Drought-mortality relationships for tropical forests.

*The rich ecology of tropical forests is intimately tied to their moisture status. Multi-site syntheses can provide a macro-scale view of these linkages and their susceptibility to changing climates. Here, we report pan-tropical and regional-scale analyses of tree vulnerability to drought. *We assembled available data on tropical forest tree stem mortality before, during, and after recent drought events, from 119 monitoring plots in 10 countries concentrated in Amazonia and Borneo. *In most sites, larger trees are disproportionately at risk. At least within Amazonia, low wood density trees are also at greater risk of drought-associated mortality, independent of size. For comparable drought intensities, trees in Borneo are more vulnerable than trees in the Amazon. There is some evidence for lagged impacts of drought, with mortality rates remaining elevated 2 yr after the meteorological event is over. *These findings indicate that repeated droughts would shift the functional composition of tropical forests toward smaller, denser-wooded trees. At very high drought intensities, the linear relationship between tree mortality and moisture stress apparently breaks down, suggesting the existence of moisture stress thresholds beyond which some tropical forests would suffer catastrophic tree mortality.

Freezing and water availability structure the evolutionary diversity of trees across the Americas.

The historical course of evolutionary diversification shapes the current distribution of biodiversity, but the main forces constraining diversification are still a subject of debate. We unveil the evolutionary structure of tree species assemblages across the Americas to assess whether an inability to move or an inability to evolve is the predominant constraint in plant diversification and biogeography. We find a fundamental divide in tree lineage composition between tropical and extratropical environments, defined by the absence versus presence of freezing temperatures. Within the Neotropics, we uncover a further evolutionary split between moist and dry forests. Our results demonstrate that American tree lineages tend to retain their ancestral environmental relationships and that phylogenetic niche conservatism is the primary force structuring the distribution of tree biodiversity. Our study establishes the pervasive importance of niche conservatism to community assembly even at intercontinental scales.

The epidemiology of emergency presentations for falls from height across Western Victoria, Australia.

BACKGROUND: In order to implement intervention strategies to prevent falls from height, epidemiological data are needed. The aim of this study was to map emergency presentations for falls from height in residents aged ≥40yr of the western region of Victoria, Australia. METHODS: Emergency presentations following a fall from height (≥1m) were obtained from electronic medical records for 2014-2016 inclusive. For each Local Government Area, age-standardised incidence rates (per 10,000 population/year) were calculated. RESULTS: The age-standardised incidence rate was lowest in the Northern Grampians (3.4 95%CI 0.8-5.9), which has several main industries including health care, agriculture and manufacturing. The highest rates occurred in Corangamite (26.0 95%CI 19.9-32.0), Colac-Otway (23.7 95%CI 18.5-28.8) and Moyne (22.5 95%CI 16.8-28.3), which are sparsely populated (15,000-20,000 people each). Patterns were similar for men and women. Most falls occurred during "leisure" (38.0%), followed by "other work" (15.4%). Men were more likely than women to experience a fall from height while undertaking work activities. Many falls occurred in the home (53.2%). CONCLUSION: Future research should inform strategies to prevent falls from height in the region. This could include specific locations such as the home or farm, and during leisure activities or work.

WITHDRAWN: The epidemiology of emergency presentations for falls across Western Victoria, Australia.

The Publisher regrets that this article is an accidental duplication of an article that has already been published, https://doi.org/10.1016/j.auec.2019.08.003. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.

Species Matter: Wood Density Influences Tropical Forest Biomass at Multiple Scales.

The mass of carbon contained in trees is governed by the volume and density of their wood. This represents a challenge to most remote sensing technologies, which typically detect surface structure and parameters related to wood volume but not to its density. Since wood density is largely determined by taxonomic identity this challenge is greatest in tropical forests where there are tens of thousands of tree species. Here, using pan-tropical literature and new analyses in Amazonia with plots with reliable identifications we assess the impact that species-related variation in wood density has on biomass estimates of mature tropical forests. We find impacts of species on forest biomass due to wood density at all scales from the individual tree up to the whole biome: variation in tree species composition regulates how much carbon forests can store. Even local differences in composition can cause variation in forest biomass and carbon density of 20% between subtly different local forest types, while additional large-scale floristic variation leads to variation in mean wood density of 10-30% across Amazonia and the tropics. Further, because species composition varies at all scales and even vertically within a stand, our analysis shows that bias and uncertainty always result if individual identity is ignored. Since sufficient inventory-based evidence based on botanical identification now exists to show that species composition matters biome-wide for biomass, we here assemble and provide mean basal-area-weighted wood density values for different forests across the lowand tropical biome. These range widely, from 0.467 to 0.728 g cm-3 with a pan-tropical mean of 0.619 g cm-3. Our analysis shows that mapping tropical ecosystem carbon always benefits from locally validated measurement of tree-by-tree botanical identity combined with tree-by-tree measurement of dimensions. Therefore whenever possible, efforts to map and monitor tropical forest carbon using remote sensing techniques should be combined with tree-level measurement of species identity by botanists working in inventory plots.

