Publications by authors named "Anne Griebel"

The eddy covariance technique, commonly applied using flux towers, enables the investigation of greenhouse gas (e.g., carbon dioxide, methane, nitrous oxide) and energy (latent and sensible heat) fluxes between the biosphere and the atmosphere.

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Globe-LFMC 2.0, an updated version of Globe-LFMC, is a comprehensive dataset of over 280,000 Live Fuel Moisture Content (LFMC) measurements. These measurements were gathered through field campaigns conducted in 15 countries spanning 47 years.

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Climate change and increasing human activities are impacting ecosystems and their biodiversity. Quantitative measurements of essential biodiversity variables (EBV) and essential climate variables are used to monitor biodiversity and carbon dynamics and evaluate policy and management interventions. Ecosystem structure is at the core of EBVs and carbon stock estimation and can help to inform assessments of species and species diversity.

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Levels of fire activity and severity that are unprecedented in the instrumental record have recently been observed in forested regions around the world. Using a large sample of daily fire events and hourly climate data, here we show that fire activity in all global forest biomes responds strongly and predictably to exceedance of thresholds in atmospheric water demand, as measured by maximum daily vapour pressure deficit. The climatology of vapour pressure deficit can therefore be reliably used to predict forest fire risk under projected future climates.

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Non-forest ecosystems, dominated by shrubs, grasses and herbaceous plants, provide ecosystem services including carbon sequestration and forage for grazing, and are highly sensitive to climatic changes. Yet these ecosystems are poorly represented in remotely sensed biomass products and are undersampled by in situ monitoring. Current global change threats emphasize the need for new tools to capture biomass change in non-forest ecosystems at appropriate scales.

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In 2020, the Australian and New Zealand flux research and monitoring network, OzFlux, celebrated its 20 anniversary by reflecting on the lessons learned through two decades of ecosystem studies on global change biology. OzFlux is a network not only for ecosystem researchers, but also for those 'next users' of the knowledge, information and data that such networks provide. Here, we focus on eight lessons across topics of climate change and variability, disturbance and resilience, drought and heat stress and synergies with remote sensing and modelling.

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Article Synopsis
  • Mistletoes contribute to tree mortality, especially during droughts, by excessively using water from their host trees.
  • In Australia, expanding mistletoe distributions are straining eucalypt species already stressed by record heat and drought, leading to increased risks of hydraulic failure.
  • The study found that infected branches showed significantly higher water loss on hot days, negatively affecting the water potential of host trees and increasing the likelihood of carbon starvation in one eucalyptus species compared to another.
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Gross primary productivity (GPP) of wooded ecosystems (forests and savannas) is central to the global carbon cycle, comprising 67%-75% of total global terrestrial GPP. Climate change may alter this flux by increasing the frequency of temperatures beyond the thermal optimum of GPP (T ). We examined the relationship between GPP and air temperature (Ta) in 17 wooded ecosystems dominated by a single plant functional type (broadleaf evergreen trees) occurring over a broad climatic gradient encompassing five ecoregions across Australia ranging from tropical in the north to Mediterranean and temperate in the south.

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Article Synopsis
  • - The FLUXNET2015 dataset encompasses ecosystem-scale data on carbon dioxide, water, and energy exchange, collected from 212 global sites contributing over 1500 site-years of data until 2014.
  • - The dataset was systematically quality controlled and processed, facilitating consistency for various applications in ecophysiology, remote sensing, and ecosystem modeling.
  • - For the first time, derived data products such as time series, ecosystem respiration, and photosynthesis estimates are included, and 206 sites are made accessible under a Creative Commons license, with the processing methods available as open-source codes.
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Topography exerts control on eco-hydrologic processes via alteration of energy inputs due to slope angle and orientation. Further, water availability varies with drainage position in response to topographic water redistribution and the catena effect on soil depth and thus soil water storage capacity. Our understanding of the spatio-temporal dynamics and drivers of transpiration patterns in complex terrain is still limited by lacking knowledge of how systematic interactions of energy and moisture patterns shape ecosystem state and water fluxes and adaptation of the vegetation to these patterns.

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Article Synopsis
  • The Cumberland Plain woodland in Sydney is critically endangered and serves as a vital habitat for melaleuca trees, which play a key role in Australia's ecosystem and carbon storage.
  • Despite their importance, melaleucas haven't been sufficiently studied regarding their potential for carbon sequestration and their ability to handle climate stress.
  • Research combining forest data and monitoring systems showed that while melaleuca forests have slightly better heat regulation, they may be more vulnerable to drought conditions, suggesting a need for conservation efforts in the face of climate change.
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Forests are an important global carbon sink but their responses to climate change are uncertain. Tree stems, as the predominant carbon pool, represent net productivity in temperate eucalypt forests but the drivers of growth in these evergreen forests remain poorly understood partly because the dominant tree species lack distinct growth rings. Disentangling eucalypt species' growth responses to climate from other factors, such as competition and disturbances like fire, remains challenging due to a lack of long-term growth data.

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