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Introduction
Mexico is home to a wide variety of ecosystems, a rich diversity of species, and high levels of endemism (Hernández-López et al., 2020). The state of Chihuahua, located in the northwest of the country, is notable for its wealth of gymnosperms and angiosperms, including over 16 taxa from the genus Pinus (Sánchez-González, 2016) and 34 species with six hybrids from the genus Quercus (Lebgue-Keleng et al., 2015).
Pine-oak forests are globally recognized for their rich biodiversity (Martin et al., 2021); however, both natural and human-related factors contribute to species loss (Singh et al., 2021). In response to this issue, Natural Protected Areas (NPA) have been established with the goal of preserving biodiversity, providing ecosystem services, and maintaining ecosystem representativeness (Tlapa-Almonte et al., 2020). These areas, like the Thick-billed Parrot Sanctuary, are considered biologically significant due to the vital relationship between flora and fauna. The thick-billed parrot (Rhynchopsitta pachyrhyncha Swainson), an endangered species, typically nests in standing dead trees of Populus tremuloides (Michx) as well as in species like Pinus strobiformis Engelm., Pseudotsuga menziesii (Mirb.) Franco and Abies concolor (Gordon) Lindl. ex Hildebr. (Comisión Nacional de Áreas Naturales Protegidas [CONANP], 2023). These conifers fall under the “subject to special protection” category in NOM-059-SEMARNAT-2010 (Secretaría del Medio Ambiente y Recursos Naturales [SEMARNAT], 2010). These conifers are located in the higher mountain regions, within areas classified as relict forests (Martínez-Sifuentes et al., 2022; Requena-Lara et al., 2020).
Altitude is one of the main variables driving changes in the diversity of a community, as it is related to the adaptation of each species and influences structural complexity due to resource availability (Sharma & Kala, 2022). For these reasons, evaluating these changes along an altitudinal gradient is crucial for understanding the ecology of forests (Bhat et al., 2020), especially in NPA, where there is often a strong correlation between structural heterogeneity, biodiversity, and the level of conservation (Duncanson et al., 2023). However, this field has seen limited analysis (Malhi et al., 2018). This is the case with the Thick-billed Parrot Sanctuary, which has studies like those by González-Gaona et al. (2021) and Miranda-Briones et al. (2022); nonetheless, it lacks research focused specifically on the tree layer. For this reason, the objectives were to analyze diversity, structure, and similarity along an altitudinal gradient within the NPA, aiming to understand how changes in altitude can affect a community where relic and endemic species primarily coexist.
Materials and Methods
Study area
The study was conducted along an altitudinal gradient ranging from 2 307 to 2 785 m within the core zone of the Thick-billed Parrot Sanctuary. This area was chosen due to the high biodiversity concentrated within small spaces, where endemic and ecologically important species are distributed, threatened by both natural and human activities (Fattorini et al., 2020). Additionally, one of the most significant factors in mountainous regions is altitude, which causes a temperature decrease of 1 °C for every 150 m. This directly affects the distribution of species in distinct zones, where populations are adapted to specific environmental requirements based on the conditions and landforms in which they live (Fattorini, 2014). The sanctuary is located in the southern part of El Largo y Anexos, municipality of Madera in western Chihuahua (Figure 1). The area has a Cb’(w2)x’ climate, classified as semi-cold sub-humid (García, 2004), with an average annual temperature ranging between 5 and 12 °C and average annual precipitation ranging from 400 to 1 200 mm (Instituto Nacional de Estadística y Geografía [INEGI], 2017a). The sanctuary covers an area of 420 ha and, according to CONANP (2023), the soil is classified as Umbrisol.
Sampling design
Altitudes were classified using the Mexican Elevation Continuum with a resolution of 15 m (INEGI, 2017b). In the core zone comprising the nesting area, three altitudinal intervals were established: 1) 2 307 to 2 466 m, 2) 2 466 to 2 625 m and 3) 2 625 to 2 785 m. At each elevation interval, 10 circular plots, each covering an area of 500 m², were randomly distributed on north-facing slopes. These slopes, with their higher moisture levels, are primarily inhabited by P. tremuloides, P. menziesii, A. concolor, and P. strobiformis-species that are ecologically important and essential for the nesting and feeding of the thick-billed parrot, the flagship species of this NPA (CONANP, 2023).
