NORMALIZED DIFFERENCE VEGETATION INDEX ANALYSIS USING NDVI AND SAVI INDICES IN THE CONSERVATION UNIT SERRA DA BORBOREMA MUNICIPAL

The nature conservation units (UC) are specially protected territorial spaces (ETEP), with creation, implementation and management provided for by Law 9985/2000, which established the National System of Conservation Units (SNUC). Over 28% of the Brazilian territory is set aside for nature conservation, in a universe of over 2,300 established Units. Paraiba, Northeast region, has 15 (fifteen) Protected Units, representing less than 1% of its territory, and the Municipal Natural Park of Serra da Borborema, classified as Full Protection UC, located in the eastern part of the city of Campina Grande, at coordinates Lat. (S) 07º23'250" and Log. (W) 35º84'331", is the only local UC. Objective : to analyze the vegetation cover of the Park through the: Normalized Difference Vegetation Index (NDVI) and the Soil Adjusted Vegetation Index (SAVI), in the period from June to September 2020. Theoretical Frame : It was used citations and authors, respecting the quadrennium 2019 and 2022, being the main ones listed here: Ministry of Environment, WWF, IUCN, IBAMA and, Felix-Trigueiro


INTRODUCTION
Urbanization has been one of the main causes of change in surface use and occupation worldwide, often with irreparable consequences for the provision of ecosystem goods and services fundamental to human physical, mental, and spiritual well-being, as well as for the maintenance of life on the planet.As strategy for territorial management, facing the anthropogenic advance on natural resources, the Conservation Units (UC), especially protected territorial spaces (ETEPs) and their environmental resources, including territorial waters (Law nº 9. 985,2000) are changing characterization and economic status.These have among their objectives to expand the geographical limits of protection of watersheds, thus becoming important territorial units for the planning and management of water resources showing itself as one of the best strategies to balance this discrepant relationship humanity/nature.
Brazil, with its more than 8.5 million km², allocates only 28% of its territory, around 2.5 million km², to the more than 2,300 Nature Conservation Units Meanwhile, the state of Paraiba, with its 56,467 km² (IBGE, 2021), conserves 348 km² with its 15 Units, being 07 federal and 08 state, which represents less than 1% of its territory.However, Campina Grande, the second city in the state in socioeconomic importance, with its territory of 596 km², has only one Conservation Unit, the Serra da Borborema Municipal Natural Park, without regulation or management instruments, such as an Advisory Council, Management Plan and technical studies, fundamental for the operation of a Conservation Unit, as foreseen by the National System of Conservation Units -Federal Law No. 9985 of July 18, 2000.
The Borborema Municipal Natural Park, located in the eastern part of Campina Grande, in the desert part of Paraiba, was established by Municipal Law No. 7.790 of December 23, 2020 after the de-activation of the Poet Juvenal de Oliveira State Park, in the same geographical location, by State Law 11.797 of October 27, 2020.The area is characterized by presenting the biophysical attributes of a transition area, between Atlantic Forest and Caatinga (typical vegetation in Brazil Northeastern region), with deciduous vegetation, composed of a tropophilous forest, transacting with xerophytic forest, following the classification in ecodynamic regimes, according to Camara (2005), in which the vegetation is based on the textural principles of the surface formations, such as, soil types and vegetation formations, combined with the water balance and climate balance.
All the evaluation of this work was based on Remote Sensing (RS) data, through the capture and recording of electromagnetic energy reflected or emitted by the Earth's surface.According to Jensen (2009), such geotechnology, has long been used in modeling various biophysical parameters of vegetation, measured from indices or dimensional radiometric measurements, which indicate the relative abundance and activity of green vegetation, the percentage of green cover, chlorophyll content, green biomass, and absorbed photosynthetically active radiation.Therefore, vegetation indices (IR) are models resulting from the combination of reflectance levels in satellite images, generally in the red and near infrared bands.Rodrigues, Ribeiro and Vaz (2016) indicate vegetation indexes, such as NDVI (Normalized Difference Vegetation Index) and SAVI (Soil Adjusted Vegetation Index), for usage, monitoring and classifying vegetation, as well as, for studying its structural parameters.NDVI is successfully used to classify global wide vegetation distribution, infer ecological and environmental variabilities, phytomass production, photosynthetic active radiation, and crop productivity, and using NDVI as an indirect measure of environmental complexity and heterogeneity is an interesting approach (Gamarra et al., 2016).

