Predicting the Potential Distribution of Stachys fontqueri Pau (Lamiaceae), a Strictly Endemic Medicinal Species of the Moroccan Rif, Under the Effects of Climate Change for Sustainable Conservation

1. Introduction

In 21st century, climate change is one of the major environmental challenges, leading to an increase in the frequency and intensity of extreme climatic events such as heat and cold waves, droughts and floods. It exerts increasing threats to ecosystems and their resources [1,2,3,4,5,6], and altering the distribution and physiological performance of the species [7]. The Mediterranean basin, including northern Morocco (classified as a "Hotspot"), is among the most sensitive to and affected regions by climate change due to rapidly rising temperatures and decreasing precipitation [6,8,9,10].

To address these environmental challenges, ecological niche modeling (ENM) is one of the most important analytical tools in ecology and biodiversity conservation biology. This approach enables the prediction of species distributions by relating occurrence data to environmental variables and has proven effective in identifying suitable habitats under current and future environmental conditions [11,12]. These models also make it possible to understand the climatic and environmental factors that control species distribution [5,13], and to predict potential shifts in their range in response to climate change [5,12,14]. Among the various ENM techniques, MaxEnt is considered one of the most robust and widely applied algorithms owing to its high predictive performance, stability, and sensitivity, particularly when modeling species distributions from presence-only data [3,4,11,15,16,17,18,19].

Medicinal and aromatic plants constitute a plant resource of considerable health and economic importance, given their widespread use in traditional medicine and their content of secondary metabolites with therapeutic properties used in the pharmaceutical and aromatic industries [20,21,22,23]. Studies have shown that these plants are highly sensitive to climate change, as variations in temperature, carbon dioxide, and ozone concentrations, as well as the increase in drought periods, affect their growth, biological production, and geographical distribution [23,24]. Furthermore, the persistence of these environmental pressures, combined with the degradation of natural habitats, threatens many wild medicinal species by altering or reducing their range, particularly in sensitive areas such as the Mediterranean basin [5,21,22,25,26,27].

Stachys fontqueri Pau, an endemic plant species of the Moroccan Rif [28,29], belonging to the genus Stachys L., one of the most prominent genera in the Lamiaceae family, and more precisely within the Lamioideae sub-family. This genus comprises between 275 and 300 species of herbaceous and shrubby plants distributed worldwide [30,31]. This species is characterized by its distinctive morphological traits, notably densely hairy stems, a deeply branched upper corolla lip, and prominent stamens [30]. It inhabits confined and fragile mountainous habitats, making it highly dependent on precise environmental conditions [26,29]. Furthermore, its limited geographical range increases its vulnerability to multiple threats, including habitat degradation, unsustainable exploitation, water drainage, Cannabis cultivation, and accelerating climate change in the Mediterranean region [26,29]. Consequently, Fennane (2018) [28] classified this species as Vulnerable at the national level.

Given the numerous threats facing S. fontqueri and its underrepresentation in botanical garden collections and seed banks on an international and national scales [26,29,32], as well as its promising agro-alimentary, ornamental and medicinal potentials [31,33,34], the conservation of this species is of growing importance. This necessitates monitoring the effects of climate change on the species' potential distribution within its natural habitat, alongside the adoption of ex situ conservation strategies combined with enhanced in situ protection.

Several researches have demonstrated the usefulness of the MaxEnt model in predicting future potential shifts in the geographic distribution of medicinal plant species in Morocco under climate change scenarios (e.g. [5,35,36,37,38]). Nevertheless, no study have yet evaluated the potential impacts of climate change on the potential distribution of S. fontqueri. Furthermore, with the exception of research focusing on its ex situ conservation status and the potential agro-alimentary and ornamental values [29,33,34], little attention has been given to the in situ conservation of this endemic species or to the combined impacts of climate change and human pressures on its potential distribution in Morocco.

Despite its endemic status, restricted geographic distribution, specialized ecological requirements, and conservation importance, the effects of climate change on the current and future distribution of S. fontqueri remain poorly understood. This knowledge gap limits the development of effective in situ conservation and management strategies necessary to ensure the long-term survival of the species.

This study aims to (i) model the current potential distribution of S. fontqueri in the Moroccan Rif, (ii) assess the effects of climate change on its distribution using ecological niche modeling, (iii) identify the most influential environmental factors shaping its distribution, and (iv) provide recommendations for its conservation and management.

