ABSTRACT
Objective: Analyse and compare the chemical characteristics of the soil in different areas within the PNCG, subjected to prescribed burning in different years (1997, 2019, 2020 and 2021), in order to verify whether these can be considered recovered.
Theoretical framework: Based on scientific articles found on search engines for scientific articles and in books in the areas of protected area management, fire management, fire and soil characteristics. This is to support the explanation of how soil characteristics, mainly chemical ones, can be modified by the action of fire.
Method: Areas with prescribed burns carried out in 1997, 2019, 2020 and 2021 were delimited. Prior to collecting soil samples, a mapping of the sampling points within each area (plot) was carried out. Subsequently, the deformed samples were collected at depths of 0 - 5 cm, 5 - 10 cm and 10 - 20 cm, at three different points in each plot. The data were subjected to statistical analysis to compare the means from the Tukey test at 5% using Sisvar and the graphs were produced with the aid of the PAST program.
Results and conclusion: Prescribed burning influenced the base contents regardless of the depth analyzed and the period. The fire increased the availability of elements such as Ca, Mg, P, K, Cu, Fe, Mn and B, however, the increase in the contents of these elements, in general, did not remain for more than one year. Thus, it affected the content of OM, SB, CTC and V% of the soil.
Implications of the research: These results indicate that significant fire activity occurs primarily in periods close to the time of its occurrence. Therefore, prescribed burning is a practice in which fire rapidly affects the chemical characteristics of the soil. As soon as the environment begins to produce more organic material, these tend to return to their natural conditions. Therefore, prescribed burning may be recommended for conservation areas in order to reduce potential forest fires.
Originality/value: Controlled use of fire to reduce combustible material in conservation areas, to avoid fire events during dry periods.
Keywords: Controlled Fire, Soil Chemical Properties, Conservation Unit.
RESUMO
Objetivo: Analisar e comparar as características químicas do solo em diferentes áreas dentro do PNCG, submetidas à queima prescrita em diferentes anos (1997, 2019, 2020 e 2021), a fim de verificar se estas podem ser consideradas recuperadas.
Referencial teórico: Baseado em artigos científicos encontrados em sites de buscas para artigos científicos e em livros nas áreas de manejo de áreas protegidas, manejo do fogo, fogo e características do solo. Isso para embasar a explicação de como as características dos solos, principalmente, as químicas, podem ser modificadas pela ação do fogo.
Método: Foram delimitadas áreas com queimas prescritas realizadas em: 1997, 2019, 2020 e em 2021. Anteriormente as coletas das amostras de solo, foi realizado um mapeamento dos pontos amostrais dentro de cada área (parcela). Posteriormente, as amostras deformadas foram coletadas nas profundidades 0 - 5 cm, 5 - 10 cm e 10 - 20 cm, em três pontos diferentes de cada parcela. Os dados foram submetidos às análises estatísticas para as comparações das médias a partir do teste de Tukey a 5% utilizando-se o Sisvar e os gráficos foram produzidos com auxílio do programa PAST.
Resultados e conclusão: A queima prescrita influenciou nos teores de bases independentemente da profundidade analisada e do período. O fogo aumentou a disponibilidade de elementos como Ca, Mg, P, K, Cu, Fe, Mn e B, porém, a elevação nos teores destes elementos, em geral, não permaneceu por mais de um ano. Dessa forma, isso afetou o teor de MO, a SB, a CTC e a V% do solo.
Implicações da pesquisa: Esses resultados indicam que a ação significativa do fogo se dá, basicamente, em períodos próximos da sua prática. Sendo assim, a queima prescrita é uma prática em que o fogo afeta rapidamente as características químicas do solo, tão logo o ambiente começa a produzir mais material orgânico, essas tendem a voltar as suas condições naturais. Portanto, esse tipo de queima poderá ser indicada para áreas de conservação, a fim de reduzir possíveis incêndios florestais.
Originalidade/valor: Utilização do fogo de forma controlada para redução de material combustível em áreas de conservação, para evitar eventos de incêndios em períodos de seca.
Palavras-chave: Fogo Controlado, Propriedades Químicas do Solo, Unidade de Conservação.
RESUMEN
Objetivo: Analizar y comparar las características químicas del suelo en diferentes áreas del PNCG, sujetas a quemas prescritas en diferentes años (1997, 2019, 2020 y 2021), para verificar si pueden considerarse recuperadas.
Marco teórico: Basado en artículos científicos encontrados en buscadores y libros sobre gestión de áreas protegidas, manejo de incendios, incendios y características del suelo. Esto busca sustentar la explicación de cómo las características del suelo, principalmente las químicas, pueden ser modificadas por la acción del fuego.
Método: Se delimitaron las áreas con quemas prescritas realizadas en 1997, 2019, 2020 y 2021. Antes de recolectar muestras de suelo, se realizó un mapeo de los puntos de muestreo dentro de cada área (parcela). Posteriormente, las muestras deformadas se recolectaron a profundidades de 0 a 5 cm, 5 a 10 cm y 10 a 20 cm, en tres puntos diferentes de cada parcela. Los datos se analizaron estadísticamente para comparar las medias de la prueba de Tukey al 5% utilizando Sisvar, y los gráficos se generaron con la ayuda del programa PAST.
Resultados y conclusión: La quema prescrita influyó en el contenido de la base, independientemente de la profundidad analizada y el período. El fuego incrementó la disponibilidad de elementos como Ca, Mg, P, K, Cu, Fe, Mn y B; sin embargo, este aumento en el contenido de estos elementos, en general, no se prolongó más de un año. Por lo tanto, afectó el contenido de materia orgánica (MO), SB, CTC y V% del suelo.
Implicaciones de la investigación: Estos resultados indican que la actividad significativa de incendios ocurre principalmente en períodos cercanos al momento de su ocurrencia. Por lo tanto, la quema prescrita es una práctica en la que el fuego afecta rápidamente las características químicas del suelo. Tan pronto como el ambiente comienza a producir más materia orgánica, esta tiende a volver a sus condiciones naturales. Por lo tanto, la quema prescrita puede recomendarse en áreas de conservación para reducir la posibilidad de incendios forestales.
Originalidad/valor: Uso controlado del fuego para reducir el material combustible en áreas de conservación y evitar incendios durante períodos secos.
Palabras clave: Incendio Controlado, Propiedades Químicas del Suelo, Unidad de Conservación.
1 INTRODUCTION
Prescribed or controlled fire refers to the use of fire in forest space, applied under meteorological conditions and in accordance with technical precepts that satisfy predetermined and well-formulated management objectives ( Wade and Lunsford , 1989). These authors reiterate that the use of the term "prescribed" is due to the set of operational procedures that ensure that the fire is controlled in its size, intensity and environmental effects.
