\chapter{Synthesis and Conclusions}\label{ch:conclusion}


\begin{refsection}

In this chapter, I first provide a summary of the main findings, their significance and the novelty of the research undertaken to address each of the three objectives of this thesis. Then, I provide an overall synthesis elaborating on the main takeaway messages about the dynamics of fire in the Cerrado uncovered by this thesis. Finally, I conclude by outlining future avenues for research in light of the findings and limitations of the present work.

\section{Summary of key findings}


\subsection{Objective 1: Determine how land use area and the climate interact to affect the burned area of the Cerrado}
\textit{What is the causal effect of land use area on the amount of burned area? How does land use area interact with the climate to affect Cerrado's burned area? What are the burned area trends across the Cerrado and how are these related to anthropic expansion and climate change?}

This objective was addressed in \textbf{Chapter \ref{ch:paper01} (Research Paper 1)}.

\textbf{Findings - }We showed that land use area reduces the fraction of burned area in Cerrado native vegetation - i.e. burned natural area. In addition, we demonstrated that human controls through land use area limit the responsiveness of burned area to climatic effects in landscapes with $\geq$ 40\% of anthropic area. Therefore, it is only in the least converted regions of the Cerrado that burned area increases in response to warm and dry conditions. Finally, regarding changes over time between 1985 and 2020, we found that burned area remained low and did not show clear changes in time in those landscapes that were already mostly converted in 1985; while the largest changes in burned area were concentrated in those landscapes that were mostly intact at the beginning of the study period. In these regions, we found that climate change caused increases in burned area where the landscapes remained mostly unconverted, while agricultural expansion brought about decreases in burned area.

\textbf{Significance - }This study addressed a knowledge gap in the literature studying the dynamics of fire in the Cerrado, as the interaction between land use area and the climate had not been previously quantified for this region. Our results contribute to the increasing literature identifying landscape fragmentation as a stronger control than climate on the burned area of savanna ecosystems \citep{archibald_climate_2010, andela_recent_2014, conciani_human-climate_2021}. These findings indicate that current predictions of generalised increases in Cerrado burned area under different scenarios of climate change \citep{silva_impacts_2019} may be overestimating the climate forcing when not accounting for current, nor future, patterns of land use area. Finally, this study identified the largest remnants of Cerrado native vegetation as being the most vulnerable to changing patterns of burned area in relation to climate change. Therefore, these are priority areas for Cerrado conservation where the implementation of prescribed burns as fire management practices may be particularly beneficial to diminish the occurrence of large burned area events \citep{santos_prescribed_2021, de_andrade_implementation_2021}, helping to maintain biodiversity levels. 


\textbf{Novelty - }This is the first study to explicitly quantify the interaction between land use area and the climate as drivers of burned area in the Brazilian Cerrado. Further, the novelty of this study also stems from the statistical methods used. First, the use of causal inference in this study is part of a growing and relatively recent trend in environmental sciences to construct statistical models that allow the interpretation of relationships between variables as causal rather than merely correlational. In addition, a rather simple but novel methodological aspect that ultimately allowed to disentangle land use area and climate effects, either when considering the full study period or the trends in time, was precisely investigating these effects conditioning on (pre)existing levels of land use area. In this study, the conditioning was done using Bayesian multilevel models, equivalent to modelling effects by level of anthropic area. Previous studies in the Cerrado did not consider this aspect, reporting as a consequence both increasing and decreasing effects of land use expansion on burned area, and not resolving the interaction with climatic effects \citep{rosan_fragmentation-driven_2022, silva_drivers_2020}. 

\subsection{Objective 2: Characterising the fire regime regions of the Cerrado and their changes through time}
\textit{What are the regions of the Cerrado presenting different fire regimes? What are the environmental characteristics of these regions? How have these fire regime regions changed through time?}

This objective was addressed in \textbf{Chapter \ref{ch:paper02} (Research Paper 2)}.