The epidemiology of emergency presentations for falls across Western Victoria, Australia.

BACKGROUND: In order to develop and implement prevention strategies for falls, comprehensive epidemiological data are required. Therefore, this study mapped emergency presentations for falls across the western region of Victoria, Australia, encompassing urban, regional and rural areas. METHODS: This cross-sectional study utilised electronic data for emergency presentations following a fall from <1m for individuals aged ≥40yr during 2014-2016 inclusive. Age-standardised incidence rates (per 1000 population/year) were calculated for each Local Government Area (LGA). RESULTS: Age-standardised falls incidence varied across the LGAs, with the lowest occurring in the Rural City of Ararat LGA (4.4; 95%CI:3.5-5.4) and the highest for the City of Warrnambool (25.1; 95%CI:23.7-26.6), Colac-Otway (24.7; 95%CI:23.0-26.4) and Moyne (23.0; 95%CI:21.2-24.8). Patterns were similar for men and women when stratified by sex across these LGAs. For men and women combined, most patients arrived at the hospital using private transportation (55.3%) or road ambulance service (43.1%). Most falls occurred during leisure activities (48.0%) in a home setting (54.8%). CONCLUSIONS: Higher rates of falls presentations were observed in southern LGAs and most commonly occurred at home, during leisure activity. Future research should identify specific intervention strategies to reduce falls in the region, based on the data reported from this study.

Size and frequency of natural forest disturbances and the Amazon forest carbon balance.

Forest inventory studies in the Amazon indicate a large terrestrial carbon sink. However, field plots may fail to represent forest mortality processes at landscape-scales of tropical forests. Here we characterize the frequency distribution of disturbance events in natural forests from 0.01 ha to 2,651 ha size throughout Amazonia using a novel combination of forest inventory, airborne lidar and satellite remote sensing data. We find that small-scale mortality events are responsible for aboveground biomass losses of ~1.7 Pg C y(-1) over the entire Amazon region. We also find that intermediate-scale disturbances account for losses of ~0.2 Pg C y(-1), and that the largest-scale disturbances as a result of blow-downs only account for losses of ~0.004 Pg C y(-1). Simulation of growth and mortality indicates that even when all carbon losses from intermediate and large-scale disturbances are considered, these are outweighed by the net biomass accumulation by tree growth, supporting the inference of an Amazon carbon sink.

Using learning networks to understand complex systems: a case study of biological, geophysical and social research in the Amazon.

Developing high-quality scientific research will be most effective if research communities with diverse skills and interests are able to share information and knowledge, are aware of the major challenges across disciplines, and can exploit economies of scale to provide robust answers and better inform policy. We evaluate opportunities and challenges facing the development of a more interactive research environment by developing an interdisciplinary synthesis of research on a single geographic region. We focus on the Amazon as it is of enormous regional and global environmental importance and faces a highly uncertain future. To take stock of existing knowledge and provide a framework for analysis we present a set of mini-reviews from fourteen different areas of research, encompassing taxonomy, biodiversity, biogeography, vegetation dynamics, landscape ecology, earth-atmosphere interactions, ecosystem processes, fire, deforestation dynamics, hydrology, hunting, conservation planning, livelihoods, and payments for ecosystem services. Each review highlights the current state of knowledge and identifies research priorities, including major challenges and opportunities. We show that while substantial progress is being made across many areas of scientific research, our understanding of specific issues is often dependent on knowledge from other disciplines. Accelerating the acquisition of reliable and contextualized knowledge about the fate of complex pristine and modified ecosystems is partly dependent on our ability to exploit economies of scale in shared resources and technical expertise, recognise and make explicit interconnections and feedbacks among sub-disciplines, increase the temporal and spatial scale of existing studies, and improve the dissemination of scientific findings to policy makers and society at large. Enhancing interaction among research efforts is vital if we are to make the most of limited funds and overcome the challenges posed by addressing large-scale interdisciplinary questions. Bringing together a diverse scientific community with a single geographic focus can help increase awareness of research questions both within and among disciplines, and reveal the opportunities that may exist for advancing acquisition of reliable knowledge. This approach could be useful for a variety of globally important scientific questions.

Drought sensitivity of the Amazon rainforest.

Amazon forests are a key but poorly understood component of the global carbon cycle. If, as anticipated, they dry this century, they might accelerate climate change through carbon losses and changed surface energy balances. We used records from multiple long-term monitoring plots across Amazonia to assess forest responses to the intense 2005 drought, a possible analog of future events. Affected forest lost biomass, reversing a large long-term carbon sink, with the greatest impacts observed where the dry season was unusually intense. Relative to pre-2005 conditions, forest subjected to a 100-millimeter increase in water deficit lost 5.3 megagrams of aboveground biomass of carbon per hectare. The drought had a total biomass carbon impact of 1.2 to 1.6 petagrams (1.2 x 10(15) to 1.6 x 10(15) grams). Amazon forests therefore appear vulnerable to increasing moisture stress, with the potential for large carbon losses to exert feedback on climate change.