The use of this type of fire is often necessary to reduce the number of forest fires and/or the susceptibility of areas to these fires, because, according to Soares and Batista (2007), even with the adoption of protectionist practices, every year, fire destroys or damages large areas of forest.
The state of Mato Grosso can benefit from this type of practice, as it has one of the highest rates of fires and deforestation caused by fire every year. These factors have helped to highlight its contribution to regional and global climate change. However, many of these fires occur in conservation units (CU), such as the Chapada dos Guimarães National Park (PNCG).
This conservation unit is located between the cities of Cuiabá and Chapada dos Guimarães, Mato Grosso, within the Cerrado biome, which has suffered annual reductions in its biodiversity due to forest fires, often caused by the improper use of fire. In this sense, the practice of prescribed burning could be valuable, especially in areas belonging to the park, and thus reduce the resulting impacts, as it can contribute to reducing the amount of biomass under the ground that could potentially serve as fuel for uncontrolled fires.
Some studies indicate that fire can influence the chemical and physical characteristics of the soil, depending on the temperature and duration of its action, reducing the ability of vegetation to regenerate after a fire event. However, it can also present broader problems, since, directly and indirectly, particulates affect soil, vegetation, animals and the air, and can spread to different places and affect the local population.
If it is proven that prescribed burning does not significantly affect the chemical characteristics of the soil or if the degradation is quickly recoverable, it may be recommended for the conservation unit under study and, thus, reduce its susceptibility to forest fires that commonly occur every year. It may also be recommended for areas where fire is used to reduce vegetation for the implementation of new crops.
To this end, the present study was developed to analyze the chemical characteristics of the soil in areas subjected to prescribed burning in the years 1997, 2019, 2020 and 2021, within the Chapada dos Guimarães National Park (PNCG) and verify whether these can be considered recovered.
2 THEORETICAL FRAMEWORK
The theoretical framework was based on scientific articles and books published in the areas of protected area management, fire management, fire and soil characteristics . For better understanding, this article presents some items within its theoretical framework, one of which characterizes the practice of prescribed burning; the other explains the differences between controlled burning and forest fire; and a final item, highlighting the chemical changes promoted in the soil after a burning event.
2.1 PRESCRIBED BURNING
Prescribed burning is the use of fire in a qualified manner, under demanding meteorological conditions, in a defined location and to achieve specific results. However, the best-known term in Brazil is controlled burning ( Wade and Lunsford , 1989). For Art (2003), controlled or prescribed burning is the forest management method in which relatively small and controlled fires are set under favorable conditions to avoid the formation of large amounts of brush or dead wood, preventing the most destructive fires during dry seasons.
Thus, it can be said that prescribed burning is a controlled burning and, as the name suggests, it is the controlled use of fire, conducted within pre-established limits of intensity, in order to achieve certain management objectives. If so, fire can also help combat undesirable species and even help promote the development of species with high forage value (Soares, 1995).
This technique consists of the deliberate application of fire to eliminate part of the forest's fuel load, particularly the most easily flammable material, such as herbaceous and shrub species. Therefore, controlled fire, applied under appropriate environmental and meteorological conditions, has been a fuel management tool (Castro et al., 2010).
Controlled burning, as a tool, helps to obtain desirable species in the composition of pastures, stimulating their growth in cases where they do not occur naturally (Rodrigues et al., 2002). Botelho et al. (2008) also indicate that the use of fire confers heterogeneity to the landscape, through the progressive establishment of a mosaic of vegetation patches with different ages. However, for this type of burning to be used, it is necessary to pay attention to certain situations. Therefore, its application in strategic areas aims to gradually replace the fires that occur during the summer period with less intense burning carried out in the winter (Fernandes et al., 2002).
In the case of pastures, for example, according to Jacques (2003), it should be carried out in winter (dry season) to eliminate material scorched by frost and to remove grass rejected by cattle, favoring new leaf growth. This occurs because temperature and relative humidity, wind speed and precipitation affect the potential for fire to spread. High temperatures and long periods of drought cause progressive drying of dead combustible material, and may even affect the water content of green vegetation, increasing the probability of ignition and the ease of fire spread (Soares and Batista, 2007).
Villares (1996) already indicates that this burning should be carried out two days after a good rain, to ensure efficient soil moistening, and in the last hours of the day, to have greater control of the flames. However, in general, the recommendation is that these areas need to be relatively small, with the size of individual burning blocks being advised to be between 10 and 50 hectares (Botelho et al., 2008).
Some authors list the main limitations to the use of fire for the purpose of burning combustible material as being the uncertainties about the ecological effects produced, public perception of fire, operational feasibility in different situations and the advantages in relation to other techniques ( Ascoli and Bovio , 2013; Marino et al., 2014). This last limitation has already been countered by Galiana and Lázaro (2010) who proved that the cost-effectiveness of controlled fire is more favourable compared to mechanical methods.
2.2 USE OF CONTROLLED (PRESCRIBED) FIRE X FOREST FIRE
There is a distinction between fire and controlled burning. According to Ibama (1998), a forest fire is the occurrence of uncontrolled fire, in any vegetative form, whose causes vary from natural to criminal, and may also be associated with accidental forms and, therefore, unexpected by the owner or person responsible for the affected area. Whereas, controlled burning is a rudimentary agricultural practice, which consists of burning natural vegetation, almost always forests, in order to prepare the land for sowing or planting (Feema, 1990).
For Araújo et al. (2005), fire is characterized by the free spread of flames without control due to topographical, climatic conditions and type of vegetation cover, dissipating large amounts of energy and reaching high temperatures. While controlled burning is characterized by the use of fire as a vegetation management tool, controlling its intensity and limits established by law.
The intensity of a forest fire will depend on the available combustible material, which can generate large amounts of energy and reach high temperatures (Soares, 1995). In general, it degrades air quality on a spatial scale, generating ecological and health impacts on people through the release of trace gases and particles into the atmosphere ( Kukavskaya et al., 2017). Meanwhile, the controlled use of fire must follow parameters such as the limits of the area to be burned and the intensity according to the objective of the burning, which can range from controlling flora species to developing plants for pasture foraging (Soares, 1995).
Controlled fire is not a wildfire, and the basic difference between them is intensity. This characteristic determines whether the fire is beneficial or merely destructive ( Úbeda et al., 2009). When implementing this fuel management technique, the fire develops at low intensities, causing insignificant changes in soil characteristics, unlike high-severity fires that can cause negative impacts on the soil ( Certini , 2005).
