Long-term Effects Of Fire Research Articles

Overstorey leaf production and emergence of sassafras saplings in a southwest Missouri oak woodland: An analysis based upon long-term effects of fire

Overstorey leaf production and emergence of sassafras saplings in a southwest Missouri oak woodland: An analysis based upon long-term effects of fire

Long-term impact of wildfire on soil physical, chemical and biological properties within a pine forest

AbstractAnthropogenic fires pose a serious threat to many terrestrial ecosystems because they can cause loss of biodiversity and carbon stocks in the biosphere. Specifically, wildfires impacting natural conservation areas such as European Natura 2000 sites (N2K) are of particular concern. The main study objective was to evaluate the long-term effects of wildfires on the organic layer and some physical, chemical and biological properties of the underlying soil mineral layer, linked to soil quality. Here, we studied two coastal Mediterranean Aleppo pine stands within an N2K site differing for the fires’ years of occurrence, the time between fires (TBF) and the time since last fire (TSLF) throughout 24 years. Furthermore, in each stand, differences in fire frequency (FF) were considered by selecting three sites—double-fire, single-fire and control (unburnt). Our results show the absence of the O-layer in double-fire sites, indicating a loss of this organic carbon (if compared to control) pool of 204 g m−2 in R2F and 139 g m−2 in M2F. Despite this loss being offset by the Corg increase in soil mineral layer, the disappearance of O-layer may compromise the ecosystem services provided by soil. In each stand, long-term fire effects were evident at both single-fire and double-fire sites for some chemical as well as biological soil properties and depended on TSLF. Increased rates of nitrogen mineralization and nitrification were found at all burned sites, persisting up to 24 years post-fire. Soil quality indicators data highlighted the recovery handicap of the microbial community within the considered period. Since our outcomes showed wildfires enduring consequences, mainly relating to TSLF and FF, on different organic and mineral soil properties, we advocate employing prompt strategies to mitigate recurring fires.

Homogenization of soil seed bank communities by fire and invasive species in the Mojave Desert

Soil seed banks help maintain species diversity through temporal storage effects and function as germination pools that can optimize fitness across varying environmental conditions. These characteristics promote the persistence of native plant communities, yet disturbances such as fire and associated invasions by non-native species can disrupt these reserves, fundamentally altering successional trajectories. This may be particularly true in deserts, where native plant communities are less adapted to fire. While studies of fire effects on desert plant communities are not uncommon, information regarding the short- and long-term effects of fire on seed banks is less available. To better understand the influence of fire and invasive species on desert seed banks, we investigated soil seed bank biodiversity from 30 wildfires that burned between 1972 and 2010 across the Mojave Desert ecoregion of North America. We assessed how characteristics of fire regimes (frequency, time since fire, and burn severity) interacted with climate and invasive plants on measures of α-, β-, and γ-diversities. Because β-diversity is a direct measure of community variability and reveals important information about biodiversity loss, we further examined the nestedness and turnover components of β-diversity. Mean α- and γ-diversities were generally higher for burned locations than in unburned reference sites, however individual fire variables had little influence on patterns of seed bank diversity. Burned area seed banks tended to be dominated by non-native invasive species, primarily two grasses, (Bromus rubens, Bromus tectorum), as well as an invasive forb (Erodium cicutarium). The most striking pattern we observed was a collective sharp decline in α-, β-, and γ-diversities with increased invasive species dominance, indicating the homogenization of seed bank communities with the colonization of invasive species after fire. Evidence of homogenization was further supported by reduced turnover and increased nestedness in burn areas compared to reference areas indicating potential biodiversity loss. Our findings highlight how biological processes such as plant invasions can combine with disturbance from fire to alter patterns of seed bank composition and diversity in desert ecosystems.

How Long Is Long? A Bibliographic Review of What Is Meant by the Long-Term Effects of Fire on Soil Properties

Wildfires pose one of the greatest threats to the world’s forests soils. After exposure to fire, forests lose many of their ecological functions; moreover, the repercussions can extend well beyond the forest itself, as the erosive processes attributable to the combustion of vegetation and the soil’s lack of protection against rainfall are likely to impact any areas of a catchment, contaminating reservoirs, estuaries and aquifers. A forest fire is not solely, therefore, an environmental issue, but also a social and economic problem. The recovery of a forest is heavily dependent on just how the soil has been affected and how rapidly the latter can be restored. Fire intensity is critical in understanding the temporal evolution of the forest, while its location—a clear determinant of its climate and the ecosystem it occupies—can undermine the functionality of the forest system and is critical in determining the duration of the effects of the fire episode. This paper undertakes a review of the literature with the aim of understanding what might be understood when studies speak of the long-term effects of fire on the soil and when a soil might be considered to have recovered from these effects. What is evident is that many variables have a role to play and that not all soil properties recover at the same rate; indeed, some may never be restored to pre-fire levels.

