Historical fire ecology and its effect on vegetation dynamics of the Lagunas de Montebello National Park, Chiapas, México

Abstract

Historical information on wildfires and dendrochronological studies offer meaningful clues about fire and climate regimes, factors that affect forest structure and dynamics. This study aimed to determine the effect of fire history on vegetation dynamics and successional pathways of areas under different fire management policies in the Lagunas de Montebello National Park (LMNP), Chiapas, México. The selected study sites were El Parque area under fire exclusion policies since 1961; Tziscao-inhabited area under fire prohibition since 1984; and Antelá area with a traditional agricultural fire management history. A Pinus oocarpa ring-width chronology was used as a proxy for climate variability to which wildfire occurrence was mapped and to determine the establishment patterns of this dominant species. Current vegetation composition and structure and fuel loads were determined to characterise the study sites. Large wildfires, like those occurring in 1984 and 1998, were associated with periods of high humidity followed by intense droughts; they were linked to strong El Niño events and severely impacted the LMNP. Vegetation dynamics indicated simplification of mesophyll forest (climax) to pine-oak-sweetgum forests, with Pinus dominating the overstorey in all sampling sites. Pine, oak and sweetgum species were the dominant juvenile trees in Antelá, El Parque and Tziscao, respectively. Late-successional seedlings (i.e., Prunus) were present in Antelá and El Parque, while were absent from Tziscao where several wildfires had occurred. Fuel accumulation in sites within protected areas subject to fire exclusion policies was very high (40-68 t ha^-1); in contrast, it was the lowest in rural Antelá (24 t ha^-1). Considering vegetation vulnerability to wildfires associated with extreme humid-dry climate events, increased fire hazard due to fuel accumulation, and the socio-ecological impacts of these events, we recommend revising the fire exclusion policies currently implemented in the LMNP and applying an integrated fire management approach that incorporates local socio-ecological conditions.

Introduction

Throughout the world, fire-exclusion policies, together with global warming, resulted in higher environmental and economic impacts of wildfires and human lives and properties lost to fire ([44]). This is a consequence of ignoring natural fire dynamics and excluding fire from fire-dependent ecosystems which increases fuel loads and changes natural fire regimes. On the other hand, it is important to understand that Indigenous communities have knowledge of and value the role of fire in protecting the diversity of biological and cultural ecosystems ([39], [6]). In México, fire management concept mostly favours an integrated approach that includes ecological, silvicultural, social, economic, preventive and suppressive aspects, as well as the technical and cultural uses of fire, to maximise the positive and minimise the negative effects of fire, preserve or restore fire regimes, and reduce wildfires ([39], [30], [38]).

A fire regime is a pattern of repeated fires through time, expressed as their frequency, season, type, severity and extension over a particular landscape ([44]). In this study, we consider a base fire regime as a natural fire regime under some human influence but not enough to alter or degrade the ecosystem. Whenever fire is excluded or occurs more frequently due to human activity and/or under conditions different from the natural ones (for example, season), the fire regime is altered and will change the ecosystem ([30], [31]). This alteration in fire regimes, specifically the increasing extent and severity of wildfires, is a growing threat to biodiversity worldwide ([49]).

The most severe fire seasons recorded in México were in 1998 (14,445 wildfires affecting 849,632 ha) and 2011 (12,113 wildfires affecting 956,405 ha - [13]). The year 1998 was one of the three strongest El Niño years ever recorded ([32]).

The Lagunas de Montebello National Park (LMNP) is an important biodiversity asset that contributes to greenhouse gas absorption and other environmental functions. It is also important from a social standpoint given the presence of vulnerable human settlements that depend on forest resources for their survival ([37]). The LMNP is dominated by fire-dependent ecosystems, according to the classification of Myers ([30]); however, it was one of the protected areas of México severely affected by the 1998 fires, as well as the State of Chiapas. Yet the integrated fire management concept is not fully recognised in the State of Chiapas nor in México; this includes the LMNP, where some communities employ fire in diverse ways while others ban its use, which is one of the causes of the mosaic of vegetation in the region.