Coordinates were recorded at the center of each plot using a Garmin® eTrex 20 GPS. Tree measurement data for individuals with a diameter at breast height (d 1.30) ≥ 7.5 cm were recorded using a Haglöf Mantax Blue® caliper, and total height (h) was measured using a Suunto® PM5-15 hypsometer. Genus and species of each individual were also identified
Data analysis
The horizontal structure was evaluated by the distribution of individuals by diameter category with a range of 5 cm; in addition, the importance value index (IVI; Curtis & McIntosh, 1951) was calculated for each altitudinal interval (Table 1).
Table 1 Ecological parameters and importance value index to determine horizontal tree structure.
| Parameter and index | Equation | Variables |
|---|---|---|
| Relative abundance |
|
n
i
= number of individuals recorded for species iN = total number of individuals |
| Relative dominance |
|
gi = basal area of species i G = total basal area |
| Relative frequency |
|
mi = frequency of the presence of species i at the sites M = total number of sites sampled |
| Importance value index |
|
Ar = relative abundance Dr = relative dominance Fr = relative frequency |
The Shannon index (H’) is frequently used to study species diversity; however, according to the parameters used, structural diversity can be evaluated (Morgenroth et al., 2020). In this regard, the maximum value of H’ is reached when abundances are equally distributed in each diameter category:
where,
ln = natural logarithm
pi = proportion of trees of the i-th diameter class
d = number of diameter classes
Species diversity was determined from the Shannon-Wiener (H’) (Shannon, 1948):
where,
ln = natural logarithm
S = number or richness of species
pi = relative abundance of species i (quotient of ni/N)
ni = total number of individuals of the i-th species
N = sum of all individuals recorded
Relative abundance evenness was generated with the Pielou index (J’) (Magurran, 1988):
where,
H’ = Shannon-Wiener index
ln = natural logarithm
S = species richness
To determine the difference between diversity values, the exponential of the Shannon index exp(H') representing the true diversity of order 1 ( q D) was used (Jost, 2006): q D = exp (H’).
Species richness was analyzed with the Margalef index (D mg ) (Margalef, 1972):
where,
N = total number of individuals in the community
ln = natural logarithm
S = total number of species present
Floristic similarity was evaluated using the quantitative Morisita-Horn index (Magurran, 1988):
where,
an i = number of individuals of the i-th species of sample A
bn j = number of individuals of the j-th species of sample B
da = Σan i 2 / aN 2
db = Σbn j 2 / bN 2
aN = number of individuals in sample A
bN = number of individuals in sample B
The validity of the sampling intensity was verified with species accumulation curves; the number of estimated species was generated from the ACE (Abundance-based Coverage Estimator), ICE (Incidence-based Coverage Estimator), Chao 1, Chao 2, Jackknife 1 and bootstrap nonparametric models in the EstimateS 9.1.0 program (Colwell, 2013).
The Shapiro-Wilk test and Levene's homoscedasticity test determined the normality of the data distribution. Subsequently, a one-way ANOVA (p < 0.05) was carried out to check for significant differences in diversity, true diversity, evenness, richness, abundance, and dominance among altitudinal intervals. For the variables that showed differences, Tukey's post hoc mean comparison (α = 0.05) was applied using IBM SPSS Statistics 23 (Zar, 2010).
Results and Discussion
Species accumulation curve
Figure 2 shows that the accumulation curves had similar results, estimating between five to six species, with a defined asymptote in all three altitudinal intervals. Stabilization was achieved starting from the third site. The average coverage values of the species, compared to the non-parametric models, were 100 % for intervals 2 and 3, while interval 1 recorded 99.7 %.
Floristic composition
Three families were recorded in the locality; the most representative was Pinaceae with three genera and five species, while Fagaceae and Salicaceae only presented one genus and one species. The conifers A. concolor, P. strobiformis and P. menziesii are the only ones listed in NOM-059-SEMARNAT-2010 (SEMARNAT, 2010) under the category subject to special protection. In addition, Pinus durangensis Martínez and Quercus sideroxyla Bonpl. are classified as endemic species (Jin et al., 2021; Rodríguez-Acosta & Coombes, 2020), which generates additional biological importance for the floristic and genetic diversity of Mexico represented in the area.