2. Materials and Methods

2.1. Study Area

The Moroccan Rif reaches a maximum elevation of 2,440 m and is characterized by a Mediterranean climate [39]. According to the Köppen–Geiger Climate Classification System (2026) [40], this climate is classified as Csa (temperate with hot, dry summers) at low and mid elevations and as Csb (temperate with warm, dry summers) at higher elevations., with an annual mean precipitation of 900 mm and an annual mean temperature of 14.5°C in the study area [41] (https://www.worldclim.org/, accessed on 28 August 2023).

The Moroccan Rif is a geographically distinct region of remarkable uniqueness within both Morocco and the Mediterranean basin. It represents one of the eleven national biogeographic divisions identified by Fennane et al. (1999) [42]. As part of the Mediterranean biodiversity hotspot, the Rif region harbors a significant proportion of Morocco’s plant diversity and is particularly rich in endemic species, many of which are classified as endangered or threatened due to their restricted distribution ranges. These taxa may be exposed to pressures related to overexploitation and/or illegal trade [29,43].

Numerous habitat types were identified within the study area, including coniferous forests dominated by Cedrus atlantica (Endl.) Carrière, Abies marocana Trab., Pinus halepensis Mill., Pinus nigra subsp. mauretanica (Maire & Peyerimh.) Heywood, Tetraclinis articulata (Vahl) Mast., and Taxus baccata L.. Deciduous and evergreen oak forests are represented by Quercus ilex L., Q. canariensis Willd., Q. faginea Lam., Q. pyrenaica Willd., and Q. suber L. The study area also includes Mediterranean matorral communities dominated by Quercus coccifera L., Pistacia atlantica Desf., P. lentiscus L., Myrtus communis L., Cistus spp., Calicotome villosa (Poir.) Link, Chamaerops humilis L., … [5,25,26,27,36].

Stachys fontqueri Pau (Lamiaceae) is a narrow endemic (stenendemic) taxon restricted to the Western Rif Mountains of northern Morocco. It is one of the 17 Stachys species found in the country and is characterized by a greenish appearance with light to moderate hairiness, rarely becoming whitish-tomentose (Figure 2) [44].

Within the Rif biogeographical subdivision, S. fontqueri occurs as small, fragmented populations inhabiting matorral communities dominated by Pistacia lentiscus and Quercus coccifera, Chamaerops humilis steppes, and coniferous forests, where it frequently coexists with other endemic or threatened species such as Abies marocana and various orchid species. The species can grow on both calcareous and acidic substrates and occurs at elevations above 280 m a.s.l. [25,26,45].

2.2. Methods

After removing duplicate, outlier, and/or erroneous records, the final dataset included 70 occurrences of Stachys fontqueri. These data were compiled from field surveys (5 occurrences) and presence data downloaded from the Global Biodiversity Information Facility (GBIF; 65 occurrences) [46]. To guarantee data quality and reliability, the dataset was subjected to manual screening to ensure the availability of precise geographic coordinates within the species' distribution range, along with an accurate recording date for the occurrence site. The occurrence data were spatially filtered using a 1 × 1 km grid, retaining a single occurrence per grid cell to reduce spatial sampling bias [5,47].

The Maxent model (Version 3.4.3, November 2020) was used to predict the ecological niche of S. fontqueri. The climatic data used for the modeling were extracted from the WorldClim database [41] and handled using ArcGIS software (v. 10.8). Initially, a set of 20 environmental and topographic variables were used to build a preliminary MaxEnt model to simulate the current potential distribution of the species, following the approach of Worthington et al. (2016) [48], Wei et al. (2018) [49], and Mechergui et al. (2025a) [3]. Following this initial modeling, four variables were excluded from further analyses due to their lack of contribution to the model (percent contribution = 0) (Table S2).

Following the initial modeling, pairwise Pearson correlation coefficients between environmental and topographic parameters were calculated using IBM SPSS Statistics 23 software. Variables exhibiting strong correlations (|r| > 0.8) were removed to reduce multicollinearity and minimize model overfitting [1,49]. For each pair of correlated variables, the one showing a higher contribution in the preliminary MaxEnt model was retained, while its correlated counterpart was discarded [3]. Following this selection procedure, five bioclimatic variables were retained for the final model, namely: Annual mean temperature (Bio1), Temperature annual range (Bio7), Precipitation seasonality (Bio15), Precipitation of the warmest quarter (Bio18), and Precipitation of the coldest quarter (Bio19) (Table S3).