Short and long-term fire effects on soil C and N in an African savanna

Fires have been an important ecosystem driver in the Earth system for millions of years. It drives ecosystem composition, diversity and structure, thus rendering numerous terrestrial ecosystems dependent on fires for maintaining ecosystem health and functioning. As an important ecological driver in many ecosystems, fires have been shown to lead to substantial impacts on soil carbon (C) and nitrogen (N). Although many global studies have looked at either short-term or long-term fire effects on soil C and N, they have contradicting outcomes. This study aimed at investigating the effect of both short- and long-term fire effects on soil C and N, C:N ratios and soil C stocks, as well as how fire-induced changes to vegetation may influence C and N distribution. Soil samples (0–5 cm) were collected under tree and shrub canopies and open, grassy areas from Annual Burn and No Burn (fire exclusion) plots at a 68-year-old long-term fire experiment. Samples were collected pre-burn, 1 m and 1 yr post-fire to determine short-term fire impacts, and from the No burn plot to determine long-term fire impacts (compared to the Annual Burn). Soils were analysed for total C, total N, C:N ratios and C stocks. Our results found that fires led to significantly higher soil C and N within the first month post-fire (p < 0.05) and remained significantly higher even up to a year later. Fires also altered soil total C and N in the long-term which saw decadal increases in C and N due to fire exclusion (p < 0.001). C:N ratios improved shortly after burning to similar C:N ratios seen in the long-term No Burn plot. Even though soil C stocks were greatest in the No Burn plot, there was also an increase in soil C stocks on the Annual Burn plot a month after the fire (p < 0.05). Lastly, trees and shrub were found to increase soil C and N below their canopies compared to open, grass-dominated areas, suggesting further indirect effects of fires on soil C and N by means of changing woody cover. These findings have implications for fire management in African savannas when considering fire suppression policies, bush encroachment and global tree-planting initiatives.

Integrating sensory ecology and predator-prey theory to understand animal responses to fire.

Fire regimes are changing dramatically worldwide due to climate change, habitat conversion, and the suppression of Indigenous landscape management. Although there has been extensive work on plant responses to fire, including their adaptations to withstand fire and long-term effects of fire on plant communities, less is known about animal responses to fire. Ecologists lack a conceptual framework for understanding behavioural responses to fire, which can hinder wildlife conservation and management. Here, we integrate cue-response sensory ecology and predator-prey theory to predict and explain variation in if, whenand how animals react to approaching fire. Inspired by the literature on prey responses to predation risk, this framework considers both fire-naïve and fire-adapted animals and follows three key steps: vigilance, cue detection and response. We draw from theory on vigilance tradeoffs, signal detection, speed-accuracy tradeoffs, fear generalization, neophobia and adaptive dispersal. We discuss how evolutionary history with fire, but also other selective pressures, such as predation risk, should influence animal behavioural responses to fire. We conclude by providing guidance for empiricists and outlining potential conservation applications.

Long-term recovery of Mediterranean ant and bee communities after fire in southern Spain

Wildfires play a determinant role in the composition and structure of animal communities, especially for groups closely associated with the vegetation and soil, such as bees or ants. The effects of fire on animal communities depend on the functional traits of each group. Here, we assessed the impacts of fire and time since fire on the taxonomic and functional responses of ant and bee communities. We sampled 35 pine forests in Andalusia (southern Spain) that had experienced fire in the past (0 to 41 years ago). Specifically, we explored whether a) fire increased taxonomic and functional diversity and changed community composition in communities in the short term and b) fire influence (increase or decrease) on ant communities would be dependent on time since fire. We found that ant and bee taxonomic richness increased regardless of time since fire. Different approaches gave the same result, such as taxonomic diversity indexes (ant abundance, ant richness and ant Shannon diversity index), the changes in species richness in ant and bee communities, as well as the higher number of ant and bee species prone to the burned habitat than to the unburned habitat, using the Ihabitat Index. Besides environmental variables (such as the effects of different Pinus species or elevation), time since fire changed the taxonomic composition of ant communities and the functional composition of bee communities. Moreover, six of the 13 ant functional traits explored differed between burned and unburned areas, with the degree of difference declining as time since fire increased. For example, burned areas contained ant communities with more ground-nesting species and strictly diurnal species, functional traits that are characteristic of open areas. In contrast, other traits persisted in burned areas over the long term, notably a higher degree of worker polymorphism and species monogyny. Our study shows how much short- and long-term effects of fire on ant and bee communities differ; while richness increases in the long-term, some functional traits are also filtered in the short-term. We suggest that fire in Mediterranean coniferous ecosystems could have a positive effect on these groups and should not be overlooked.

