Transplant Experiments Point to Fire Regime as Limiting Savanna Tree Distribution

Plant species range shifts are predicted to occur in response to climate change. The predictions are often based on the assumption that climate is the primary factor limiting the distribution of species. However the distribution of grassy biomes in Africa cannot be predicted by climate alone, instead interactions between vegetation, climate and disturbance structure the ecosystems. To test if climatic variables, as predicted by an environmental niche model, determine the distribution limits of two common savanna tree species we established a transplant experiment at a range of latitudes and altitudes much broader than the distribution limits of our study species. We planted seedlings of two common savanna trees, Senegalia nigrescens and Colophospermum mopane, at eight paired high and low elevation sites across an 850 km latitudinal gradient in South African savannas. At each site seedlings were planted in both grassy and cleared plots. After 2 years of growth, rainfall, temperature and location inside or outside their distribution range did not explain species success. Grass competition was the only variable that significantly affected plant growth rates across all sites, but grass competition alone could not explain the distribution limit. Species distributions were best predicted when maximum tree growth rates were considered in relation to local fire return intervals. The probability of sapling escape from the fire trap was the most likely determinant of distribution limits of these two species. As trees grew and survived 100 s of kilometers south of their current range limits we conclude that climate alone does not explain the current distribution of these trees, and that climate change adaptation strategies for savanna environments based only on climatic envelope modeling will be inappropriate

p21 promotes oncolytic adenoviral activity in ovarian cancer and is a potential biomarker

The oncolytic adenovirus dl922-947 replicates selectively within and lyses cells with a dysregulated Rb pathway, a finding seen in > 90% human cancers. dl922-947 is more potent than wild type adenovirus and the E1B-deletion mutant dl1520 (Onyx-015). We wished to determine which host cell factors influence cytotoxicity. SV40 large T-transformed MRC5-VA cells are 3-logs more sensitive to dl922-947 than isogenic parental MRC5 cells, confirming that an abnormal G1/S checkpoint increases viral efficacy. The sensitivity of ovarian cancer cells to dl922-947 varied widely: IC50 values ranged from 51 (SKOV3ip1) to 0.03 pfu/cell (TOV21G). Cells sensitive to dl922-947 had higher S phase populations and supported earlier E1A expression. Cytotoxicity correlated poorly with both infectivity and replication, but well with expression of p21 by microarray and western blot analyses. Matched p21+/+ and -/- Hct116 cells confirmed that p21 influences dl922-947 activity in vitro and in vivo. siRNA-mediated p21 knockdown in sensitive TOV21G cells decreases E1A expression and viral cytotoxicity, whilst expression of p21 in resistant A2780CP cells increases virus activity in vitro and in intraperitoneal xenografts. These results highlight that host cell factors beyond simple infectivity can influence the efficacy of oncolytic adenoviruses. p21 expression may be an important biomarker of response in clinical trials