To assess the potential impacts of climate change on the distribution of S. fontqueri, the same set of selected environmental variables was projected onto future climate conditions derived from General Circulation Model (GCMs). Future climate data were obtained from the BCC-CSM2-MR and MIROC6 models under two Shared Socio-economic Pathways (SSP) scenarios: SSP1-2.6, representing a low-emission pathway, and SSP5-8.5, representing a high-emission pathway, for the period 2061–2080. All climatic datasets were processed at a spatial resolution of 30 arc-second, which is considered suitable for species distribution modeling and provide reliable estimates of habitat suitability [47]. To account for uncertainty in future climate projections, the SSP1-2.6, and SSP5-8.5 scenarios, under two GCMs, were chosen to represent a range of plausible socioeconomic and greenhouse gas emission pathways, spanning from low- to high-emission futures [50].

The MaxEnt model configuration was set to a maximum number of 500 iterations, with a convergence threshold of 0.00001. To generate a different random partition of test data and background points for each model run, the "random seed" option was enabled. Model performance was assessed using a 10-fold cross-validation procedure, and predictions were generated in a logistic output format [51,52]. For the feature classes, the "Auto" setting was applied, while the regularization multiplier was maintained at its default value of 1. This modeling approach, which improves the robustness of performance estimates, is particularly suitable for species with limited occurrence records [51].

Model performance was evaluated using the Area Under the Curve (AUC) of the Receiver Operating Characteristic (ROC) [53]. This parameter reflects the probability that a randomly selected presence site is assigned a higher suitability score than a randomly selected background or absence site [54]. A value of 0.5 indicates a random prediction, whereas a value of 1.0 represents perfect model discrimination [55]. In addition to the AUC, model performance was evaluated using the True Skill Statistic (TSS), a threshold-dependent metric that combines sensitivity and specificity, with −1<TSS<1. Values greater than 0.8 indicate excellent model performance [5]. The TSS was calculated based on Maximum training sensitivity plus specificity Logistic Threshold, using formula: TSS = 1 − Omission Rate − Fractional Predicted Area.

To compare habitat suitability under climate scenarios, MaxEnt outputs were imported into ArcGIS 10.8 and analyzed using the Reclassify tool within the Spatial Analyst extension. MaxEnt predicts habitat suitability for each grid cell on a continuous scale ranging from 0 to 1. To distinguish suitable from unsuitable habitats, the Maximum Test Sensitivity Plus Specificity (MTSPS) threshold, a robust and widely adopted criterion in species distribution modeling, was applied [5,56,57]. Habitat suitability maps were reclassified into two categories: suitable habitat (p > MTSPS) and unsuitable habitat (p ≤ MTSPS) [5].

The response curves generated by MaxEnt, describing the relationship between the species' probability of presence and environmental variables, were analyzed. Those demonstrating strong consistency between the environmental variables and the predicted probability of presence were retained. Their interpretation was based on biological relevance, showing that variations in environmental variables generally induce smooth and predictable responses in the species' probability of presence, without extreme fluctuations [3,4,57].

3. Results

3.1. Model Evaluation

The high values of the AUC of the five models developed to assess the current and future potential distribution of Stachys fontqueri demonstrated excellent predictive performance. The mean AUC values were 0.921 ± 0.027, 0.930 ± 0.027, 0.929 ± 0.044, 0.929 ± 0.035, and 0.926 ± 0.039 for the current climate model and the CSM2-SSP1-2.6, CSM2-SSP5-8.5, MIROC6-SSP1-2.6, and MIROC6-SSP5-8.5 scenarios, respectively. The consistently high AUC values, approaching 1, together with the low standard deviations (0.027–0.044), indicate strong model performance and stability. In addition, the TSS values varied from 0.81 to 0.83, further confirming the high predictive accuracy and reliability of the models.

The models predicted suitable habitats that closely match the currently known geographic distribution of S. fontqueri in northern Morocco. Nevertheless, the four projected scenarios identified additional areas of high habitat suitability in the Ketama–Targuist, Bouhachem, Bab Taza, and Tangier regions, where no occurrences of the species have been documented to date. These areas may represent potential habitats for the species and should be prioritized for future botanical surveys and conservation assessments.