Population dynamics and individual growth dynamics of Larix gmelinii under non-stand replacing fire

The population dynamics and individual growth dynamics of dominant tree species in boreal forests are associated with fire regimes. Fire regimes in the boreal forests of eastern Siberia are dominated by non-stand replacing (NSR) fire types. Fire drives population demographics by triggering tree mortality and births, and affects the post-fire growth dynamics of surviving individuals. When a non-stand replacing fire occurs, population dynamics fluctuate and individual growth changes occur simultaneously. The Great Xing’an Mountains is located at the southern edge of the eastern Siberia boreal forest and research on fire regimes and stand dynamics in this region are scarce. Understanding the effect of fire on the population structure and individual growth of the dominant species in the stand and the disturbance mechanisms are essential to understand the develop of boreal forests in the context of climate warming. In this study, three Larix gmelinii stands disturbed by NSR fire in the Great Xing’an Mountains were selected and established plots, and control stand plots were established at similar site conditions. We conducted a forest inventory and used dendrochronological methods to reveal the short- and long-term effects of NSR fire disturbance on the population dynamics and individual growth of the dominant species of L. gmelinii. Specifically, the effects of NSR fire on stand structure, the relationship between L. gmelinii demographics and disturbance, and the response of growth dynamics to disturbance were analyzed. Finally, the history of potential disturbance at stand level was reconstructed. The study found that common NSR fire affect the biomass and species composition of L. gmelinii forests. Fire disturbance contributes to the younger age structure of L. gmelinii populations. However, The NSR fire may limit the size of L. gmelinii populations but does not necessarily destroy population resilience depending on stand conditions. Irregular fluctuations in population survival and mortality curves are directly related to historical disturbance events. The NSR fire can inhibit the growth of surviving trees for 1–2 years, resulting in temporary growth asynchrony. The population dynamics fluctuations and temporal patterns of growth release signals can reconstruct historical disturbance events at the stand level. For example, the MH intra-group (Mohe Luogu River Nature Reserve burned stand&Mohe Luogu River Nature Reserve unburned stand) probably experienced a high-severity fire in 1880–1900, the TH intra-group (Tahe Nature Reserve burned stand&Tahe Nature Reserve unburned stand) experienced a high-severity fire around 1930, and THB (Tahe Nature Reserve burned stand) suffered stand-replacing. Overall, irregular fluctuations in population survival and mortality curves have been directly related to historical disturbance events. These findings provide direct evidence of the short- and long-term effects of fire on the survival and growth of L. gmelinii populations.

Fuel Connectivity, Burn Severity, and Seedbank Survivorship Drive Ecosystem Transformation in a Semiarid Shrubland

Fig. 1. One day, we arrived at what was supposed to be the first day of a week of field measurements for a study on long-term fire effects (Mahood & Balch 2019). To our dismay, a huge fire burned almost the entire study area that had just been contained. Photo credit: Adam Mahood. Fig. 2. Our original plan was not going to work. But we had just driven 15 hours to northern Nevada, so we had to do something. We decided to do a seed bank study, where we collected soil cores on either side of the fire perimeter, along a gradient of burn severity. (a) is a soil core, (b) is the greenhouse table where we germinated the seeds. (c) It was very obvious to both see where the edge of the fire was as well as visually assess the burn severity (pictured, C. Nick Whittemore). Photo credit: Adam Mahood. Fig. 3. We went back the following May to measure initial recovery (pictured, Dylan Murphy). Photo credit: Adam Mahood. Fig. 4. Many places had diverse flora in the spring following the fire. Photo credit: Adam Mahood. Fig. 5. We returned 3 years after the fire to measure recovery once the community stabilized. By then, many of the plots were dominated by cheatgrass. Photo credit: Adam Mahood. These photographs illustrate the article “Fuel connectivity, burn severity, and seedbank survivorship drive ecosystem transformation in a semiarid shrubland” by Adam L. Mahood, Michael J. Koontz, and Jennifer K. Balch published in Ecology. https://doi.org/10.1002/ecy.3968