Furthermore, the temperatures to which forest soils are subjected during controlled fire are largely restricted to the most superficial layer of the soil. It is generally accepted that around 8 to 10% of the heat generated during a forest fire is radiated towards the ground, with this value being even lower when it comes to controlled fire (Castro et al., 2010). As for air temperature, studies carried out in the Cerrado showed that its maximum values, during intense burning events, vary from 85 °C to 884 °C. The residence time for air temperatures greater than 60 °C, for the Cerrado, varies from 100 to 250 seconds (Miranda et al. 1993; Miranda, 2010).
Therefore, the use of fire can be a beneficial practice, but it is necessary to use appropriate techniques to avoid environmental and economic losses. A study conducted in the state of Goiás by Lara et al. (2007) assessed the economic impacts caused by the use of fire on rural properties and concluded that the economic losses for farmers were significant, both for those who used fire as a technique and for those who did not. The cause of this was the lack of knowledge of techniques and the lack of investment in prevention methods.
Accidents involving the use of fire are consequences when this practice is used without adequate preventive measures. Poorly extinguished bonfires during natural resource exploration activities, such as hunting, fishing, logging, and sparks carried by the wind can also cause forest fires (Dias, 2012). Therefore, it can be considered that fire used as controlled burning can cause forest fires, due to the user's lack of knowledge and commitment regarding minimum precautions (Ribeiro and Martins, 2014).
2.3 THE INFLUENCE OF FIRE ON THE CHEMICAL CHARACTERISTICS OF SOIL
With burning, forest biomass and soil organic matter undergo abrupt mineralization, especially in layers up to 0.5 cm deep in the soil, due to ash ( Owensby and Wyrill , 1973; Coutinho, 1990). Thus, as it is a nutrient mineralizing agent, under adequate temperature conditions, fire makes certain nutrients available to the soil, interfering with their availability to the plant (Simon et al., 2016). According to Melo et al. (2006), the action of fire can cause changes in the chemical attributes of the soil, which is subject to the release of CO2 and N, the mineralization of organic matter and the increase in the levels of macronutrients on the soil surface through ash.
Through studies on soil chemistry after burning, Debano et al. (1998) concluded that the N cycle will be modified by burning the soil, as the amount of ammoniacal N is considerably increased. With this action, N is rapidly nitrified and easily leached.
However, Soares and Batista (2007) emphasize that the mineralization of organic matter is dependent on three main factors: the type of vegetation in the studied area, the incorporation of organic matter and the intensity of the flames. In low-intensity fires, there is not enough temperature rise for the disintegration of organic matter to a depth of 2.5 cm.
For Nardoto et al. (2006), with the burning of plant matter there is a great loss of C, N and S through volatilization or suspension of particles. Other elements, such as Ca, Mg and K, require very high temperatures to volatilize and therefore end up being deposited on the soil.
According to Couto et al. (2006), the temperature for volatilization of Ca and Mg is greater than 1,100 °C and this temperature is not reached in burnings in cerrado areas, therefore, the greatest amount of loss occurs through wind. P, which is considered the limiting nutrient in soil fertility, is lost in intermediate quantities between these two groups ( Nardoto et al., 2006).
Pivello and Coutinho (1992), studying the effect of fire in cerrado areas in Brazil, found that 95% of N, 51% of P, 44% of K, 52% of Ca, 42% of Mg and 59% of S can be released into the atmosphere after burning. Studying the chemical modifications of burned soil in native grassland, Rheinheimer et al. (2003) described that, in soil where vegetation was burned, K values were much higher than in unburned units.
Thus, the macronutrients most affected by burning are Ca, K, Mg and S, because they showed a positive correlation with soil OM in burned areas (Couto et al., 2006). However, initially, ash may accumulate on the soil surface, which makes P and exchangeable bases available in mineralized form ( Rheinheimer et al., 2003). According to Freitas and Sant'Anna (2004), plant remains are rich in Ca, making it available in large quantities in the soil, in mineralized form.
Salomão et al. (2019) observed that the use of controlled burning caused an increase in P, K, Ca and Mg in the period of up to three months after the incidence of the flames, in addition to having caused a reduction in the values of exchangeable acidity and potential acidity in the soil. In this case, the percentages of organic matter also showed higher values after the burning action, especially in the medium term.
Regarding the OM content, Takahashi et al. (2018) concluded that its content was higher near the soil surface and higher in burned areas compared to intact areas with natural vegetation. This is due to the accelerated mineralization process caused by the fires. In addition, this process can decrease the concentration of Al 3+ in the surface layer of the soil, increasing the pH value, thus making the soil less acidic.
However, although the burning of plant residues can increase the levels of exchangeable bases and decrease the levels of H + and Al 3+ , it can also, in the long term, decrease soil fertility, since ash is easily carried away by leaching (Oliveira et al., 2014). At this point, the action of fire will result in higher Al saturations (m%) and potential soil acidity (Jacques, 2003).
In a study, Kellman (1985) demonstrated that, in cerrado areas, immediately after the fire, large flows of nutrients appear only on the soil surface (first 10 cm) and are quickly immobilized, probably by adsorption in the exchange complex in the case of cations and by fixation in combination with Fe and Al in the case of P. These increases disappear after three months after the fire.
Contrary to these results, when studying the influence of fires on the soil in two areas of the Tocantins Cerrado, Noleto et al. (2020) found that fire was not a factor capable of modifying the physical and chemical composition, since the macro and micronutrient contents, as well as other soil fertility parameters, did not show significant results in the two areas. There were also no results of interference in soil pH between these areas, since the two presented similar values and the soils were extremely acidic.
3 METHOD
3.1 STUDY AREA
The research was carried out in areas belonging to the conservation unit (UC) of the Chapada dos Guimarães National Park - PNCG (Figure 1), close to the Véu de Noiva Waterfall, where the Cerrado biome predominates (Legal Jurisdiction - Legal Amazon). The park area is 32,630 hectares and is located in the Cuiabá River basin, where the sources of the Coxipó and Manso Rivers are located.
The climate of the region is Aw , characterized by being tropical, with a dry season in winter and rainfall in summer, according to the Köopen and Geiger climate classification. The average local temperature is 24.6 °C and the average annual rainfall is 1,838 mm. According to Alvares et al. (2013), the region presents a diversity of environments due to variations in altitude (250 to 800 m) and relief (hills, plateaus and valleys), with specific plant formations, mainly savannah and grassland, with diverse phytophysiognomies: riparian forest, gallery forest, dry forest, cerradão, cerrado stricto sensu (dense cerrado, typical cerrado, rupestrian cerrado), dirty field, clean field, vereda and palm grove.
3.2 SOIL SAMPLING
Soil collections were carried out in cerrado fragments within the PNCG, where prescribed burning was carried out by employees of the Chico Mendes Institute for Biodiversity Conservation ( ICMbio ), namely: area with burning in 1997, burning in 2019, burning in 2020 and, the last, with burning in 2021 (Figure 2).
