Fire forbids fifty-fifty forest

Nes, Egbert H. van; Staal, Arie; Hantson, Stijn; Holmgren, Milena; Pueyo, Salvador; Bernardi, Rafael E.; Flores, Bernardo M.; Xu, Chi; Scheffer, Marten

doi:10.1371/journal.pone.0191027

Cited by 55 publications

(66 citation statements)

References 66 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Indeed, both fires and herbivores show a steep increase in abundance below a critical tree cover (Figure a,e). It is this shape that allows for the existence of alternative stable states under a range of assumed growth and loss curves for tree cover (Kitzberger, Aráoz, Gowda, Mermoz, & Morales, ; Van Nes et al., ; also see Supporting Information Figure S9). This parallel structure of the two feedbacks is worth highlighting, but it is important to also recognize their differences.…”

Section: Discussionmentioning

confidence: 99%

“…Apart from differences between ecosystem types, there are differences among continents in ecosystem structure (Xu et al., ) and in fire ecology (Lehmann et al., ). For example, fire frequency is relatively high in Africa (Giglio, Randerson, & van der Werf, ; Van Nes et al., ), although that may be counteracted by relatively low fire intensity (Dantas & Pausas, ) and relatively high recovery from disturbances in that continent (Schwalm et al., ).…”

Section: Discussionmentioning

confidence: 99%

“…We organized the empirical fire probabilities in bins of tree cover (bin width 2%) and annual rainfall (bin width 100 mm/year). The fire probability‐tree cover relation prob F ( T ) (per year) follows a double Hill function (Van Nes et al., ):

p r o b_{F} (T) = p_{1} \frac{T^{p_{3}}}{T^{p_{3}} + {p_{2}}^{p_{3}}} \frac{{p_{4}}^{p_{5}}}{{p_{4}}^{p_{5}} + T^{p_{5}}}

…”

Section: Methodsmentioning

confidence: 99%

“…Several recent theoretical (e.g., Lasslop, Brovkin, Reick, Bathiany, & Kloster, ; Schertzer, Staver, & Levin, ; Staver & Levin, ; Van Nes, Hirota, Holmgren, & Scheffer, ) and empirical advances (e.g., D'Onofrio, von Hardenberg, & Baudena, ; Dantas, Hirota, Oliveira, & Pausas, ; Flores et al., ; Hoffmann et al., ; Murphy & Bowman, ; Staver et al., ; Van Nes et al., ) support the hypothesis that fire‐vegetation feedbacks provide one of the dominant mechanisms explaining the main patterns of tree‐cover distributions across the tropics. The continuous grass layers that characterize tropical savannas fuel fires which, in turn, enhance landscape openness and grass growth by killing trees or removing their aboveground biomass; on the other hand, closed forest canopies suppress fires, thereby contributing to maintain a tree‐dominated closed landscape (Murphy & Bowman, ; Van Nes et al., ).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Resilience of tropical tree cover: The roles of climate, fire, and herbivory

Staal

Nes

Hantson

et al. 2018

Global Change Biology

Self Cite

View full text Add to dashboard Cite

Fires and herbivores shape tropical vegetation structure, but their effects on the stability of tree cover in different climates remain elusive. Here, we integrate empirical and theoretical approaches to determine the effects of climate on fire- and herbivore-driven forest-savanna shifts. We analyzed time series of remotely sensed tree cover and fire observations with estimates of herbivore pressure across the tropics to quantify the fire-tree cover and herbivore-tree cover feedbacks along climatic gradients. From these empirical results, we developed a spatially explicit, stochastic fire-vegetation model that accounts for herbivore pressure. We find emergent alternative stable states in tree cover with hysteresis across rainfall conditions. Whereas the herbivore-tree cover feedback can maintain low tree cover below 1,100 mm mean annual rainfall, the fire-tree cover feedback can maintain low tree cover at higher rainfall levels. Interestingly, the rainfall range where fire-driven alternative vegetation states can be found depends strongly on rainfall variability. Both higher seasonal and interannual variability in rainfall increase fire frequency, but only seasonality expands the distribution of fire-maintained savannas into wetter climates. The strength of the fire-tree cover feedback depends on the spatial configuration of tree cover: Landscapes with clustered low tree-cover areas are more susceptible to cross a tipping point of fire-driven forest loss than landscapes with scattered deforested patches. Our study shows how feedbacks involving fire, herbivores, and the spatial structure of tree cover explain the resilience of tree cover across climates.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

p r o b_{F} (T) = p_{1} \frac{T^{p_{3}}}{T^{p_{3}} + {p_{2}}^{p_{3}}} \frac{{p_{4}}^{p_{5}}}{{p_{4}}^{p_{5}} + T^{p_{5}}}