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For Silva et al (2016), the Normalized Difference Vegetation Index (NDVI) or commonly recognized by the acronym in English NDVI (Normalized Difference Vegetation Index), in particular, allows to characterize and quantify biophysical parameters in vegetated areas.The NDVI is a model resulting from the combination of the level of reflectance in satellite images in the red and near infrared bands (Ponzoni & Shimabukuro, 2007), and can be differently affected by the architecture of the canopy, the chemical characteristics of the leaves, the substrate and the presence of water, and such agents interfere in the spectral response of vegetation, modifying the reflectance of targets on the surface (Baret & Guyot, 1991).
According to Huerte (1988), the Soil Adjusted Vegetation Index -SAVI, consists of the equation that has as variables the red and near infrared bands, and aims to minimize the effects of soil brightness on other vegetation indices, by incorporating a constant "L", for soil adjustment in the NDVI equation, keeping the value within the range -1 to +1.
Protected areas is a term that defines a clearly demarcated, recognized, dedicated, and managed geographic space, through legal or other effective means, to achieve the long-term conservation of nature with associated ecosystem services and cultural values (IUCN, 2020), corroborating with the International Union for Conservation of Nature, presented in 1984 a conservation ethic that called into question the urgent need to reorient human actions around environmental conservation issues, having as a fundamental principle the idea that development must be sustainable, i.e., it must provide economic progress and social well-being while always respecting the environment's capacity to support such demands (Souza, 2017).
Brazil has a large number of protected areas in different modalities recognized by the environmental legislation, and instituted as an environmental management instrument, the "Specially Protected Territorial Spaces (ETEPs)", such as the Permanent Preservation Areas (APP), the Legal Reserves (RL) and the Conservation Units (UC), among others.The creation of these areas can be considered an important strategy for controlling the territory since it establishes limits and dynamics for specific use and occupation, and this control and the criteria for use that are normally applied to them are frequently attributed to the valorization of the natural resources existing in them or, still, to the need to safeguard biomes, ecosystems and rare or endangered species (Medeiros, 2005).
In 2018, the Socio-environmental Institute disclosed, through its Protected Areas System (SisArp), that in Brazil there were 151 federal full-protection UCs, which corresponded to about 50,596,214 hectares (ha), and 185 federal sustainable-use UCs, which corresponds to 115,589,811 hectares, which together, total 336 areas and are equivalent to 19.5% of the National territory.
According to Souza (2017), there is a discrepancy in the numbers, when stating that most of the UCs of the Full Protection Unit (UPI) type are of the Park category, accounting for 399 established units.Of these, 329 are from the State sphere, in the Park category, with 205 units, whose objective is the preservation of natural ecosystems of great ecological relevance and scenic beauty, with its use restricted to scientific research and the development of educational activities, environmental interpretation and recreation with contact with nature, ecological tourism.Thus, it is understood that the sphere can be considered the key piece in the protection of a larger number of Full Protection UC's.Although the total number of protection areas that cover this sphere is lower than that of the federal sphere, which denotes the great need for actions and public policies for investment, inspection, expansion, and protection of such areas.
However, even though Brazil is one of the countries that contributed the most in the world to the preservation of nature through the creation of areas of environmental protection against degradation until the year 2008.After that year the country has been suffering from events that contribute to the modification of these areas, or even the extinction of Conservation 5 Units.According to WWF-Brazil (2019) the "life span" of the UCs affected by events that come to harm their existence, considering the time from the creation of the areas until their downgrading, resizing, or declassification was, on average, 15 years.Among the reasons that contribute to the Public Authorities allowing alterations in an area of environmental preservation is the development of the road network.In 2018, for example, about 110 Conservation Units were in the sights of infrastructure projects, which corresponds to an area of approximately 30,000 km², being located mainly in the states of Pará and Amazonas.According to the National Logistics Plan (PNL), which was under consultation until March 2018, and which foresees investments in this area until the year 2025, 80 Conservation Units will be affected by the expansion of roads, seven by railroads and 28 for the expansion of the waterway network, all located in the Amazon biome.Five will be affected by highways and railroads concomitantly, and nine will be within the areas of influence of highways and waterways (WWF -BRASIL, 2019).
Paraiba is the 15th Brazilian state in territorial extension, with 4.1 million inhabitants, in its 56,467 km² (IBGE, 2021), it conserves 348 km² in 15 Units, 07 federal and 08 state, which represents less than 1% of its territory (PARAÍBA, 2020).Campina Grande, the second city in the state in socioeconomic importance, has a territory of 596 km² and has only one Conservation Unit, the Serra da Borborema Municipal Natural Park, still without regulation or management instruments, such as an Advisory Council and management plan, as foreseen by the National System of Conservation Units -Federal Law no.9.985 of July 18, 2000.
The Serra da Borborema Municipal Natural Park has been impacted in its vegetation by infrastructure and leisure works, under the justification of expansion of the local road network and investment in event tourism.Thus, it is essential to analyze the negative impacts caused by these works, in terms of loss of ecosystem services to the city, which correspond to the direct and indirect benefits obtained by humans from the functioning of ecosystems, which conceptually became relevant in the political, economic and scientific fields, being incorporated into conventions and reports on the environment and agriculture of international organizations (Muñoz & Freitas, 2017).
According to the Millennium Ecosystem Assessment (MEA, 2005), ecosystem services can be classified into four categories: provisioning services, regulating services, supporting services, and cultural services.Of these four types, Serra da Borborema Municipal Natural Park provides the regulating services and cultural services directly.Included in the first group of services, which are characteristic of areas with a high density of vegetation, as shown in Figure 1, are the services of air purification, retention of solid particles in suspension, absorption of carbon dioxide, protection of the soil against erosion, maintenance of the microclimate balance and the conservation and knowledge of biodiversity.6 The second group includes the cave paintings (Image 2), recorded in the park's "Pedra do Sapo", which can be explored by schools, universities and other institutions interested in the production of historical and cultural knowledge about the primitive people who lived there.
For Souza (2017), the landscapes of UC's, such as Parks and Reserves, have great importance for society as a strategic resource, as a function of ecosystem services, stock of biodiversity in situ, as well as a place of scenic beauty valued by industrial societies, these being important requirements for their recognition within land planning.
Considering the importance of the Serra da Borborema Municipal Natural Park for the region where it is located, especially for the municipality of Campina Grande, as well as other UC's spread throughout Brazil, such as the Federal Full Protection UC Jamanxim National Park, located in the State of Pará, where 819.2 km² have been affected by railroads (9% of the total area), and knowing that the Park is undergoing intense degradation processes in favor of the country's economic "development", we ask ourselves: how to measure the impacts caused on the vegetation of these UC's because of infrastructure works that are being executed in their legal limits of existence?The answer to this question would be through the analysis of the normalized difference indices -NDVI and SAVI -of these areas, used here as tools for prior assessment of impact on the environment.
For Berger (2019) the Soil Adjusted Vegetation Index (SAVI), with the introduction of a constant "L", seeks to minimize the effect of the soil, and has also been used for forest formations.In the target area of this study, one can see the existence of typical Atlantic Forest vegetation, with large trees.
Therefore, this research aimed to analyze the vegetation cover of the Nature Conservation Unit, belonging to the Full Protection group, the Serra da Borborema Municipal Natural Park, using the normalized difference vegetation indices -NDVI and SAVI, highlighting the transience and endemism characteristics, as well as verifying the conservation potential of the area and its environmental importance for the region, in face of the global climate changes to come.7