This study intends to inform forest management decisions in the LMNP, taking into account the interactions between human populations and the environment. Both elements determine the current cultural fire regimes in the region and should be considered in the development of strategies for integrated fire management in a participative and intercultural approach to address global wildfire problems ([40], [7], [8]).

The objectives of this study were to determine the effect of different fire histories on forest species dynamics and the successional routes of the pine-oak-sweetgum forests of the LMNP. We also considered the impact of different fire management approaches currently applied in the LMNP and its surrounding areas in relation to the risks of catastrophic wildfires under future climate change scenarios that predict extreme wet years followed by severe dry years, such as those experienced in this area in the last few decades. We addressed the research question: what is the effect of different fire management options on the vegetation of the LMNP? We tested the hypothesis that the different fire management histories of the LMNP have differently affected ecological succession and forest fire hazard.

Materials and methods

Study area

The LMNP is located in the central-eastern region of the State of Chiapas, México (from 16° 04′ 40″ to 16° 10′ 20″ N and 91° 37′ 40″ to 91° 47′ 47″ W), at an altitudinal range of 1500-1800 m a.s.l. (Fig. 1). The LMNP was stablished in 1959 to protect the high species richness of the mesophyll mountain forests. Some of the causes of the most severe disturbances to these ecosystems and the region’s pine-oak forests are the extensive conversion to coffee plantations and pastureland for cattle ranching, illegal and unmanaged logging, and illicit extraction of local flora and fauna. Frequent and large wildfires began to affect the area due to this fragmentation of the landscape and to climate change, which is associated with more extensive and severe droughts ([37]). Currently, the park’s area (6,425 ha) is under the administration of the National Commission of Natural Protected Areas ([14]).

Fig. 1 - Location of the study area, sampling areas and forest sites.

Results

Dendrochronological studies

Climate variability and wildfire occurrence

The dendrochronological study involved dating a total of 159 P. oocarpa increment cores. The inter-series correlation was 0.396, which was significantly higher than the minimum correlation of 0.328 (p).

Given the proximity of the different study sites ( 0.865 (5 years). Dashed horizontal green and red lines indicate values one standard deviation above or below the mean, respectively; extreme climatic events occurred out of this range. The flame symbols represent wildfires that occurred during extreme dry weather conditions, i.e., in 1984 and 1998.">Fig. 2).

Fig. 2 - Ring-width chronology (residual version) of Pinus oocarpa representative of the dominant climatic conditions in the Lagunas de Montebello National Park. The chronology integrated ring-width series from all sampled sites in the study area. The ring-width index (RWI) of all sampled individuals were smoothed by a flexible decadal line (spline). The dotted horizontal line represents the chronology mean (1.0). The grey vertical curves represent annual values of the dendrochronological series, while the black flexible line is a decadal spline fit to the series to highlight the occurrence of low-frequency events ( > 5 years). Dashed horizontal green and red lines indicate values one standard deviation above or below the mean, respectively; extreme climatic events occurred out of this range. The flame symbols represent wildfires that occurred during extreme dry weather conditions, i.e., in 1984 and 1998.

Based on the annual index values of the chronology and the standard deviation of the mean (5 years). Dashed horizontal green and red lines indicate values one standard deviation above or below the mean, respectively; extreme climatic events occurred out of this range. The flame symbols represent wildfires that occurred during extreme dry weather conditions, i.e., in 1984 and 1998.">Fig. 2), wetter climatic events occurred in 1861, 1868, 1893, 1919, 1946-1947, 1950, and 1996, while extremely dry years occurred in 1859, 1862, 1866, 1870, 1874, 1879, 1889, 1894, 1899-1900, 1916, 1944, 1955, 1971, 1984, and 1998. The LMNP’s local authorities reported the occurrence of large wildfires in 1984 and 1998 (5 years). Dashed horizontal green and red lines indicate values one standard deviation above or below the mean, respectively; extreme climatic events occurred out of this range. The flame symbols represent wildfires that occurred during extreme dry weather conditions, i.e., in 1984 and 1998.">Fig. 2).

