ENVIRONMENTAL CHANGES IN A KEY REGION OF THE PAMPA: A QUANTITATIVE ANALYSIS OF LAND USE IN THE IBIRAPUITÃ ENVIRONMENTAL PROTECTION AREA (RIO GRANDE DO SUL) AND SURROUNDINGS

Objective: To analyze land use patterns in the Environmental Protection Area (APA) of Ibirapuitã (Rio Grande do Sul, RS) and surrounding municipalities between 1985 and 2022. Theoretical framework: Although the South Brazilian Pampa biome is traditionally associated with low-impact agriculture, there is a recent advance in the conversion of natural vegetation in areas of remnants of native fields such as southwestern RS. This region is home to the Ibirapuitã APA, the largest conservation unit in the Pampa biome in RS (more than 300,000 ha). Methods: Based on land use maps obtained from the MapBiomas platform, the areas of each land use class were extracted and quantified using geoprocessing techniques. We then compared the annual trajectories of land use classes in the internal perimeter of the APA and the surrounding area using descriptive statistics. Results: During the analyzed period, the areas of natural land use classes (native grassland and forest) remained stable within the APA, while in the surrounding municipalities the areas of native grasslands were markedly reduced and mostly replaced by agriculture and urbanization. Implications: The Ibirapuitã APA proved to be strategic for the conservation of native fields in this region of the southern Brazilian Pampas. Novelty: By comparing land use trajectories in the internal perimeter and surroundings of the conservation unit, this study provides the first assessment of the effectiveness of the Ibirapuitã APA in maintaining the natural vegetation of the South-Brazilian Pampa biome.


INTRODUCTION
The Pampa is a biome composed predominantly of humid country formations that occupy about 1 million km² in the temperate portion of South America, extending along the entire territory of Uruguay, the Argentine provinces of Corrientes, Entre Rios, Santa Fe, Córdoba, Buenos Aires and La Pampa and, in the Brazilian territory, the southern and western portions of the state of Rio Grande do Sul (Paruelo et al. 2007;Soriano et al. 1992).In Brazil, the Pampa occupies most of the state of Rio Grande do Sul (170,000 km 2 ; about 68% of the state area) (IBGE, 2019)and is responsible for hosting both large water sources and significant biodiversity (Lange & Pillar, 2015;Pallarés et al., 2005).As for the latter, so far more than 12,500 species of animals, plants, fungi and microorganisms have been registered in the area of the South Brazilian Pampa (Andrade et al., 2023).
The occupation of the territory in the South Brazilian Pampa biome was traditionally associated with low impact farming activities (C.Ribeiro & Quadros, 2015).However, from the second half of the 20th century, the occupation in the South Brazilian Pampa biome began to incorporate in a growing way activities of agriculture (mainly crops of soybeans, corn and rice), cultivated pastures and forestry (e.g., eucalyptus, Pinus and acacia) (Oliveira et al., 2017;Vélez-Martin et al., 2015).
This progressive change in land use in the South Brazilian Pampa has resulted in an accelerated process of conversion of native country formations; estimates for the second decade of the 21st century indicate that remnants of native fields occupy about one-third of the original area (Baeza et al., 2022).This process has made the Pampa the second largest native vegetation loss by 2022 (MapBiomas Project, 2023).In all, net loss of native field areas reached about 19,000 km 2 , while agricultural areas increased by about 21,000 km 2 and those of cultivated pastures by 6,000 km2 (Baeza et al., 2022).
The process of the loss of the native country formations did not occur in a homogeneous manner in the South Brazilian Pampa (Lamb & Hasenack, 2009).While field areas of the Central Depression, Coastal Plain and Mission Plateau regions concentrated most of the converted areas (with losses of ~50% of the original area) (Andrade et al. 2015;Vélez-Martin et al. 2015), the southwestern regions of the state of Rio Grande do Sul still hold more than half (i.e., about 60,000 km²) of the original native grassland vegetation (Andrade et al., 2015;Cordeiro & Hasenack, 2009).
However, geoprocessing analyzes restricted to the 21st century have identified an expansion of summer crops (especially soybeans and rice) in the state's Western and Southwest Frontier region (Kuplich et al., 2018) , thus making them the new agricultural frontier of the State (Osmari, 2019).These changes took place in parallel with the reduction of the herd of cattle in historical areas and originally intended for agro-pastoral activities with low environmental impact (Kuplich et al. 2018;Osmari 2019;C. Ribeiro & Quadros 2015).
In this way, identifying the current and historical patterns of land use in this region of the state of Rio Grande do Sul is essential for the monitoring of the areas of native vegetation in the Pampa biome.In this context, the analysis of geospatial information banks (such as land use maps) made publicly available free of charge through open access platforms such as MapBiomas (Souza et al., 2020) it can greatly aid , as well as promote sustainable land use strategies in a region of expanding the agricultural frontier into an endangered biome.

