Using exclusion rate to unify niche and neutral perspectives on coexistence

The competitive exclusion principle is one of the most influential concepts in ecology. The classical formulation suggests a correlation between competitor species similarity and competition severity, leading to rapid competitive exclusion where species are very similar; yet neutral models show that identical species can persist in competition for long periods. Here, we resolve the conflict by examining two components of similarity – niche overlap and competitive similarity – and modeling the effects of each on exclusion rate (defined as the inverse of time to exclusion). Studying exclusion rate, rather than the traditional focus on binary outcomes (coexistence vs exclusion), allows us to examine classical niche and neutral perspectives using the same currency. High niche overlap speeds exclusion, but high similarity in competitive ability slows it. These predictions are confirmed by a well-known model of two species competing for two resources. Under ecologically plausible scenarios of correlation between these two factors, the strongest exclusion rates may be among moderately similar species, while very similar and highly dissimilar competitors have very low exclusion rates. Adding even small amounts of demographic stochasticity to the model blurs the line between deterministic and probabilistic coexistence still further. Thus, focusing on exclusion rate, instead of on the binary outcome of coexistence versus exclusion, allows a variety of outcomes to result from competitive interactions. This approach may help explain species coexistence in diverse competitive communities and raises novel issues for future work

Wildfire ignition-distribution modelling: a comparative study in the Huron-Manistee National Forest, Michigan, USA

Abstract. Wildfire ignition distribution models are powerful tools for predicting the probability of ignitions across broad areas, and identifying their drivers. Several approaches have been used for ignition-distribution modelling, yet the performance of different model types has not been compared. This is unfortunate, given that conceptually similar speciesdistribution models exhibit pronounced differences among model types. Therefore, our goal was to compare the predictive performance, variable importance and the spatial patterns of predicted ignition-probabilities of three ignition-distribution model types: one parametric, statistical model (Generalised Linear Models, GLM) and two machine-learning algorithms (Random Forests and Maximum Entropy, Maxent). We parameterised the models using 16 years of ignitions data and environmental data for the Huron-Manistee National Forest in Michigan, USA. Random Forests and Maxent had slightly better prediction accuracies than did GLM, but model fit was similar for all three. Variables related to human population and development were the best predictors of wildfire ignition locations in all models (although variable rankings differed slightly), along with elevation. However, despite similar model performance and variables, the map of ignition probabilities generated by Maxent was markedly different from those of the two other models. We thus suggest that when accurate predictions are desired, the outcomes of different model types should be compared, or alternatively combined, to produce ensemble predictions

Morbidity and mortality of paediatric burns patients at Maputo Central Hospital, Mozambique

Background: The incidence of paediatric burn injuries is increasing in Africa. Paediatric burn injuries are among the leading causes of preventable morbidity and mortality in sub-Saharan Africa. Research on the morbidity and mortality in this setting is much needed.Methods: We conducted a prospective questionnaire-based analysis of paediatric burn patients presenting to the Maputo Central Hospital during a five-month period. Interviews were conducted with the children's caretakers by 2 paediatric surgery residents and 1 paediatrician at the Eduardo Mondlane Medical School in Maputo, with the aid of nursing staff.Results: Questionnaires were completed for 66 patients. Most burns occurred from scald injuries (n = 46), particularly from cooking (n = 27) and bathwater (n = 19), followed by fire injuries (n = 16). Burns occurred more frequently in the afternoon (n = 26) and morning (n = 23). Many patients reported no adult caretaker present at the time of the burn injury (n = 24). Most burns were grade II (n = 49). Nearly half of the patients received a blood transfusion (n = 30). One-third of the patients underwent operative surgical debridement (n = 21). Skin grafting was performed on a subset of these patients (n = 13). A large number of patients developed a wound infection (n = 39). All deaths occurred in patients who were admitted to the paediatric intensive care unit and had sepsis (n = 9). The mean total body surface area (TBSA) of burn deaths was 37% (range 20% to 50%), and many deaths were secondary to fire burns (6 of 9; 66.7%).Conclusions: Most paediatric burn injuries occur in association with domestic activities, such as cooking and bathing. Adult caretakers are frequently not present at the time of the burn injury. Mortality rates are high, especially for large body surface area burns caused by fire. Educational programmes may help reduce the incidence of burns and the associated morbidity and mortality. The improvement and expansion of emergency and intensive burn care services may help to improve survival.Keywords: burns; morbidity; mortality; paediatrics; paediatric surgery; Mozambiqu

PC19. FIBRIN SEALANTS DO NOT REDUCE THE RATE OF SEROMA FORMATION IN POST-MASTECTOMY BREAST RECONSTRUCTION: A SYSTEMATIC REVIEW AND META-ANALYSIS

PURPOSE: Breast reconstruction using Deep Inferior Epigastric Perforator (DIEP) and Latissimus dorsi (LD) flaps following mastectomy are associated with seroma formation. We performed an updated systematic review and meta-analysis on the effects of fibrin sealant on donor site complications following DIEP and LD flap breast reconstruction. METHODS: A comprehensive literature search was conducted in March 2021, using PubMed, OVID, and Cochrane. Articles analyzing the efficacy of fibrin glue in reducing donor site morbidity in DIEP and LD breast reconstruction were included. The outcomes assessed were seroma rate formation and duration of drainage. RESULTS: 17,265 articles were screened, and 9 articles were selected for analysis, which comprised 632 surgical sites in 611 patients. When comparing fibrin glue and quilting to quilting alone, there was no significant difference in seroma formation (Pooled Risk Ratio (RR) 0.51). Similarly comparing fibrin glue alone to no fibrin glue, there was no significant difference in the rate of seroma formation (Pooled RR 1.03). There also was no significant difference in the duration of drainage in those who received fibrin glue versus those who did not (Pooled RR -0.85) and in those who received fibrin glue and quilting versus quilting alone (Pooled RR -2.13). CONCLUSION: The existing literature supports that using fibrin glue is not associated with a decrease in seroma rate formation or drainage duration in DIEP and LD flaps.Lewis Katz School of Medicin

