Water Filtration Using Plant Xylem

Effective point-of-use devices for providing safe drinking water are urgently needed to reduce the global burden of waterborne disease. Here we show that plant xylem from the sapwood of coniferous trees – a readily available, inexpensive, biodegradable, and disposable material – can remove bacteria from water by simple pressure-driven filtration. Approximately 3 cm3 of sapwood can filter water at the rate of several liters per day, sufficient to meet the clean drinking water needs of one person. The results demonstrate the potential of plant xylem to address the need for pathogen-free drinking water in developing countries and resource-limited settings

Incorporating non-stomatal limitation improves the performance of leaf and canopy models at high vapour pressure deficit

Vapour pressure deficit (D) is projected to increase in the future as temperature rises. In response to increased D, stomatal conductance (gs) and photosynthesis (A) are reduced, which may result in significant reductions in terrestrial carbon, water and energy fluxes. It is thus important for gas exchange models to capture the observed responses of gs and A with increasing D. We tested a series of coupled A-gs models against leaf gas exchange measurements from the Cumberland Plain Woodland (Australia), where D regularly exceeds 2 kPa and can reach 8 kPa in summer. Two commonly used A-gs models were not able to capture the observed decrease in A and gs with increasing D at the leaf scale. To explain this decrease in A and gs, two alternative hypotheses were tested: hydraulic limitation (i.e., plants reduce gs and/or A due to insufficient water supply) and non-stomatal limitation (i.e., downregulation of photosynthetic capacity). We found that the model that incorporated a non-stomatal limitation captured the observations with high fidelity and required the fewest number of parameters. Whilst the model incorporating hydraulic limitation captured the observed A and gs, it did so via a physical mechanism that is incorrect. We then incorporated a non-stomatal limitation into the stand model, MAESPA, to examine its impact on canopy transpiration and gross primary production. Accounting for a non-stomatal limitation reduced the predicted transpiration by ~19%, improving the correspondence with sap flow measurements, and gross primary production by ~14%. Given the projected global increases in D associated with future warming, these findings suggest that models may need to incorporate non-stomatal limitation to accurately simulate A and gs in the future with high D. Further data on non-stomatal limitation at high D should be a priority, in order to determine the generality of our results and develop a widely applicable model. © The Author(s) 2019. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: [email protected]. was supported by a PhD scholarship from Hawkesbury Institute for the Environment, Western Sydney University. M.G.D.K. acknowledges funding from the Australian Research Council (ARC) Centre of Excellence for Climate Extremes (CE170100023), the ARC Discovery Grant (DP190101823) and support from the NSW Research Attraction and Acceleration Program. EucFACE was built as an initiative of the Australian Government as part of the Nation-building Economic Stimulus Package and is supported by the Australian Commonwealth in collaboration with Western Sydney University. It is also part of a Terrestrial Ecosystem Research Network Super-site facility

Cephalopholis aitha, Rusty Hind

This is relatively small, uncommon reef species is widely distributed, but poorly known. It is not targeted by fisheries and there are no known major threats; therefore, it is listed as Least Concern. The change in status from the previous assessment reflects an improved application of the Red List categories and criteria, as well as a better understanding of available data

The likelihood of extinction of iconic and dominant herbivores and detritivores of coral reefs: the parrotfishes and surgeonfishes

Parrotfishes and surgeonfishes perform important functional roles in the dynamics of coral reef systems. This is a consequence of their varied feeding behaviors ranging from targeted consumption of living plant material (primarily surgeonfishes) to feeding on detrital aggregates that are either scraped from the reef surface or excavated from the deeper reef substratum (primarily parrotfishes). Increased fishing pressure and widespread habitat destruction have led to population declines for several species of these two groups. Species-specific data on global distribution, population status, life history characteristics, and major threats were compiled for each of the 179 known species of parrotfishes and surgeonfishes to determine the likelihood of extinction of each species under the Categories and Criteria of the IUCN Red List of Threatened Species. Due in part to the extensive distributions of most species and the life history traits exhibited in these two families, only three (1.7%) of the species are listed at an elevated risk of global extinction. The majority of the parrotfishes and surgeonfishes (86%) are listed as Least Concern, 10% are listed as Data Deficient and 1% are listed as Near Threatened. The risk of localized extinction, however, is higher in some areas, particularly in the Coral Triangle region. The relatively low proportion of species globally listed in threatened Categories is highly encouraging, and some conservation successes are attributed to concentrated conservation efforts. However, with the growing realization of man's profound impact on the planet, conservation actions such as improved marine reserve networks, more stringent fishing regulations, and continued monitoring of the population status at the species and community levels are imperative for the prevention of species loss in these groups of important and iconic coral reef fishes

Towards species‐level forecasts of drought‐induced tree mortality risk

Predicting species-level responses to drought at the landscape scale is critical to reducing uncertainty in future terrestrial carbon and water cycle projections. We embedded a stomatal optimisation model in the Community Atmosphere Biosphere Land Exchange (CABLE) land surface model and parameterised the model for 15 canopy dominant eucalypt tree species across South-Eastern Australia (mean annual precipitation range: 344–1424 mm yr−1). We conducted three experiments: applying CABLE to the 2017–2019 drought; a 20% drier drought; and a 20% drier drought with a doubling of atmospheric carbon dioxide (CO2). The severity of the drought was highlighted as for at least 25% of their distribution ranges, 60% of species experienced leaf water potentials beyond the water potential at which 50% of hydraulic conductivity is lost due to embolism. We identified areas of severe hydraulic stress within-species’ ranges, but we also pinpointed resilience in species found in predominantly semiarid areas. The importance of the role of CO2 in ameliorating drought stress was consistent across species. Our results represent an important advance in our capacity to forecast the resilience of individual tree species, providing an evidence base for decision-making around the resilience of restoration plantings or net-zero emission strategies