The role of browsers in maintaining the openness of savanna grazing lawns

In savannas, ruminant herbivores can have divergent impacts on tree recruitment and subsequent woody cover. Whereas heavy grazing by cattle results in woody thickening, intensive grazing by wildlife instead tends to be associated with lower woody cover. To disentangle why woody cover is low in areas heavily grazed by wildlife, we investigated (a) whether grazing lawns attract indigenous mammalian browsers, and if a preference for short-grass habitat decreases with browser body mass as predator susceptibility decreases; and (b) whether browser attraction to grazing lawns translates into the suppression of woody plants, including seedlings and saplings, thus maintaining the openness of heavily grazed short-grass areas. In Kruger National Park, South Africa, we contrasted browser abundance (using dung counts) on grazing lawns and on low-herbivory sites characterised by tall grass. Additionally, a herbivore exclosure experiment was set up to investigate the combined impact of browser removal and grass height habitat type on seedling survival and sapling growth of a dominant woody plant species. Finally, in Hluhluwe-iMfolozi Park (HiP), we examined the long-term (10 years) impact of browser removal on the growth rates of a range of woody species, monitored across ten sites along a gradient of herbivory ranging from grazing lawn to tall grass. Steenbok and impala selected short- over tall grass as preferred browsing sites, while elephant preferred tall grass. Browser abundance on short grass decreased with browser body mass, indicating that predator avoidance might be a key factor driving mesoherbivores to utilise grazing lawns. Seedling survival was lowest on grazing lawns when browsers were present, with mortality occurring in two out of every three seedlings. Similarly, sapling growth was lowest on grazing lawns, although browser removal had no significant effect. Evidence for increased browser impact on grazing lawns was clearest from our long-term herbivore exclosure experiment in HiP, which demonstrated that browsers strongly modify the growth rates of woody plants in short-grass habitats. Synthesis. These results provide support for the hypothesis that browsers, particularly browsing mesoherbivores and mixed feeders, are attracted to short-grass habitats, and that they help maintain grazing lawn openness by suppressing seedling survival and woody plant growth where grass is kept short by grazers.SUPPORTING INFORMATION: Table S1. Proportion short grass calculated as the mean proportion of grass height below 10 cm, recorded at ten sites in HiP (Hluhluwe and iMfolozi Game Reserves). The mean number of grazer dung piles per year (species: buffalo, blue wildebeest, impala, warthog, white rhino and zebra) are shown for each site. Values in brackets represent standard errors.Figure S1. The effect of grass height and exclosure status (fenced vs. unfenced) on tree height gain (mean ± SE). Browsing impact on tree height gain was higher in areas with short grass i.e. browsers utilised trees in short-grass ecosystems more than in tall-grass ecosystems. Results of linear regression analyses are displayed for the unfenced treatment of two dominant woody plant species: a) D. cinerea (R2 = 0.38, p = 0.05) and b) A. nilotica (R2 = 0.44, p = 0.11), and for two woody plant functional types: c) fine-leaved (R2 = 0.33, p = 0.09) and d) broad-leaved (R2 = 0.60, p = 0.02), across 10 sites in Hluhluwe-iMfolozi Park for the period 2000-2009.DATA AVAILABILITY STATEMENT: Data are available from the Dryad Digital Repository https://doi-org.uplib.idm.oclc.org/10.5061/dryad.76hdr7st3 (Voysey et al., 2020).The USAID/NAS program ‘Partnerships for Enhanced Engagement in Research' (sub-grant 2000004946, Cycle 3) and the South African National Research Foundation, Department of Science and Technology, Innovation and Priority Research Masters Scholarship.http://www.wileyonlinelibrary.com/journal/jechj2022Plant Production and Soil Scienc

Anthropogenic modifications to fire regimes in the wider Serengeti‐Mara ecosystem

Fire is a key driver in savannah systems and widely used as a land management tool. Intensifying human land uses are leading to rapid changes in the fire regimes, with consequences for ecosystem functioning and composition. We undertake a novel analysis describing spatial patterns in the fire regime of the Serengeti‐Mara ecosystem, document multidecadal temporal changes and investigate the factors underlying these patterns. We used MODIS active fire and burned area products from 2001 to 2014 to identify individual fires; summarizing four characteristics for each detected fire: size, ignition date, time since last fire and radiative power. Using satellite imagery, we estimated the rate of change in the density of livestock bomas as a proxy for livestock density. We used these metrics to model drivers of variation in the four fire characteristics, as well as total number of fires and total area burned. Fires in the Serengeti‐Mara show high spatial variability—with number of fires and ignition date mirroring mean annual precipitation. The short‐term effect of rainfall decreases fire size and intensity but cumulative rainfall over several years leads to increased standing grass biomass and fuel loads, and, therefore, in larger and hotter fires. Our study reveals dramatic changes over time, with a reduction in total number of fires and total area burned, to the point where some areas now experience virtually no fire. We suggest that increasing livestock numbers are driving this decline, presumably by inhibiting fire spread. These temporal patterns are part of a global decline in total area burned, especially in savannahs, and we caution that ecosystem functioning may have been compromised. Land managers and policy formulators need to factor in rapid fire regime modifications to achieve management objectives and maintain the ecological function of savannah ecosystems