3.2. Bioclimatic Factors

The potential distribution area of S. fontqeuri in Moroccan Rif were mostly affected by Precipitation Seasonality (Bio15), which contribute 61.6%, 43.8% and 38.1% for current, MIROC6-SSP5-8.5, and CSM2-SSP1-2.6 future climatic scenarios respectively. However, the Temperature Annual Range (Bio7) that have the greatest effect on habitat suitability under CSM2-SSP5-8.5 and MIROC6-SSP1-2.6, which contribute 55.8% and 43.6% respectively (Table 1).

3.3. Response Curves

Under current climate, the response curves derived from the ecological niche modeling of S. fontqueri indicated a high probability of species occurrence for Precipitation Seasonality (Bio15) values ranging from 77 to 88 mm, an Annual Mean Temperature (Bio1) below 12.8 °C, and a Temperature Annual Range (Bio7) below 17.4 °C and between 26.4 and 28.4 °C. A similar trend was observed under the CSM2-SSP1-2.6 scenario, where the highest occurrence probabilities were associated with the same key bioclimatic variables identified under current climatic conditions, although with slightly higher values. Specifically, high occurrence probabilities were associated with Bio15 values between 80 and 92 mm, Bio7 values below 19.6 °C and between 27.4 and 29 °C, and Bio1 values below 17.4 °C.

Under the CSM2-SSP5-8.5 scenario, Temperature Annual Range (Bio7) emerged as the most influential factor determining habitat suitability, with optimal values ranging from 28.4 to 30.3 °C. This was followed by Annual Mean Temperature (Bio1) below 16.1 °C and Precipitation of the Coldest Quarter (Bio19) between 460 and 540 mm. In addition, Precipitation Seasonality (Bio15) ranged from 78 to 92 mm.

Under both the SSP1-2.6 and SSP5-8.5 scenarios projected by the MIROC6 model, the highest probabilities of occurrence for S. fontqueri were associated with similar bioclimatic variables and relatively comparable value ranges. Under the SSP1-2.6 scenario, high probabilities of occurrence were linked to a Temperature Annual Range (Bio7) between 28.4 and 30.2 °C, Precipitation Seasonality (Bio15) between 77.5 and 88.5 mm, and an Annual Mean Temperature (Bio1) below 15 °C. In contrast, under the SSP5-8.5 scenario, the highest occurrence probabilities were associated with Bio15 values between 77.5 and 88 mm, Bio7 values between 28.6 and 30.6 °C, and Bio1 values below 17.2 °C.

3.4. Potential Current Distribution Area of Stachys fontqeuri

The modeling of the potential distribution of Stachys fontqueri under current climatic conditions indicates that the species could occupy relatively extensive, although fragmented, suitable habitats concentrated in the mountainous massifs of the Moroccan Rif, particularly in Jbel Moussa, Jbel Kelti, and the Talassemtane National Park. However, the predicted suitable habitat also extends to surrounding areas, including Bouhachem Natural Park, the Tangier region, Bab Taza, Ketama, and Issaguen, covering a total suitable habitat area of approximately 3244.3877 km² (Table 2, Figure 3)

3.5. Effect of Climate Change on the Potential Distribution Area of Stachys fontqueri

Compared to the current potential distribution, the potential distribution area of S. fontqeuri under all future climate scenarios, was projected to decrease in the study area (23.25% to 29.59% of suitable habitat loss). The CSM2- SSP5-8.5 seems to be the most unfavorable climatic scenario for the endemic species (Table 2).

When considering climatic factors alone and disregarding human influences, S. fontqueri is projected to face a risk of habitat contraction in the Moroccan Rif. Future climate projections indicate a marked decline in the extent of suitable habitats for the species throughout Moroccan Rif by 2070 (Figure 4)

4. Discussion

Climate change is one of the major drivers of biodiversity decline in the Mediterranean Basin [2,6]. Its impacts are particularly severe on endemic and threatened species, especially when combined with human pressures [5]. As an endemic taxon of forest clearings and calcareous scrublands, Stachys fontqueri contributes to local biodiversity and plays an important role in maintaining habitat integrity in the Moroccan Rif [29]. Therefore, modelling the potential habitat changes and the response of the species to climate change are essential to develop effective conservation strategies.