All areas have phytophysiognomic characteristics of cerrado sensu stricto; however, those that suffered fires in 2020 and 2021 have plants with lower characteristics and an open canopy. The area that burned in 2019 was in a medium stage (during the analysis period for this study), in which the canopy was able to cover part of the soil and had a greater amount of leaf litter under this soil. In the area that burned in 1997, the canopy was larger and almost completely covered the soil, in addition to presenting a diversity of vegetation with larger height and low-lying plants. The latter was used as a standard for comparison, since there is no area within the UC that has not undergone some type of burning (controlled or wildfire).
3.3 COLLECTION PROCEDURES
From the areas (plots) selected according to the year in which the prescribed burning occurred, the first procedures for collection were the location of each environment and, subsequently, the collection points. In each of the four delimited plots, deformed samples were collected at three different points, at depths of 0 - 5 cm, 5 - 10 cm and 10 - 20 cm. These collections were carried out in two seasonal periods, dry and wet, between the years 2021 and 2022.
To collect each sample, a shovel and hoe were used to open a mini trench, and the sample was removed from the wall of this mini trench at the desired depth. To determine the depth of the trench and thus perform the collection correctly, it was measured using a tape measure. Afterwards, the collected sample was placed in a bucket previously identified according to the depth, to avoid mixing samples between different depths.
At the end of the collections in each plot, the sample was homogenized, forming a composite sample with 300 to 500 grams of soil, which was sent to the laboratory.
These samples were analyzed to obtain the following chemical characteristics: pH (in CaCl 2 ), P (phosphorus, in mg dm -3 ), K (potassium, in mg dm -3 ), Ca+Mg (calcium + magnesium, in cmol c dm -3 ), Al (aluminum, in cmol c dm -3 ), Cu (copper, in mg dm -3 ), Fe (iron, in mg dm -3 ), Mn (manganese, in mg dm -3 ), B (boron, in mg dm -3 ), MO (organic matter, in g dm -3 ), SB (sum of bases, in cmol c dm -3 ), CEC (cation exchange capacity, in cmol c dm - 3 ) and V (base saturation, in %).
3.4 STATISTICAL ANALYSIS
Statistical analyses were performed using principal component analysis (PCA) to study the structure of interrelationships (correlations) between the large number of variables from chemical analyses of soils collected at different depths. According to Dillon and Golldstein (1984) and Reis (2001), using this technique, it is possible to initially identify the isolated dimensions of the data structure and then determine the degree to which each variable is explained by each dimension or factor.
Varimax method of orthogonal rotation of factors was used . Varimax is a process in which the reference axes of the factors are rotated around the origin until some other position is reached. The objective was to redistribute the variance of the first factors to the others and achieve a simpler and theoretically more significant factorial pattern (Reis, 2001). The factors were chosen using the latent root technique, according to Hair Jr et al. (2005).
The factor loading matrix, which measures the correlation between common factors and observable variables, was determined using the correlation matrix, according to Jolliffe (2002). These analyses were performed using SPSS 19 software (SPSS, 2010).
dendrogram of the original responses and the main components was generated , considering the hierarchical Cluster analysis based on the correlation coefficient between the responses.
4 RESULTS AND DISCUSSIONS
4.1 MAIN COMPONENTS FOR ENVIRONMENTS AND SOIL CHEMICAL CHARACTERISTICS
Information regarding principal component analyses for environments considered as 1 (burning in 1997), 2 (burning in 2019), 3 (burning in 2020) and 4 (burning in 2021) and the chemical characteristics of the soils in these environments are presented in Table 1.
Among the environments affected by fire, information related to chemical bases (Ca + Mg), SB, CTC, V% and pH, identified in soil analyses, were characterized as more important than the environments themselves.
Regarding the pH in the 0-5 cm layer, for example, there was a variation between 3.9 in the areas burned in 2019 and 2021 during the rainy season, and 4.3 in the area burned in 2020. This was similar to what happened during the dry season and in the other layers, corroborating that prescribed burning promotes a reduction in soil pH in the first years, due to the combustion of organic material. However, the action of the available bases soon occurs and organic material is once again produced, allowing the soil pH to increase.
According to Faria et al. (2011), the small increase in pH, Ca and Mg values after a period of time after the fire event can be explained by the fact that burning generates oxides, and thus neutralizes acidity and adds these nutrients to the soil. However, this increase is momentary and, soon, the pH will change due to the loss of these ashes and the bases present in them. Brown and Davis (1974) consider that burning can reduce acidity, especially near the soil surface, and this change may be enough to stimulate nitrification and vegetative growth of the understory.
In areas with more organic material under the soil, such as in 1997, there was a reduction in Al availability. According to Costa et al. (2011), as the pH increases, potential acidity tends to decrease. This reduction in Al availability is important because its presence causes a consequent reduction in root growth and development and, therefore, reduces nutrient absorption, which can harm the overall development of the plant (Simon et al., 2016). However, as the pH decreases, potential acidity tends to increase, since pH refers to the free protons in the soil (H + ) and potential acidity is the sum of H + Al (Santos et al., 2014).
However, low pH values were observed in all of them, which is explained by the fact that the study area is in a biome in which the Latosol class predominates . According to Malavolta and Klienmann (1985) , Latosols , which are the majority in the Cerrado, have a high degree of weathering, therefore, their natural fertility is low, they present high acidity and low base contents. This acidification is related to the release of H + into the soil solution, which is an acidifying agent (Da Ros et al., 2017). Therefore, more than 95% of Latosols are dystrophic and acidic, with pH between 4.0 and 5.5 and extremely low available P contents, less than 1 mg dm -3 (Resende et al., 1995). This occurred in the present case.
This influence on soil pH may have occurred as a result of Ca+Mg levels . The average for Ca+Mg was 1.23 cmol c dm -3 in the area burned in 2020, during the rainy season, which occurred after one of the lowest averages in the area burned in 2021, in the 0-5 cm layer. This shows that in the year of the burning, the ash produced probably still acts, with its action being more intense after one year. However, with rapid action, as the Ca+Mg content in the soil soon reduces again.
Considering this same layer, in the dry season, the increase in the Ca+Mg content occurred in 2021, similar to that observed for 2020, and a subsequent reduction in 2019, a period in which, probably, the action of the ash produced by the burning had already been exhausted. It increased again later, due to the action of the organic matter deposited on the soil surface, until reaching the average of 0.50 cmol c dm -3 of the burned area in 1997. This condition is common in Cerrado soils, which tend to be poor in bases, which promotes the observation of a more acidic pH.