\textbf{Findings - }This study delineated the fire regime regions of the Cerrado in four consecutive periods between 1985 and 2020, finding that the fire regime regions of the Cerrado have profoundly changed over the past almost forty years, both geographically and in terms of fire characteristics. Only two aspects seem to have remained constant between 1985-1993 and 2012-2020: a) the identified fire regime regions in each period were organised along a gradient of fire activity, which was the main feature differentiating them (i.e. regions with large fires also had a tendency to have numerous and frequent fires, and vice versa); and b) the identification of a region in the north of the Cerrado characterised by rather large numbers of small fires and a later peak of the fire season. Further, we found that the gradient of fire activity was opposed to a gradient of increase in the presence of human activities. This seemed a general pattern across the Cerrado, except for one fire regime region near the Amazon rainforest and a few forest areas in the north of the Cerrado in the period 1985-1993, and some scattered areas in the period 2012-2020, pointing at the importance of other factors like vegetation type influencing fire regimes. Finally, most of the southern parts of the Cerrado experienced losses in fire activity concomitant to land use expansion, while other areas either experienced gains in, or maintained high levels of, fire activity. 


\textbf{Significance - }This study clearly revealed the profound changes experienced by the Cerrado's fire regimes over the past four decades. Importantly, it showed how the fire regimes of the Cerrado are increasingly portraying the land use footprint on this region, highlighting the large-scale loss of Cerrado native vegetation and the wider impacts disrupting ecosystem processes and their disturbance regimes. Further, it underscored the importance of landscape fragmentation as a major determinant, and driver of change, of savannas fire regimes. \textbf{Chapter \ref{ch:paper02} (Research Paper 2)} expanded on the findings of \textbf{Chapter \ref{ch:paper01} (Research Paper 1)} showing opposing temporal changes in fire activity. These processes emphasise the double-sided pressures on these tropical savannas: while part of the Cerrado is being lost to agricultural land uses and experiencing decreases in fire activity, other areas are experiencing increases in the size and frequency of fires. Since only about 3\% of the Cerrado is under strict protection, these findings underscore the urgent need to expand the protected areas of the Cerrado, as well as the need to implement fire management strategies that contribute to Cerrado conservation within protected areas but also in private lands.

\textbf{Novelty - }This is the first study delineating the regions of the Cerrado with different fire regimes without assuming geographical boundaries \textit{a priori}. In addition, it delineates the fire regime regions in different periods, analysing how both the regions and their fire characteristics have changed through time, which is not a common approach in the literature, and the first time this has been done for the Cerrado. Further, this study uses a hierarchical clustering algorithm with a spatially contiguity constraint to identify the fire regime regions, unlike the unconstrained clustering methods commonly used in the literature that can lead to very fragmented fire regime regions \citep{archibald_defining_2013}, which can hamper the interpretation of patterns at regional scales.



\subsection{Objective 3: Quantifying and comparing the fire regimes ignited by lightning and humans}
\textit{What is the proportion of lightning to human-ignited fires? How does it change throughout the year and across the Cerrado? How do these two types of fires compare?}

This objective was addressed in \textbf{Chapter \ref{ch:paper03} (Research Paper 3)}.

\textbf{Findings - } This study estimated that, in the period 2019-2023, 7.5\% (95\% confidence interval, CI, [6.7, 8.3]\%) of fires were ignited annually by lightning, while 89.1\% (95\% CI, [86.9, 91.3]\%) were ignited by humans, and 3.4\% (95\% CI, [2.7, 4.1]\%) did not have a clear cause of ignition. Therefore, humans are the major cause of fires in the Brazilian Cerrado, creating an excessive number of ignitions in comparison to lightning. Further, we found that humans lengthen the fire season threefold starting fires throughout the dry season (May to October), while most lightning-caused fires took place in the transition period from the dry to the wet season (September and October). In addition, we found that humans create higher fire frequencies and ignite fires in more flammable conditions than lightning, even when comparing fires starting in the same month. Finally, our results indicate that these differences in flammability at ignition led to the more extreme fire behaviours observed in some human-caused fires. Indeed, the most extreme human-caused fires were about ten times larger, or two times more intense, than their lightning-caused counterparts, and took place in generally drier and hotter weather conditions. 

