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Mean cover (%) by relative gradient position for the C4 grass and evergreen shrub functional types included in our vegetation structure and microclimate fire spread probability model. Error bars are standard errors of the mean
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Positive feedbacks influenced by direct and indirect interactions between fire, vegetation, and microclimate can allow pyrophilic and pyrophobic ecosystems to co-occur in the same landscape, resulting in the juxtaposition of flammable and non-flammable vegetation. To quantify the drivers of these feedbacks, we combined measurements of vegetation, f...
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Background: The availability of preferred habitats determines the spatial and temporal distribution of herbivores in savanna ecosystems. Understanding habitat preference of a targeted wildlife species is crucial for developing effective conservation strategies. Habitat preference of large grazers in connection to grass height and post-fire effect h...
Citations
... Fires are a natural part of ecological function in many parts of the world, and are widely acknowledged as a disturbance that can affect the ecological function of soil, flora and fauna in various ecosystems [1][2][3][4][5][6]. In recent decades, the incidence of fires has burgeoned due to anthropogenic mediated land use changes [7,8] and natural environmental factors such as prolonged summer droughts [9], lightning strikes [10,11], high combustibility of vegetation [12], increased net primary productivity [13], prolonged fire seasons [14,15], and a rapidly changing climate [16,17]. The increase in fire frequency has put fire regimes at the vanguard of global change, because fires can cause positive feedback loops that potentially compound global climate change [18]. ...
... Several researchers have documented the effects of fire on plant communities and have revealed the links between plants and animals after a fire disturbance [5,12]. Much of these works have revealed that fire can have positive, negative, and neutral effects on soils, organisms and plants [29,30]. ...
Globally, wildfires and prescribed fires are becoming more prevalent and are known to affect plant and animals in diverse ecosystems. Understanding the responses of animal communities to fire is a central issue in conservation and a panacea to predicting how fire regimes may affect communities and food webs. Here, a global meta-analysis of 2581 observations extracted from 208 empirical studies were used to investigate the effect of fire on aboveground and belowground fauna (e.g., bacteria, fungi, small mammals, arthropods). Overall, results revealed that fire had a negative effect on biomass, abundance, richness, evenness, and diversity of all faunas. Similarly, when considering wildfires and prescribed fires the data revealed that both fire regimes have negative effects on fauna. Similarly, fire had negative impacts on aboveground and aboveground fauna across most biomes and continents of the world. Moreover, there was little evidence of changes in pH, moisture and soil depth on soil organisms suggesting that other factors may drive community changes following a fire disturbance. Future research in fire ecology should consider the effects of fire across several species and across larger geospatial scales. In addition, fire effects on faunal community structure must be studied under contrasting global fire regimes and in light of the effects of climate change.
... Such fire feedbacks may have led to large homogeneous patches and resulted in co-occurrence being detected only at broader scales or not at all. In addition, larger patches may be created by feedbacks in fire-prone systems that affect the landscape at a broader spatial scale than the spatial scale of variation in the local environment (e.g., soil type; Liu and Mladenoff 2013), because feedbacks can support the establishment of organisms in environments where they may not be able to persist in the absence of the feedback (Wilson and Agnew 1992;D'Odorico et al. 2013;Just et al. 2016). In other words, while the local environment may structure vegetation in smaller patches in the absence of fire, fire feedbacks may result in larger patches with northern and southern species co-occurrence detected only at broader scales. ...
Context
Ecological structure in ecotones, defined by how species from adjacent systems co-occur, affects ecosystem functions and climate change responses. Ecotone structure can vary spatially, yet variability in broader-scale ecotones is poorly understood. In Wisconsin (USA) the Tension Zone is an ecoregional ecotone, separating northern and southern ecosystems.
Objectives
Characterize ecotone structure in the Tension Zone, examine how structure varied spatially, and identify how environmental drivers affected structure.
Methods
Using historical (1800s) tree occurrence data, we examined co-occurrence of northern and southern species at multiple scales (1.0 km to 7.5 km) at different locations in the Tension Zone, identifying the finest scale at which co-occurrence was detected. We assessed relationships between co-occurrence and environmental variables.