…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Resilience of tropical tree cover: The roles of climate, fire, and herbivory

Staal

Nes

Hantson

et al. 2018

Global Change Biology

Self Cite

View full text Add to dashboard Cite

show abstract

“…, van Nes et al. ) are widely prevalent in nature. Studies have shown that systems with high positive feedback among individuals are likely to be bistable (Xu et al.…”

Section: Methodsmentioning

confidence: 99%

Inferring critical thresholds of ecosystem transitions from spatial data

Majumder

Tamma

Ramaswamy

et al. 2019

Ecology

View full text Add to dashboard Cite

Ecosystems can undergo abrupt transitions between alternative stable states when the driver crosses a critical threshold. Dynamical systems theory shows that when ecosystems approach the point of loss of stability associated with these transitions, they take a long time to recover from perturbations, a phenomenon known as critical slowing down. This generic feature of dynamical systems can offer early warning signals of abrupt transitions. However, these signals are qualitative and cannot quantify the thresholds of drivers at which transition may occur. Here, we propose a method to estimate critical thresholds from spatial data. We show that two spatial metrics, spatial variance and autocorrelation of ecosystem state variable, computed along driver gradients can be used to estimate critical thresholds. First, we investigate cellular‐automaton models of ecosystem dynamics that show a transition from a high‐density state to a bare state. Our models show that critical thresholds can be estimated as the ecosystem state and the driver values at which spatial variance and spatial autocorrelation of the ecosystem state are maximum. Next, to demonstrate the application of the method, we choose remotely sensed vegetation data (Enhanced Vegetation Index, EVI) from regions in central Africa and northeast Australia that exhibit alternative states in woody cover. We draw transects (8 × 90 km) that span alternative stable states along rainfall gradients. Our analyses of spatial variance and autocorrelation of EVI along transects yield estimates of critical thresholds. These estimates match reasonably well with those obtained by an independent method that uses large‐scale (250 × 200 km) spatial data sets. Given the generality of the principles that underlie our method, our method can be applied to a variety of ecosystems that exhibit alternative stable states.

show abstract

Origins of abrupt change? Postfire subalpine conifer regeneration declines nonlinearly with warming and drying

Hansen

Turner

2019

Ecological Monographs

View full text Add to dashboard Cite

Robust tree regeneration following high‐severity wildfire is key to the resilience of subalpine and boreal forests, and 21st century climate could initiate abrupt change in forests if postfire temperature and soil moisture become less suitable for tree seedling establishment. Using two widespread conifer species, lodgepole pine (Pinus contorta var. latifolia) and Douglas‐fir (Pseudotsuga menziesii var. glauca), we conducted complementary experiments to ask (1) How will projected early‐ to mid‐21st‐century warming and drying affect postfire tree seedling establishment and mortality? (2) How does early seedling growth differ between species and vary with warming and drying? With a four‐year in situ seed‐planting experiment and a one growing season controlled‐environment experiment, we explored effects of climate on tree seedling establishment, growth, and survival and identified nonlinear responses to temperature and soil moisture. In our field experiment, warmer and drier conditions, consistent with mid‐21st‐century projections, led to a 92% and 76% reduction in establishment of lodgepole pine and Douglas‐fir. Within three years, all seedlings that established under warmer conditions died, as might be expected at lower elevations and lower latitudes of species’ ranges. Seedling establishment and mortality also varied with aspect; approximately 1.7 times more seedlings established on mesic vs. xeric aspects, and fewer seedlings died. In the controlled‐environment experiment, soil temperatures were 2.0°–5.5°C cooler than the field experiment, and warming led to increased tree seedling establishment, as might be expected at upper treeline or higher latitudes. Lodgepole pine grew taller than Douglas‐fir and produced more needles with warming. Douglas‐fir grew longer roots relative to shoots, compared with lodgepole pine, particularly in dry soils. Differences in early growth between species may mediate climate change effects on competitive interactions, successional trajectories, and species distributions. This study demonstrates that climate following high‐severity fire exerts strong control over postfire tree regeneration in subalpine conifer forests. Climate change experiments, such as those reported here, hold great potential for identifying mechanisms that could underpin fundamental ecological change in 21st‐century ecosystems.

show abstract

Fire forbids fifty-fifty forest

Cited by 55 publications

References 66 publications

Resilience of tropical tree cover: The roles of climate, fire, and herbivory

Resilience of tropical tree cover: The roles of climate, fire, and herbivory

Inferring critical thresholds of ecosystem transitions from spatial data

Origins of abrupt change? Postfire subalpine conifer regeneration declines nonlinearly with warming and drying

Contact Info

Product

Resources

About