Comment on "The extent of forest in dryland biomes"

Bastin et al (Reports, 12 May 2017, p. 635) infer forest as more globally extensive than previously estimated using tree cover data. However, their forest definition does not reflect ecosystem function or biotic composition. These structural and climatic definitions inflate forest estimates across the tropics and undermine conservation goals, leading to inappropriate management policies and practices in tropical grassy ecosystems

Fire and biodiversity in the Anthropocene

The workshop leading to this paper was funded by the Centre Tecnològic Forestal de Catalunya and the ARC Centre of Excellence for Environmental Decisions. L.T.K. was supported by a Victorian Postdoctoral Research Fellowship (Victorian Government), a Centenary Fellowship (University of Melbourne), and an Australian Research Council Linkage Project Grant (LP150100765). A.R. was supported by the Xunta de Galicia (Postdoctoral Fellowship ED481B2016/084-0) and the Foundation for Science and Technology under the FirESmart project (PCIF/MOG/0083/2017). A.L.S. was supported by a Marie Skłodowska-Curie Individual Fellowship (746191) under the European Union Horizon 2020 Programme for Research and Innovation. L.R. was supported by the Australian Government’s National Environmental Science Program through the Threatened Species Recovery Hub. L.B. was partially supported by the Spanish Government through the INMODES (CGL2014-59742-C2-2-R) and the ERANET-SUMFORESTS project FutureBioEcon (PCIN-2017-052). This research was supported in part by the U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station.BACKGROUND Fire has shaped the diversity of life on Earth for millions of years. Variation in fire regimes continues to be a source of biodiversity across the globe, and many plants, animals, and ecosystems depend on particular temporal and spatial patterns of fire. Although people have been using fire to modify environments for millennia, the combined effects of human activities are now changing patterns of fire at a global scale—to the detriment of human society, biodiversity, and ecosystems. These changes pose a global challenge for understanding how to sustain biodiversity in a new era of fire. We synthesize how changes in fire activity are threatening species with extinction across the globe, highlight forward-looking methods for predicting the combined effects of human drivers and fire on biodiversity, and foreshadow emerging actions and strategies that could revolutionize how society manages fire for biodiversity in the Anthropocene. ADVANCES Our synthesis shows that interactions with anthropogenic drivers such as global climate change, land use, and biotic invasions are transforming fire activity and its impacts on biodiversity. More than 4400 terrestrial and freshwater species from a wide range of taxa and habitats face threats associated with modified fire regimes. Many species are threatened by an increase in fire frequency or intensity, but exclusion of fire in ecosystems that need it can also be harmful. The prominent role of human activity in shaping global ecosystems is the hallmark of the Anthropocene and sets the context in which models and actions must be developed. Advances in predictive modeling deliver new opportunities to couple fire and biodiversity data and to link them with forecasts of multiple drivers including drought, invasive plants, and urban growth. Making these connections also provides an opportunity for new actions that could revolutionize how society manages fire. Emerging actions include reintroduction of mammals that reduce fuels, green fire breaks comprising low-flammability plants, strategically letting wildfires burn under the right conditions, managed evolution of populations aided by new genomics tools, and deployment of rapid response teams to protect biodiversity assets. Indigenous fire stewardship and reinstatement of cultural burning in a modern context will enhance biodiversity and human well-being in many regions of the world. At the same time, international efforts to reduce greenhouse gas emissions are crucial to reduce the risk of extreme fire events that contribute to declines in biodiversity. OUTLOOK Conservation of Earth’s biological diversity will be achieved only by recognition of and response to the critical role of fire in shaping ecosystems. Global changes in fire regimes will continue to amplify interactions between anthropogenic drivers and create difficult trade-offs between environmental and social objectives. Scientific input will be crucial for navigating major decisions about novel and changing ecosystems. Strategic collection of data on fire, biodiversity, and socioeconomic variables will be essential for developing models to capture the feedbacks, tipping points, and regime shifts characteristic of the Anthropocene. New partnerships are also needed to meet the challenges ahead. At the local and regional scale, getting more of the “right” type of fire in landscapes that need it requires new alliances and networks to build and apply knowledge. At the national and global scale, biodiversity conservation will benefit from greater integration of fire into national biodiversity strategies and action plans and in the implementation of international agreements and initiatives such as the UN Convention on Biological Diversity. Placing the increasingly important role of people at the forefront of efforts to understand and adapt to changes in fire regimes is central to these endeavors.PostprintPeer reviewe