Bioclimatic variables provide valuable predictors for understanding plant distribution patterns and for modeling the potential effects of climate change on habitat suitability, thereby enabling the assessment of current and future species distribution patterns [38,58]. However, the results of ecological niche models should be interpreted with caution, as they do not fully account for important ecological processes such as biotic interactions, dispersal capacity and barriers, evolutionary history, and human activities [5,58,59,60,61,62].

The models applied to analyze the ecological niche of S. fontqueri showed high predictive performance, with AUC values ranging from 0.921 to 0.930 and TSS values between 0.81 and 0.83. These performance metrics are in close agreement with those reported by El Haddouti et al. (2026) [5] and Jaouani et al. (2025) [38] for species distribution models in northern Morocco, further confirming the robustness and reliability of the modeling approach [54]. The resulting habitat suitability maps indicate that most of the currently known populations of S. fontqueri are located within the core of the potential distribution area predicted by the models (Figure 3).

However, the absence of S. fontqueri from several areas predicted to be suitable, including Jbel Bouhachem, Bab Taza, Ketama, Issaguen, and the Tangier region, deserves attention. This discrepancy may be explained by the influence of additional factors that were not incorporated into the models but are known to shape the species' realized distribution, including local abiotic conditions and human disturbances such as overgrazing, wildfires, deforestation, and illegal plant collection [5,63,64]. Alternatively, the apparent absence of the species may simply reflect insufficient botanical investigations, underscoring the need for field validation of habitats identified as suitable by the ecological niche models [5].

Ecological niche modeling of S. fontqueri revealed that its potential geographic distribution is strongly influenced by three key bioclimatic variables: Precipitation Seasonality (Bio15) and the two temperature-related variables, Temperature Annual Range (Bio7) and Annual Mean Temperature (Bio1). These variables consistently emerged as the main predictors under both current climatic conditions and the four future climate scenarios. In contrast, Annual Mean Temperature (Bio1) was identified as the most influential predictor of the potential distribution of Stachys inflata Benth. in Iran [47]. Similarly, in northern Morocco, Bio1 and Bio7 have been reported among the principal determinants of the distribution of two Lamiaceae species, Origanum compactum Benth. and O. elongatum (Bonnet) Emb. & Maire [38].

The high contribution of Precipitation Seasonality (Bio15) to the current potential distribution of S. fontqueri in the Moroccan Rif (61.6%) is biologically consistent with the ecological requirements of the species. S. fontqueri is endemic to the western Rif, a region characterized by a Mediterranean climate with pronounced seasonal variability in precipitation, a key factor for species whose phenology, growth, and survival are closely linked to rainfall patterns [37,38]. In this context, Precipitation Seasonality (Bio15) is an important indicator of seasonal water stress, as increasing contrasts between the wet and dry seasons can create unfavorable conditions for species survival [65]. Precipitation Seasonality (Bio15) remained one of the most influential predictors under future climate scenarios (CSM2-SSP1-2.6 and MIROC6-SSP5-8.5), although its contribution was lower than under current climatic conditions (Table 1). This trend suggests that, under climate change, the predictive importance of precipitation variables tends to decline, whereas temperature-related variables become increasingly influential in determining suitable habitats for species [66,67].

The prominent contribution of Precipitation Seasonality (Bio15) to the ecological niche modeling of S. fontqueri differs from the findings of Hosseini et al. (2024) [18] for Thymus species in Iran, where the most influential environmental variables varied among species. Altitude was identified as the most significant predictor of the distribution of Thymus fedtschenkoi Ronniger and T. pubescens Boiss. & Kotschy ex Čelak., whereas precipitation-related variables, particularly Precipitation of the Driest Month (Bio14), also played an important role, especially for T. fedtschenkoi. In contrast, Shaban et al. (2023) [47] identified a combination of climatic variables, including Annual Mean Temperature (Bio1), Mean Temperature of the Wettest Quarter (Bio8), and Annual Precipitation (Bio12), as the principal determinants of the distribution of Stachys inflata, with relative contributions of 41.1%, 39.06%, and 37%, respectively. This variability indicates that no single environmental variable consistently dominates species distribution models; rather, the relative importance of environmental predictors is determined by the specific ecological requirements of each species and the environmental conditions prevailing within its natural habitat [68].