THEORETICAL FRAME
Significant changes in land use in the South Brazilian Pampa began in the 1960s, a period from which Rio Grande do Sul primary production showed strong growth associated with the expansion of soybean and other grain cultivation (C.Ribeiro & Quadros, 2015).Similar trajectories occurred concomitantly along the other ranges of the South American Pampa (i.e., Uruguay and Central-North Argentina) (Pallarés et al., 2005), and intensified in the 1990s and the 21st century (Baeza et al. 2022;Oliveira et al. 2017).
The growing rates of loss of temperate grassland formations have led to the recognition of the deficit in conservation actions and the immediate need for inclusion of these biomes in global monitoring and conservation agendas (IUCN, 2010).In the specific case of Brazil, this includes the official recognition of the South Brazilian Pampa as a biome by the IBGE (Brazilian Institute of Geography and Statistics) in 2004, as well as the subsequent update of its coverage area in 2019 IBGE, 2004IBGE, , 2019. .Brazilian environmental legislation states that it is the duty of the federal entities to promote the protection of the natural heritage by means of public policies, among which are the creation of conservation units, environmental monitoring policies and the stimulation of the sustainable use of ecosystems.In relation to conservation units, however, there is a noticeable deficit in protected areas in the specific case of the South Brazilian Pampa fields, as less than 1% of its area of coverage is located in conservation units (Gerhard Ernst Overbeck et al., 2007), with the notable exception of the Ibirapuitã Environmental Protection Area (APA) (an area of about 317,000 ha), located in the southwestern part of the state (MMA & IBAMA, 1999).
Likewise, government public policies carry out the mapping and monitoring of the suppression of the natural vegetation of Brazilian biomes by means of the processing of satellite images, based on the experience of the Amazon and Cerrado biomes (MMA, 2008).However, the mapping and monitoring of non-forest biomes (such as the South Brazilian Pampa) was included only from the first decade of the 21st century and effectively implemented only from the second decade (MMA, 2008;MMA 365, 2015).In addition to federal monitoring policies, recent multi-institutional initiatives such as MapBiomas Project (i.e., universities, NGOs and startups) (Baeza et al., 2022;Souza et al., 2020)  Although the creation of protected areas and the monitoring help to contain the process of converting natural vegetation, one specificity of the South Brazilian Pampa biome is that the effectiveness of the application of the creation of integral protection units in the specific case is in part insufficient, since the presence of certain disorders is crucial for the maintenance of rural formation and to avoid the advance of forest formations (Gerhard E. Overbeck et al., 2009;Gerhard Ernst Overbeck et al., 2007).
In this way, initiatives aimed at the sustainable use of the fields assume crucial importance for the conservation of the native country formations in the south of Brazil (Gerhard Ernst Overbeck et al., 2007).These include encouraging low-impact livestock activities, which help maintain native fields and discouraging mechanized farming; examples include the Alianza del Pastizal (Altmann & Berger Filho, 2020), an initiative that stimulates livestock farming in native fields and with low environmental impact management strategies (e.g., limited number of heads in each herd to avoid overgrazing and excessive trampling).
The APA of Ibirapuitã was created in 1992 with the objective of proposing to help the conservation of native country formations in the south of Brazil; its area of more than 317,000 ha expands over four municipalities (Alegrete, Santana do Livramento, Quaraí and Rosário do Sul) (MMA & IBAMA, 1999).
In Rio Grande do Sul, the process of converting native fields to agricultural crops was concentrated especially in the region of the fields of the Plateau of Missions, which became the region with the largest area of converted native vegetation (Andrade et al. 2015;Vélez-Martin et al. 2015).However, geoprocessing analyzes restricted to the 21st century have identified increasing conversion trends in areas of native grasslands in the southwest of the state of Rio Grande do Sul (Figure 1).This trend was a result of the transformation of native fields into grain cultivation systems (Rhoden et al., 2022).In addition, a recent study (S.Ribeiro et al., 2021) found that 11 out of 13 Pampa conservation units studied had human land uses (range: 0.8-39%) in the legally defined area, demonstrating that most Pampa conservation units are not immune to anthropogenic pressures Variação na área de cobertura de formação campestre natural nos municípios que abrangem a APA do Ibirapuitã (RS, Brasil) both within and around them, particularly from agriculture.Surprisingly, the APA of Ibirapuitã was not included in the study.