\textbf{Significance - }This study fills a clear gap in the literature addressing how current human-caused fires differ from naturally ignited ones, and providing numerical evidence that humans ignite a much larger number of fires than lightning, something that was previously assumed but had not yet been quantified \citep{pivello_use_2011}. Still, this study also demonstrated that lightning ignites a considerable percentage of fires, as had been previously suggested in some Cerrado protected areas \citep{ramos-neto_lightning_2000}, indicating that global models estimating low numbers of lightning ignitions in tropical savannas and grasslands \citep{janssen_extratropical_2023} may be underestimating the amount of fires caused by lightning in this biome. Crucially, it also demonstrated that most fires in the larger remnants of Cerrado native vegetation are ignited by humans, and that these fires are generally larger and more intense than lightning-ignited ones. These findings are important in relation to the results from \textbf{Chapter \ref{ch:paper01} (Research Paper 1)} showing the relation between increasing trends in burned area and climate change, as they indicate that humans also contribute to these increases by causing the fires. Finally, the excess number of ignitions and more extreme behaviour of fires caused by humans highlights the need to address the regulations on the use of fire as part of non-conservation human activities that either cause fires directly on native vegetation, or cause fires that escape into these areas. 


\textbf{Novelty - }This is the first study providing a quantification of the proportion of lightning and human-ignited fires for the whole Brazilian Cerrado, and comparing the characteristics of fires ignited naturally and by humans in this region. In addition, to the best of my knowledge, this study went further than previous studies using the same well-established ignition-cause attribution method \citep{larjavaara_lightning_2005} in two aspects. First, we used two attribution score thresholds, one threshold to identify those fires most likely caused by lightning and another one to identify those fires most likely caused by humans. In this manner, those fires with intermediate attribution score thresholds were classified as not having a clear ignition cause and were excluded from the comparison between lightning and human fires. Further, we also assessed the uncertainty on the estimated proportion of each type of fire, which has not been done before (e.g. \citet{menezes_lightning_2022}). 

\section{Thesis synthesis and conclusions}


This thesis has investigated how the patterns of fire of the Brazilian Cerrado have changed over the past few decades shaped by agricultural land use expansion and climate change. In particular, it has explored different aspects of fire in relation to the two main mechanisms by which humans influence fire regimes, namely altering fuel - primarily through landscape fragmentation resulting from land use activities - and ignitions, and how these two interact or combine with climatic effects.

This work began by understanding how land use area and the climate interact to affect the Cerrado's burned area, a key aspect to disentangle the current spatiotemporal dynamics of fire of tropical savannas and grasslands. \textbf{Chapter \ref{ch:paper01} (Research Paper 1)} showed that human controls on fire through land use area lead to low burned areas in native vegetation. Further, it provided a clear demonstration of the landscape fragmentation controls on the climatic effects on burned natural area, suggested by previous research in the Cerrado \citep{conciani_human-climate_2021} and observed in African savannas \citep{archibald_climate_2010, andela_recent_2014}. Crucially, this first study illustrated that there is a clear difference between the fire dynamics of the highly converted areas of the Cerrado and those of the mostly intact landscapes, precisely as a result of the different level of landscape fragmentation. This distinction provides a fundamental basis to interpret the current patterns of fire of the Cerrado, and it was recurrently observed in subsequent chapters of this thesis.