Similar results were obtained in studies carried out by Pomianoski et al. (2006) and Salomão et al. (2019) when they observed that burning caused increases in Ca levels, but after one year they returned to the initial values. This increase is linked to the release of oxides in the ash. According to Moreira and Malavolta (2004), the mineralization of OM results not only in the accumulation of total nitrogen (TN), but also of P, K, Ca and Mg. In addition, it leads to greater protection of C and N levels within the soil aggregates, promoting physical stability to the system ( Loss et al., 2011).
The increase in the availability of Ca and Mg probably influenced the values of SB and V, since these elements are bases and are used in the calculations of these chemical characteristics. It can be seen that the prescribed burning promoted an increase in the levels of bases in the period of up to one year after the fire event, in the 0-5 cm layer. However, this availability was rapid, which is why a reduction in this level was already observed in the area burned in 2019. Meanwhile, in the layers below, 5-10 cm and 10-20 cm, the increase in SB occurred in the years following the burning, with subsequent reductions to the values observed in the area burned in 1997. This proves that the effects of burning are rapid and do not last for more than one year after the practice.
In general, the highest V values were observed in the rainy season, due to the increase in base levels, which promoted a reduction in Al content and an increase in soil pH. In the 5-10 cm layer, in the dry season, there was an increase in V from 2021 to 2020, followed by a reduction until reaching the value found in the 1997 area, probably due to what was observed for the CTC in these areas.
4.2 ANALYSIS OF MAIN COMPONENTS BY ENVIRONMENT SUBJECT TO PRESCRIBED BURNING
When analyzing the data groups within each environment using a PCA, it is possible to observe that the area where burning occurred in 1997 (Figure 3) is made up of two distinct groups.
In group 1, the following chemical characteristics were identified: P, K, Al, MO, Cu, B, Mn, Fe and pH; while in group 2, Ca+Mg , SB, CTC and V% were found. This is probably because MO influenced the levels of micronutrients, since it is considered their source, and pH influenced the increase in the availability of P and K and the reduction of Al. By promoting these improvements and, due to the increase in the levels of Ca+Mg , there was an increase in SB, CTC and V%, which are characteristics that require the levels of bases to be known.
According to Meurer (2007), OM regulates the availability of micronutrients such as Cu and Mn, in addition to having the ability to generate negative charges, increasing the soil's CEC.
Regarding K, according to Sobral et al. (2015), its availability depends on organic matter in soils with low clay content and forest cover, in which the deposition of litter is essential for biogeochemical cycling, which probably occurred in the present case. Mendonza et al. (2000) explain that K from burning is leached in the long term, making the soil impoverished. Furthermore, its greater availability in burned soil is due to its mineralization after burning. However, after the production of more organic material, the K content tends to increase again, which was observed in the present case.
According to Chiodini et al. (2013), this occurs because the functional groups present in OM can stably bind to highly positively charged ions. In this case, the formation of stable complexes of humus with Al3 + and other heavy metals detoxifies the soil, because it ends up retaining Al that may be at toxic levels for the plant. This may have improved soil conditions for bases such as Ca+Mg and, consequently, SB and V, as previously mentioned.
In the environment where burning occurred in 2019 (Figure 4), three distinct groups were observed.
In group 1, the following chemical characteristics are present: P, K, Al, MO, B, Cu, Mn, Fe and CEC; in group 2, Ca+Mg , SB and V%; and, in the third group, only pH. This is similar to what occurred when analyzing the main components for the environment with burning in 1997. However, in this case, the CEC was more related to group 1, probably due to the MO content, which also improves cation exchange in the soil.
In the environment where burning occurred in 2020 (Figure 5) there are two distinct groups.
In group 1 are the chemical characteristics: P, K, Al, MO, B, Cu, Mn, Fe, CTC, Ca+Mg , SB and V%; while in group 2, there is pH. Due to this, both burning and the production of organic material affect all these characteristics, increasing or reducing the availability of nutrients and, consequently, the others such as SB, CTC and V%.
In the environment where burning occurred in 2021 (Figure 6), there are two distinct groups.
Group 1 is formed by P, K, Al, B, Cu, Mn, Fe, CTC, Ca+Mg , SB and V%; while in group 2, pH and OM are found. In this case, pH and OM possibly stood out in similar groups, but distinct from the other characteristics because, in the year of the burning, OM will be the most affected, mainly in the most superficial layer, and its rapid mineralization affected the pH at that time.
4.3 DENDROGRAM FOR ANALYSING ENVIRONMENTS SUBJECT TO PRESCRIBED BURNING
When analyzing the environments where prescribed fire occurred, it was found that they can be divided into two groups (Figure 7).
One group includes the 2020 area, which was the one that showed the least similarity to the other areas. This result may be related to the characteristics of the environment itself. The area classified as "burned in 2021" has a slope, which allows the movement and transport of material to the "burned in 2020" area, which, in turn, also has a slope that probably allows the loss of this material, since this area gives access to a precipice.
The second group is subdivided into two subgroups; the first subgroup contains the 2019 area, and the second subgroup contains the 2021 and 1997 areas. This similarity between the 2019 and 2021 areas may have occurred due to the burning of organic material, which allowed an increase in the soil organic matter content and consequent release of micronutrients and P. It was found that, as for micronutrients, their highest levels occurred in the 2019 and 2021 areas. In the 2019 area, probably due to the increase in the deposition of organic material, a few years after the fire event; and in the 2021 area, due to rapid mineralization due to burning. According to Coutinho (1990), the mineralization of vegetation cover by controlled burning increases the availability of nutrients for the vegetative growth of plants at an average depth of five centimeters in the form of ash rich in K, P, and Ca.
Regarding Cu, in general, for the two periods analyzed, levels were observed that decreased as the prescribed burning time progressed. According to Abreu et al. (2007), Cu is retained by humic and fulvic acids , forming stable complexes. Therefore, organic Cu complexes play an important role in both its mobility and its availability to plants ( Alloway , 1995).
This was also observed for Fe levels, which were generally higher during the rainy season. According to Dechen and Nachtigall (2007), OM influences Fe availability, and adequate OM levels provide better use of Fe by plants, due to its acidifying and reducing characteristics, as well as the ability of certain humic substances to form chelates under adverse pH conditions.
B levels were also affected; however, in general, prescribed burning led to a reduction in availability in the first year and an increase after one year, due to the burning of organic material in the dry season; and an increase in the year of burning, in the rainy season, with subsequent reductions. According to Abreu et al. (2007), this occurs because most of the B available to plants is found in soil OM.
To corroborate these results, we can analyze what happened to the OM after the prescribed burning. The OM content decreased in the year of the prescribed burning, in the 0-5 cm layer, which was expected, since one of the objectives of this practice is to reduce the amount of plant material that can serve as fuel. However, when it was burned, the amount of material that can become soil organic matter was reduced. In the rainy season, this reduction occurred one year after the burning, increasing again the following year when, probably, more plant material had already been produced. Meanwhile, in the dry season, the greatest reduction was in 2021 and the increase occurred one year later. This proves that the effects of burning occur quickly and the tendency is for recovery in subsequent years.