Field of Study
The APA of Ibirapuitã has more than 315,000 ha of area (more than 224,000 ha of native fields only); most of its area is located within the limits of Santana do Livramento municipality (MMA & IBAMA, 1999) (Figure 2; Table 1).For the area of study, the data extracted from the MapBiomas Project corresponded to a total of 13 land use classes.For each class, we perform a descriptive analysis of the annual trajectories of the gross coverage values, and calculate the average, standard deviation and coefficient of variation (CV) of the coverage area of each class based on the 38 replicas (one value for each year) (Table 2).
In addition to thin-scale analysis (i.e., with the raw values of each class originally extracted), we regroup the 13 land use classes into different hierarchies to analyze land use trajectories on thicker scales of analysis.
This analysis step was conducted in two steps and followed the division corresponding to the caption code of Mapbiomas that groups the original classes into larger groupings (accessed on October 1, 2023 via the link: Finally, we compare the coefficient of variation (CV) of the coverage area of each classification (Level 1: 'Natural x Non-natural'; Level 2: subclasses).
At all stages, the analyzes took into account two levels of interpretation: (i) the internal perimeter of the APA ("APA") and (ii) the total area of municipalities outside the perimeter of the APA ("Envolta").

RESULTS AND DISCUSSION
Between 1985 and 2022, there was an increase of areas of coverage of non-natural classes in both the area outside the APA of the surrounding municipalities, although at different intensities (Table 3).However, the trajectories of areas of coverage of the different land use classes showed different patterns between the territory of the APA of Ibirapuitã and in the area outside the APA of the surrounding municipalities.Regarding the classes of natural land use (forest and field), there was a small reduction in native field areas and a small increase in forest formations in the APA of Ibirapuitã (Figure 4).On the other hand, in areas outside the APA the coverage of forest formations remained stable, the areas of native grassland formations suffered a more marked reduction (Figure 5).In all, in this 38-year time window, the total coverage of classes of natural land use presented a trend of stability in the area internal to the APA of Ibirapuitã, and of reduction in the area of the municipalities surrounding the APA of Ibirapuitã (Figure 6).In the study area of this article, the continuous decrease in the coverage of natural vegetation detected in areas outside the APA confirms the trend of transformations of the natural landscape of the Pampa in anthropogenic areas, observed in the last three decades both in the South American Pampa as a whole (Baeza et al., 2022) and in South Brazilian Pampa (Oliveira et al., 2017).In fact, analyzes of suppression rates of native vegetation for Brazilian biomes that used automatic processing of satellite images showed that the South Brazilian Pampa is the second biome that lost most native vegetation for the period between 1985and 2022(MapBiomas Project, 2023).
According to the grouping of land use into large classes, there was an increase in agricultural activities and non-vegetated areas in the external area (Figure 7, Figure 8).More detailed analyzes of the grouping of non-natural classes show that there was an increase in soybean areas and urban areas (Figure 3).
The trend of preferential loss of native grassland formations corroborates recent trends both in the southwest region (Rhoden et al., 2022) and in the southern region of the state of Rio Grande do Sul, where authors detected the advance of agriculture over the fields of the Pampa biome (instead of the other natural formations) (Kuplich et al., 2018).Given that most of the loss of natural areas in the South Brazilian Pampa occurs through the conversion of areas from natural countryside formations to grain cultivation, researchers attribute these transformations as a reflection of the change of agrarian space in Rio Grande do Sul from pastoral activities of livestock production to agro-industrial complexes (Osmari, 2019;C. Ribeiro & Quadros, 2015;Sampaio & Fürstenau, 2003).13 The above results can be explained by the boom in international commodity prices observed in the first two decades of the 21st century; the expansion of soybean production positively impacted the economic variables of both the State of Rio Grande do Sul and the municipalities of the territory of APA (Rhoden et al., 2022).the APA management plan allows for agricultural activities within its perimeter (MMA & IBAMA, 1999), the occupation by minimum levels of soybean and rice crops in the legally defined area is equivalent to the values of the best preserved areas of the Pampa detected in a previous study (values between 1-3%) (S.Ribeiro et al., 2021) corroborating that this APA was essential to guarantee the sustainable use of the territory in this period, maintaining the areas of natural pasture in the biome (Rhoden et al., 2022)even in the context of the development of a new agricultural frontier (MapBiomas Project, 2023).