Larval dispersal and fishing pressure influence recruitment in a coral reef fishery

Understanding larval connectivity patterns in exploited fishes is a fundamental prerequisite for developing effective management strategies and assessing the vulnerability of a fishery to recruitment overfishing and localised extinction. To date, however, researchers have not considered how regional variations in fishing pressure also influence recruitment. We used genetic parentage analyses and modelling to infer the dispersal patterns of bumphead parrotfish Bolbometopon muricatum larvae in the Kia fishing grounds, Isabel Province, Solomon Islands. We then extrapolated our Kia dispersal model to a regional scale by mapping the available nursery and adult habitat for B. muricatum in six regions in the western Solomon Islands, and estimated the relative abundance of adult B. muricatum populations in each of these regions based on available adult habitat and historical and current fishing pressure. Parentage analysis identified 67 juveniles that were the offspring of parents sampled in the Kia fishing grounds. A fitted larval dispersal kernel predicted that 50% of larvae settled within 30 km of their parents, and 95% settled within 85 km of their parents. After accounting for unsampled adults, our model predicted that 34% of recruitment to the Kia fishery was spawned locally. Extrapolating the spatial resolution of the model revealed that a high proportion of the larvae recruiting into the Kia fishing grounds came from nearby regions that had abundant adult populations. Other islands in the archipelago provided few recruits to the Kia fishing grounds, reflecting the greater distances to these islands and lower adult abundances in some regions. Synthesis and applications. This study shows how recruitment into a coral reef fishery is influenced by larval dispersal patterns and regional variations in historical fishing pressure. The scales of larval connectivity observed for bumphead parrotfish indicate that recruitment overfishing is unlikely if there are lightly exploited reefs up to 85 km away from a heavily fished region, and that small (<1 km2) marine-protected areas (MPAs) are insufficient to protect this species. We recommend greater efforts to understand the interactions between larval dispersal and gradients of fishing pressure, as this will enable the development of tailored fisheries management strategies

Leaf economics and plant hydraulics drive leaf : wood area ratios

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordData accessibility: All data are archived and are available from the TRY plant trait data base: www.try-db.org (https://doi.org/10.1111/j.1365-2486.2011.02451.x).Biomass and area ratios between leaves, stems and roots regulate many physiological and ecological processes. The Huber value Hv (sapwood area/leaf area ratio) is central to plant water balance and drought responses. However, its coordination with key plant functional traits is poorly understood, which prevents developing trait-based prediction models. Based on theoretical arguments, we hypothesise that global patterns in Hv of terminal woody branches can be predicted from variables related to plant trait spectra, i.e., plant hydraulics and size and leaf economics. Using a global compilation of 1135 species-averaged Hv , we show that Hv varies over 3 orders of magnitude. Higher Hv are seen in short small-leaved low-SLA shrubs with low Ks in arid relative to tall large-leaved high-SLA trees with high Ks in moist environments. All traits depend on climate but climatic correlations are stronger for explanatory traits than Hv . Negative isometry is found between Hv and Ks , suggesting a compensation to maintain hydraulic supply to leaves across species. This work identifies the major global drivers of branch sapwood/leaf area ratios. Our approach based on widely available traits facilitates the development of accurate models of aboveground biomass allocation and helps predict vegetation responses to drought.Spanish Ministry of Economy and Competitiveness (MINECO)University of NottinghamSwedish Research Council Forma

Identifying areas at risk of drought-induced tree mortality across South-Eastern Australia

South-East Australia has recently been subjected to two of the worst droughts in the historical record (Millennium Drought, 2000–2009 and Big Dry, 2017–2019). Unfortunately, a lack of forest monitoring has made it difficult to determine whether widespread tree mortality has resulted from these droughts. Anecdotal observations suggest the Big Dry may have led to more significant tree mortality than the Millennium drought. Critically, to be able to robustly project future expected climate change effects on Australian vegetation, we need to be able to assess the vulnerability to drought of Australian trees. Here, we implemented a model of plant hydraulics into the Community Atmosphere Biosphere Land Exchange (CABLE) land surface model. We parameterised the drought response behaviour of five broad vegetation types, based on a common garden dry-down experiment with species originating across a rainfall gradient (188–1125 mm yr1 ) across South-East Australia. The new hydraulics model significantly improved (~35–45 % reduction in root mean square error) CABLE’s previous predictions of latent heat fluxes during periods of water stress at two eddy covariance sites in Australia. Landscape-scale predictions of the greatest percentage loss of hydraulic conductivity (PLC), 40–60 %, were broadly consistent with satellite estimates of regions of the greatest change in both droughts. In neither drought did CABLE predict that trees would have reached critical PLC in widespread areas (i.e. it projected a low mortality risk), although the model highlighted critical levels near the desert regions of South-East Australia where few trees live. Overall, our experimentally constrained model results imply significant resilience to drought conferred by hydraulic function, but also highlight critical data and scientific gaps. Our approach presents a promising avenue to integrate experimental data and make regional-scale predictions of potential drought-induced hydraulic failure