CATALISE: A multinational and multidisciplinary Delphi consensus study. Identifying language impairments in children

© 2016 Bishop et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Delayed or impaired language development is a common developmental concern, yet there is little agreement about the criteria used to identify and classify language impairments in children. Children\u27s language difficulties are at the interface between education, medicine and the allied professions, who may all adopt different approaches to conceptualising them. Our goal in this study was to use an online Delphi technique to see whether it was possible to achieve consensus among professionals on appropriate criteria for identifying children who might benefit from specialist services. We recruited a panel of 59 experts representing ten disciplines (including education, psychology, speech-language therapy/pathology, paediatrics and child psychiatry) from English-speaking countries (Australia, Canada, Ireland, New Zealand, United Kingdom and USA). The starting point for round 1 was a set of 46 statements based on articles and commentaries in a special issue of a journal focusing on this topic. Panel members rated each statement for both relevance and validity on a sevenpoint scale, and added free text comments. These responses were synthesised by the first two authors, who then removed, combined or modified items with a view to improving consensus. The resulting set of statements was returned to the panel for a second evaluation (round 2). Consensus (percentage reporting \u27agree\u27 or \u27strongly agree\u27) was at least 80 percent for 24 of 27 round 2 statements, though many respondents qualified their response with written comments. These were again synthesised by the first two authors. The resulting consensus statement is reported here, with additional summary of relevant evidence, and a concluding commentary on residual disagreements and gaps in the evidence base

Anthropogenic modifications to fire regimes in the wider Serengeti-Mara ecosystem

Fire is a key driver in savannah systems and widely used as a land management tool. Intensifying human land uses are leading to rapid changes in the fire regimes, with consequences for ecosystem functioning and composition. We undertake a novel analysis describing spatial patterns in the fire regime of the Serengeti‐Mara ecosystem, document multidecadal temporal changes and investigate the factors underlying these patterns. We used MODIS active fire and burned area products from 2001 to 2014 to identify individual fires; summarizing four characteristics for each detected fire: size, ignition date, time since last fire and radiative power. Using satellite imagery, we estimated the rate of change in the density of livestock bomas as a proxy for livestock density. We used these metrics to model drivers of variation in the four fire characteristics, as well as total number of fires and total area burned. Fires in the Serengeti‐Mara show high spatial variability—with number of fires and ignition date mirroring mean annual precipitation. The short‐term effect of rainfall decreases fire size and intensity but cumulative rainfall over several years leads to increased standing grass biomass and fuel loads, and, therefore, in larger and hotter fires. Our study reveals dramatic changes over time, with a reduction in total number of fires and total area burned, to the point where some areas now experience virtually no fire. We suggest that increasing livestock numbers are driving this decline, presumably by inhibiting fire spread. These temporal patterns are part of a global decline in total area burned, especially in savannahs, and we caution that ecosystem functioning may have been compromised. Land managers and policy formulators need to factor in rapid fire regime modifications to achieve management objectives and maintain the ecological function of savannah ecosystems.Natural Environment Research Council, Grant/Award Number: JZG10015; Leverhulme Trust, Grant/Award Number: IN‐2014‐022; Vetenskapsrådet; Sida and Formas, Grant/Award Number: 2016‐06355.http://wileyonlinelibrary.com/journal/gcbhj2019Zoology and Entomolog