Growth series of P. oocarpa

Dendrochronological information (from 1998, when the last large wildfire occurred, to 2018) allowed the estimation of the accumulated radial increase of P. oocarpa rings in the three study sites (Fig. 3). The differences in the accumulated growth of P. oocarpa trees between FUAA (10.14 cm) and FEAT (3.60 cm) sites, and between FUAA and FEAP (3.58 cm) sites were statistically significant (p < 0.01). In contrast, accumulated growth was not significantly different (p > 0.05) between FEAT and FEAP.

Fig. 3 - Mean annual accumulated growth increase of tree rings from P. oocarpa individuals in each study site in the Lagunas de Montebello National Park.

Age structure and recruitment rates of P. oocarpa populations and fire history of the LMNP

Statistically significant relationships (pa, Fig. 4c and Fig. 4e). These results indicate that the increase in diameter was associated with the number of tree rings in each diameter class in each of the three study sites. In addition, our analyses allowed to infer recruitment pulses of new P. oocarpa individuals through the DBH-age relationship and the frequency histogram of individuals by age class (Fig. 4b, Fig. 4d and Fig. 4f).

Fig. 4 - (a), (c) and (e): The relationship between diameter at breast height (cm) and age (years) of P. oocarpa populations in FUAA, FEAP and FEAT, respectively; (b), (d) and (f): frequency histograms of the number of trees per age class (years) for P. oocarpa populations in FUAA, FEAP and FEAT, respectively.

Discussion

Climate patterns associated with wildfires

Climate patterns obtained from the dendrochronological analysis of Pinus oocarpa ring widths showed that the occurrence of large wildfires in the LMNP region was associated with a sequence of extreme humid periods followed by periods of extreme drought (5 years). Dashed horizontal green and red lines indicate values one standard deviation above or below the mean, respectively; extreme climatic events occurred out of this range. The flame symbols represent wildfires that occurred during extreme dry weather conditions, i.e., in 1984 and 1998.">Fig. 2). This pattern was evident for wildfires in 1998 that occurred after a previous humid period in 1996-1997, followed by an extreme dry event in 1998 occasioned by a strong El Niño year. The same situation arose in 1971, when a relatively humid period in 1968-1969 was followed by an extreme dry year and in 1944, when the humid years of 1946-1947 were followed by a severe drought in 1949 (5 years). Dashed horizontal green and red lines indicate values one standard deviation above or below the mean, respectively; extreme climatic events occurred out of this range. The flame symbols represent wildfires that occurred during extreme dry weather conditions, i.e., in 1984 and 1998.">Fig. 2). Forest fuel loads increase and become more available during alternating pluvial and drought periods, respectively ([2], [18]); these events have triggered extensive and intense wildfires in different regions of México and Central and South America ([17], [18], [8]).

Several previous studies on fire frequency in mixed-temperate forests of central and northern México found that humid climatic conditions prevailing 1 to 2 years prior to a dry year favoured fine material production, an important condition for the occurrence of wildfires ([19], [10]). Likewise, the years of recorded wildfires in southern México have been associated with previous moderate La Niña events (rainy years) followed by intense El Niño events (dry years). This was particularly evident during 1987, 1998, 2014 and 2017, when record numbers of 10.942, 14.445, 12.113, and 8.886 wildfires, respectively, were reported ([12]). This pattern reveals the vulnerability of Mexican ecosystems to increasing wildfire risk under the current climate change conditions, particularly in protected areas where fuel management programmes are scarcely applied.

Following the wildfire footprint in the LMNP

The age frequency analysis performed in this study allowed us to reconstruct P. oocarpa recruitment events in the LMNP. The prevailing age structure of plant populations in natural areas is an indicator of the ability of a particular species to respond to environmental disturbances such as wildfires ([16]). For instance, a study of Pinus oocarpa var. ochoterenae Martínez in Sola de Vega, Oaxaca showed that fire removes needle litter and grasses, allowing seed direct contact with the mineral soil, which favours germination and promotes natural regeneration, whereas adult tree mortality is kept low (5.3% - [28]).