Results
Co-occurrence emerged at different scales, related to interacting climate and soil variables and location within the ecotone. Northern and southern trees co-occurred at broader scales near ecotone center and at locations with higher climatic water availability and sandier soils; they co-occurred at finer scales in locations with higher climatic water availability and richer soils. Sites with xeric tree species were associated with broader-scale co-occurrence.
Conclusions
We detected spatially variable structure within the Tension Zone, resulting from multi-scale processes among underlying environmental drivers. Finer-scale co-occurrence may have resulted from competition in high-resource environments, while broader scale co-occurrence may have been driven by fire and associated feedbacks. Characterizing structure in an ecoregional ecotone adds to a growing body of evidence that finer-scale factors play a role in defining the characteristics, functions, and responses of broader-scale ecotones.
... In the advent of climate change, wildfire intensity and season length is increasing globally [1]. To control and mitigate the negative effects of wildfires, computational models exist which attempt to understand and predict the physical characteristics and evolution of these events [2][3][4]. To improve the accuracy of these models and make them more event oriented, we can include alternative, more diverse data sources [5,6]. ...
The intensity of wildfires and wildfire season length is increasing due to climate change, causing a greater threat to the local population. Much of this population are increasingly adopting social media, and sites like Twitter are increasingly being used as a real-time human-sensor network during natural disasters; detecting, tracking and documenting events. The human-sensor concept is currently largely omitted by wildfire models, representing a potential loss of information. By including Twitter data as a source in our models, we aim to help disaster managers make more informed, socially driven decisions, by detecting and monitoring online social media sentiment over the course of a wildfire event. This paper implements machine learning in a wildfire prediction model, using social media and geophysical data sources with Sentiment Analysis to predict wildfire characteristics with high accuracy. We also use wildfire-specific attributes to predict online social dynamics, as this has been shown to be indicative of localised disaster severity. This may be useful for disaster management teams in identifying areas of immediate danger. We combine geophysical satellite data from the Global Fire Atlas with social data provided by Twitter. We perform data collection and subsequent analysis & visualisation, and compare regional differences in online social sentiment expression. Following this, we compare and contrast different machine learning models for predicting wildfire attributes. We demonstrate social media is a predictor of wildfire activity, and present models which accurately model wildfire attributes. This work develops the concept of the human sensor in the context of wildfires, using users’ Tweets as noisy subjective sentimental accounts of current localised conditions. This work contributes to the development of more socially conscious wildfire models, by incorporating social media data into wildfire prediction and modelling.
... Fowler 1986 ). These could result from heterogeneity of fire impacts induced by varying microclimatic conditions such as temperature, wind, and relative humidity, uneven distribution of fuel, varying burn times, incipient moisture, microtopography, and traffic patterns ( Hoffmann et al. 2012 ;Just et al. 2016 ). ...
Prescribed burning is sometimes advocated as a means for controlling Kentucky bluegrass (POPR) in invaded grazing lands. However, little is known about the effects of fire on POPR seed survival. We exposed seeds of POPR (c.v. Kenblue), placed in shallow metal dishes, at ground level to prescribed burns while monitoring temperature at the soil surface and at 10 cm above ground with thermocouples and assessed subsequent seed germinability. Maximum surface temperatures during the test burns averaged 271°C ± 23°C but varied widely (range 41°C–509°C) while maximum temperature at 10 cm above ground was slightly higher (301°C ± 25°C). Burning inhibited seed survival or the ability to germinate (Kolmogorov-Smirnov P < .0001). Germination of the POPR seeds in the control dishes averaged 93% ± 1%. Average germination for burned locations was 37% ± 7% and was distributed bimodally; it was absent or strongly inhibited in 59% of the samples but much less affected (≥ 60% normal germination) in the remaining 41% of locations. Germination success was similar in burned plots previously managed with both grazing and fire (35% ± 10%) or previously managed by fire alone (38% ± 11%), but it was significantly and inversely correlated to maximum surface temperature during the burn (Spearman r = −0.49, P < 0.005). However, we observed a binary pattern of high and low seed germination response across the entire gradient of recorded surface temperatures, including instances of highly disparate values for seed survival in samples located within 60 cm of each other. Such extreme variability may result from unburned or superficially affected safe sites that originate from heterogeneity of fire impacts. This study suggests prescribed burning can kill POPR seeds near the soil surface, especially those located in standing litter and dry thatch. However, some seeds under these layers and closer to the mineral soil surface may be less impacted.