Long-Term Effects of Fire Severity and Climatic Factors on Post-Forest-Fire Vegetation Recovery

As a major disturbance to forest ecosystems, wildfires pose a serious threat to the ecological environment. Monitoring post-fire vegetation recovery is critical to quantifying the effects of wildfire on ecosystems and conducting forest resource management. Most previous studies have analyzed short-term (less than five years) post-fire recovery and limited the driving factors to temperature and precipitation. The lack of long-term and multi-faceted observational analyses has limited our understanding of the long-term effects of fire on vegetation recovery. This study utilized multi-source remote sensing data for a long time series analysis of post-fire vegetation recovery in China based on Google Earth Engine (GEE) cloud computing platform. Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Normalized Burn Ratio (NBR), and Normalized Difference Moisture Index (NDMI) were selected to quantify the low, moderate, and high severity of burned areas. Ridge Regression Model (RRM) was used to analyze the relationship between 15 driving factors and the vegetation regeneration process. The results show that it took at least 7–10 years for the vegetation index to recover to the pre-fire level after a forest fire. The recovery rate of high severity combustion areas was the fastest within the first two years. From the results of Ridge Regression, it came out that the overall fitting degree of the model with NDVI as the dependent variable was superior than that with EVI. The four variables of temperature, precipitation, soil temperature, and soil moisture were able to explain the change in more detail in vegetation indices. Our study enriches the research cases of global forest fires and vegetation recovery, provides a scientific basis for the sustainable development of forest ecosystems in China, and provides insight into environmental issues and resource management.

Fire in lichen-rich subarctic tundra changes carbon and nitrogen cycling between ecosystem compartments but has minor effects on stocks

Abstract. Fires are predicted to increase in Arctic regions due to ongoing climate change. Tundra fires can alter carbon and nutrient cycling and release a substantial quantity of greenhouse gases with global consequences. Yet, the long-term effects of tundra fires on carbon (C) and nitrogen (N) stocks and cycling are still unclear. Here we used a space-for-time approach to investigate the long-term fire effects on C and N stocks and cycling in soil and aboveground living biomass. We collected data from three large fire scars (&gt;44, 28, and 12 years old) and corresponding control areas and used linear mixed-effect models in a Bayesian framework to analyse long-term development of C and N stocks and cycling after fire. We found that tundra fires had no long-term effect on total C and N stocks because a major part of the stocks was located belowground in soils which were largely unaltered by fire. However, fire had a strong long-term effect on stocks in the aboveground vegetation, mainly due to the reduction in the lichen layer. Fire reduced N concentrations in graminoids and herbs on the younger fire scars, which affected respective C/N ratios and may indicate an increased post-fire competition between vascular plants. Aboveground plant biomass was depleted in 13C in all three fire scars. In soil, the relative abundance of 13C changed with time after fire. Our results indicate that in lichen-rich subarctic tundra ecosystems, the contribution of fires to the release of additional carbon to the atmosphere might be relatively small as soil stocks appear to be resilient within the observed time frame.

Fire after clear-cut harvesting minimally affects the recovery of ecosystem carbon pools and fluxes in a Great Lakes forest

Effective forest carbon (C) management requires an understanding of how stand-replacing disturbances affect C pools and fluxes over successional timescales, and how the growth of secondary forests compares with that of undisturbed forests. In the upper Great Lakes region, fires that followed clear-cut harvesting shaped a century-old cohort of secondary forests, but the long-term effects of fire on C cycling in this relatively fire-averse landscape remain poorly understood. We examined how two different stand-replacing disturbances – one with and the other without fire – influenced C pools and fluxes through a century of stand development, comparing secondary aspen-dominated (Populus) forests with legacy late successional stands encompassing the ages and species compositions that would be prevalent today in the absence of stand replacement. Our work at the University of Michigan Biological Station (UMBS) used experimental forest chronosequences established following clear-cut harvesting or clear-cut harvesting followed by fire, along with three > 130-yr-old late successional deciduous broadleaf (DBF), evergreen needleleaf (ENF), and mixed (MIX) forest functional types. The successional trajectories and values of total (above- and belowground) ecosystem C mass, net primary production (NPP), and net ecosystem production (NEP) were similar regardless of whether fires occurred following clear-cut harvesting. Moreover, 80 + year old secondary forests’ C pools and fluxes were comparable to late successional ENF and MIX, but were at times lower than DBF. While the century-old secondary forests and legacy stands served as consistent C sinks over the last century, more extreme temperatures in recent years may be eroding NEP by accelerating C losses from soils. We conclude that the compounding effects of fire and clear-cut harvesting were similar to those from clear-cut harvesting alone, possibly because of the disturbance-adapted properties of pioneer species, most notably aspen; however, our results also suggest that changing climate rather than prior disturbance may jeopardize the future of this long-term terrestrial C sink.

