2.3. Delimitation of permanent preservation areas (APP)
For the delimitation of APP, four classes were considered (Frame 2), according to the criteria established by Law No. 12,651 of May 25, 2012, which establishes criteria, definitions, and limits of APPs [
33]. All methodological steps for mapping the APPs were carried out in the QGIS software, version 3.26, and are presented in
Figure 2.
• Mapping of APP for watercourses:
For watercourses, the "buffer" command was applied to delimit buffer zones of 30 meters on each side, considering that during the rainy season, the width of each watercourse does not exceed 10 meters. However, the BHRI has watercourses that exceed 10 meters in width during the rainy season, and to map them, it was necessary to use land use and land cover data.
After obtaining the land use and land cover data for the BHRI, the Water Bodies were imported in polygonal format, and the Water Bodies class was edited to remove polygons of lakes, lagoons, reservoirs, among others. This allowed for the selection of polygons that delimit watercourses, where each segment with a width greater than 10 meters was re-applied the "buffer" command according to the width as per
Table 3. Subsequently, the "union" command was applied after using the "buffer" command of 30 meters on the watercourses with different categories mentioned in
Table 3, generating the final Watercourse APP results.
Table 2.
Damping width to be used for APP generation according to the width of the water courses.
Table 2.
Damping width to be used for APP generation according to the width of the water courses.
Width of the watercourse (meters) |
Damping width for APP generation (meters) |
30, 40 e 50 |
50 |
60, 80, 90, 100 e 190 |
100 |
220, 240 e 550 |
200 |
• Mapping of the APP for springs:
The springs were manually marked using the QGIS version 3.26 editor, based on the hydrography generated in the previous step. Each watercourse beginning was marked with a point, generating a point vector containing 576 springs. After this step, the "buffer" command available in QGIS version 3.26 was executed to delimit a 50-meter preservation radius around each of the springs, resulting in the delineation of the APP of springs.
• Mapping of the APP of slope:
Using the SRTM (Shuttle Radar Topography Mission) elevation data, specifically SRTM V3 provided by NASA, the Digital Elevation Model (DEM) of the study area was reprojected and added to QGIS version 3.26, where slope values of the BHRI (Base Hidrográfica do Rio Itapemirim) were calculated. Subsequently, slope values were classified, assigning NoData to slopes less than 45 degrees and a value of 1 to slopes greater than this threshold. The resulting raster from this processing was converted to vector, generating the APP of slope.
• Mapping of the APP of top of hill:
The methodology of Silva et al. (2016) was used within the QGIS software version 3.26, and it involves several steps, from image acquisition to obtaining the APP zones, including:
1. Download of SRTM scenes for the study área;
2. Removal of elevation values >= 1800 meters using the "Raster Calculator" tool;
3. Execution of the "r.fill.dir" algorithm to fill spurious depressions in the Digital Elevation Model (DEM) and obtain the Hydrologically Consistent Digital Elevation Model (HCDEM).
4. Inversion of the HCDEM using the following equation, executed via the "Raster Calculator", and obtaining the raster "mdehc_inv":
hcdem_inv = (HCDEM – 10000)*(-1)
5. Execution of the "r.terraflow" algorithm on the "mdehc_inv" raster to obtain the limits of the peaks’ base, resulting in the output raster "limite_bases";
6. Conversion of "limite_bases" to vector format, keeping the same name;
7. Execution of the "Zonal Statistics" tool, using the "limite_bases" vector on the "hcdem" raster. This tool calculates maximum, minimum, mean, range, and other values within the raster, considering the limits of the vector. Output: "zonal_statistics_hcdem";
8. Calculation of the slope, in degrees, from the "hcdem" raster. Output raster: "slope";
9. Execution of the "Zonal Statistics" tool, using the "limite_bases" vector on the "declividade" raster. This aims to obtain the average slope for each area. Output: "zonal_statistics_slope";
10. Selection and extraction of average slopes >= 25 degrees (from the "zonal_statistics_declividade");
11. Calculation of the range in the "zonal_statistics_hcdem" layer (adding the "amplitude" column):
amplitude = altitude_max - altitude_min
Note: after the execution of "Zonal Statistics", the "range" column can be used as equivalent to amplitude, as it represents the difference between the maximum and minimum values.
