Aim
The incidence of major fires is increasing globally, creating extraordinary challenges for governments, managers and conservation scientists. In 2019–2020, Australia experienced precedent‐setting ...fires that burned over several months, affecting seven states and territories and causing massive biodiversity loss. Whilst the fires were still burning, the Australian Government convened a biodiversity Expert Panel to guide its bushfire response. A pressing need was to target emergency investment and management to reduce the chance of extinctions and maximise the chances of longer‐term recovery. We describe the approach taken to rapidly prioritise fire‐affected animal species. We use the experience to consider the organisational and data requirements for evidence‐based responses to future ecological disasters.
Location
Forested biomes of subtropical and temperate Australia, with lessons for other regions.
Methods
We developed assessment frameworks to screen fire‐affected species based on their pre‐fire conservation status, the proportion of their distribution overlapping with fires, and their behavioural/ecological traits relating to fire vulnerability. Using formal and informal networks of scientists, government and non‐government staff and managers, we collated expert input and data from multiple sources, undertook the analyses, and completed the assessments in 3 weeks for vertebrates and 8 weeks for invertebrates.
Results
The assessments prioritised 92 vertebrate and 213 invertebrate species for urgent management response; another 147 invertebrate species were placed on a watchlist requiring further information.
Conclusions
The priority species lists helped focus government and non‐government investment, management and research effort, and communication to the public. Using multiple expert networks allowed the assessments to be completed rapidly using the best information available. However, the assessments highlighted substantial gaps in data availability and access, deficiencies in statutory threatened species listings, and the need for capacity‐building across the conservation science and management sectors. We outline a flexible template for using evidence effectively in emergency responses for future ecological disasters.
Each year, an average of 45 tropical cyclones affect coastal areas and potentially impact forests. The proportion of the most intense cyclones has increased over the past four decades and is ...predicted to continue to do so. Yet, it remains uncertain how topographical exposure and tree characteristics can mediate the damage caused by increasing wind speed. Here, we compiled empirical data on the damage caused by 11 cyclones occurring over the past 40 years, from 74 forest plots representing tropical regions worldwide, encompassing field data for 22,176 trees and 815 species. We reconstructed the wind structure of those tropical cyclones to estimate the maximum sustained wind speed (MSW) and wind direction at the studied plots. Then, we used a causal inference framework combined with Bayesian generalised linear mixed models to understand and quantify the causal effects of MSW, topographical exposure to wind (EXP), tree size (DBH) and species wood density (ρ) on the proportion of damaged trees at the community level, and on the probability of snapping or uprooting at the tree level. The probability of snapping or uprooting at the tree level and, hence, the proportion of damaged trees at the community level, increased with increasing MSW, and with increasing EXP accentuating the damaging effects of cyclones, in particular at higher wind speeds. Higher ρ decreased the probability of snapping and to a lesser extent of uprooting. Larger trees tended to have lower probabilities of snapping but increased probabilities of uprooting. Importantly, the effect of ρ decreasing the probabilities of snapping was more marked for smaller than larger trees and was further accentuated at higher MSW. Our work emphasises how local topography, tree size and species wood density together mediate cyclone damage to tropical forests, facilitating better predictions of the impacts of such disturbances in an increasingly windier world.
The global proportion of the most intense cyclones is increasing and it remains uncertain how damage to tropical forests will change with increasing wind speed. We compiled empirical data on the damage caused by cyclones from forests representing tropical regions worldwide to better understand the effects of wind speed, topographical exposure to wind, and tree characteristics on the proportion of damaged trees and on the probability of snapping or uprooting. Our work emphasises how local topography, tree size and species wood density together mediate cyclone damage to tropical forests, facilitating better predictions of the impacts of such disturbances.