Fire disturbance promotes biodiversity of plants, lichens and birds in the Siberian subarctic tundra.

Fire shapes the world's terrestrial ecosystems and has been influencing biodiversity patterns for millennia. Anthropogenic drivers alter fire regimes. Wildfires can amplify changes in the structure, biodiversity and functioning of the fast-warming tundra ecosystem. However, there is little evidence available, how these fires affect species diversity and community composition of tundra ecosystems over the long term. We studied long-term fire effects on community composition and diversity at different trophic levels of the food web in the subarctic tundra of Western Siberia. In a space-for-time approach we compared three large fire scars (>44, 28 and 12years old) to unburnt controls. We found that diversity (measured as species richness, Shannon index and evenness) of vascular and non-vascular plants and birds was strongly affected by fire, with the greatest species richness of plants and birds for the intermediate-age fire scar (28years). Species composition of plants and birds still differed from that of the control >44years after fire. Increased deciduous shrub cover was related to species richness of all plants in a hump-shaped manner. The proportion of southern (taiga) bird species was highest in the oldest fire scar, which had the highest shrub cover. We conclude that tundra fires have long-term legacies with regard to species diversity and community composition. They may also increase landscape-scale species richness and facilitate range expansions of more southerly distributed species to the subarctic tundra ecosystem.

Climate instability causing the decline of a Neotropical savanna lizard population (Squamata: Tropiduridae)

Abstract Populations that evolved in predictable seasonal environments might not have mechanisms to deal with unpredictable climate change. Assessing whether these populations can cope with recent increases in climate extremes and variability can better inform conservation efforts. We investigated the effects of climate deviations and fire on the population dynamics of the lizard Tropidurus torquatus in the Cerrado of Brazil. We decomposed six climate variables into seasonal and non-seasonal components and assessed which factors, along with long- and short-term effects of fire, better accounted for variation in the survival and recruitment of a T. torquatus population monitored for 12 years. Survival was not associated with climate seasonality, and instead minor fluctuations were related to temperature extremes. Recruitment benefited from long-term fire effects and had a strong seasonal component accounting for most of the variation in the population. Climate deviations caused severe changes in the number of recruits each year, with an overall negative effect on population growth. Population growth was more sensitive to recruitment than to survival, resulting in a sharp population decline over the study period. Tropidurus torquatus, and perhaps other species that evolved in similar conditions, can mitigate the demographic effects of fire but lack mechanisms to deal with climate deviation occurring over relatively short periods.

Quantitative reconstruction of vegetation cover from modern pollen rain in the Cerrado biome of Brazil

Fossil pollen assemblages are an important tool to reconstruct vegetation variability at centennial and millennial-scales. However, in the Cerrado biome of Brazil, the influence of the local vegetation, the heterogeneity of the landscape and the accuracy of pollen identification leads to a wide margin of error in interpretation. In this study, we present a method of quantitative reconstruction of past vegetation cover (forest, savanna, and grassland) that accounts for these different aspects. Our method is based on analysis of 47 surface samples collected in the southern Cerrado biome (east-central Brazil). First, we defined criteria that can be used to identify the local ecosystem (lake, marsh, palm swamp, or gallery forest) represented by the pollen assemblages. The pollen assemblages were then compared to data extracted from vegetation maps, resulting in the assessment of three pollen score equations related to each of the vegetation types (forest, savanna, and grassland). Based on these scores, we developed linear regression models that can be used to reconstruct the proportion of each type of land cover from pollen assemblages. We compared the results obtained for three different areas (respectively with 300 m, 500 m, and 1 km radius) to evaluate the size of the pollen source area for the Cerrado sites. We apply our models to two fossil pollen records to illustrate their use and application. Our method for the quantitative reconstruction of past land cover in the Cerrado biome is a new tool to investigate climate drivers and the long-term effects of fire in this Neotropical savanna.

The Latent Dirichlet Allocation model with covariates (LDAcov): A case study on the effect of fire on species composition in Amazonian forests.