12. Selection and extraction of features where the value of "amplitude" >= 100 m;
13. Identification of areas where slope >= 25 degrees and amplitude >= 100 m using the "extract by location" tool, predicate "equal";
14. Calculating the minimum height for the upper third: adding a column "terco" to the previously extracted layer (item 13):
terco = altura_maxima - (amplitude/3)
15. Rasterizing the resulting layer from the previous step, using the column "terco" as the output value (output raster: "min_alt_terco"). This procedure can be done using the "v.to.rast" algorithm;
16. Extracting from "hcdem" the pixels where the values are greater than or equal to "min_alt_terco". Output: "app_topofhill";
17. Vectorizing "app_topofhill", exporting only the pixels with value = 1. Output: "app_topofhill_final".
• Mapping of the APP total:
The map of the total APP of BHRI was generated by grouping the data acquired individually from each of the four APP classes. The tabular cross-tabulation technique was used to quantify and determine the percentage of each land use and land cover class in the APP total, through map overlay.
2.5. Selection of forest fragments based on landscape ecology metrics índices
The characterization and evaluation of forest landscape ecology metrics were performed using the QGIS software version 3.26, Fragstats 4.2, and the LecoS plugin 3.0.1, as depicted in
Figure 3.
2.5.1. Landscape ecology metrics indices
The polygons of forest fragments were selected from the land use and land cover map obtained from previous steps, resulting in a vector file of forest fragments. In order to compare conservation indices, the fragments were grouped based on their area, following the classification proposed by Santos et al. (2018), as very small (C1 < 10 ha), small (10 ≤ C2 < 50 ha), moderate (50 ≤ C3 < 100 ha), and large (C4 ≥ 100 ha). A buffer distance of 100 meters was adopted for measuring central area metrics (COUTO-SANTOS; CONCEIÇÃO; FUNCH, 2015). The metrics used for quantifying landscape structure are described in Frame 3.
The equations for landscape metrics used are described in Mcgarigal and Marks (1995), Lang and Blashke (2007), and Peluzio (2017), for the respective groups, as follows:
•
Area metrics: Refers to the sum of the areas of all fragments of the study class (Equation 1).
Where,
CA: sum of the areas of all fragments that belong to a certain class, in hectares; and,
: area of the i-th fragment corresponding to the evaluated class, in hectares.
•
Density and size metrics: Represented by a set of equations that determine the Total number of patches or classes under study (Equation 2), Mean patch size (Equation 3), Standard deviation of mean patch size (Equation 4), and Coefficient of variation of mean patch size (Equation 5).
Where,
NP: total number of patches within the same class or landscape (dimensionless);
number of patches of a class, if NP is at the landscape level, or one patch if NP is at the class level (dimensionless);
MPS: mean patch size, in hectares;
area of the i-th patch in the j-th class, in hectares;
j: number of patches in the class (dimensionless);
PSSD: standard deviation of mean patch size, in hectares;
number of patches in the j-th class (dimensionless); and,
PSCoV: oefficient of variation of mean patch size, in percentage.
•
Metrics of edge: were represented by the sum of the perimeter of Total edge (Equation 6) and the Relative edge density in relation to the study area (Equation 7).
Where,
TE: sum of all edges of class or landscape, in meters;
edge (perimeter) of the i-th fragment, in meters;
ED: edge density, in meters per hectare; and,
CA: total area of the class, in hectares.
•
Shape metrics: were represented by the Mean Shape Index (Equation 8), which equals 1 when the fragments are circular and increases with the irregularity of the shape of the class, and by the Fractal Dimension (Equation 9), where values approach 1 for shapes with simple perimeters and increase with the complexity of the shape of the class.
Where,
MSI: mean shape index (dimensionless);
perimeter of the fragment, in meters;
area of fragment i in class j, in hectares;
J: number of fragments (dimensionless);
number of fragments in the class (dimensionless); and
MPFD: mean fragment perimeter fractal dimension (dimensionless).
•
Metric of central area: It was presented by the total central area (Equation 10), which is the sum of all central areas of the class.
In which,
TCA: total central area, in hectares; and,
interior area of fragment ij, in hectares.
•
Proximity metric: It was presented by the average distance to the nearest neighbor (Equation 11).
Where,
MNND: mean nearest neighbor distance, in meters;
minimum distance from fragment ij to its nearest neighbor, in meters; and,
number of fragments in class i that have a nearest neighbor (adimensional).
2.5.2. Selection of forest fragments using Fuzzy logic
Were considered as having better preservation potencial, the fragments belonging to the “very high” class within the Fuzzy Gamma application.