According to Table 2, intervals 1 (2 307 to 2 466 m) and 2 (2 466 to 2 625 m) showed six taxa compared to interval 3 (2 625 to 2 785 m) which harbored five species. This is probably due to the decrease in available habitable surface area due to the topography of the mountains, as well as the decrease in temperature, strong winds, steep slopes and soil creep. However, due to climate change, there is the option that lowland vegetation will migrate upwards (Fattorini et al., 2020) and taxa with fragmented distribution, specialized habitat or endemics will be suppressed because of environmental pressure (Mendoza-Fernandez et al., 2022) and low genetic diversity (Salgotra & Chauhan, 2023), as could be the case of Abies and Pseudotsuga cohabiting in cold and humid areas in the mountains (Chang et al., 2021).
Although the sanctuary is located in northwestern Mexico, a region of greater conifer richness (Gernandt & Pérez-De la Rosa, 2014), NPA had lower values in richness compared to those indicated in other studies conducted within the same physiographic province of the Sierra Madre Occidental (Flores-Morales et al., 2022; Rascón-Solano et al., 2022).
Table 2 Floristic composition at three elevation intervals (I1 = 2 307 to 2 466 m, I2 = 2 466 to 2 625 m, I3 = 2 625 to 2 785 m) at the Thick-billed Parrot Sanctuary in Madera, Chihuahua.
| Species | Common name | Presence | Family |
|---|---|---|---|
| Abies concolor (Gordon & Glend.) Lindl. ex Hildebr. | White fir | I1, I2, I3 | Pinaceae |
| Pinus arizonica Engelm. | Arizona pine | I1, I2, I3 | Pinaceae |
| Pinus durangensis Martínez | Durango pine | I1 | Pinaceae |
| Pinus strobiformis Engelm. | White pine | I1, I2, I3 | Pinaceae |
| Populus tremuloides Michx. | Golden aspen | I2, I3 | Salicaceae |
| Pseudotsuga menziesii (Mirb.) Franco | Douglas-fir | I1, I2, I3 | Pinaceae |
| Quercus sideroxyla Bonpl. | Santa rosa oak | I1, I2 | Fagaceae |
Abundance
According to Table 3, the species P. strobiformis, A. concolor, and P. arizonica had the highest abundance in intervals 2 (2 466 to 2 625 m) and 3 (2 625 to 2 785 m), collectively representing 72.02 % and 91.57 %, respectively, in each interval. In contrast, P. tremuloides had the lowest relative abundance in both intervals, with values below 6 %. On the other hand, in interval 1 (2 307 to 2 466 m), P. strobiformis (35.71 %) and P. arizonica (24.73 %) made up 60.44 %, while A. concolor had the lowest percentage at 0.55 %. These results are consistent with the Land Use and Vegetation Map Series VII (INEGI, 2021), which reports that about 40 % (98 695 ha) of El Largo and Anexos ejido is covered by pine vegetation.
Table 3 Abundance, dominance, frequency, and importance value index (IVI) by altitudinal interval in the Thick-billed Parrot Sanctuary in Madera, Chihuahua.
| Species | Abundance (trees·ha-1) | RA (%) | Basal area (m2·ha-1) | BA (%) | Frequency | RF (%) | IVI (%) |
|---|---|---|---|---|---|---|---|
| Interval 1 (2 307 to 2 466 m) | |||||||
| Pinus strobiformis | 260 | 35.71 | 8.26 | 26.89 | 10 | 23.81 | 28.80 |
| Pinus arizonica | 180 | 24.73 | 9.70 | 31.57 | 10 | 23.81 | 26.70 |
| Pseudotsuga menziesii | 140 | 19.23 | 8.39 | 27.28 | 5 | 11.90 | 19.47 |
| Quercus sideroxyla | 100 | 13.74 | 3.35 | 10.91 | 9 | 21.43 | 15.36 |
| Abies concolor | 4 | 0.55 | 0.25 | 0.80 | 6 | 14.29 | 5.21 |
| Pinus durangensis | 44 | 6.04 | 0.78 | 2.55 | 2 | 4.76 | 4.45 |
| Total | 728 | 100 | 30.73 | 100 | 42 | 100 | 100 |
| Interval 2 (2 466 to 2 625 m) | |||||||
| Pinus strobiformis | 228 | 33.93 | 7.32 | 22.84 | 9 | 21.95 | 26.24 |
| Pinus arizonica | 156 | 23.21 | 8.34 | 26.04 | 10 | 24.39 | 24.55 |
| Pseudotsuga menziesii | 92 | 13.69 | 6.86 | 21.43 | 6 | 14.63 | 16.58 |
| Abies concolor | 100 | 14.88 | 3.49 | 10.91 | 9 | 21.95 | 15.91 |