Our study casts light on the effects of fire on natural conservation areas under different management conditions, since we can compare the results for sites with a history of limited fire use by humans (FEAP and FEAT) with those for another site where fire has been used for traditional agricultural purposes for a long period (FUAA). In this respect, wildfires are the major disturbance in FEAP and FEAT, while shifting cultivation (involving the clearing and burning of vegetation) represents additional disturbances to the natural system in FUAA.

The age frequency histogram for P. oocarpa trees recovered from FUAA (Fig. 4a, Fig. 4b) shows that the individuals in the dominant age class (49% of the total population) established in this site 20 to 40 years ago, while 30.2% of this population consisted of younger individuals (less than 20 years old).

Considering the above, seed germination requires favourable light and climatic conditions of temperature and humidity, and effective recruitment of new trees takes place a few years after the occurrence of fire ([37]). The dominant recruitment pattern of P. oocarpa in FUAA (Fig. 4b) appears to be associated with the large wildfires that occurred in 1984 and 1998. Effective recruitment of new individuals took place in FUAA in 1985, when humid conditions prevailed in the area as indicated by the larger ring-width indices (RWIs) of P. oocarpa for that year (RWI = +1.11), as well as for 1999 (RWI = +1.04) and 2000 (RWI = +0.89 - 5 years). Dashed horizontal green and red lines indicate values one standard deviation above or below the mean, respectively; extreme climatic events occurred out of this range. The flame symbols represent wildfires that occurred during extreme dry weather conditions, i.e., in 1984 and 1998.">Fig. 2). These humid periods in the LMNP aligned with La Niña events recorded in 1985, 1999, and 2000. These events were followed by 1-2 years of drought, when wildfires were recorded, e.g., in 1984 (RWI = -0.78) and 1998 (RWI = -0.62 - 5 years). Dashed horizontal green and red lines indicate values one standard deviation above or below the mean, respectively; extreme climatic events occurred out of this range. The flame symbols represent wildfires that occurred during extreme dry weather conditions, i.e., in 1984 and 1998.">Fig. 2), paralleling the occurrence of El Niño events ([22]).

Anthropogenic factors also contribute to the environmental and physical conditions of dominant forests ([16]). The local inhabitants’ practice of firewood extraction and use in FUAA promotes the clearing of the forest, letting more incoming light; this also shortens the time of permanence of forest fuels in the zone (Tab. 4), which ameliorates the effect of fires on vegetation. For instance, Pantoja et al. ([33]) recorded a 98.9% survival of P. oocarpa individuals in areas treated with low-intensity prescribed burns, compared to much lower survival rates (37.6%) after severe wildfire in Corazón del Valle, Chiapas.

All these factors seem to contribute to a higher rate of recruitment of new P. oocarpa individuals and favour a higher increase in accumulated radial growth (65% - Fig. 3) in FUAA compared to FEAP and FEAT. A positive effect of fire on the establishment of new P. oocarpa var. ochoterenae individuals was also observed in Sola de Vega, Oaxaca, where 38.850 saplings ha^-1 were recorded two years after a wildfire ([28]). Similar effects were observed in Sololá, Guatemala, five months after experimental prescribed burns, where 3100 seedlings ha^-1 and 1000 sprouts ha^-1 of P. oocarpa were recorded in burned sites vs. 1200 seedlings ha^-1 in the unburned control plot ([34]).

Pinus oocarpa age class distribution showed a different pattern in the strictly protected FEAP site. The majority of individuals were in the mature age classes of 41-60 and 61-80 years, representing over 61% of the population. No individuals under 20 years of age were found in this site, suggesting low regeneration of pines (Fig. 4d). The long exclusion of fires could explain the low occurrence of young pines in FEAP. It is important to note that P. oocarpa is a fire-dependent species that requires frequent low-intensity fires that reduce litter and grasses and allow more light to reach the forest floor, thus enabling tree regeneration ([40]). On the other hand, the 1984 wildfires seem to have promoted the recruitment of this species, since 15% of the population was between 31 and 36 years of age. It is also possible that large wildfires occurred by the end of the 1950s and the beginning of the 1960s, as well as in 1948-1949, which would explain the dominance of 41-60-year and 61-80-year age classes (Fig. 4d).