Results from \textbf{Chapter \ref{ch:paper01} (Research Paper 1)} also showed that declines in burned natural area over time occurred as a result of large-scale land use expansion, while increases in burned natural area were related to climate change and restricted to areas of the Cerrado that had remained largely unconverted over the past four decades. This relation between decreases in burned area and agricultural expansion is in agreement with recent research indicating that fire is not commonly used in the conversion of Cerrado's native savannas and grasslands to agricultural lands, except in the conversion of Cerrado's forest vegetation, and that fire activity reduces gradually over time in all cases after the conversion event \citep{ribeiro_time_2024}. Together, these findings indicate that the observed increases in burned area in the Cerrado's most intact regions, as reported in \textbf{Chapter \ref{ch:paper01} (Research Paper 1)}, may not necessarily be attributed to the limited native vegetation conversion they experienced, but rather to climate change and, possibly, other anthropic uses of fire.

In \textbf{Chapter \ref{ch:paper02} (Research Paper 2)}, we expanded the study of the dynamics of fire in the Cerrado by characterizing fire regimes in a more complete way, and identified the different fire regime regions in consecutive periods. This study showed the nuances in the spatiotemporal patterns of fire uncovered when more fire characteristics in addition to burned area are considered. Overall, the main aspect differentiating the fire regime regions at a certain moment in time was their level of fire activity, which varied inversely to the level of human impact on the landscape. In a similar fashion to the results of \textbf{Chapter \ref{ch:paper01} (Research Paper 1)}, \textbf{Chapter \ref{ch:paper02} (Research Paper 2)} found opposing trends in fire activity, and a clear distinction between highly converted areas with overall low fire activity levels, and the more intact areas presenting high levels of fire activity. Therefore, we encountered again the dichotomy in the patterns of fire of the Cerrado, which seems to have deepened throughout the past four decades. However, \textbf{Chapter \ref{ch:paper02} (Research Paper 2)} also highlighted some exceptions to the relation between increases in land use area and decreases in fire activity. Indeed, in some areas in the western-most border with the Amazon rainforest and in the north of the Cerrado, predominantly formed of forests, increases in fire activity could be related to land use expansion as a result of the use of fire in forest vegetation conversion \citep{ribeiro_time_2024}.

Considering the findings from \textbf{Chapter \ref{ch:paper01} (Research Paper 1)} and \textbf{Chapter \ref{ch:paper02} (Research Paper 2)}, we can conclude that agricultural activities and the extent of land use area are the dominant driver of the current fire regimes of the Cerrado. These studies contribute to the wider literature indicating that human socioeconomic activities linked to land uses limit the extent of fires in savannas primarily through the introduction of fuel discontinuities and through active fire suppression \citep{archibald_what_2009, archibald_climate_2010}. Nonetheless, it is important to underline that the land use imprint on the spatiotemporal patterns of fire of the Cerrado is a symptom of the main process threatening this region's ecosystems: the large-scale loss of native vegetation to croplands and pastures.

Finally, this thesis addressed the cause of fire ignitions, one of the major outstanding questions in the study of Cerrado's fire regimes. The results of \textbf{Chapter \ref{ch:paper03} (Research Paper 3)} demonstrated that humans are the main cause of fire ignitions across the Cerrado, and showed that human activities extend the occurrence of fires to the full dry season, increase fire frequency, and create more extreme fire behaviour than lightning. Still, the spatial patterns of fire observed both for lightning and human-caused fires were, once more, mostly influenced by the patterns of land uses, with few and small fires observed in highly converted landscapes.

Interestingly, \textbf{Chapter \ref{ch:paper03} (Research Paper 3)} demonstrated that humans are the main cause of fire ignitions in the least fragmented areas of the Cerrado. This finding links back to \textbf{Chapter \ref{ch:paper01} (Research Paper 1)} and the question on whether the increases in burned natural area observed in these intact regions in relation to climate change were also mediated by human intervention. Findings in \textbf{Chapter \ref{ch:paper03} (Research Paper 3)} indicated that, indeed, the excess of human ignitions and their timing during the dry season could be coupling with climate change to explain the increasing trends in burned area observed over the most intact areas of the Cerrado. Accordingly, these investigations suggest that while climate change is setting the stage for larger and more intense fires to occur in these areas, it is humans who start these fires in flammable conditions and with high frequencies. 