CONCLUSIONS
In the study area of this article, the continuous decrease in the coverage of natural vegetation detected in areas outside the APA confirms the trend of transformations of the natural landscape of the Pampa in anthropogenic areas, observed in the last three decades both in the South American Pampa as a whole (Baeza et al., 2022) and in South Brazilian Pampa (Oliveira et al., 2017).In fact, analyzes of suppression rates of native vegetation for Brazilian biomes that used automatic processing of satellite images showed that the South Brazilian Pampa is the second biome that lost most native vegetation for the period between 1985and 2022(MapBiomas Project, 2023).
For the period studied (1985 to 2022), the difference in the coefficients of variation of the areas of coverage of the natural and non-natural use classes between the Ibirapuitã APA and the surroundings corroborates the essential role of this conservation unit for the maintenance of the native Pampa biome formations (Rhoden et al., 2022), as it was associated with a lower intensity of decrease in the coverage of natural vegetation (i.e.native grasslands) in the region studied.
Although Ibirapuitã's APA allows for various types of management, the small decrease in grassland formations associated with the small increase in forest formations on its perimeter suggests that the fields were replaced by forests.This pattern informs the need for on-site investigations to verify whether this process occurred due to the exclusion by bovine grazing as detected in other localities (Gerhard E. Overbeck et al., 2009) and is essential for future management plans in the area.
Due to its location in the southwest of the state of Rio Grande do Sul, the area of study of this article is configured as strategic for the development of livestock and at the same time for the conservation of the natural countryside formations of the South Brazilian Pampa.Being located in agricultural frontier areas, discussions about the occupation and sustainable use of native fields, and the development of the South Brazilian Pampa can help increase the proximity of government plans and programs of environmental monitoring to the reality of the Pampian region in the state of Rio Grande do Sul, and thus stimulate the sustainable use of native field areas.
they generate annual maps of land use and Environmental Protection area (Rio Grande do Sul) and Surroundings ___________________________________________________________________________ Rev. Gest.Soc.Ambient.| Miami | v.18.n.1 | p.1-16 | e04234 | 2024.4 coverage, using automatic classification processes applied to satellite images, with the advantage of generating open data, thus making it possible to carry out mapping analyzes for specific areas.

Figure 1 .
Figure 1.Trajectory of the coverage of native vegetation in the total area of coverage of the four municipalities of the APA of Ibirapuitã (Alegrete, Santana do Livramento, Quaraí and Rosário do Sul) between the years 1985 and 2022.Source: Adapted from MAPBIOMAS, collection 8 (MapBiomas Project, 2023).

Figure 2 .
Figure 2. Location of the Ibirapuitã Environmental Protection Area and its surrounding municipalities.Source: Authors, 2023.