The making of the database for the application of fuzzy logic was carried out in the computation applications Microsoft Excell® and QGIS 3.26. The database came from the previous methodological stage, using the metrics by fragmente and no longer by class. The landscape mtrics vectors área, border, shape and central area selected for characterization of the importance of the fragments were converted into a raster with a size of 30 meter cell. For each raster image, a pertinence function was defined with a degree of certainty that varies between “0 and 1”, in which the forest fragment with the highest degree of conservation and, consequently, the greatest potential for the passage of the ecological corridor was indicated when the real value of the variable assumes “1” and fragments with zero potential to integrate the ecological corridor were indicated when the real value of the variable assumes “0”, according to [
26].
The structuring to be done with fuzzy logic allows a more realistic point of view when compared to other techniques due to its flexible description. There is less interference from the researcher, since the weight of each variable is not defined, but the maximum, average and minimum for the data to be accepted in the model [
34].
Metrics were selected by excluding redundant metrics and selecting representative metrics from the groups specified in Frame 3, with CA, TE, TCA, ED and MSI considered important for determining the degree of preservation of the fragments and, consequently, the relevance of adhesion of these fragments in the formation of EC.
For the CA, TE and TCA metrics, the increasing sigmoidal functions (Fuzzy Large) were adjusted for each fragment. This function makes it possible to represent the gradual variation around the matrix image, in which fragments that will come to be considered priority with larger area values have a greater chance of assuming a value of 1. The value to be defined at the central point was the one that confers a degree of relevance of 0.5 with a propagation value of 5, which defines the shape and characteristic of the transition zone (χ), expressed by Equation 12.
Where,
μ(χ): corresponds to the degree of membership of the Large function from the variables;
a: parameter that determines the slope of the curve; and,
c: value at the midpoint where μ(χ) acquires 0.5.
The Fuzzy Small function was applied to the ED and MSI metrics, since for these variables, smaller input values will produce outputs closer to 1. The value defined at the central point was the one that gave a degree of membership of 0.5, with propagation value of 5, given Equation 13.
Where,
μ(χ): corresponds to the degree of membership of the Small function from the variables;
a: parameter that determines the slope of the curve; and,
c: value at the midpoint where μ(χ) acquires 0.5.
The Jenks optimization method, which has the spatial reclassification function, was applied to the matrix images of the metrics CA, TCA, TE, ED and MSI, generating the following classes of fragments: very high potential, high potential, moderate potential, low potential and very low potential.
After the previous steps (Fuzzy small and Fuzzy large), Fuzzy Gamma was applied to combine the variables (CA, TE, TCA, ED and MSI). The Fuzzy Gamma operator makes it possible to handle a set of variables that have diffuse values through an overlay technique, in which it allows the increasing effect of the Fuzzy sum and the decreasing effect of the Fuzzy product to be combined [
27,
35]
As the objective of this stage is to select the fragments with the greatest potential for passing through the ecological corridor with values closer to 1, the value of the γ parameter used was 0.90, given by Equation 14.
Where,
µᵢ: Fuzzy association values for i = 1, 2, ..., 5;
n: the raster data layer, that is, the number of variables in the study; and,
γ: a coefficient with values between 0 and 1.
The matrix resulting from the overlapping of variables was called the Landscape Ecology Index (LEI). Finally, the Jenks optimization method, which has the spatial reclassification function, was applied to the raster image resulting from the superimposition of variables (LEI), producing the following classes of fragments: very high potential, high potential, moderate potential, low potential and very low potential.
2.6. Delimitation of the ecological corridor (EC)
For the delimitation of the ecological corridor, an adaptation of the shortest course methodology, proposed by Santos et al (2022), was used, the width of the CE was established at 50% of the Brazilian resolution of CONAMA nº 09/96. The spatial basis used was derived from the previous steps, namely: a) boundary of the Itapemirim river basin, b) land use and occupation, c) permanent preservation areas defined in accordance with current Brazilian legislation, d) index of landscape ecology, e) digital elevation model, f) source polygon, Caparaó National Park, g) destination polygon, Serra das Torres State Natural Monument. In
Figure 4 it is possible to visualize the flowchart containing the methodological steps used for the delimitation of the ecological corridor.
The choice of the UC, Caparaó National Park and Serra das Torres State Natural Monument, as a model area for the application of the methodology was made because both selected units have significant importance for the conservation of the region’s biodiversity, with the presence of endemic and endangered species. Caparaó National Park is known for housing Pico da Bandeira, the third highest point in Brazil, as well as remnants of Atlantic Forest and altitude fields. Serra das Torres State Natural Monument, on the other hand, is a conservation unit created with the objective of preserving a high-altitude cerrado area, also with rare and endangered species, which will allow for the evaluation of the effectiveness of ecological corridor proposals in the context of BHRI, contributing to conservation planning and management in the region.
