance)

 

This article has also been published in:

The TERN newsletter February 2017

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Global efforts to understand ecosystem drought sensitivity

A landmark global experiment that investigates the impact of drought on our ecosystems, and helps to predict and mitigate their continental and regional-scale impacts.

Climate change is predicted to increase both drought frequency and intensity and the latest science from the IPCC indicates that such an increase will cause abrupt and irreversible change in the composition, structure, and function of terrestrial ecosystems.  However, just how ecosystems will respond to increased drought isn’t clearly understood.  Nor are the factors that make some ecosystems more sensitive than others.

To address this knowledge gap an international group of scientists affiliated with the US National Science Foundation-funded Drought-Net Research Coordination Network (Drought-Net), is working at research sites all over the globe to understand terrestrial ecosystem sensitivity to drought and the mechanisms underlying response patterns.

Experimental plots with custom-built shelters designed to reduce rainfall and simulate predicted future drought conditions have been established at TERN sites as part of this landmark global experiment.

Shelters’ for the Drought-Net experiment have been established at a number of TERN’s environmental monitoring sites, including Great Western Woodlands in WA (above)
Associate Professor Sally Power of Western Sydney University is on the international steering group for Drought-Net and says: “access to TERN’s research infrastructure and the integrative, networked approach that it facilitates is enabling us to further our predictive understanding of Australian and global terrestrial ecosystem sensitivity to drought.”

‘Drought shelters’ for the Drought-Net experiment have been established by TERN’s partners at a number of TERN’s environmental monitoring sites, including Great Western Woodlands in WA, Cumberland Plain in NSW, and the Victorian Dry Eucalypt SuperSite at Wombat Forest.

Ecologists on opposite sides of the continent working at TERN’s Great Western Woodlands and Cumberland Plain sites are restricting up to 65% of rainfall at 18 Drought-Net plots and monitoring changes in soil moisture and biomass.

Drought-Net’s coordinated experimental network, with identical protocols and comparable measurements, facilitates comparative studies at such broad continental—and indeed global—scales.

In addition, the Desert Ecology Research Group (DERG) at The University of Sydney has also established drought shelters at the Desert Ecology Plot Network, which is one of TERN’s long-term research sites in Queensland’s Simpson Desert.

Researchers at these sites are imposing an 85% reduction in rainfall and have completed surveys of plant composition and productivity and collected soil samples in a bid to better understand the environmental drivers of change in arid landscapes.

This research could be used by rangeland and agriculture managers to develop management strategies that incorporate the impacts an increasingly warm climate with extreme rainfall patterns will have on arid landscapes.

While TERN has helped facilitate Australia’s participation in the global Drought-Net project possible, Sally notes that this is only the beginning.

“By maintaining and expanding TERN’s nation-wide research infrastructure, Australia’s capacity to collaborate on important projects like this will be significantly enhanced—as will our contribution to global climate science.”

  • Much of the data collected for the Drought-Net experiment—will become accessible to the global research community in coming years. So watch this space and we will keep you updated through the TERN Newsletters and most likely the TERN Data Discovery Portal.

‘Drought Shelters’ at TERN’s Great Western Woodlands site (above) and Cumberland Plain site (below) are restricting up to 65% of rainfall to simulate predicted future drought conditions so that researchers can better understand how ecosystems respond to a drier climate

This article has also been published in:

The TERN newsletter January 2017

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And, by the Australian Energy and Water Exchange Initiative (OzEWEX)

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Angry summers and the ecosystem science of heat waves

As Australia swelters through another hot summer, a team of researchers is using TERN data to assess how heat waves affect the energy balance, carbon uptake, water use, and overall health of Australia’s ecosystems.

2017 has kicked off with severe heat waves throughout Australia’s southern and eastern states and it seems there’s more hot weather on its way. We know heat waves can pose risks to our power supply, public transport, and personal health, but how do our ecosystems respond?

Thanks to TERN’s flux monitoring infrastructure, data now exist to enable researchers to investigate the impact that heat waves have on Australian ecosystems. This work is especially important to help us plan for a future that is likely to include more frequent and extreme heat wave conditions.

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To see what happens to ecosystems during heat waves, researchers have used data from seven TERN OzFlux sites located in three distinct climate and ecosystem types: Mediterranean woodlands (red dots), temperate woodlands (light green dots), and a temperate forest (dark green dot). Data collected by the flux tower at TERN’s Great Western Woodlands SuperSite in WA (below) was one of the Mediterranean woodland sites (photo courtesy of Suzanne Long)

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The angry summer of ‘13

To see what happens to ecosystems during heat waves, researchers have used the data captured by several TERN flux towers during the ‘Angry Summer of 2012/2013’.

The study across southern Australia combined data on carbon and water exchange (or fluxes) between the land and atmosphere with results from CSIRO’s BIOS2 model to investigate the effect of the 2012/’13 heat wave on six woodlands and one forest known for their resilience toward hot and dry conditions.

Ecosystems can switch from carbon sink to source

Dr Eva van Gorsel of the Australian National University and Dr James Cleverly of the University of Technology Sydney are part of the investigative team, whose work has just been published in the journal Biogeosciences.

“The heat wave caused increased respiration in all ecosystems, and carbon uptake was reduced so much at woodland sites that they switched into carbon sources,” says Eva. “Unlike the woodland ecosystems that were severely impacted by the heat wave, the forest site kept sequestering carbon during this short-term heat extreme.”