1. Edaphic specialization among species may lead to greater productivity and resource use efficiency across heterogenous landscapes than could be achieved in the absence of specialization. Although ...this idea has been tested conceptually and in garden experiments, it has rarely been examined in undisturbed forests. 2. To address this gap in our knowledge, we measured aboveground net primary productivity (aboveground biomass increment plus litterfall; ANPP) and phosphorus use efficiency (ANPP/P uptake) for stands on infertile schist soil and fertile basalt soil on the Atherton Tablelands, Australia. We also measured aboveground biomass production and estimated P use efficiency (PUE) for 52 tree species within these stands. Soil P fractions and radiation use efficiency (ANPP/percent intercepted radiation) were also measured. 3. Phosphorus use efficiency was markedly variable (CV = 44%) among species across soil types. Phosphorus use efficiency of obligate specialists on infertile soil was twice as high as species common on both soil types. Plastic responses within species were also significant, with trees on infertile soil having 45% greater PUE than trees on fertile soil. At the ecosystem level, genotypic and phenotypic traits accounted for 49% and 29% of the total PUE variance. Phosphorus-efficient trees (PUE >8 kg biomass g⁻¹ P uptake) on schist soils contributed more to stand-level species richness (schist = 73%, basalt = 20%), basal area (schist = 86%, basalt = 18%) and production (schist = 82%, basalt = 10%) than did P-efficient species on basalt soils. 4. Forest on schist soils achieved higher PUE than forest on basalt soils by partitioning more P to leaves rather than wood and by retaining P for longer periods of time before losing it via tissue senescence. These PUE traits enabled forest on schist to achieve similar ANPP and radiation use efficiency (i.e. PUE was not traded for radiation use efficiency). It is possible that opportunity costs of high PUE may exist among other life-history traits. 5. These results suggest that plasticity in traits that confer P conservation is significant, but limited, and that maximum P conservation at the landscape level must be achieved via genetic differences between species. Although this highlights the importance of genetic conservation in forests, it also demonstrates that high P conservation is possible with relatively few, but markedly plastic species.
Dual-phase molten salt-ceramic membranes show high permselectivity for CO2 when molten carbonate is supported in a porous oxygen-ion and/or electron conductor. In this arrangement, the support likely ...contributes to permeation. Thus, if one is to understand and ultimately design membranes, it is also important to perform experiments with an inert support where permeation relies upon the molten carbonate properties alone. Here, a nominally inert material (Al2O3) was used in order to restrict permeation to molten carbonate. Model Al2O3 dual-phase membranes were fabricated using laser drilling to provide an order of magnitude difference in molten salt-gas interfacial area between feed and permeate sides. Molten carbonate thickness in the model membranes was also varied, independent of the molten salt-gas interfacial area. For all thicknesses studied, CO2 permeation rates showed a significant temperature dependence from 500 to 750 °C, suggesting an activated process was rate-limiting, likely a permeate-side molten salt-gas interfacial process, i.e. desorption of CO2. We applied these findings in asymmetric hollow-fibre supports, a geometry with inherent modularity and scalability, by developing a new carbonate infiltration method to control molten carbonate distribution within the hollow fibre. Compared to a conventionally prepared dual-phase hollow-fibre membrane with an uncontrolled distribution of carbonates, permeation rates were increased by up to 4 times when the molten salt was confined to the packed-pore network, i.e. without infiltrating the hollow-fibre micro-channels. X-ray micro-CT investigations supported the idea that the resulting increase in interfacial area for desorption of CO2 was the key structural difference contributing to increased permeation rates. For CO2 separation, where large volumes of gas must be processed, such increases in permeation rates will reduce the demand for membrane materials, although one must note the higher permeation rates achievable with oxygen-ion and/or electron conducting supports.
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•Nominally electronically insulating supports to restrict permeation to molten carbonate.•Model membranes with controlled molten carbonate thickness and interfacial area.•Permeate-side desorption of CO2 identified as potential rate-limiting step.•X-ray micro-CT determination of interfacial area in complex membrane microstructure.•Permeation rate increase in dual-phase hollow fibre membranes.
