The spatially varying influence of humans on fire probability in North America

Probably not a substantial claim: may not pass S3 (load-bearing).

The bivariate relationship between fire activity and anthropogenic variable shows broadly similar patterns to the partial dependence plots.

“The bivariate relationship between fire activity and anthropogenic variable show broadly similar patterns to the partial dependence plots (figure D1).”

May combine two claims.

All three anthropogenic variables were useful in explaining fire probability models, but their relative importance varied substantially among hexels.

“All three anthropogenic variables were useful in explaining fire probability models, but their relative importance varied substantially among hexels.”

May combine two claims.

Anthropogenic effects were usually substantially greater than enduring features and lightning, and even greater than climate in some areas.

“Anthropogenic effects were usually substantially greater than enduring features and lightning, and even greater than climate in some areas.”

May combine two claims.

Enduring features ranked third in terms of importance in all hexels except four (hex1, hex5, hex8, hex10), where this category was the least important and lightning had the third-highest contribution.

“Enduring features ranked third in terms of importance in all hexels except four (hex1, hex5, hex8, hex10), where this category was the least important and lightning had the third-highest contribution.”

May combine two claims.

The relationship between fire activity and human influence varied as a function of the specific anthropogenic variable, but was overall fairly coherent among hexels.

“The relationship between fire activity and human influence varied as a function of the specific anthropogenic variable, but was overall fairly coherent among hexels.”

May combine two claims.

Fire activity increased monotonically as a function of RdlsVol in some hexels (hex3, hex4, hex5, hex6, hex7, hex13), decreased in some hexels (hex10, hex12, hex15, hex16), and was unimodal in others (hex3, hex8, hex9, hex14).

“Fire activity increased monotonically as a function of RdlsVol in some hexels (hex3, hex4, hex5, hex6, hex7, hex13), decreased in some hexels (hex10, hex12, hex15, hex16), and was unimodal in others (hex3, hex8, hex9, hex14).”

May combine two claims.

Area burned usually decreased as a function of increasing LogPopDens, except in hexels where there was a strong (hex8) or moderate unimodal response (hex1, hex2, and hex3).

“Area burned usually decreased as a function of increasing LogPopDens, except in hexels where there was a strong (hex8) or moderate unimodal response (hex1, hex2, and hex3) (figure 3).”

May combine two claims.

In some parts of the continent (southwestern US, Florida, and the Great Lakes area), the authors observed the unimodal relationship reported by Syphard et al (2007), whereby the peak in fire ignitions occurred at intermediate population densities, suggesting that both intense human activity and the near absence of humans is associated with fewer fires.

“In some parts of the continent (southwestern US, Florida, and the Great Lakes area), we observed the unimodal relationship reported by Syphard et al (2007), whereby the peak in fire ignitions occurred at intermediate population densities, suggesting that both intense human activity and the near absence of humans is associated with fewer fires.”

• cites Syphard et al 2007Not checked yet

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May combine two claims.

The HumanFoot variable had a decaying form in all hexels, though the range of slopes varied considerably.

“The HumanFoot variable had a decaying form in all hexels, though the range of slopes varied considerably (figure 4).”

May combine two claims.

The anthropogenic category was ranked as the most important in four hexels (hex2, hex7, hex9, hex12) and the second-most important in the remaining 12 hexels.

“The anthropogenic category was ranked as the most important in four hexels (hex2, hex7, hex9, hex12) and the second-most important in the remaining 12 hexels.”

May combine two claims.

The test AUC averaged 0.776 among hexels and ranged from 0.672 (hex13) to 0.891 (hex8).

“The test AUC averaged 0.776 among hexels, and ranged from 0.672 (hex13) to 0.891 (hex8).”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Almost a century of active fire suppression has led to unintended biomass accumulation that consequently increased the average size and intensity, as well as ecological impact, of modern fires.

“Almost a century of active fire suppression has led to unintended biomass accumulation that consequently increased the average size and intensity, as well as ecological impact, of modern fires (Keane et al 2002).”

• cites Keane et al 2002Not checked yet

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Classified as probably not a substantial claim. May combine two claims.

Although recent increases in fire activity have been largely attributed to a warmer and drier climate, it is increasingly recognized that in some areas humans may have played a role.