According to Braida et al. (2006), soil OM is essential for nutrient cycling, metal complexation and soil biota activity. Therefore, its presence in the most superficial layers, where a large part of the root system is concentrated, is a beneficial aspect in the agricultural system. This is because, for Soares and Batista (2007), the mineralization of nutrients after a fire releases them for immediate absorption by subsequent plants, although many of the soluble elements can be leached through the soil profile or even carried away by floods. However, these effects tend to disappear in the medium term when nutrients are leached by rainfall ( Knicker , 2007).
5 FINAL CONSIDERATIONS
Prescribed burning altered the chemical characteristics of the soil, regardless of the depth and seasonal period analyzed, proving that fire is capable of altering them. Ca+Mg , SB, CTC, V and pH were the chemical characteristics considered most important within the environments studied.
However, its effects are rapid and, within a maximum of two years after the fire has passed, the chemical characteristics of the soil will have returned to natural conditions.
Therefore, prescribed burning is an efficient practice in reducing combustible material and can be used in conservation units, as it only affects the chemical characteristics of the soil for a short time.
Results such as these show that prescribed burning, if properly controlled, can be a viable alternative for large vegetated areas such as national parks, as a practice to prevent forest fires, especially in the Cerrado biome, as is common every year. If the practice is well described in its management plan, the national park can use the practice, after training personnel for it, because, at least with regard to the recovery of the chemical characteristics of the soil, this occurs quickly. This is because prescribed burning does not allow the fire to reach great depths in the soil and/or high temperatures.
Further work should be carried out if the objective is to test this practice in another biome, as the soil characteristics may be different from the conditions observed in the present study.
REFERENCES
Abreu, C. A., Lopes, A. S. & Santos, G. (2007). Micronutrientes. In: Novais, R. F., Alvarez V, V. H., Barros, N. F., Fontes, R. L. F., Cantarutti, R. B. & Neves, J. C. L. (Ed.). Fertilidade do Solo. Viçosa: SBCS. p. 645-736.
Alloway, B. J. (1995). Heavy metals in soils. London: Blackie Academic & Professional.
Alvares, C. A., Stape, J. L., Sentelhas, P. C., Moraes, G., Leonardo, J. & Sparovek, G. (2013). Köppen's climate classification map for Brazil. Meteorologische Zeitschrift, 22(6), 711-728. doi: 10.1127/0941-2948/2013/0507
Araújo, E. A. & Ribeiro, G. A. (2005). Impactos do fogo sobre a entomofauna do solo em ecossistemas florestais. Natureza & Desenvolvimento, 1(1), 75-85.
Art, H. W. (2003). Dicionário de Ecologia e Ciências Ambientais. São Paulo: Companhia de Melhoramentos.
Ascoli, D. & Bovio, G. (2013). Prescribed burning in Italy: issues, advances and challenges. iForest-Biogeosciences and Forestry, 6(2), 79-89. doi: https://doi.org/10.3832/ifor0803-006
Botelho, H., Fernandes, P. & Loureiro, C. (2008). Guia de campo para fogo controlado em matos. Vila Rela: UTAD.
Braida, J. A., Reichert, J. M., Veiga, M. & Reinert, D. J. (2006). Resíduos vegetais na superfície e carbono orgânico do solo e suas relações com a densidade máxima obtida no ensaio proctor. Revista Brasileira de Ciência do Solo, 30(4), 605-614. doi: https://doi.org/10.1590/S0100-06832006000400001
Brown, A. A. & Davis, K. P. (1974). Forest Fire: control and use. New York: Mcgraw-Hill.
Castro, A. M., Meixedo, J. P. & Vivas, A. (2010). Avaliação do impacto do fogo controlado na vulnerabilidade dos solos florestais - uma contribuição. Indústria e Ambiente, 62, 26-28. doi:
Certini, G. (2005). Effects of fire on properties of forest soils: a review. Oecologia, 143, 1-10.
Chiodini, B. M., Silva, A. G., Negreiros, A. B. & Magalhães, L. B. (2013). Matéria orgânica e a sua influência na nutrição de plantas. Cultivando o Saber, 6(1), 181-190.
Costa, M. S. S. M., Pivetta, L. A., Steiner, F., Costa, L. A. M., Castoldi, G. & Gobbi, F. C. (2011). Atributos químicos do solo sob plantio direto afetado por sistemas de cultura e fontes de adubação. Revista Brasileira de Ciências Agrárias, 6(4), 579-587. doi: https://doi.org/10.5039/agraria.v6i4a997
Coutinho, L. M. (1990). O cerrado e a ecologia do fogo. Ciência Hoje, 12(68), 22-30.
Couto, E. G., Chig, L. A., Cunha, C. N. & Loureiro, M. F. (2006). Estudo sobre o impacto do fogo na disponibilidade de nutrientes, no banco de sementes e na biota de solos da RPPN SESC Pantanal. Rio de Janeiro: SESC.
Da Ros, C. O., Silva, V. R., Silvestrin, T. B., Silva, R. F. & Pessotto, P. P. (2017). Disponibilidade de nutrientes e acidez do solo após aplicações sucessivas de água residuária de suinocultura. Revista Brasileira de Tecnologia Agropecuária, 1(1), 35-44.
Debano, L. F., Neary, D. G. & Ffolliott, P. F. (1998). Fire's effects on ecosystems. New York: John Wiley & Sons. 333p.
Dechen, A. R. & Nachtigall, G. R. (2007). Elementos requeridos a nutrição de plantas. In: Novais, R. F., Alvarez V, V. H., Barros, N. F., Fontes, R. L. F., Cantarutti, R. B. & Neves, J. C. L. (Ed.). Fertilidade do Solo. Viçosa: SBCS. p. 91-132.
Dias, G. F. (2012). Queimadas e incêndios florestais, cenários e desafios: subsídios para educação ambiental. Brasília: MMA/IBAMA.
Dillon, W. R. & Goldstein, M. (1984). Multivariate analysis: methods and applications. New York: John Wiley & Sons.
Faria, A. B. C., Blum, C. T., Chitsondzo, C., Lombardi, K. C. & Batista, A. C. (2011). Efeitos da intensidade da queima controlada sobre o solo e diversidade da vegetação de campo em Irati - PR, Brasil. Revista Brasileira de Ciências Agrárias, 6(3), 489-494. doi: https://doi.org/10.5039/agraria.v6i3a932
Feema - Fundação Estadual de Engenharia de Meio Ambiente (RJ). (1990). Vocabulário básico de meio ambiente. Rio de Janeiro: Petrobrás.