The global wildland–urban interface

The wildland–urban interface (WUI) is where buildings and wildland vegetation meet or intermingle1,2. It is where human–environmental conflicts and risks can be concentrated, including the loss of houses and lives to wildfire, habitat loss and fragmentation and the spread of zoonotic diseases3. However, a global analysis of the WUI has been lacking. Here, we present a global map of the 2020 WUI at 10 m resolution using a globally consistent and validated approach based on remote sensing-derived datasets of building area4 and wildland vegetation5. We show that the WUI is a global phenomenon, identify many previously undocumented WUI hotspots and highlight the wide range of population density, land cover types and biomass levels in different parts of the global WUI. The WUI covers only 4.7% of the land surface but is home to nearly half its population (3.5 billion). The WUI is especially widespread in Europe (15% of the land area) and the temperate broadleaf and mixed forests biome (18%). Of all people living near 2003–2020 wildfires (0.4 billion), two thirds have their home in the WUI, most of them in Africa (150 million). Given that wildfire activity is predicted to increase because of climate change in many regions6, there is a need to understand housing growth and vegetation patterns as drivers of WUI change

Probabilistic fire spread forecast as a management tool in an operational setting

Background: An approach to predict fire growth in an operational setting, with the potential to be used as a decision-support tool for fire management, is described and evaluated. The operational use of fire behaviour models has mostly followed a deterministic approach, however, the uncertainty associated with model predictions needs to be quantified and included in wildfire planning and decision-making process during fire suppression activities. We use FARSITE to simulate the growth of a large wildfire. Probabilistic simulations of fire spread are performed, accounting for the uncertainty of some model inputs and parameters. Deterministic simulations were performed for comparison. We also assess the degree to which fire spread modelling and satellite active fire data can be combined, to forecast fire spread during large wildfires events. Results: Uncertainty was propagated through the FARSITE fire spread modelling system by randomly defining 100 different combinations of the independent input variables and parameters, and running the correspondent fire spread simulations in order to produce fire spread probability maps. Simulations were initialized with the reported ignition location and with satellite active fires. The probabilistic fire spread predictions show great potential to be used as a fire management tool in an operational setting, providing valuable information regarding the spatial–temporal distribution of burn probabilities. The advantage of probabilistic over deterministic simulations is clear when both are compared. Re-initializing simulations with satellite active fires did not improve simulations as expected. Conclusion: This information can be useful to anticipate the growth of wildfires through the landscape with an associated probability of occurrence. The additional information regarding when, where and with what probability the fire might be in the next few hours can ultimately help minimize the negative environmental, social and economic impacts of these firesinfo:eu-repo/semantics/publishedVersio

Housing Arrangement and Location Determine the Likelihood of Housing Loss Due to Wildfire

Surging wildfires across the globe are contributing to escalating residential losses and have major social, economic, and ecological consequences. The highest losses in the U.S. occur in southern California, where nearly 1000 homes per year have been destroyed by wildfires since 2000. Wildfire risk reduction efforts focus primarily on fuel reduction and, to a lesser degree, on house characteristics and homeowner responsibility. However, the extent to which land use planning could alleviate wildfire risk has been largely missing from the debate despite large numbers of homes being placed in the most hazardous parts of the landscape. Our goal was to examine how housing location and arrangement affects the likelihood that a home will be lost when a wildfire occurs. We developed an extensive geographic dataset of structure locations, including more than 5500 structures that were destroyed or damaged by wildfire since 2001, and identified the main contributors to property loss in two extensive, fire-prone regions in southern California. The arrangement and location of structures strongly affected their susceptibility to wildfire, with property loss most likely at low to intermediate structure densities and in areas with a history of frequent fire. Rates of structure loss were higher when structures were surrounded by wildland vegetation, but were generally higher in herbaceous fuel types than in higher fuel-volume woody types. Empirically based maps developed using housing pattern and location performed better in distinguishing hazardous from non-hazardous areas than maps based on fuel distribution. The strong importance of housing arrangement and location indicate that land use planning may be a critical tool for reducing fire risk, but it will require reliable delineations of the most hazardous locations

Mammal responses to global changes in human activity vary by trophic group and landscape

Wildlife must adapt to human presence to survive in the Anthropocene, so it is critical to understand species responses to humans in different contexts. We used camera trapping as a lens to view mammal responses to changes in human activity during the COVID-19 pandemic. Across 163 species sampled in 102 projects around the world, changes in the amount and timing of animal activity varied widely. Under higher human activity, mammals were less active in undeveloped areas but unexpectedly more active in developed areas while exhibiting greater nocturnality. Carnivores were most sensitive, showing the strongest decreases in activity and greatest increases in nocturnality. Wildlife managers must consider how habituation and uneven sensitivity across species may cause fundamental differences in human–wildlife interactions along gradients of human influence.Peer reviewe