... In the advent of climate change, wildfire intensity and season length is increasing globally [1]. To control and mitigate the negative effects of wildfires, computational models exist which attempt to understand and predict the physical characteristics and evolution of these events [2][3][4]. To improve the accuracy of these models and make them more event oriented, we can include alternative, more diverse data sources [5,6]. ...
... We investigated distribution-limiting factors in two ecotypes of an endemic bunchgrass. Wiregrass (Aristida beyrichiana) is a dominant understory species in pine savannas of the southeastern U.S., growing along xeric to mesic hydrologic gradients that span slight elevational differences (~30 cm to 10 m; Wells and Shunk 1931;Christensen 2000;Orzell and Bridges 2006;Crandall and Platt 2012;Just et al. 2016). Wiregrass is often used to restore longleaf (Pinus palustris) understories, but ecotypic responses to conspecific plant-soil feedbacks and different soil conditions may affect restoration outcomes. ...
Purpose
Previous research alludes to two wiregrass (Aristida beyrichiana) ecotypes from mesic and xeric environments. It is unknown whether these ecotypes are restricted by conspecific plant-soil feedbacks or specific components of mesic and xeric soils. We investigated whether biomass production of wiregrass ecotypes grown in mesic and xeric soil was affected by conspecific plant-soil feedbacks, and whether wiregrass ecotypes responded differently to the soil biota and nutrients that characterize each of the two soil types.
Methods
We established a greenhouse experiment to compare the biomass production of mesic and xeric wiregrass ecotypes in mesic and xeric soil. To establish the effects of conspecific soil conditioning, each soil type was either conditioned or unconditioned by wiregrass. To to isolate the effects of soil biota and nutrients, each combination of soil type and conditioning was replicated in three soil manipulations (i.e., whole, inoculated, and sterile soil) where each wiregrass ecotype was grown.
Results
Biomass of the xeric ecotype was marginally greater in xeric soil than in mesic soil. The mesic ecotype tended to grow more in mesic than xeric soil, but it was not significant. Soil conditioning did not affect biomass production of either ecotype. Soil biota coupled with nutrients affected biomass production of both ecotypes when not growing in their own soil.
Conclusions
We found some evidence for wiregrass ecotypes that have increased growth in their own soil type, but not for conspecific plant-soil feedbacks. Ecotypes were affected by negative interactions with soil biota when growing in a different type. Thus, the soil environment should be considered when sourcing seeds for restoration.
... Nevertheless, there has been increased attention given to the subject world-widely [55,66]. The factors behind fire spread behaviour depend heavily on local physical, environmental and meteorological variables [78,71,50], such as vegetation density distribution, landscape slope, fuel continuity and wind dynamics. For reasons including high dimensionality and the lack of historical data, among others, current fire modelling systems, for instance, those based on Rothermel equation [67], NWP(numerical weather prediction)-driven forecasting and Cellular Automation (CA) [2], remain highly empirical [58]. ...