“Although this phenomenon has been largely attributed to a warmer and drier climate, it is increasingly recognized that, in some areas, humans may have played a role (Stephens et al 2007, McWethy et al 2013).”

• cites Stephens et al 2007Not checked yet

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• cites McWethy et al 2013Not checked yet

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Probably not a substantial claim: may not pass S3 (load-bearing).

Many regions where human ignitions are prevalent are also subject to intense fire management programs aimed at extinguishing fires before they become large.

“Globally, humans are usually responsible for the majority of ignitions; however, many regions where human ignitions are prevalent are also subject to intense fire management programs aimed at extinguishing fires before they become large (Stocks et al 2002, Stephens 2005).”

• cites Stocks et al 2002Not checked yet

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• cites Stephens 2005Not checked yet

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Probably not a substantial claim: may not pass S3 (load-bearing).

Some recent increases in fire activity in parts of the continent, notably in the west, may be due to a legacy of fire management policies that were too successful.

“Paradoxically, some of the recent increases in fire activity in parts of the continent, notably in the west, may be due to a legacy of fire management policies that were too successful (Stephens and Ruth 2005).”

• cites Stephens and Ruth 2005Not checked yet

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Classified as probably not a substantial claim.

In many parts of the world, people increase fire activity beyond what is naturally expected by deliberately or accidentally setting fire to natural vegetation.

“In many parts of the world, people increase fire activity beyond what is naturally expected by deliberately or accidentally setting fire to natural vegetation (Carcaillet et al 2009, Bowman et al 2011).”

• cites Carcaillet et al 2009Not checked yet

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• cites Bowman et al 2011Not checked yet

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May combine two claims.

The remote least-disturbed areas often have lower lightning densities, leading the authors to believe they may be ignition limited at the spatiotemporal scale of the study.

“These remote areas, however, also often have lower lightning densities, leading us to believe that they may be ignition limited at the spatiotemporal scale of the study.”

May combine two claims.

The heavily populated regions of southeastern North America, where a culture of prescribed burning has existed for centuries, have highly active fire regimes that are largely human dominated.

“In contrast, the heavily populated regions of southeastern North America, where a culture of prescribed burning has existed for centuries, have highly active fire regimes that are largely human dominated (Waldrop et al 1992, Slocum et al 2007).”

• cites Waldrop et al 1992Not checked yet

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• cites Slocum et al 2007Not checked yet

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Probably not a substantial claim: may not pass S3 (load-bearing).

In other regions or ecosystems, such as parts of North America, land-use change and a culture of aggressive fire suppression may limit fire activity.

“Conversely, in other regions or ecosystems of the world, such as in parts of North America, land-use change and a culture of aggressive fire suppression may limit fire activity (Cumming 2005, Finney et al 2009).”

• cites Cumming 2005Not checked yet

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• cites Finney et al 2009 sourceNot checked yet

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Probably not a substantial claim: may not pass S3 (load-bearing).

Globally, humans are usually responsible for the majority of ignitions.

“Globally, humans are usually responsible for the majority of ignitions; however, many regions where human ignitions are prevalent are also subject to intense fire management programs aimed at extinguishing fires before they become large (Stocks et al 2002, Stephens 2005).”

• cites Stocks et al 2002Not checked yet

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• cites Stephens 2005Not checked yet

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May combine two claims.

An initial surge in area burned at the time of European settlement due to slash-and-burn practices in some areas was followed by a large-scale reduction in fire activity largely due to fire suppression and human modifications to natural vegetation cover.

“An initial surge in area burned at the time of settlement due to slash-and-burn practices in some areas (Weir and Johnson 1998) was followed by a large-scale reduction in fire activity that was largely the result of fire suppression and human modifications to the natural vegetation cover (Marlon et al 2008).”

• cites Weir and Johnson 1998Not checked yet

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• cites Marlon et al 2008Not checked yet

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Classified as probably not a substantial claim. May combine two claims.

The authors selected a subset of variables that were not highly correlated with one another and also had good explanatory power for predicted area burned across North America.

“Although a large set of independent variables was initially considered for modeling, we selected a subset of variables that were not highly correlated with one another and also had good explanatory power for predicted area burned across North America (table 1; figure B1).”