Under the future climate scenarios CSM2-SSP5-8.5 and MIROC6-SSP1-2.6, Temperature Annual Range (Bio7) emerged as the most influential predictor, with relative contributions of 55.8% and 43.6%, respectively. This shift in the dominant climatic drivers suggests that, under accelerated climate warming, annual thermal constraints are likely to replace precipitation-related constraints as the primary factors regulating habitat suitability for S. fontqueri. Similar transitions have been reported for other Mediterranean plant species that are particularly sensitive to climate change [3,38]. The shift described above indicates that thermal variability plays a key role in regulating the physiological performance and reproductive capacity of the species. Large annual temperature fluctuations may affect the species distribution range and disrupt essential biological processes, including flowering phenology and fruit production [65]. Furthermore, all four future climate scenarios predicted an increase of approximately 1–2 °C in Temperature Annual Range (Bio7) relative to current climatic conditions. Such an increase is expected to exacerbate environmental aridity and intensify thermal stress, thereby imposing greater physiological constraints on the species [7].

Except the CSM2-SSP5-8.5 scenario, Annual Mean Temperature (Bio1) ranked as the third main influential bioclimatic variable determining the potential distribution of S. fontqueri in the Moroccan Rif under future climate scenarios, with relative contributions ranging from 11.9% to 19.9% (Table 1). In contrast, this thermal variable was identified as the primary predictor of the potential distribution of S. inflata in Iran, contributing 41.10% to the MaxEnt model [47], and of Heteromera philaenorum Maire & Weiller in North Africa, contributing 28.9% [4]. Annual Mean Temperature is a fundamental predictor in ecological niche modeling because it provides an estimate of the total energy input available within an ecosystem throughout the year, which can strongly influence the metabolic rates, growth, and physiological performance of the species [65].

Ecological niche modeling under current climate revealed that the predicted suitable habitat of S. fontqueri is mainly distributed across the Rif Mountains, covering an estimated total area of approximately 3,244 km². The most suitable habitats are located around Talassemtane National Park, Jbel Moussa, and Jbel Kelti. This occurrence in the Rif mountains may be attributed to suitable climatic conditions, particularly an Annual Mean Temperature (Bio1) below 12.8 °C, a Temperature Annual Range (Bio7) below 17.4 °C and between 26.4 and 28.4 °C, and Precipitation Seasonality (Bio15) ranging from 77 to 88 mm. Together, these conditions provide a cool and relatively humid environment that is conducive to the growth and persistence of the species [69,70,71].

Future climate projections predicted a contraction of the suitable habitat of S. fontqueri under all four climate scenarios evaluated, with habitat losses ranging from 23.25% to 29.59% under the high-emission scenarios MIROC6-SSP5-8.5 and CSM2-SSP5-8.5. These findings are consistent with the trends commonly reported for endemic and geographically restricted species in the Mediterranean region under the influence of climate change [2,38]. The projected range contraction occurs primarily along the southern and eastern margins of the species' current potential distribution, suggesting a gradual retreat toward the coolest and most humid climatic refugia of the western Rif [72]. It is noteworthy that the low-emission scenarios also predicted substantial habitat losses, with reductions of 29.50% and 26.73% under the CSM2-SSP1-2.6 and MIROC6-SSP1-2.6 scenarios, respectively. These results highlight that, even under ambitious greenhouse gas mitigation pathways, climate change is expected to exert considerable pressure on this narrow endemic species [50].

Overall, the projected contraction of the potential distribution of S. fontqueri is consistent with the findings of Hosseini et al. (2024) [18], who reported substantial reductions in suitable habitats for several Thymus species by 2050 and 2070 as a consequence of increasing thermal and water stress under climate change. Similarly, Shaban et al. (2023) [47] predicted a marked decline in the most suitable habitats for S. inflata under future climate scenarios. Collectively, these studies indicate that climate warming not only leads to a reduction in the extent of suitable habitats but also alters the environmental drivers governing habitat suitability, with temperature-related variables becoming increasingly important under future climate scenarios [73,74].

At the regional scale, previous studies have reported a widespread decline in biodiversity across the Moroccan Rif, driven by both local environmental conditions and increasing human pressures [5,25,26,43,75]. In addition to the impacts of climate change projected in the present study, our field surveys revealed several ongoing threats to the natural habitats of S. fontqueri, including livestock grazing, cannabis cultivation, and water abstraction, even within protected areas such as Talassemtane National Park. Furthermore, the proximity of some populations to urban centers, particularly the cities of Tetouan and Fnideq, may expose the species to increased risks of habitat fragmentation, loss of connectivity among populations, overexploitation, and even complete habitat destruction associated with urban and infrastructure development [76,77].