Findings in \textbf{Chapter \ref{ch:paper03} (Research Paper 3)} suggested that naturally occurring fire regimes would consist of far lower numbers of fires than is currently observed in the Cerrado, and that these would take place in generally less flammable conditions. Still, results from this study also indicated that lightning does ignite a substantial amount of fires and that, occasionally, these fires occur in climatic conditions enabling considerably large or intense fires. Based on these observations, we can speculate that the structure of Cerrado vegetation would be less open than at present if lightning was the only source of fire ignitions, as suggested in other subtropical savannas \citep{van_wilgen_fire_2000}, but also that some large lightning-caused fires could take place with a certain frequency causing larger openings in the vegetation. However, our findings also demonstrated that the current patterns of lightning-caused fires are deeply influenced by humans, either through landscape fragmentation or by shaping the fire histories of the landscape, as both these processes create fuel discontinuities, which in turn affect the occurrence and fire behaviour of subsequent fires \citep{fidelis_year_2018}. Therefore, the patterns of lightning-caused fires reported in \textbf{Chapter \ref{ch:paper03} (Research Paper 3)} should not be considered as strictly natural.

Overall, we can expect the changes in fire regimes reported in this thesis to bring about ecological changes to Cerrado's ecosystems, particularly to the structure and composition of their vegetation \citep{pivello_understanding_2021, abreu_biodiversity_2017, pinheiro_dinamica_2009}. In the areas with larger remnants of native vegetation, burned area and fire sizes have increased over the past few decades and, crucially, fires have taken place with elevated frequencies and with exacerbated behaviour. Because fire favours grasses and herbaceous vegetation \citep{medeiros2008post}, we can expect a further retreat of forest patches and a further opening of the vegetation in these areas \citep{pivello_understanding_2021}. These ecological effects may be stronger at the transition with tropical rainforest and in the northern parts of the Cerrado where tree canopy is denser. Still, even though savanna and grassland species present adaptations to fire, vegetation can eventually lose its capacity to resist fire and to recover from its effects when fires are too frequent or when they are particularly intense \citep{pinheiro_dinamica_2009, pivello_understanding_2021}. One of the main concerns resulting from these processes is the loss of biodiversity, both among tree species \citep{abreu_biodiversity_2017} and among grasses, herbs and shrubs \citep{pivello_understanding_2021}.

Concomitantly to the large-scale agricultural conversion and to the increases in fire activity in unconverted areas of Cerrado, there have been other processes linked to humans and fires over the past decades. In particular, active fire suppression in certain protected areas of the Cerrado has been a major conservation strategy for several decades, as signaled repeatedly in the literature \citep{durigan_zero-fire_2020, mistry_community_2016, pivello_understanding_2021, fidelis_year_2018}. These suppression practices have brought about woody encroachment in these areas and generalised biodiversity losses among light-demanding species but also among Cerrado tree specialists \citep{abreu_biodiversity_2017}. These processes have also caused fuel accumulation contributing to the occurrence of fires with unprecedented sizes and behaviour \citep{fidelis_year_2018}, which have more chances of causing vegetation mortality as their high temperatures and residence times can surpass fire protections \citep{medeiros2008post}.

The vegetation composition and the extent of savannas and grasslands in South America has dynamically changed over the past few thousands of years responding to several episodes of climate change \citep{araujo2025human}, as well as to other events such as the extinction of mega-herbivores and the arrival of humans \citep{dantas2020megafauna, araujo2025human}. Therefore, similarly to what happened with these environmental changes, we can expect Cerrado vegetation to change in response to ongoing climate change and to human-caused changes in fire regimes. As such, Cerrado vegetation may further open in some areas in response to drying conditions and exacerbated fire activity; or it may evolve towards closed ecosystems if fire is reduced and favoured by increasing atmospheric carbon concentrations \citep{stevens_savanna_2017} - a process of woody encroachment that may have been ongoing throughout the Holocene since megafauna extinction \citep{doughty2016impact}.