The climatic data obtained for this region from the dendrochronological study indicate humid conditions in 1950 (RWI = +1.38), 1951 (RWI = +1.05) and 1955-1956 (RWI = +0.90), which occurred after extreme dry years when wildfires occurred, for example, in 1948 (RWI = -0.9), 1949 (RWI = -0.84), and 1951-1952 (RWI = -1), respectively (5 years). Dashed horizontal green and red lines indicate values one standard deviation above or below the mean, respectively; extreme climatic events occurred out of this range. The flame symbols represent wildfires that occurred during extreme dry weather conditions, i.e., in 1984 and 1998.">Fig. 2). The abovementioned humid periods matched weak (1950 and 1951) and moderate (1955-1956) La Niña events, while the 1951-1952 drought period matched a moderate El Niño event ([22]). According to this, and similar to FUAA’s case, P. oocarpa recruitment processes in FEAP are associated with periods of high or even extreme humidity under La Niña conditions.

The dominant age class in FEAT was 61-80 years (35% of the P. oocarpa population). As in the case of FEAP, this class corresponds to mature individuals probably established after the 1948-1949 wildfires. However, unlike FEAP, young trees

The 20-40-year age class was also represented in FEAT (23%), as in the other two sites, indicating that the 1984 wildfires covered the entire study area. The age class with the lowest frequency in FEAT was that of 41-60 years, associated with the 1958 wildfires in the case of FUAA and FEAP. However, the magnitude of these wildfires does not appear to have positively affected the recruitment of young individuals. During interviews, the inhabitants of the FEAT site mentioned an extremely severe wildfire that occurred in the area in 1962 that would correspond to that particular age class. According to the information retrieved from the cross section of one P. oocarpa individual from FEAT, this wildfire occurred in 1962.

The results of the dendrochronological study showed that humid periods after 1962 were not very evident nor very prolonged in FEAT; therefore, it is likely that this condition interfered with the effective recruitment of new individuals in this site. In addition, the significant accumulation of forest fuels shown in previous studies suggests that the 1962 wildfire could have reached a very high magnitude. This wildfire occurred only four years after the 1958 wildfire; therefore, a second wildfire event in such a short time could also have eliminated any recently recruited seedlings and saplings.

The link between extreme humid-dry climatic events and wildfires and subsequent P. oocarpa regeneration in this study reflects the correlation between climate variability and synchronous reproduction in seed plants in most of the Earth’s biomes ([4]). For instance, in boreal forests of North America, the onset of El Niño leads to regional drought and heat pulses that facilitate both wildfires and floral bud initiation in Picea glauca. The masting in the following year, as well as the reduction in litter and creation of canopy openings caused by fire, favours P. glauca recruitment ([4]).

Forest fuel loads

The fuel loads of a particular ecosystem depend on the patterns of growth, site productivity and type of vegetation, and they can increase under natural and human disturbances, including fire exclusion from an ecosystem ([6], [44]). The fuel loads observed in the three sampled sites were apparently related to the type of fire management in each case. Thus, the FUAA site where fire is still used for agricultural purposes had the lowest values for forest fuel load, which were similar to the values for P. oocarpa pine forests of Villaflores, Chiapas (27.3 t ha^-1), where fire is regularly applied for cattle raising and agricultural purposes ([41]).

As expected, the largest accumulation of forest fuels was observed in the sites subject to fire exclusion (p < 0.05). In FEAP, besides fire exclusion, vegetation is sanitised by cutting down trees affected by bark beetles. This may explain, in part, the availability of firm woody fuels observed in this site. In FEAT, in addition to the exclusion of fires, firewood extraction is prohibited in the Ocotal sector. This seems to have contributed to a very high accumulation of forest fuels (68.0 t ha^-1) at this site which surpasses the loads recorded for FEAP and is even higher than those previously found in a tropical pine-oak forest with several years of fire exclusion (45.2 t ha^-1), located in a similar region in Villaflores, Chiapas ([42]).