Although a previous study revealed the presence of a few seed lots of S. fontqueri conserved ex situ in the seed bank of the Scientific Institute (Rabat, Morocco) [32], additional efforts must be made to conserve a sufficient quantity of seeds in seed banks, prioritizing those in Morocco. Furthermore, it is necessary to proceed with germination, propagation, and reintroduction trials of the species into its degraded habitats, as well as the restoration of its natural habitat, as recommended by the Global Strategy for Plant Conservation (GSPC) (http://www.plants2020.net/, accessed 29 Jun 2026) [78].

In parallel, these ex situ conservation measures can be complemented by consultation with local communities to raise awareness about the ecological, socioeconomic, and heritage importance of S. fontqueri and to promote the sustainable management of its natural habitat. Moreover, the promotion of in situ conservation measures, such as the extension of protected areas and/or the implementation of existing laws, such as Law 29-05 of 2 July 2011 designed to protect wild species from illegal collection and trade [79], constitute additional solutions to protect the species. The in situ conservation of this endemic species and its natural habitat, especially near the city of Tetouan, could curb biological invasion and provide opportunities for regional and global biodiversity conservation, restoration, and education [76]. Finally, effective conservation plans should include the management and mitigation of human pressures, notably overgrazing, forest fires, and illegal plant harvesting and trade [43,75].

This study constitutes a valuable contribution to understanding the effects of climate change on the potential distribution of S. fontqueri in the Moroccan Rif. Nevertheless, it presents certain limitations, particularly regarding the use of a limited number of bioclimatic variables for modeling the species' ecological niche. Although the five bioclimatic variables were selected for their contribution and statistical independence, they may not adequately represent all the ecological processes shaping the species’ geographic distribution. Beyond climate, other elements could affect the survival of the species, namely habitat fragmentation, pastoralism, land-use change, and fires [5,25,26]. These factors may constrain the colonization of newly suitable areas projected by the models. Furthermore, the habitat predicted as suitable do not always correspond to the species’ current distribution. This mismatch highlights the importance to conducting additional field surveys to validate the predicted suitable areas and of incorporating additional ecological, biotic, and human factors into future models to enhance predictive accuracy [5,47].

5. Conclusions

This study evaluated the potential impacts of climate change on the distribution of Stachys fontqueri in the Moroccan Rif. Our results identified three key bioclimatic variables as the primary determinants of the species' potential suitable habitat: Precipitation Seasonality (Bio15), Temperature Annual Range (Bio7), and Annual Mean Temperature (Bio1). The most suitable habitats are concentrated within Talassemtane National Park, Jbel Moussa, and Jbel Kelti, which appear to represent climatically stable refugia for the long-term persistence of S. fontqueri. Future climate projections consistently predicted a contraction of suitable habitats under all climate scenarios considered, with habitat losses ranging from 23.25% to 29.59% by 2070. Nevertheless, new potentially suitable habitats may emerge in parts of the eastern Rif, particularly around Ketama and Issaguen.

Considering the combined effects of climate change and the numerous anthropogenic pressures identified during our field surveys, the contraction of suitable habitats for S. fontqueri could be even more severe than predicted if existing environmental regulations are not effectively implemented and if in situ and ex situ conservation measures remain insufficient. Morphological and genetic studies aimed at identifying the most resilient populations, together with investigations of seed germination requirements to support natural regeneration, would contribute significantly to the long-term conservation of this endemic species. In addition, botanical surveys should be intensified in areas predicted to be suitable but not yet inventoried, including Jbel Bouhachem, Bab Taza, Ketama, Issaguen, and the Tangier region, to verify the presence of the species and identify key habitat corridors. Strengthening the ex situ conservation of its genetic resources in support of the objectives of the Global Strategy for Plant Conservation, implementing long-term monitoring of natural populations and land-use dynamics, the adoption of sustainable resource management practices, and community-based awareness initiatives about the ecological and socio-economic importance of S. fontqueri would help mitigate the combined impacts of human activities and climate change while enhancing the species’ resilience in Moroccan Rif.