Understanding and predicting the effect of global change phenomena on biodiversity is challenging given that biodiversity data are highly multivariate, containing information from tens to hundreds of species in any given location and time. The Latent Dirichlet Allocation (LDA) model has been recently proposed to decompose biodiversity data into latent communities. While LDA is a very useful exploratory tool and overcomes several limitations of earlier methods, it has limited inferential and predictive skill given that covariates cannot be included in the model. We introduce a modified LDA model (called LDAcov) which allows the incorporation of covariates, enabling inference on the drivers of change of latent communities, spatial interpolation of results, and prediction based on future environmental change scenarios. We show with simulated data that our approach to fitting LDAcov is able to estimate well the number of groups and all model parameters. We illustrate LDAcov using data from two experimental studies on the long‐term effects of fire on southeastern Amazonian forests in Brazil. Our results reveal that repeated fires can have a strong impact on plant assemblages, particularly if fuel is allowed to build up between consecutive fires. The effect of fire is exacerbated as distance to the edge of the forest decreases, with small‐sized species and species with thin bark being impacted the most. These results highlight the compounding impacts of multiple fire events and fragmentation, a scenario commonly found across the southern edge of Amazon. We believe that LDAcov will be of wide interest to scientists studying the effect of global change phenomena on biodiversity using high‐dimensional datasets. Thus, we developed the R package LDAcov to enable the straightforward use of this model.

COVER IMAGE

The cover image is based on the Original Article Short- and long-term effects of fire on stem hydraulics in Pinus ponderosa saplings by Raquel Partelli-Feltrin et al., https://doi.org/10.1111/pce.13881.

Physiological responses to fire that drive tree mortality.

This article comments on: Short- and long-term effects of fire on stem hydraulics in Pinus ponderosa saplings.

Long-term fire effects on vegetation and topsoil properties in beech forests of Manjaca Mountain (western Bosnia and Herzegovina)

Wildfires are an important driver of land degradation, with detrimental impacts on soil properties, usually leading to decreasing soil fertility and erosion, which affect vegetation recovery. This study investigates the long-term impact of wildfires on topsoil horizons and vegetation in Bosnia and Herzegovina, where land degradation is causing significant economic and ecological losses. Ten years after a wildfire, 12 plots were installed in areas affected by low- and medium-severity fire, and in unburned areas. Morphological, physical and chemical soil properties were explored on each plot, together with vegetation cover (number and cover of species). Soil organic matter, carbon, nitrogen and available phosphorus contents in medium- and low-severity fire affected plots are approximately half of those recorded in unburned plots, showing detrimental long-term impacts on soil fertility. Soil cation exchange capacity, pH and available potassium did not show significant differences between fire- and non-fire-affected plots. The number of plant species in medium-severity fire-affected plots is significantly lower than in low-severity and unburned plots. Differentiated plant groups are led by herbaceous (ground-breaking and weed) species. This study shows that wildfires can have long-term impacts on topsoil horizons and vegetation in limestone areas, threatening the sustainability of forest ecosystems.

Short- and long-term effects of fire and vegetation cover on four lizard species in Amazonian savannas

Ecological succession in tropical savannas is limited by seasonal fire, which affects habitat quality. Although fire may cause negligible or positive effects on animals occupying savannas, most short-term studies (months to a few years) are based on a single temporal sampling snapshot, and long-term studies (decades) are rare. We sampled four lizard species (Rainbow Whiptail, Cnemidophorus lemniscatus (Linnaeus, 1758); Striped Whiptail, Kentropyx striata (Daudin, 1802); Grass Anole, Norops auratus Duméril and Bibron, 1837 = Anolis auratus Daudin, 1802; Amazon Racerunner, Ameiva ameiva (Linnaeus, 1758)) in Amazonian savannas to test the effects of fire and vegetation cover on lizard densities at two temporal scales. In the short term, we use three sampling snapshots to test the effects of fire and vegetation cover on estimated lizard densities over the subsequent 1–5 years. In the long term, we test the effects of fire and changes in vegetation cover over 21 years on current lizard density differences. In the short term, species responses were usually consistent with foraging and thermoregulation modes. However, the results were not consistent among species and years, although the variances in species density explained by year as a random factor were generally low. In the long term, the main effects of fire and vegetation cover show that lizard densities may change spatially, but not necessarily temporarily. Wildfire is a natural resource of savannas and apparently have little impact on resident lizards of that ecosystem.