Fuels are one of the three factors, the others being weather and topography, that determine fire behaviour. Thus, when there is accumulation of fuels due to fire exclusion, wildfire incidence, intensity and severity can increase ([30]). These wildfires can transform into large forest fires, especially under extreme weather conditions.

Latin America has experienced events of this type, such as those that occurred in the Cerrado of Brazil in 2015, Chile in 2017 and Bolivia in 2019; the fire regimes in all these places have been altered due to fire exclusion or suppression policies ([18], [17], [45], [8]). México is no exception; large fires occurred in the critical seasons of 1998 and 2011, which are documented and also recorded in people’s memories. Some studies have demonstrated the negative effects of fire when fuel loads are high or when fires of higher intensity and severity are relatively infrequent. Such is the case reported by Cadena-Zamudio et al. ([9]) in a study of temperate oak and pine-oak forests in Jalisco, México, which showed that the greater the intensity and severity of the fire, the more the soil’s chemical properties (pH and chemical components) are affected and the diversity of species in the understorey is reduced.

The high fuel loads in the LMNP are not very encouraging for the FEAT and FEAP conservation areas, since they represent a high wildfire hazard, especially considering that extreme drought has been predicted for the region during the 2018-2023 period ([27]). The only component of the fire triangle that can be manipulated is fuel. The management of fuel loads in the area is one of the potential solutions to prevent catastrophic wildfires, such as those experienced in 1998. A high-severity fire in the LMNP is likely when drought and an ignition factor coincide, as long as planned fire management and cultural uses of fire continue to be excluded, as pointed out by Ponce-Calderón et al. ([35]). In this case, the authorities should be prepared to fight major wildfires.

Fire use is not only a tool to prevent large wildfires, but also serves to maintain ecological processes, biodiversity and landscapes ([29]). Wynecoop et al. ([50]) highlighted the importance of retaining fuel management practices that are part of the local populations’ cultural knowledge to promote fire reduction and improve the joint management of ancestral territories influenced by fire. The Cerrado of Brazil and the Canaima National Park of Venezuela are examples of how protection of the ecosystem and fire management by local communities can effectively coexist in order to reduce the threat of large wildfires, especially under the effects of climate change ([5], [18]).

Vegetation dynamics associated with wildfire occurrence: three different fire histories in one community

The mesophyll forest in the LMNP is currently reduced to small areas within the park. This ecosystem has a restricted distribution and is not as extensive as the pine and oak forests. While there are indicator species specific to these ecosystems, i.e., Prunus brachybotrya, Synardisia venosa and Styrax magnus ([37]), the mesophyll forest is characterised by a combination of different functional types ranging from deciduous to evergreen species. Liquidambar styraciflua is a characteristic species of the mesophyll forest at 600-2000 m a.s.l., although it does not appear to be a dominant species ([43]). These characteristics of the mesophyll forest, along with high moisture requirements, absence of direct sunlight in its understorey, and structured soils, make it more vulnerable to different types of disturbances, such as wildfires and climate change. The mesophyll forest is concentrated towards the windward sides of the Sierra Madre Oriental (800-1400 m a.s.l.) at the cloud condensation height level ([43]).

There is a rich tradition of natural resource use in Indigenous practice in Mesoamerica and the whole Chiapas region ([24], [35]). Fire, in particular, has been an essential management tool used in agriculture, hunting, and fruit gathering by Indigenous communities throughout Latin America ([7]).

In this sense, the study of the composition, structure and dynamics of the vegetation of the pine-oak-sweetgum forests under different fire histories in and around the LMNP represents an excellent opportunity to evaluate the impact of fire and the climatic variability of the region on the successional dynamics of these ecosystems.

Based on fire-adaptation characteristics, the following vegetation development stages were found in the LMNP (Fig. 5).