| Populus tremuloides | 40 | 5.95 | 4.28 | 13.37 | 4 | 9.76 | 9.69 |
| Quercus sideroxyla | 56 | 8.33 | 1.73 | 5.41 | 3 | 7.32 | 7.02 |
| Total | 672 | 100 | 32.03 | 100 | 41 | 100 | 100 |
| Interval 3 (2 625 to 2 785 m) | |||||||
| Pinus strobiformis | 248 | 37.35 | 10.42 | 31.13 | 10 | 22.73 | 30.40 |
| Abies concolor | 208 | 31.33 | 11.98 | 35.78 | 10 | 22.73 | 29.94 |
| Pinus arizonica | 152 | 22.89 | 8.83 | 26.37 | 10 | 22.73 | 24.00 |
| Pseudotsuga menziesii | 44 | 6.63 | 2.04 | 6.09 | 9 | 20.45 | 11.06 |
| Populus tremuloides | 12 | 1.81 | 0.21 | 0.64 | 5 | 11.36 | 4.60 |
| Total | 664 | 100 | 33.47 | 100 | 44 | 100 | 100 |
RA: relative abundance, BA: Relative basal area and RF: Relative frequency.
Figure 3 shows that abundance decreased as altitude increased. Interval 1 had 728 trees·ha-1, interval 2 had 672 trees·ha-1, and interval 3 recorded 664 trees·ha-1 (Table 3). The ANOVA showed a significant difference at least between two intervals (df = 29, F = 7.54, and p = 0.003), and Tukey's test demonstrated that abundance was significantly higher in the lower interval compared to the upper (p = 0.0038) and middle intervals (p = 0.0116). However, there was no significant difference between intervals 2 and 3 (p = 0.8969).
Figure 3 Mean abundance and standard error by altitudinal interval (1 = 2 307 to 2 466 m, 2 = 2 466 to 2 625 m, 3 = 2 625 to 2 785 m) at the Thick-billed Parrot Sanctuary in Madera, Chihuahua. Altitudinal intervals with different letters are significantly different in abundance according to Tukey's test (p < 0.05).
Horizontal distribution
The distribution of individuals by diameter class in intervals 1 (2 307 to 2 466 m) and 2 (2 466 to 2 625 m) presented an inverted ‘J’ shape and the 10, 15 and 20 cm classes recorded more than 55 % of their individuals; interval 3 (2 625 to 2 785 m) also has the characteristic distribution of an irregular forest with a bias to the right and 54.82 % of its abundance was recorded in the 20, 25 and 30 cm classes (Figure 4). These results are similar to those reported by Hernández-Moreno et al. (2020) in irregular forest stands with and without management with a Liocurt curve distribution in the Monarch Butterfly Biosphere Reserve.
Figure 4 Distribution of individuals by diameter category at three altitudinal intervals (1 = 2 307 to 2 466 m, 2 = 2 466 to 2 625 m, 3 = 2 625 to 2 785 m) at the Thick-billed Parrot Sanctuary in Madera, Chihuahua
This behavior generally suggests efficient regeneration, because young individuals will potentially replace mature trees in the community and the high proportion of young trees may be related to the silvicultural inactivity that ceased approximately two decades ago in the sanctuary (CONANP, 2023). It should be noted that forest management generates a shortage of mature trees due to extraction when they reach a certain size (Addo-Fordjour et al., 2022) and reduces the presence of standing dead trees that provide microhabitats (Tavankar et al., 2021) and environmental services (Lutz et al., 2021).
Structural complexity is the result of the variety of species, ages and sizes that a community possesses and directly influences the availability of microhabitats for animals, plants and microorganisms (Zhao et al., 2022). According to the structural diversity analysis with H', the highest value was found in interval 2 with 1.99, followed by interval 1 with 1.93 and interval 3 with 1.91. The maximum value is due to the homogeneous distribution in the diameter classes (Figure 4) and, consequently, the lower values were generated by the unequal distribution in the categories, which may allow the shelter of a higher diversity of associated organisms, because a greater differentiation in the structure increases the development of niches (Stein et al., 2014).