Characterization of the study area
The Full Protection Conservation Unit, Serra da Borborema Municipal Natural Park, with approximately 276 ha, is located in the eastern portion of the municipality of Campina Grande, in the hinterland of the state of Paraíba, at coordinates Lat (S) 07º23'250" and Long (W) 35º84'331", bordering the municipality of Massaranduba (Figure 1).The study area is located on the eastern edge of the Borborema plateau, on crystalline rocks of the Precambrian, in the climatic limits of the semi-arid tropical range, in the phytogeographic transition zone of the Agreste (Feliciano & Neto, 2003).According to the Köppen classification, the predominant climate is of type As' -hot and humid, with rains in autumn and winter.
The temperatures vary from 16º to 32º C, the average annual precipitation is 800mm (INMET-SUDENE, 1990), with higher monthly values from April to July, and lower from October to March.
The Park area is characterized as a phytogeographic transition area as it presents typical species from both the Atlantic Forest and Caatinga biomes, including rare and threatened species from both biomes.The UC Serra da Borborema Municipal Natural Park has landscape typologies with interesting values from a natural and cultural point of view, presenting itself as deciduous, composed of a tropophilous forest, both in a small posterior southeastern portion and in the front north/western area, transacting with a xerophilous savanna, and in the central and eastern portions, site of granite outcroppings, from which typically xerophilous vegetation emerges, although at the base of the outcroppings, remnants of typical forest vegetation can be identified.