Probably not a substantial claim: may not pass S3 (load-bearing).

At the forest/tundra transition characterizing the northernmost band of hexels, the presumed human influence may be partly masked by other gradients in climate and vegetation.

“This may be the case at the forest/tundra transition characterizing the northernmost band of hexels, for example, where the presumed human influence may be partly masked by other gradients in climate and vegetation.”

The quote only partly states this claim.

Fire activity today-as it has been for millennia-is mainly regulated by top-down controls.

“Climate is nevertheless the dominant environmental control on fire in most of North America, thereby supporting the claim that its fire activity today-as it has been for millennia-is mainly regulated by top-down controls (Swain 1973, Flannigan et al 2005, Guyette et al 2012).”

• cites Swain 1973Not checked yet

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• cites Flannigan et al 2005Not checked yet

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• cites Guyette et al 2012Not checked yet

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Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

As observed in this study, Bistinas et al (2013) found this relationship to be spatially variable, but there are discrepancies in the direction of relationships (positive and negative) between the two studies.

“As observed in this study, Bistinas et al (2013) found this relationship to be spatially variable, but there are discrepancies in the direction of relationships (positive and negative) between the two studies.”

• cites Bistinas et al 2013Not checked yet

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Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

Two limitations with the fire data-inconsistent reporting from 1984 to 1995 in Ontario north of 54°N and unmapped or incorrectly mapped unburned islands for many fire perimeters-are not expected to greatly affect estimates of area burned at the spatial extent of a hexel.

“We noted two limitations with these data: (1) fires were inconsistently reported from 1984 to 1995 in Ontario north of 54°N and (2) unburned islands were not mapped (or incorrectly mapped) for many of the fire perimeters in the dataset.Neither limitation is expected to greatly affect estimates of area burned at the spatial extent of a hexel.”

May combine two claims.

Some of the most remote areas of the western US may be ignition limited because they encompass high mountains and because lightning ignitions are deficient at very high elevations.

“Some of the most remote areas of the western US may also be ignition limited simply because they encompass some of the highest mountains and because lightning ignitions are deficient at very high elevations (Dissing and Verbyla 2003) (figure E1).”

• cites Dissing and Verbyla 2003Not checked yet

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Classified as probably not a substantial claim. May combine two claims.

Partial dependence plots measure the effect of a variable when the value of all other variables are held constant at their means, to statistically control for the effect of non-anthropogenic variables on fire probability.

“We use partial dependence plots, which measure the effect of a variable when the value of all other variables are held constant at their means, to statistically control for the effect of non-anthropogenic variables on fire probability.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The invasion of exotic cheatgrass species has profoundly modified fire regimes in parts of the western US.

“the invasion of exotic cheatgrass species (Bromus spp.) have profoundly modified fire regimes in parts of the western US (Balch et al 2013, Parks et al 2015)”

• cites Balch et al 2013Not checked yet

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• cites Parks et al 2015Not checked yet

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Classified as probably not a substantial claim.

A large number of fire presences and background points were sampled to ensure that the appropriate degree of variability was captured for statistical modeling.

“A large number of fire presences and background points were sampled to ensure that the appropriate degree of variability was captured for statistical modeling.”

May combine two claims.

Though the results show a remarkably coherent negative influence of humans on fire, the specific nature-and hence outcome-of the human-fire relationship is far from uniform.

“Though our results show a remarkably coherent negative influence of humans on fire, the specific nature-and hence outcome-of the human-fire relationship is far from uniform.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

The 30-year climate variables for 1981-2010 represent a slight mismatch to the fire data time period but are not expected to greatly influence the results.

“This time period represents a slight mismatch to that of the fire data , but is not expected to greatly influence the results.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The authors opted for a regularization value of four and did not use the 'hinge' feature, which tends to produce unrealistic (i.e., overfit) responses.

“To this end, we opted for a regularization value of four and did not use the 'hinge' feature, which tends to produce unrealistic (i.e., overfit) responses.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Over areas where humans are responsible for most or all of the fire ignitions, the relationship between wildfire and humans could be positive.

“this relationship could in fact be positive over areas where humans are responsible for most (or all) of the fire ignitions.”