CATALISE: A multinational and multidisciplinary Delphi consensus study. Identifying language impairments in children

Delayed or impaired language development is a common developmental concern, yet thereis little agreement about the criteria used to identify and classify language impairments inchildren. Children's language difficulties are at the interface between education, medicineand the allied professions, who may all adopt different approaches to conceptualising them.Our goal in this study was to use an online Delphi technique to see whether it was possibleto achieve consensus among professionals on appropriate criteria for identifying childrenwho might benefit from specialist services. We recruited a panel of 59 experts representingten disciplines (including education, psychology, speech-language therapy/pathology, paediatricsand child psychiatry) from English-speaking countries (Australia, Canada, Ireland,New Zealand, United Kingdom and USA). The starting point for round 1 was a set of 46statements based on articles and commentaries in a special issue of a journal focusing onthis topic. Panel members rated each statement for both relevance and validity on a sevenpointscale, and added free text comments. These responses were synthesised by the firsttwo authors, who then removed, combined or modified items with a view to improving consensus.The resulting set of statements was returned to the panel for a second evaluation(round 2). Consensus (percentage reporting 'agree' or 'strongly agree') was at least 80 percentfor 24 of 27 round 2 statements, though many respondents qualified their responsewith written comments. These were again synthesised by the first two authors. The resultingconsensus statement is reported here, with additional summary of relevant evidence, and aconcluding commentary on residual disagreements and gaps in the evidence base.</p

State of wildfires 2023–24

Climate change is increasing the frequency and intensity of wildfires globally, with significant impacts on society and the environment. However, our understanding of the global distribution of extreme fires remains skewed, primarily influenced by media coverage and regional research concentration. This inaugural State of Wildfires report systematically analyses fire activity worldwide, identifying extreme events from the March 2023–February 2024 fire season. We assess the causes, predictability, and attribution of these events to climate change and land use, and forecast future risks under different climate scenarios. During the 2023–24 fire season, 3.9 million km2 burned globally, slightly below the average of previous seasons, but fire carbon (C) emissions were 16 % above average, totaling 2.4 Pg C. This was driven by record emissions in Canadian boreal forests (over 9 times the average) and dampened by reduced activity in African savannahs. Notable events included record-breaking wildfire extent and emissions in Canada, the largest recorded wildfire in the European Union (Greece), drought-driven fires in western Amazonia and northern parts of South America, and deadly fires in Hawai’i (100 deaths) and Chile (131 deaths). Over 232,000 people were evacuated in Canada alone, highlighting the severity of human impact. Our analyses revealed that multiple drivers were needed to cause areas of extreme fire activity. In Canada and Greece a combination of high fire weather and an abundance of dry fuels increased the probability of fires by 4.5-fold and 1.9–4.1-fold, respectively, whereas fuel load and direct human suppression often modulated areas with anomalous burned area. The fire season in Canada was predictable three months in advance based on the fire weather index, whereas events in Greece and Amazonia had shorter predictability horizons. Formal attribution analyses indicated that the probability of extreme events has increased significantly due to anthropogenic climate change, with a 2.9–3.6-fold increase in likelihood of high fire weather in Canada and a 20.0–28.5-fold increase in Amazonia. By the end of the century, events of similar magnitude are projected to occur 2.22–9.58 times more frequently in Canada under high emission scenarios. Without mitigation, regions like Western Amazonia could see up to a 2.9-fold increase in extreme fire events. For the 2024–25 fire season, seasonal forecasts highlight moderate positive anomalies in fire weather for parts of western Canada and South America, but no clear signal for extreme anomalies is present in the forecast. This report represents our first annual effort to catalogue extreme wildfire events, explain their occurrence, and predict future risks. By consolidating state-of-the-art wildfire science and delivering key insights relevant to policymakers, disaster management services, firefighting agencies, and land managers, we aim to enhance society’s resilience to wildfires and promote advances in preparedness, mitigation, and adaptation