Issue Title: Themed Issue: Forest Diversity and Management: Safeguarding the Earth's Biota Ghylls are linear valley features cut into the sandy beds of the Weald of south-eastern England. The ghyll's ...indigenous woodlands are highly species rich at the small scale, support distinctive assemblages of cryptogamic plants, and are unique to south-east England. Field surveys were carried out for 48 ghyll woodlands in the Weald with a GIS used to examine the ecology, landform and conservation status of the ghyll woodlands. The data were analysed using spatial and multi-variate techniques in order to identify sub-groups or ghyll woodland communities based upon species composition, topography and geology. The ghylls are shown to be reasonably uniform for canopy vegetation type and structure and for their geological and soil characteristics. However, analysis shows that geomorphology, understorey and field layer variability may act as stronger indicators of site conditions and character. Further analysis focused on the level and extent of nature conservation protection that these unique and ancient systems receive. The study concludes that despite their ecological importance and potentially international significance, ghyll woodlands are poorly understood and protected.PUBLICATION ABSTRACT
In 2005 and 2010 the Amazon basin experienced two strong droughts, driven by shifts in the tropical hydrological regime possibly associated with global climate change, as predicted by some global ...models. Tree mortality increased after the 2005 drought, and regional atmospheric inversion modelling showed basin-wide decreases in CO2 uptake in 2010 compared with 2011 (ref. 5). But the response of tropical forest carbon cycling to these droughts is not fully understood and there has been no detailed multi-site investigation in situ. Here we use several years of data from a network of thirteen 1-ha forest plots spread throughout South America, where each component of net primary production (NPP), autotrophic respiration and heterotrophic respiration is measured separately, to develop a better mechanistic understanding of the impact of the 2010 drought on the Amazon forest. We find that total NPP remained constant throughout the drought. However, towards the end of the drought, autotrophic respiration, especially in roots and stems, declined significantly compared with measurements in 2009 made in the absence of drought, with extended decreases in autotrophic respiration in the three driest plots. In the year after the drought, total NPP remained constant but the allocation of carbon shifted towards canopy NPP and away from fine-root NPP. Both leaf-level and plot-level measurements indicate that severe drought suppresses photosynthesis. Scaling these measurements to the entire Amazon basin with rainfall data, we estimate that drought suppressed Amazon-wide photosynthesis in 2010 by 0.38 petagrams of carbon (0.23-0.53 petagrams of carbon). Overall, we find that during this drought, instead of reducing total NPP, trees prioritized growth by reducing autotrophic respiration that was unrelated to growth. This suggests that trees decrease investment in tissue maintenance and defence, in line with eco-evolutionary theories that trees are competitively disadvantaged in the absence of growth. We propose that weakened maintenance and defence investment may, in turn, cause the increase in post-drought tree mortality observed at our plots.
Drought threatens tropical rainforests over seasonal to decadal timescales, but the drivers of tree mortality following drought remain poorly understood. It has been suggested that reduced ...availability of non-structural carbohydrates (NSC) critically increases mortality risk through insufficient carbon supply to metabolism ('carbon starvation'). However, little is known about how NSC stores are affected by drought, especially over the long term, and whether they are more important than hydraulic processes in determining drought-induced mortality. Using data from the world's longest-running experimental drought study in tropical rainforest (in the Brazilian Amazon), we test whether carbon starvation or deterioration of the water-conducting pathways from soil to leaf trigger tree mortality. Biomass loss from mortality in the experimentally droughted forest increased substantially after >10 years of reduced soil moisture availability. The mortality signal was dominated by the death of large trees, which were at a much greater risk of hydraulic deterioration than smaller trees. However, we find no evidence that the droughted trees suffered carbon starvation, as their NSC concentrations were similar to those of non-droughted trees, and growth rates did not decline in either living or dying trees. Our results indicate that hydraulics, rather than carbon starvation, triggers tree death from drought in tropical rainforest.
Understanding the relationship between photosynthesis, net primary productivity and growth in forest ecosystems is key to understanding how these ecosystems will respond to global anthropogenic ...change, yet the linkages among these components are rarely explored in detail. We provide the first comprehensive description of the productivity, respiration and carbon allocation of contrasting lowland Amazonian forests spanning gradients in seasonal water deficit and soil fertility. Using the largest data set assembled to date, ten sites in three countries all studied with a standardized methodology, we find that (i) gross primary productivity (GPP) has a simple relationship with seasonal water deficit, but that (ii) site‐to‐site variations in GPP have little power in explaining site‐to‐site spatial variations in net primary productivity (NPP) or growth because of concomitant changes in carbon use efficiency (CUE), and conversely, the woody growth rate of a tropical forest is a very poor proxy for its productivity. Moreover, (iii) spatial patterns of biomass are much more driven by patterns of residence times (i.e. tree mortality rates) than by spatial variation in productivity or tree growth. Current theory and models of tropical forest carbon cycling under projected scenarios of global atmospheric change can benefit from advancing beyond a focus on GPP. By improving our understanding of poorly understood processes such as CUE, NPP allocation and biomass turnover times, we can provide more complete and mechanistic approaches to linking climate and tropical forest carbon cycling.
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