The large and catastrophic wildfires have been increasing across the globe in the recent decade, highlighting the importance of simulating and forecasting fire dynamics in near real-time. This is extremely challenging due to the complexities of physical models and geographical features. Running physics-based simulations for large wildfire events in near real-time is computationally expensive, if not infeasible. In this work, we develop and test a novel data-model integration scheme for fire progression forecasting, that combines Reduced-order modelling, recurrent neural networks (Long-Short-Term Memory), data assimilation, and error covariance tuning. The Reduced-order modelling and the machine learning surrogate model ensure the efficiency of the proposed approach while the data assimilation enables the system to adjust the simulation with observations. We applied this algorithm to simulate and forecast three recent large wildfire events in California from 2017 to 2020. The deep-learning-based surrogate model runs around 1000 times faster than the Cellular Automata simulation which is used to generate training data-sets. The daily fire perimeters derived from satellite observation are used as observation data in Latent Assimilation to adjust the fire forecasting in near real-time. An error covariance tuning algorithm is also performed in the reduced space to estimate prior simulation and observation errors. The evolution of the averaged relative root mean square error (R-RMSE) shows that data assimilation and covariance tuning reduce the RMSE by about 50% and considerably improves the forecasting accuracy. As a first attempt at a reduced order wildfire spread forecasting, our exploratory work showed the potential of data-driven machine learning models to speed up fire forecasting for various applications.
... Replicate historical burn frequencies for the focal region (Just et al. 2016). ...
... A burn plan that spatially and temporally mimics natural fire via heterogeneity of burn timing and burned patch size throughout a property, as much as is feasible given funding limitations and stakeholder interest (Quinn-Davidson and Varner 2012), can increase structural diversity and benefit RCWs and other species endemic to fire-mediated pine forests (Lesmeister et al. 2013, Darracq et al. 2016). The Recovery Plan recommends a "lush, herbaceous understory", but this may not be possible at all sites because soil characteristics and landscape features influence how areas burn (Kirkman et al. 2004, Just et al. 2016. For example, Kirkman et al. (2004) determined that hydric depressions at a property managed with frequent fire (1-3 year interval) had greater overstory richness but lower understory richness than well-drained, upland sites, and ~20% of the variation in understory species richness could be attributed to the ecosystem type alone (n = 104 stands). ...
The Red-cockaded Woodpecker (Dryobates borealis, RCW) was listed under the U.S. Endangered Species Act in 1973 due to significant population declines resulting from habitat loss and fragmentation, and the species has been intensively managed since then. We reviewed management strategies commonly used to conserve the RCW, emphasizing studies conducted after publication of the most recent Recovery Plan in 2003, to evaluate the efficacy of each strategy across the RCW’s range and identify demographic and environmental factors that influence the success of each strategy. Of the management strategies reviewed, outcomes from prescribed fire vary the most across the RCW’s range, because prescribed fire is influenced by the site’s vegetation, abiotic conditions, and land use history. The abundance of cavity kleptoparasites varies across sites, but kleptoparasite control is only a high priority in small RCW populations. The long-term effectiveness of artificial cavities and translocations, which are highly effective across the RCW’s range in the short-term, requires suitable habitat, which is strongly influenced by prescribed fire. Regional variation in RCW management may be needed, because RCW populations that are not in archetypical suitable habitat (sensu Recovery Plan Standards) may benefit from management methods that are not suitable for large RCW populations in archetypical habitats (e.g., installing many cavity restrictor plates and cavity inserts). RCW management strategies have been studied most in the South Central Plains and Southeastern Plains ecoregions, and more research in other ecoregions would be valuable. We encourage consideration of how management varies according to population demographics and site characteristics as opposed to a “one-size fits all” management approach for the RCW, which inhabits broad geographic ranges and sites of varying productivity and will continue to rely on management efforts after downlisting or delisting from the Endangered Species Act.
... The ecotone between these two vegetation types is of particular interest as this is where vegetation properties will intergrade and where fire is most likely to cross-over from shrubland and enter woodland ecosystems (Gartner et al., 2012). Ecotones between fire-prone and fire sensitive vegetation can be dynamic, changing with fire history, and can be challenging to manage (Nicholas et al., 2011;Just et al., 2016). However, they also provide opportunities to protect fire sensitive vegetation through active fuel management or clearing of fire breaks located near edges (Parks et al., 2015). ...