Still, recent transformations of the Cerrado have taken place at an extraordinary fast pace, which contrasts with Holocene transformations - even if some may have been rather fast for geological time scales \citep{dantas2020megafauna}. Indeed, as shown in this thesis and in other studies, the fire regimes of the Cerrado have changed at an unprecedented large scale in just about five to six decades in relation with human activities \citep{silva_putting_2021, mataveli_analysis_2017, da2024assessing}. Such fast-paced processes have been simultaneous to - and also caused by - the widespread conversion of Cerrado native vegetation and to the anthropic climate change taken place during the same period. The combination of these processes are impacting Cerrado's ecosystems, with particularly harmful effects on their rich biodiversity \citep{klink_conservation_2005}. Therefore, the conservation of Cerrado at scale is absolutely urgent to stop the loss of native vegetation. Further, conservation needs to address the fire regimes that affect the remnants of Cerrado, particularly to preserve and enhance this region's biodiversity.

In conclusion, this thesis has highlighted the high and increasing level of anthropisation of the Cerrado's fire regimes. We have shown that humans are altering the Cerrado's fire regimes through the two main mechanisms of fire control: modifying the vegetation continuity through land use activities and fragmentation, and through ignitions. Further, we have repeatedly highlighted that the spatial patterns of fire of the Cerrado primarily reflect the patterns of land use area, independently of the fire ignition cause. In fact, we have demonstrated that controls on fire through landscape fragmentation are so strong that limit the climatic effects on Cerrado's burned natural area. Finally, we also conclude that humans are directly responsible for both the increases and decreases in fire activity observed across the Cerrado, the two main directions of change of this region's fire regimes over the past four decades: agricultural expansion brings about decreases in fire activity, while humans facilitate increases in fire activity in the larger remnants of native vegetation by creating ignitions throughout the dry season in the context of climate change.






\section{Future research directions}

This thesis has addressed key aspects to understanding how, and in relation to what, the fire regimes of the Brazilian Cerrado have changed over the past few decades, regarding the interaction between anthropic land uses and the climate \textbf{(Chapter \ref{ch:paper01}, Research Paper 1)}, the identification of the Cerrado's fire regimes and their changes through time \textbf{(Chapter \ref{ch:paper02}, Research Paper 2)}, and the characterisation of fires depending on their ignition cause \textbf{(Chapter \ref{ch:paper03}, Research Paper 3)}. These findings, along with the statistical and geospatial analysis methods employed in this thesis, open new avenues for future research, which are summarised in the following list:

\begin{enumerate}

    \item One of the unexplored aspects of this thesis, and generally in the literature studying spatiotemporal patterns of fires in Cerrado using spaceborne data, is related to the characterisation of fire severity. This is primarily due to a lack of sufficient research across the Cerrado linking measurements of fire severity on the field to vegetation indices obtained from satellite data. Thus, future research could focus on addressing this research gap for the different vegetation forms of the Cerrado. 

    \item Further, future research could be directed at identifying and monitoring, through field-based studies, the ecosystem processes and characteristics that are being impacted by different fire regimes. This would imply going beyond studying the effects of single fires, but rather considering the effects of the overall fire histories of a region. Findings could then complement the larger-scale characterisation of Cerrado's fire regimes to identify those areas of the Cerrado that are already experiencing harmful patterns of fire.   

    \item A clear gap in the study of fires in tropical savannas and grasslands, and more generally across the world, are the small fires missed by satellite-based products \citep{jones_state_2024, ramo_african_2021}, particularly over agricultural areas \citep{rodrigues_how_2019}. Thus, further efforts devoted to improving the mapping of small fires would enable a more complete characterisation of fire regimes, as well as improving the estimation of the contributions of different ecosystems to carbon emissions \citep{van_der_werf_global_2017}.
    