Methodology
Since the beginning of the 1970s, remote sensing works have made use of sensors from the Landsat -Land Remote Sensing Satellite series of satellites of the National Aeronautics and Space Administration (NASA), which operate in the Visible Region, which includes band 3, comprising all electromagnetic radiation in the 400 to 700nm spectral range.Most of this radiation that falls on the vegetative canopy is absorbed by the photosynthesizing pigments in the mesophyll of the leaves, and in this spectral range, both the reflectance and the transmittance of the leaves are less than 15% (fifteen percent).For the infrared region, the electromagnetic radiations whose wavelengths are between 700 nm and 1 nm, and is divided into three parts: the near infrared (700 to 1,300 nm), which is located in band 4; the mid infrared (1,300 to 2,500 nm) located in band 5; the far infrared (2,500 to 1 nm), located in band 6 of the TM sensor, and in this region of the electromagnetic spectrum, evidence of the mechanism of internal reflection in the leaves is very strong (Novo, 2008).
For this work we used a Landsat 8 OLI satellite image from 09/17/2020 at 12:29:20 pm, provided by the U.S. Geological Survey -USGS, processed using the free software QGis 3.10.In the SEMI AUTOMATIC CLASSIFICATION PLUGIN -SCP complement, the atmospheric correction of the image was performed, and then we used the Raster calculator to calculate the Normalized Difference Vegetation Index (NDVI) and the Soil Adjusted Vegetation Index (SAVI).
The NDVI and SAVI indices vary between values near (-1) for water; near zero (0) for exposed soil; and near (+1) indicating the presence of dense tree vegetation, mainly.Bands 4 and 5 (Near and Red Infrared) were used, being operated through equations ( 1) and (2) proposed by Huete (1988), respectively, and using the correction factor L = 0.50, which adequately adjusts to the reality of the vegetations of the Serra da Borborema Municipal Natural Park.
Therefore, the NDVI is obtained through the ratio of the difference in near infrared (PVI) and red (V) reflectance by the sum of the same variables.This value represents the presence of vegetation, the higher it is, the greater is the vegetative quantity of the site.
The SAVI, an index adjusted from the NDVI, was created to optimize soil-related adjustments, and thus reduce soil "noise" in interaction with textural information such as vegetation type and water load.
The SAVI is defined by the equation: 9 Where: IVP is the near infrared band; V is the red band; L is the adjustment factor for the soil.
The adjustment factor L will depend on the characteristics of the environment, which can assume values ranging from 0.25 to 1, where in the presence of denser vegetation, the value of 0.25 is used; for vegetation with intermediate density, the value of 0.50; for areas with low vegetation density the value of 1 is used (Jensen, 2009).The L = 0.50 was used according to the local reality of the Serra da Borborema Park, then a vegetation map was prepared containing intervals for five classes: high, moderately high, moderate, low and exposed soil.