Dominance
Table 3 shows the information on dominance by interval. In the upper interval (2 625 to 2 785 m), A. concolor had the highest dominance value with 11.98 m2·ha-1, followed by P. strobiformis with 10.42 m2·ha-1, while P. tremuloides has the lowest dominance with 0.21 m2·ha-1. For interval 2 (2 466 to 2 625 m), P. arizonica showed the highest basal area with 8.34 m2·ha-1; on the other hand, Q. sideroxyla recorded the lowest figure with 1.73 m2·ha-1. For interval 1 (2 307 to 2 466 m), P. arizonica with 9.70 m2·ha-1and P. menziesii with 8.39 m2·ha-1 were the highest taxa in dominance.
Figure 5 indicates that dominance showed no significant difference in the three altitudinal intervals (df = 29, F = 2.05 and p = 0.154). Other authors such as Khadanga et al. (2023) recorded a positive relationship between dominance and altitude, which can be attributed to the extraction of large trees through logging activities that are more frequent in the lower parts of the mountain. These practices were conducted in the area until the year 2000 (CONANP, 2023).
Figure 5 Average basal area and standard error by altitudinal interval (1 = 2 307 to 2 466 m, 2 = 2 466 to 2 625 m, 3 = 2 625 to 2 785 m) in the Thick-billed Parrot Sanctuary in Madera, Chihuahua. Altitudinal intervals with the same letter indicate statistical similarity in basal area according to Tukey's test (p > 0.05)
Importance value index
According to Table 3, all species had an IVI lower than 50 % for the three altitudinal intervals. This suggests that at the current successional stage of the forest, no single taxon dominates, contrasting with the findings of Quintero-Gradilla et al. (2019) and Rodríguez-Pacheco et al. (2023), who reported that a species from the Pinus genus accounted for approximately 50 % of the ecological weight in each community in disturbed areas.
In the upper interval (2 625 to 2 785 m), P. strobiformis and A. concolor, with values close to 30 %, had the highest ecological weight. This may be due to the inclusion of these species in the NOM-059-SEMARNAT-2010 (SEMARNAT, 2010), and because, being at the highest elevation, they have experienced less anthropogenic impact, leading to greater preservation. Similar results have been reported by Holguín-Estrada et al. (2021) and Matiullah et al. (2022), where Pinus and Abies recorded the highest IVI in temperate forests.
For the middle interval (2 466 to 2 625 m), the species with the highest IVI were P. strobiformis and P. arizonica, each with values around 25 %. Similarly, in the lower interval (2 307 to 2 466 m), P. strobiformis had the highest percentage at 28.8%, followed by P. arizonica at 26.7 %. These results demonstrate the importance of the Pinus genus, likely due to silvicultural activities that altered the structure to favor commercially valuable species (Rendón-Pérez et al., 2021), such as P. arizonica, which holds significant economic interest in Chihuahua (Rascón-Solano et al., 2021).
Diversity indices
Species diversity along an altitudinal gradient is related to changes in temperature, precipitation, productivity, and soil characteristics (Fattorini et al., 2020). The Shannon-Wiener index, with values below 2, indicated low diversity in the tree stratum for the three intervals (Table 4). The H’ results are lower than those recorded by García-García et al. (2019) and López-Serrano et al. (2022) in temperate forests excluded from forestry activities. Although diversity decreased as altitude increased, no significant differences were found between intervals (df = 29, F = 0.95, and p = 0.401). It is important to note that several authors report a decrease in diversity as the altitudinal gradient increases (Lee et al., 2021; Rana et al., 2020).
Table 4 Diversity and richness indices at each altitudinal interval in the Thick-billed Parrot Sanctuary in Madera, Chihuahua.
| Interval | Shannon (H') | Pielou (J’) | True diversity ( q D) | Margalef (D mg ) |
|---|---|---|---|---|
| 1 (2 307 to 2 466 m) | 1.26 ± 0.05 a | 0.85 ± 0.03 a | 3.57 ± 0.20 a | 0.68 ± 0.04 a |
| 2 (2 466 to 2 625 m) | 1.22 ± 0.04 a | 0.77 ± 0.03 a | 3.40 ± 0.15 a | 0.74 ± 0.05 a |
| 3 (2 625 to 2 785 m) | 1.13 ± 0.08 a | 0.73 ± 0.05 a | 3.18 ± 0.26 a | 0.68 ± 0.04 a |
Means ± standard error with the same letter in each column indicate no significant differences between altitudinal intervals according to Tukey's test (p > 0.05).