May combine two claims.

The stretch of values in roadless volume is more heavily weighted towards distance from roads (low-impact areas), translating into a more diverse set of human-fire relationships.

“That is, the 'stretch' of values in this metric is more heavily weighted towards the distance from roads (i.e., low-impact areas), translating into a more diverse set of human-fire relationships.”

Classified as probably not a substantial claim. May combine two claims.

The lightning dataset had only partial overlap with the study time period and a coarser resolution than the other variables, but was deemed acceptable for depicting lightning strike patterns at the spatial scale of the study.

“In spite of the lightning dataset having only partial overlap with the time period of the study and a coarser resolution than the other variables, it was deemed acceptable for depicting lightning strike patterns at the spatial scale of this study.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Parisien et al (2011) observed a consistently negative response of area burned to the Human Footprint Index at four spatial scales in the boreal forest of Canada.

“Parisien et al (2011) observed a consistently negative response of area burned to the Human Footprint Index at four spatial scales in the boreal forest of Canada.”

• cites Parisien et al (2011)Not checked yet

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May combine two claims.

To reduce spatial autocorrelation in model residuals, a random subset of total fire-presence points was selected for model building, 100 such subsets were used and their results averaged, and this strategy was appropriate across the study area because it limited overfitting while yielding robust models of area burned for each hexel.

“To reduce spatial autocorrelation in model residuals, a random subset of total fire-presence points were selected for model building.One hundred such subsets were used and their results were subsequently averaged (see Parisien et al 2012).This strategy was appropriate across the study area because it limited overfitting while yielding robust models of area burned for each hexel.”

• cites Parisien et al 2012Not checked yet

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Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Model evaluation followed the method of Parisien et al (2012) and was performed on each of the 100 subset models and subsequently averaged for each hexel.

“Model evaluation followed the method of Parisien et al (2012) and was performed on each of the 100 subset models and subsequently averaged for each hexel.”

• cites Parisien et al (2012)Not checked yet

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Probably not a substantial claim: may not pass S4 (based).

It is usually impossible to know the state of the vegetation at the time of burning.

“it is usually impossible to know the state of the vegetation at the time of burning.”

May combine two claims.

Anthropogenic effects on fire across North America are complex and variable, as variable as the biophysical environment that defines them.

“it also paints a complex picture of anthropogenic effects on fire across the continent-one where fire is as variable as the biophysical environment that defines it.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Human-induced changes to the seasonality of fire occurrence may lead to fairly drastic ecological changes in some biomes.

“human-induced changes to the seasonality of fire occurrence, though difficult to detect, may lead to fairly drastic ecological changes in some biomes (Le Page et al 2010).”

• cites Le Page et al 2010Not checked yet

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Probably not a substantial claim: may not pass S3 (load-bearing).

Vegetation-related variables have often been incorporated into large-scale biophysical models of fire.

“vegetation-related variables have been often incorporated into to large-scale biophysical models of fire (Sturtevant and Cleland 2007, Hawbaker et al 2013, Liu and Wimberly 2015).”

• cites Sturtevant and Cleland 2007Not checked yet

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• cites Hawbaker et al 2013Not checked yet

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• cites Liu and Wimberly 2015Not checked yet

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Classified as probably not a substantial claim.

There is compelling evidence that biota affects spatial and temporal patterns of fire activity.

“There is compelling evidence that biota affects spatial and temporal patterns of fire activity (Girardin et al 2013, Terrier et al 2013)”

• cites Girardin et al 2013Not checked yet

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• cites Terrier et al 2013Not checked yet

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Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Using the percentage of pixels where fire was observed as a provides a fair, yet underestimated, approximation of prevalence.

“This provides a fair, yet underestimated, approximation of prevalence.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Liu and Wimberly (2015) found that humans had a greater impact on fire size than fire occurrence of high-severity burns in the western US.

“Liu and Wimberly (2015), for example, found that humans had a greater impact on fire size than fire occurrence of high-severity burns in the western US.”

• cites Liu and Wimberly (2015)Not checked yet

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Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing), S4 (based).

Detailed vegetation information at the time of burn would have likely substantially improved the models.

“detailed vegetation information at the time of burn would have likely substantially improved our models.”