RESULTS AND DISCUSSION
It was found that the classes that offer greater protection with respect to vegetation cover (high and moderately high) were reduced, and consequently the other classes, i.e., those that show less protection to the soil were shown to have increased in extent.
The Normalized Difference Vegetation Index (NDVI) showed results from 0.4562 to 0.7255.Its lowest values, in the range of 0.4562 to 0.5908, correspond to the areas of exposed soil, roads, rocky outcrops, and water.The highest values presented, 0.6582 to 0.7255, refer to the areas in initial stage of regeneration and the areas occupied by the tropophilous forest physiognomy, with vegetation characteristic of Atlantic Forest, which corresponds to a vegetation with medium density, which were predominant in the previous areas and among the rocky outcroppings, as well as in the areas of the xerophytic forest physiognomy, in the most preserved portions of the Park (East and Southeast).
For the results with greater accuracy of the Normalized Difference Vegetation Index (NDVI), being applied the Soil Adjusted Vegetation Index (SAVI), as evidenced also, in Figure 2 and Image, the results in 05 classes, showed between 0.2861 and 0.4548, The lowest predominant values refer to the rocky outcrops, degraded areas, dam, roads and exposed soil, in the range of 0.2861 to 0.3283.The highest values of this index correspond to the areas of tropophilous forest physiognomy and agropastoral areas in the surroundings.In the eastern portion, where there is a predominance of vegetation physiognomy of xerophytic forest, the index showed intermediate values of 0.3704 to 0.4126, due to a more thinned vegetation, with less canopy cover.
According to Viganó (2011), the NDVI is closely related to the Leaf Area Index (LAI), however one of its limits is the saturation of its data in relation to high values of LAI, which can then justify the increase in the difference between the values of the indices as the density of vegetation increases.Another point to be considered, according to Ponzoni, Shimabukuro and Kuplich (2012), is the influence of canopy shadows on NDVI values.For them, in areas with more spaced vegetation, the data can be overestimated due to the greater action of the plant remains, especially in arboreal vegetation, such as the tropophilous forest type.
Therefore, using the Soil Adjusted Vegetation Index (SAVI), the transitional character of the physiognomy is evident, as well as the changes in the Park area and its surroundings, such as the advance of anthropic activities, mineral exploration, farming and ranching activities, and the opening of access roads to the urban sprawl in the region.

CONCLUSION
This work infers that the urban expansion and the process of land use and occupation, in the city of Campina Grande/PB, advances over areas of scenic, cultural and environmental value, such as the recently created Serra da Borborema Municipal Natural Park, imposing on the region, with exuberant remnants of the typically Brazilian biomes -Caatinga and Atlantic Forest, a worrying anthropic pressure.
By applying the Normalized Difference Vegetation Indices, NDVI and SAVI, the transitional character of the local physiognomy is perceived, with the predominance of Caatinga species in detriment to the seasonality of the Atlantic Forest species, which shape an open canopy, of evident exuberance, which justifies the maintenance of the Conservation Unit that presents itself with a great aptitude for providing environmental and ecosystem services, and as a potential local climatic conditioner, of utmost importance in the face of the influential regional and global climate changes.

Figure 1
Figure 1 Location of the Serra da Borborema Municipal Natural Park Source: Authors 2022 since IBGE -SIRGAS

Figure 2
Figure 2 Map of NDVI and SAVI vegetation indices of the Serra da Borborema Municipal Natural Park, located in the municipality of Campina Grande -PB Source: Authors Normalized Difference Vegetation Index Analysis Using Ndvi and Savi Indices in the Conservation Unit Serra da Borborema Municipal Nature Park, Campina Grande, Paraíba, Brazil _________________________________________________________________________ Rev. Gest.Soc.Ambient.| Miami | v.17.n.1 | p.1-13 | e03116 | 2023.