Environmental
Changes in a Key Region of the Pampa: A Quantitative Analysis of Land use in the Ibirapuitã Environmental Protection area (Rio Grande do Sul) and Surroundings ___________________________________________________________________________ Rev. Gest.Soc.Ambient.| Miami | v.18.n.1 | p.1-16 | e04234 | 2024.6 3.2 Assessment of Change in Land Use and Coverage in Ibirapuitã and Surrounding APA To evaluate the change in land use in the Ibirapuitã APA coverage area and in the area outside the APA in the municipalities in which it is located, we have extracted annual land use data from the MapBiomas Project (MapBiomas Brasil, 2022; Souza et al., 2020).The MapBiomas Project is a multi-institutional initiative to generate annual maps of land use and coverage from automatic classification processes applied to satellite images.In particular, MapBiomas' ground cover maps are based on Landsat satellite images (pixel size = 30 x 30 m).The full description of the project can be found at [http://mapbiomas.org].Land use data were obtained for the time interval between 1985 and 2022, available in Collection 8 of the Annual Maps of Land Use and Coverage of Brazil (accessed on October 1, 2023 via the link: [https://brasil.mapbiomas.org/colecoes-mapbiomas]. [https://brasil.mapbiomas.org/wpcontent/uploads/sites/4/2023/09/Legenda-Colecao-8-Descricao-Detalhada-PDF-PT-3-1.pdf]:First, we regroup the 13 classes into two classes: 'Natural' and 'Non-natural'.• 'Natural' includes natural vegetation cover (forest and native fields), water bodies, wetlands and rocky outcrops.• The 'Unnatural' class included: agriculture, agricultural-grazing mosaic, urban areas, and other unvegetated areas (e.g., bare soil, assumed as agricultural soil).In a second step, we regroup the classes into five subclasses of land use: • 'Forest'; • 'Natural non-forest training' (wetlands and native fields); • "Agriculture" (all classes of agriculture generally, including forestry); • 'Bodies of water'; and • 'non-vegetated areas' (sandy and urban areas).

Figure 3 .
Figure 3. Map of land use classes in the APA of Ibirapuitã and in the areas outside the APA in the surrounding municipalities in the years 1985 and 2022.Land use in areas outside the APA in the years (A) and 2022 (B).Land use in Ibirapuitã APA coverage area in the years 1986 (A) and 2022 (B), respectively.Source: Authors, 2023.

Figure 4 .
Figure 4. Changes in coverage in the APA territory of Ibirapuitã between 1985.Vertical dotted line indicates the year of creation of the APA of Ibirapuitã (1992).Source: Authors, 2023.

EnvironmentalFigure 5 .
Figure 5. Coverage area trajectories of land use classes in areas outside the APA in the surrounding municipalities between 1985 and 2022.Source: Authors, 2023.

Figure 6 .
Figure 6.Coverage trajectory of the natural and non-natural land use classes in the APA territory of Ibirapuitã and in the areas outside the APA in the surrounding municipalities between 1985 and 2022.Source: Authors, 2023.

EnvironmentalFigure 7 .
Figure 7. Coverage trajectory of land use classes in the territory of the APA of Ibirapuitã and in the areas outside the APA in the surrounding municipalities between 1985 and 2022.Source: Authors, 2023.

Figure 8 .
Figure 8. Coverage trajectory of land use classes for agriculture in the territory of the APA of Ibirapuitã and in the areas outside the APA in the surrounding municipalities between 1985 and 2022.Source: Authors, 2023.

Table 1 .
Total area of the municipalities studied and Total and relative area of the APA of Ibirapuitã in each municipality.

Table 2 .
Average, standard deviation (SD) and coefficient of variation (CV) of land use classes extracted from the MapBiomas Project for the study area.
Environmental Changes in a Key Region of the Pampa: A Quantitative Analysis of Land use in the Ibirapuitã Environmental Protection area (Rio Grande do Sul) and Surroundings ___________________________________________________________________________ Rev. Gest.Soc.Ambient.| Miami | v.18.n.1 | p.1-16 | e04234 | 2024.

Table 3 .
Area of coverage of natural and non-natural classes in 1985 and 2022 in the area of study.