“But, what we also found is that the heat wave depleted the available soil water at the forest site, leaving the ecosystem highly vulnerable to heat events of higher intensity or longer duration,” adds James.

Ecosystem resilience and recovery

The research team, made up of 20 Australian and international researchers, also investigated the impact intermittent rain has on the recovery of ecosystems following heat waves.

They found that the temperate woodlands recovered quickly following rain after the first, more intense part of the heat wave, whereas the Mediterranean woodlands remained carbon sources throughout the duration of the heat wave.

The team reported in their paper that “The response of the woodlands is the first direct evidence that the carbon sinks of large areas of Australia may not be sustainable in a future climate with an increased number, intensity and duration of heat waves.”

Australian heat waves unlike those overseas

Project researcher Dr. Sebastian Wolf of the Swiss Federal Institute of Technology in Zurich (ETH Zurich) says that there is a fundamental difference in this Australian heat wave to what has previously been observed in Europe and US.

“Heat waves in Europe and California have been shown to result in surplus energy (from reduced cloud coverage) that, in combination with drying, leads to a feedback loop that further increases surface temperatures.”

“But, in contrast to these other studies, incoming radiation and available energy were largely unaffected by the 2013 heat wave in Australia. The heating feedback in the woodlands was driven by drying and thus shifts of the available energy towards sensible heat, thereby warming the surface even further. In the forest ecosystem this feedback was not observed.”

“These findings highlight the important role Australian forest ecosystems play in mitigating the effects of heat waves.”

Predicting a more extreme future

This study highlights the important ecosystem services Australia’s woodlands and forests provide—particularly considering the increased prevalence of droughts and temperature extremes projected in the future—and is another example of how TERN’s infrastructure is continuing to catalyse advances in our knowledge of the land-atmosphere exchange of carbon and water across a range of ecosystems.

By accumulating more data about ecosystem processes, uniquely captured via TERN’s flux towers, researchers can contribute to improve our understanding of ecosystem functioning.

A better understanding of ecosystem processes is critical for further development of predictive models which are needed to predict the impacts extreme climatic events will have on Australia’s ecosystems and their services into the future.

This article has also been published in:

The TERN newsletter January 2017

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And, by the Australian Energy and Water Exchange Initiative (OzEWEX)

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Drought ends great green boom and Australia’s carbon budget shifts

Science can’t prevent extreme events. But good ecosystem science is a demonstrably cost-effective way to increase our understanding of the complexities of their impacts, and therefore better inform preparedness and adaptation by communities, industries and management agencies.

A international team from UTS and NASA has used satellite imagery and ground observations collected and made openly available by TERN AusCover and TERN OzFlux infrastructure (OzFlux tower below) to show that the record-breaking green boom of 2011 of central Australia has finished and drought conditions have returned (images courtesy of Aaron Greenville, above, and Suzanne Long, below) 

Dr Xuanlong Ma and his colleagues from the University of Technology Sydney and NASA’s Goddard Earth Science Division have used satellite imagery and ground observations from TERN AusCover and TERN OzFlux to show that the record-breaking green boom of 2011 in the savannas and grasslands of central Australia has finished and drought conditions have returned.

Australia has a naturally variable climate and this finding was no surprise for the researchers, so why does it matter?  Well, put simply, plants absorb less carbon dioxide during dry periods because the process costs water, so a reduction in the absorption of CO2 due to drought can seriously alter Australia’s carbon budget.

In fact, Xuanlong and his team reported that “Each year, land plants absorb the equivalent of more than a quarter of the carbon emissions generated by burning fossil fuels and deforestation. This helps to partly offset global increases in atmospheric CO₂ concentration. In 2011, this ‘land carbon sink’ was unusually large, thanks largely to the greening of Australia’s vegetation, which accounted for 60% of the global carbon uptake anomaly that year.”

Sometimes the combination of heat and drought can be so stressful that plants die, ultimately decomposing or burning and releasing all of their stored carbon back to the atmosphere.

And, according to the data from this study, this is exactly what happened across Australia during the second half of 2012 and into 2013, diminishing the large net carbon uptake the 2010-11 wet year delivered (0.97 Pg in 2010-11 to only 0.08 Pg in 2012-13).

Today, Australia’s semi-arid landscapes remain dry.  That is until the next big deluge arrives and they once again start absorbing CO2 from the atmosphere and storing it as carbon in the landscape.

A very interesting finding as reported by this study is that extreme wet years are getting wetter, wilder and more common—especially in central and northwestern Australia.

“Given a significant increasing trend in extreme wet year precipitation over Australia, we suggest that carbon sink episodes will exert greater future impacts on global carbon cycle.” said Xuanlong and the UTS/NASA team.

“A wilder future with more rain during wet years will have important implications, not only for carbon uptake by plants, but also for many other important issues such as flood risk management, water rights and increased bushfire danger once the landscape dries out again.  We had better keep an eye on that.”

This research using TERN data is yet another clear indication of the very significant role Australia’s terrestrial ecosystems do, and will continue to, play in Australia’s carbon cycle. And, further justification for continued ecosystem observation using TERN’s national infrastructure.

A downpour over Cravens Peak in central western Queensland in November 2011 (image courtesy of Aaron Greenville)

This article has also been published in:

The TERN newsletter December 2016:

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