For least cost path analysis, it will consist of determining the path of least resistance between two points (origin and destination). The resistance of each cell is represented by weights, based on some factor, or combination of factors, that affect the passage through the area.
Cost matrix images were generated, which represent some factor or combination of factors, as in the case of landscape metrics, which affect movement across an area. Costs will be defined in such a way as to prevent or limit the possibility of the corridor passing through undesirable areas such as built-up areas and roads. For each class, the suitability cost was determined, on a scale of 1 to 100, with the highest costs attributed to those where corridors should not pass, according to the different forms of use, giving rise to the friction map. Based on the UCT map, the costs were defined for each class, according to Moreira (2019), as shown in Frame 4. For Permanent Preservation Areas, springs, watercourses, slope and hill top, the complementary costs (SANTOS et al., 2022) (
Table 3), in addition to areas of Subnormal Clusters (SBCL) (
Table 4).
The selected forest fragments, through the analysis of the landscape ecology indices, received a cost value as follows (
Table 5): very high potential received a cost of 1, since it generates a matrix image that allows the passage of the corridor through such areas, very low potential received cost 20, which makes the passage of the corridor in this area less interesting than in areas containing fragments of very high potential, but no less interesting than areas of forestry. The costs attributed to the different classes of forest fragments were based on the association of these classes with the land use and land cover costs in Frame 4.
The slope map was obtained using a 30m SRTM image, divided into three classes, namely: low (slope < 20º); moderate (slope between 20 to 45º) and high (slope > 45º). As terrains with gentler slopes demand less energy expenditure by the fauna, these areas had a lower cost (
Table 6).
Based on the assigned weights, cost matrix images were generated for each parameter. For each raster image, its respective statistical weight was calculated using the Analytic Hierarchy process – AHP [
36] hierarchical method, as shown in
Table 7.
Using the matrix cost images of each parameter and their respective statistical weights, we obtained the total cost matrix image (Equation 15).
In which,
WT: total cost raster image (dimensionless);
: statistical weight of land use and land cover cost raster image (dimensionless);
: statistical weight of riparian forest protection cost raster image (dimensionless);
: statistical weight of landscape ecology index cost raster image (dimensionless);
: statistical weight of slope cost raster image (dimensionless);
: statistical weight of subnormal agglomerate cost raster image (dimensionless);
: land use and land cover cost raster image (dimensionless);
: riparian forest protection cost raster image (dimensionless);
: landscape ecology index cost raster image (dimensionless);
: slope cost raster image (dimensionless); and,
: subnormal agglomerate cost raster image (dimensionless).
2.7. Priority areas for forest recovery
To define the priority areas for recovery and conservation at the BHRI, pedology and lithology data provided by GEOBASES and the thematic map of biological importance available by the Ministry of the Environment - MMA were used. were converted to matrix format (raster), and their respective statistical weight was calculated using the Analytic Hierarchy Process – AHP [
36]. Weights from 1 to 100 were assigned to the degree of relevance that the Information Plans (IP) had regarding the conservation of forest fragments and water resources within the hydrographic basin and the ecological corridor, where the lowest values were considered as areas with greater interest for preservation and the highest value, the places with less interest for environmental conservation. In
Figure 5 it is possible to visualize the flowchart containing the methodological steps used to delimit the priority areas for forest recovery. The weights for each IP were also defined, according to [
37] (Frame 5).
The slope map was made from the Slope tool, using the DEM of the Itapemirim river basin, where it was subsequently reclassified into their respective classes.
With the assigned weights, cost matrix images were generated for each Information Plan (PI). For each raster image, its respective statistical weight was calculated using the Analytic Hierarchy Process – AHP [
36]. The AHP is a multicriteria decision method for judging the relative weights of the different factors in the model. Pairwise comparison matrices are constructed and preferences summarized in terms of relative importance value [
38] (
Table 8).
With the cost matrix images of each parameter and their respective statistical weights, the total cost matrix image was obtained (Equation 16).
In which,
CT: total cost raster image (dimensionless);
: statistical weight of land use and cover cost raster image (dimensionless);
: statistical weight of APP cost raster image (dimensionless);
: statistical weight of pedology cost raster image (dimensionless);
: statistical weight of lithology cost raster image (dimensionless);
: statistical weight of slope cost raster image (dimensionless);
: statistical weight of biological importance cost raster image (dimensionless);
: land use and cover cost raster image (dimensionless);
: APP cost raster image (dimensionless);
: pedology cost raster image (dimensionless);
: lithology cost raster image (dimensionless);
: slope cost raster image (dimensionless);
: biological importance cost raster image (dimensionless).