    \item Future studies could conduct more tailored research to further differentiate the fires created by different human communities (e.g. indigenous peoples, traditional pastoral communities, or activities related to industrial agriculture) as well as by lightning. This would improve our understanding about how the various human fire regimes differ among them and in comparison to naturally-ignited fires, but also whether any of these groups - for example, industrial agriculture - may be the predominant cause of human fires across the Cerrado.

    \item Future studies could focus on understanding the climatic conditions in which lightning strikes are conducive to fires on different types of savanna vegetation. This could be used to model lightning-caused fire regimes in different climate and vegetation scenarios to investigate questions regarding how the Cerrado, and savannas in general, may have expanded in the past.% Further, similar studies could be carried out to model predictions about future lighting-ignited fires under different scenarios of climate change.

    \item Future studies could replicate similar approaches to the methods applied in \textbf{Chapter \ref{ch:paper01} (Research Paper 1)} to quantify the interaction between land use area and climate in other savannas of the world. Understanding whether the shape of the interaction or the extent of land use controls on climate effects change depending on the region in relation to differences in vegetation or socioeconomic factors could inform more nuanced projections of burned area in tropical savannas and grasslands.

    \item Causal inference offers a very powerful approach to understanding relations between different factors and processes in nature. \textbf{Chapter \ref{ch:paper01} (Research Paper 1)} opens the stage to use causal inference to explore the factors affecting other fire characteristics (e.g. fire size or frequency), as well as to explore the use of more sophisticated statistical analyses for cause-effects relations (e.g. convergent cross mapping that allows causality analysis of dynamical systems \citep{setty_loss_2023}).  

    \item Currently, there is no established common way of calculating fire variables (like frequency, seasonality, or length of the fire season), and different studies use different methodologies. Future research could be devoted to comparing methods and identifying optimal ways of calculating or measuring some of these variables. Standardising these methods would facilitate comparison between studies.

    \item The methods used in \textbf{Chapter \ref{ch:paper02} (Research Paper 2)} to assess the number of fire regime regions in which to divide the Cerrado are designed to identify a unique, most optimal, number of clusters. However, there are other methods (e.g. \citet{lambiotte_random_2014}) that allow to identify meaningful partitions of the data (i.e. number of clusters) at different levels. Future studies could use these methods to investigate whether, apart from the few and generally large fire regime regions identified in this thesis, there could be other partitions of the Cerrado into smaller regions that would also capture meaningful patterns of fire. These approaches could be used to investigate the level at which different drivers of fire may become relevant \citep{lambiotte_random_2014}. For example, findings of \textbf{Chapter \ref{ch:paper02} (Research Paper 2)} point at landscape fragmentation as a determining factor distinguishing fire regimes, but there could be other factors becoming important at smaller scales.

    \item Given the depth of changes in the fire regimes of the Cerrado observed in \textbf{Chapter \ref{ch:paper02} (Research Paper 2)}, future studies could explore methodologies to allow the fire regime regions to evolve dynamically over time (e.g. \citet{lughofer_dynamic_2012}). That is, instead of generating independent clustering solutions for each consecutive time period, the clusters obtained at the beginning of the time series could be updated in subsequent time steps as fire characteristics change. Developing these methods could provide a relevant science advance in the study of changing fire regimes in different areas of the world.

    \item The statistical methods used in the literature to quantify fire regimes, like the ones used in \textbf{Chapter \ref{ch:paper02} (Research Paper 2)}, are generally reductionist. For example, to characterise the fire sizes of a certain region, usually the median or a high percentile of the distribution are used. But, perhaps, there could be ways of harnessing more completely the information of the full probability distributions of the fire variables. For example, instead of characterising the fire regimes of a region as a vector of fire variables, the fire regimes could be expressed as an envelope of probability distributions. Potentially, this type of approach could allow more nuanced characterisation of fire regimes and comparisons between regions. 
    

\end{enumerate}



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