Fig. 5 - Vegetation dynamics in the Lagunas de Montebello National Park under fire occurrence and cultural management practices. From top to bottom: mesophyll forest, pine-oak-sweetgum forest, pine forest, and grassland.

Conclusions

The ring-width chronology of P. oocarpa developed for the LMNP, extending from 1856 to 2018, constituted a proxy for the dominant climatic conditions of the study area. Extreme climatic events expressed as one standard deviation above or below the mean were characterised by wet conditions one or two years before a wildfire event and dry conditions in the wildfire year.

New forest stands have emerged in sites where severe wildfires have occurred in the past in dry years (El Niño) which followed wet years (La Niña). We propose the following model of vegetation dynamics that considers natural regeneration and population changes in relation to the occurrence of wildfires in the LMNP.

Under the occurrence of wildfires, processes of ecosystem change will proceed through different paths according to these conditions: when fire frequency is very high (i.e., annual) only grasslands or pastures persist, limiting the establishment of pine forests, but when fires are less frequent, a mixed pine-oak forest is observed. Pine forests also occur under dry conditions. When wildfires are infrequent, oak and sweetgum species form an association with pine trees. In wetter sites where fire has been excluded, species characteristic of mountain mesophyll forest occur, such as oak, sweetgum, Podocarpus spp. and Prunus spp.

In this region, the wide knowledge and practices of local communities provide legitimacy for fire use, and should be integrated into fire management plans, as well as linking forest and biodiversity protection and sustainable livelihoods of the population to fire ecology, fire prevention and firefighting objectives. Thus, traditional cultural practices of rural and Indigenous communities, such as firewood extraction, opening and rehabilitation of firebreaks, and local organisation for controlled burning of agricultural land, can reduce the frequency and impact of wildfires, as a direct consequence of decreased fuel loads preventing the spread of fires. Thus, the support and promotion of indigenous fire practices and prescribed burns could provide low-technology, sustainable solutions to deal with the threats of wildfire and represent a valuable strategy of adaptation to climate change scenarios that predict megafires.

List of abbreviations

The following abbreviations have been used throughout the paper:

* ANOVA: Analysis of variance;

* DBH: Diameter at breast height;

* EPS: Expressed Population Signal;

* INIFAP: Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias;

* IVI: Importance Value Index;

* LMNP: Lagunas de Montebello National Park;

* PROC TTEST: TTEST Procedure in SAS^®;

* PROC NPAR1WAY: SAS/STAT^® NPAR1WAY Procedure;

* R^2: R squared statistical coefficient;

* TL: Time lag:

* RWI: Ring Width Index.

Acknowledgements

We are grateful to the Antelá and Tziscao communities for allowing us to carry out our study in their areas. The lead author acknowledges CONACYT and ECOSUR for funding this study as part of her Ecological and Sustainable Development doctorate research. The participation of BAB was under the framework of the LANDMARC project “LAND-use based Mitigation for Resilient Climate pathways”, the European Union’s Horizon2020 research and innovation programme under grant agreement no. 869367.

Author Contributions

LPPC conceived the study and methodology, took field measurements, curated the samples, processed data, performed statistical analysis and bibliographic investigations, conceptualised the ecological model, and wrote the original draft; DART conceived the study, contributed to data processing and validation, statistical analysis (forest fuels, ecology), bibliographic investigations, methodology, overall supervision, ecological model conceptualisation and review, and the writing, reviewing and editing of the paper; JVD, conceived the study and methodology, took field measurements, curated the data, validated the data processing, carried out statistical analysis (dendrochronology), provided resources, software, supervision, and training, contributed to the writing, reviewing and editing of the paper, and acquired funding for the study; BAB participated in conceptualisation and development of the research paper structure and content, bibliographic investigation, supervision, data processing validation and statistical analysis, ecological model conceptualisation and reviewing, and writing and editing the paper; GCAG, conceived the study, administered the project, provided resources and supervision, wrote, reviewed and edited the paper, and acquired funding; and GVC, conceived the study, provided supervision, and wrote, reviewed and edited the paper.

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