The analysis of true diversity showed that interval 1 (2 307 to 2 466 m), with 3.57 effective species, is 1.05 and 1.12 times more diverse than intervals 2 (2 466 to 2 625 m) and 3 (2 625 to 2 785 m), respectively. Additionally, interval 2 is 1.07 times more diverse than interval 3. While there is some variability in the number of effective species, this variation was not statistically significant (df = 29, F = 0.872, p = 0.433; Table 4).
Pielou’s evenness index highlights the uniformity level within the community (Useni-Sikuzani et al., 2022). The three intervals showed high evenness with an average value above 0.70, but no significant differences were found (df = 29, F = 2.68 and p = 0.092) (Table 4).
Species richness is an important parameter for assessing anthropogenic and natural impacts, developing conservation strategies (Lelli et al., 2019), and monitoring areas of interest due to variety of organisms (Perrin & Waldren, 2020). The Margalef richness index did not reveal a pattern of increasing or decreasing richness associated with the altitudinal intervals, showing values of 0.68 for the lower and upper intervals, and 0.74 for the middle interval (Table 4). These results are classified as low richness, as they are below 2 (Margalef, 1972). Based on ANOVA, no significant differences were found between the three intervals (df = 29, F = 0.48 and p = 0.626).
Floristic similarity
Figure 6 illustrates the dendrogram generated using the Morisita-Horn index, which shows high similarity in the clustering of the three intervals. The greatest affinity was observed between intervals 1 (2 307 to 2 466 m) and 2 (2 466 to 2 625 m), with a value of 93 %, as both shared five species, excluding P. durangensis and P. tremuloides, which were the least abundant in their respective intervals. Intervals 2 and 3 (2 625 to 2 785 m) are 92 % similar, sharing five species; P. strobiformis is the most abundant, differing only in the presence of Q. sideroxyla, which was recorded in interval 2. The upper and lower intervals showed the least similarity at 75 %, as they share four taxa.
Figure 6 Dendrogram of the cluster generated by the quantitative Morisita-Horn index and abundance for the three altitude intervals (1 = 2 307 to 2 466 m, 2 = 2 466 to 2 625 m, 3 = 2 625 to 2 785 m) at the Thick-billed Parrot Sanctuary in Madera, Chihuahua
Differences in species composition along an altitudinal gradient are related to environmental, edaphic, and physiological processes (Murga-Orrillo et al., 2021). For instance, in the lower interval, Q. sideroxyla was one of the most abundant species, primarily found at altitudes between 2 000 and 2 500 m (Lebgue-Keleng et al., 2015). In contrast, A. concolor became more abundant as the gradient increased, because it mainly dominates in high, cold areas with steep slopes that experience snow accumulation (Werner et al., 2019). Meanwhile, P. durangensis may indicate deep soils rich in nitrogen, calcium, and potassium (Secretaría de Medio Ambiente y Recursos Naturales [SEMARNAT] & Comisión Nacional Forestal [CONAFOR], 2014).
Species affinity agrees with Bhat et al. (2020) and Song et al. (2021), who report a linear reduction in species similarity with increasing altitude. Moreover, the floristic similarity of the present study is higher than that reported by Rosaliano Evaristo et al. (2022) in oak forests in the physiographic province of the Transmexican Volcanic Belt and that of Ramos-Hernández et al. (2024) between a pine, pine-oak and an altered forest in Nuevo León with a similarity lower than 60 %.
Conclusions
The Thick-billed Parrot Sanctuary is of great ecological importance due to the endemic, relict, and specially protected species it hosts, primarily from the Pinaceae family. Dominance, diversity, and evenness indices were statistically similar among altitudinal intervals; however, dominance showed an upward trend with increasing elevation, in contrast to the indices and effective species, which decreased. Additionally, the altitudinal gradient showed a high similarity, with the lowest value recorded at the extremes, indicating that changes in habitat conditions may lead to a gradual turnover in species composition. This study in the Natural Protected Area provides crucial information for developing management programs and evaluating the relict forest, which is beneficial both for society and for the conservation of the national vegetation.