Semi-arid landscapes are of interest to fire ecologists because they are generally located in the climatic transition zone between arid lands (where fires tend to be rare due to lack of fuel, but are enhanced following large rainfall episodes) and more mesic regions (where fire activity tends to be enhanced following severe rainfall deficits). Here we report on the characteristics of the contemporary fire regimes operating in a semi-arid region of inland south-western Australia with rainfall averaging around 300 mm per annum. To characterize fire regimes, we analyzed a geodatabase of fire scars (1960–2018) to derive fire preferences for each major vegetation type and fire episode and used known fire intervals to model fire hazard over time and calculate typical fire frequencies. We also used super epoch analysis and correlations to explore relationships between annual fire extent and rainfall received before the fire. We found fires strongly favored sandplain shrublands, and these tended to experience hot crown fires once every 100 years (median fire interval), with fire hazard increasing linearly over time. In contrast, fires were rare in eucalypt woodland and other vegetation types, with a median interval of 870 years and broadly consistent fire hazard over time. Annual fire extent was most strongly linked with high rainfall in the year prior to fire, and this was particularly so for eucalypt woodlands. Large-scale fires in shrublands tended to favor areas burnt in previous large fires, whereas in woodlands they favored edges. In conclusion, we found divergent fire regimes across the major vegetation types of the region. Sandplain shrublands were similar to Mediterranean shrublands in that they experienced intense stand-replacing wildfires which recovered vigorously although slowly, meaning burnt shrublands did not experience fires again for at least 25 and 100 years on average. In contrast, eucalypt woodlands were fire sensitive (trees readily killed by fire) and experienced fires mostly around the edges, spreading into core areas only after large rainfall events elevated fuel levels. Overall, both vegetation types subscribed to typical arid-zone fire regimes where elevated rainfall, and not drought, promoted fires, although the role of fuel accumulation over time was more important in the shrublands.
... Populations of L. subcoriacea have been observed in four vegetation communities in North Carolina (Schafale 2012;Wall et al. 2013 Fort Bragg is divided into over 1200 burn units that are burned on a roughly 3-year rotation. In general, there is complete burning of the understory in upland communities, but the wetland areas experience intermittent burning (Sorrie et al. 2006;Just et al. 2016). This leads to varied fire return intervals within burn units and within L. subcoriacea populations located in the four vegetation communities. ...
... Rather, the fire return interval at these specific locations may have previously been more frequent, maintaining a different vegetation community than the current that allowed L. subcoriacea recruitment sometime in the past. Dynamic changes in local vegetation communities due to changes in fire frequency are anticipated (Sorrie et al. 2006;Schafale 2012;Gray et al. 2016); Streamhead Pocosins and the ecotones between pocosins and xeric uplands are particularly susceptible to short-term reductions in fire frequency and can quickly become dominated by evergreen shrubs due to feedbacks between vegetation and fire behavior (Just et al. 2016). ...
Understanding demographic vital rates and the factors that affect those rates are key components of successful conservation strategies for many threatened and endangered rare plant species. Lindera subcoriacea is a rare dioecious shrub that occupies isolated wetland habitats in a small number of locations in the southeastern United States. The species faces a number of threats to its continued persistence, including habitat destruction, invasive species, and population isolation. From 2011 to 2019, we collected demographic information from 290 L. subcoriacea individuals within 28 populations on Fort Bragg, North Carolina and used the data to estimate demographic vital rates in unburned populations and after being exposed to prescribed fire. We then constructed population matrices and estimated population growth rates under a 3-, 5-, and 10-year return interval. Results indicated that L. subcoriacea individuals have high survivorship in both burned and unburned populations, seed production was reduced 1- and 2-year post-fire, seed production was highly uneven across individuals, seedling recruitment was extremely low, and simulated population growth rates were only above 1.0 under the 10-year fire return interval. Taken together, these results indicate that (1) L. subcoriacea populations are persisting with population growth rates close to one, (2) the short-term impacts of fire on the overall population growth rate of L. subcoriacea, while only 2–3% may determine long-term population viability, and (3) extremely uneven seed production and limited recruitment of seedlings into larger size classes make L. subcoriacea populations vulnerable to stochastic demographic processes.