Fernandes, P., Botelho, H. & Loureiro, C. (2002). Manual de formação para a técnica do fogo controlado. Vila Real: Utad.
Freitas, L. C. & Sant'anna. G. L. (2004). Efeitos do fogo nos ecossistemas florestais. Revista da Madeira, 13(79), 196-112.
Galiana, L. & Lazaro, A. (2010). Potential barriers and factors for success. Best practices of fire use - prescribed burning and suppression fire programmes in selected case-study regions in Europe. European Forest Institute Research Report, 24, 155-162.
Hair Jr, J. F., Anderson, R. E., Tatham, R. L. & Black, W. C. (2005). Análise multivariada de dados. 5. ed. Porto Alegre: Bookman.
Ibama - Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis. (1998). Programa de prevenção e controle às queimadas e aos incêndios florestais no arco do desflorestamento - PROARCO. Brasília: IBAMA.
Jacques, A. V. A. (2003). A queima das pastagens naturais: efeitos sobre o solo e a vegetação. Ciência Rural, 33(1), 177- 181. doi: https://doi.org/10.1590/S0103-84782003000100030
Jolliffe, I. T. (2002). Principal component analysis. New York: Springer.
Kellman, M. (1985). Nutrient retention by savanna ecosystems: III. response to artificial loading. The Journal of Ecology, 73(3), 963-972.
Knicker, H. (2007). How does fire affect the nature and stability of soil organic nitrogen and carbon? A review. Biogeochemistry, 85(11), 91-118.
Kukavskaya, E. A., Buryak, L. V., Kalenskaya, O. P. & Zarubin, D. S. (2017). Transformation of the ground cover after surface fires and estimation of pyrogenic carbon emissions in the dark-coniferous forests of Central Siberia. Contemporary Problems of Ecology, 10, 62-70.
Lara, D. X., Fiedler, N. C. & Medeiros, M. B. D. (2007). Uso do fogo em propriedades rurais do Cerrado em Cavalcante. Ciência Florestal, 17(1), 9-15. doi: https://doi.org/10.5902/198050981930
Loss, A., Pereira, M. G., Giácomo, S. G., Perin, A. & Anjos, L. H. C. (2011). Agregação, carbono e nitrogênio em agregados do solo sob plantio com integração lavoura-pecuária. Pesquisa Agropecuária Brasileira, 46(10), 1269-1276. doi: https://doi.org/10.1590/S0100-204X2011001000022
Malavolta, E. & Kliemann, H. J. (1985). Desordens nutricionais no cerrado. Piracicaba: Potafos.
Marino, E., Hernando, C., Planelles, R., Madrigal, J., Guijarro, M. & Sebastián, A. (2014). Forest fuel management for wildfire prevention in Spain: a quantitative SWOT analysis. International Journal of Wildland Fire, 23(3), 373-384. doi: 10.1071/WF12203
Melo, V. F., Schaefer, C. E. G. R., Fontes, L. E. F., Chagas, A. C., Lemos Junior, J. B. & Andrade, R. P. (2006). Caracterização física, química e mineralógica de solos da colônia agrícola do Apiaú (Roraima, Amazônia), sob diferentes usos e após queima. Revista Brasileira de Ciência do Solo, 30(1), 1039-1050. doi: https://doi.org/10.1590/S0100-06832006000600013
Mendonza, H. N. S., Lima, E., Anjos, L. H. C., Silva, L. A., Ceddia, M. B. & Antunes, M. V. M. (2000). Propriedades químicas e biológicas de solo de tabuleiro cultivado com cana-deaçúcar com e sem queima da palhada. Revista Brasileira de Ciência do Solo, 24, 201-207. doi: https://doi.org/10.1590/S0100-06832000000100022
Meurer, E. J. (2007). Fatores que influenciam o crescimento e o desenvolvimento das plantas. In: Novais, R. F., Alvarez V, V. H., Barros, N. F., Fontes, R. L. F., Cantarutti, R. B. & Neves, J. C. L. (Ed.). Fertilidade do Solo. Viçosa: Sbcs. p. 65-90.
Miranda, A. C., Miranda, H. S., Dias, I. F. O. & Dias, B. F. S. (1993). Soil and air temperatures during prescribed Cerrado fires in Central Brazil. Journal of Tropical Ecology, 9(3), 313-320. doi: https://doi.org/10.1017/S0266467400007367
Miranda, H. S. (2010). Efeitos do regime de fogo sobre a estrutura de comunidades de Cerrado. Brasília: Ibama.
Moreira, A. & Malavolta, E. (2004). Dinâmica da matéria orgânica e da biomassa microbiana em solo submetido a diferentes sistemas de manejo na Amazônia Ocidental. Pesquisa Agropecuária Brasileira, 39(11), 1103-1110. doi: https://doi.org/10.1590/S0100-204X2004001100008
Nardoto, G. B., Bustamante, M. M. C., Pinto, A. S. & Klink, C. A. (2006). Nutrient use efficiency at ecosystem and species level in savanna areas of Central Brazil and impacts of fire. Journal of Tropical Ecology, 22(2), 191-201. doi: https://doi.org/10.1017/S0266467405002865
Noleto, P. F., Noleto, P. C., Sousa, K. F. & Guimarães, A. P. M. (2020). Influência das queimadas para a qualidade orgânica de duas áreas do cerrado tocantinense. Natural Resources, 10(1), 1-9. doi: https://doi.org/10.6008/CBPC2237-9290.2020.001.0001
Oliveira, A. P. P., Lima, E., Anjos, L. H. C., Zonta, E. & Pereira, M. G. (2014). Sistemas de colheita da cana-de-açúcar: conhecimento atual sobre modificações em atributos de solos de tabuleiro. Revista Brasileira de Engenharia Agrícola e Ambiental, 18(9), 939-947. doi: https://doi.org/10.1590/1807-1929/agriambi.v18n09p939-947
Owensby, C. & Wyrill, J. (1973). Effects of range burning on Kansas Flint Hills soil. Journal of Range Management, 26(3), 185-188. doi: 10.2307/3896687
Pivello, V. R. & Coutinho, L. M. (1992). Transfer of macronutrients to the atmosphere during experimental burnings in an open Cerrado (Brazilian Savanna). Journal of Tropical Ecology, 8(4), 487-497. doi: https://doi.org/10.1017/S0266467400006829
Pomianoski, D. J. W., Dedecek, R. A. & Vilcahuaman, L. J. M. (2006). Efeito do fogo nas características químicas e biológicas do solo no sistema agroflorestal da bracatinga. Boletim de Pesquisa Florestal, (52), 93-118. doi:
Redin, M., Santos, G. F., Miguel, P., Denega, G. L., Lupatini, M., Doneda, A. & Souza, E. L. (2011). Impactos da queima sobre atributos químicos, físicos e biológicos do solo. Ciência Florestal, 21 (2), 381-392. doi: https://doi.org/10.5902/198050983243
Reis, E. (2001). Estatística multivariada aplicada. Lisboa: Silabo.
Resende, M., Curi, N., Resende, S. B. & Corrêa, G. F. (1995). Pedologia: base para distinção de ambientes. Viçosa: Neput.
Rheinheimer, C. D. S. J., Santos, F. P., Barcelos, V. B., Mafra, A. A. L. & Antonio, J. (2003). Modificações nos atributos químicos de solo sob campo nativo submetido à queima. Ciência Rural, 33(1), 49-55. doi: https://doi.org/10.1590/S0103-84782003000100008
Ribeiro, G. A. & Martins, M. C. (2014). Incêndios Florestais. Viçosa: Suprema.
Rodrigues, C. A. G., Crispim, S. M. A & Comastri Filho, J. A. (2002). Queima controlada no Pantanal. Corumbá: Embrapa Pantanal. (Documentos, n.35).
Salomão, A., Emílio, P., Hirle, W. & Eurico, R. (2019). Estudo da influência das queimadas nas propriedades química e banco de sementes dos solos do Vale do Mucuri. Research, Society and Development, 8(12), 1-13.
Santos, L. B., Castagnara, D. D., Bulegon, L. G., Zoz, T., Oliveira, P. S. R., Gonçalves Junior, A. C. & Neres, M. A. (2014). Substituição da adubação nitrogenada mineral pela cama de frango na sucessão aveia/milho. Bioscience Journal, 30(1), 272-281.
Silva, D. M. & Batalha, M. A. (2008). Soil - vegetation relationships in Cerrado under different fire frequencies. Plant and Soil, 311(1-2), 87-96.
Simon, C. A., Ronqui, M. B., Roque, C. G., Desenso, P. A. Z., Souza, M. A. V., Kühn, I. E., Camolese, H. S. & Simon, C. P. (2016). Efeitos da queima de resíduos do solo sob atributos químicos de um latossolo vermelho distrófico do cerrado. Nativa, 4(4), 217-221. doi: 10.14583/2318-7670.v04n04a06
Soares, R. V. (1995). Prevenção e combate a incêndios florestais. In: FÓRUM NACIONAL SOBRE INCÊNDIOS FLORESTAIS, 1.; REUNIÃO CONJUNTA IPEF-FUPEF-SIF, 3. Anais... [S.l.: s.n.]. p. 6-10.
Soares, R. V. & Batista, A. C. (2007). Incêndios florestais: controle, efeito e uso do fogo. Curitiba: Fupef.
Sobral, A. C., Peixoto, A. S. P., Nascimento, V. F., Rodgers, J. & Silva, A. M. (2015). Natural and anthropogenic influence on soil erosion in a rural watershed in the Brazilian southeastern region. Regional Environmental Change, 15(4), 709-720.
Spss. (2010). SPSS Base 19 applications guide. Chicago: SPSS Inc.
Takahashi, R. A., Camargos, A. C. P., Batista, S. P., Santos, P. B., Limache, D. E. S., Castelo, L. R. & Vieira, L. T. A. (2018). Efeito das queimadas nos parâmetros abióticos do solo em áreas de Cerrado no Parque Estadual de Juquery, Franco da Rocha, SP. Vita Scientia, 1(1), 17-20.
Úbeda, X., Outeiro, L., Pereira, P. & Miguel, A. (2009). Incendios forestales en España. Ecosistemas terrestres y suelos. Cerdà, A. & Mataix-Solera, J. (Ed.). Estudios sobre las consecuencias del fuego en las propiedades del suelo y la erosión en Catalunya. Valencia: CÁTEDRA DE DIVULGACIÓ DE LA CIÈNCIA, Universitat de València. p. 25-53.
Villares, J. B. (1966). Melhor queimar em etapas. Coopercotia, 23(204), 53-54.
Wade, D. D. & Lunsford, J. D. (1989). A guide to prescribed fire in southern forests. Tech. Atlanta: Usda Forest Service.
You have requested "on-the-fly" machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Show full disclaimer
Neither ProQuest nor its licensors make any representations or warranties with respect to the translations. The translations are automatically generated "AS IS" and "AS AVAILABLE" and are not retained in our systems. PROQUEST AND ITS LICENSORS SPECIFICALLY DISCLAIM ANY AND ALL EXPRESS OR IMPLIED WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES FOR AVAILABILITY, ACCURACY, TIMELINESS, COMPLETENESS, NON-INFRINGMENT, MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Your use of the translations is subject to all use restrictions contained in your Electronic Products License Agreement and by using the translation functionality you agree to forgo any and all claims against ProQuest or its licensors for your use of the translation functionality and any output derived there from. Hide full disclaimer
© 2025. This work is published under https://rgsa.emnuvens.com.br/rgsa/about/editorialPolicies#openAccessPolicy (the "License"). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.
Abstract
Objective: Analyse and compare the chemical characteristics of the soil in different areas within the PNCG, subjected to prescribed burning in different years (1997, 2019, 2020 and 2021), in order to verify whether these can be considered recovered. Theoretical framework: Based on scientific articles found on search engines for scientific articles and in books in the areas of protected area management, fire management, fire and soil characteristics. This is to support the explanation of how soil characteristics, mainly chemical ones, can be modified by the action of fire. Method: Areas with prescribed burns carried out in 1997, 2019, 2020 and 2021 were delimited. Prior to collecting soil samples, a mapping of the sampling points within each area (plot) was carried out. Subsequently, the deformed samples were collected at depths of 0 - 5 cm, 5 - 10 cm and 10 - 20 cm, at three different points in each plot. The data were subjected to statistical analysis to compare the means from the Tukey test at 5% using Sisvar and the graphs were produced with the aid of the PAST program. Results and conclusion: Prescribed burning influenced the base contents regardless of the depth analyzed and the period. The fire increased the availability of elements such as Ca, Mg, P, K, Cu, Fe, Mn and B, however, the increase in the contents of these elements, in general, did not remain for more than one year. Thus, it affected the content of OM, SB, CTC and V% of the soil. Implications of the research: These results indicate that significant fire activity occurs primarily in periods close to the time of its occurrence. Therefore, prescribed burning is a practice in which fire rapidly affects the chemical characteristics of the soil. As soon as the environment begins to produce more organic material, these tend to return to their natural conditions. Therefore, prescribed burning may be recommended for conservation areas in order to reduce potential forest fires. Originality/value: Controlled use of fire to reduce combustible material in conservation areas, to avoid fire events during dry periods.