Livestock grazing is widely recognized as a primary driver of vegetation degradation, particularly in natural ecosystems rich in diverse native plant species. Overgrazing significantly alters plant community structures, reduces diversity, and disrupts interactions essential for ecosystem resilience (Crovo et al., 2021; Pelliza et al., 2021; Macheroum and Chenchouni, 2022; Abebe et al., 2024). Beyond altering vegetation directly, livestock grazing can cause physical and biochemical changes to soil. The trampling and grazing activities of livestock often result in soil compaction and physical damage, diminishing soil porosity and aeration (Jones et al., 2022; Song et al., 2023; Xu et al., 2023; Blanco-Sepúlveda et al., 2024; Ma et al., 2024; Mushinski et al., 2024). These processes disrupt nutrient cycles, impair biogeochemical functions, and negatively impact soil biota, ultimately reducing ecological health and productivity.

The ecological impact of livestock grazing extends to the disruption of biological community balance and stability, affecting both interspecific and intraspecific relationships within ecosystems (Tian et al., 2019; Öllerer et al., 2019; Filazzola et al., 2020). For instance, overgrazing can interfere with pollination dynamics, altering the mutualistic interactions between native plants and their pollinators (Chen et al., 2022; Kral-O’Brien et al., 2023; SStevenson, 2023). It also disrupts natural herbivory patterns and seed dispersal mechanisms, which can even indirectly affect carnivores by altering the availability of prey species reliant on healthy plant communities (Filazzola et al., 2020; Ugarte et al., 2019; Thapa-Magar et al., 2020; Wilkinson et al., 2020; Pozo et al., 2021).

The severity of grazing impacts is influenced by factors such as livestock density, the duration of grazing practices, and the effectiveness of grazing management strategies. In particular, a lack of seasonal timing and control of grazing events exacerbates resource overuse, further degrading vegetation and soil quality (Narantsetseg et al., 2018; Pulido et al., 2018). These pressures become especially concerning in the context of climate change, where warming temperatures and altered precipitation patterns add additional stressors. As habitats experience shifts in temperature and moisture, the resilience of native plant communities becomes increasingly compromised (Oñatibia et al., 2020; Wei et al., 2022). This synergistic effect of climate-induced stress and unmanaged grazing accelerates vegetation loss, posing a severe threat to the long-term sustainability of these ecosystems. Consequently, there is a critical need for adaptive management strategies that mitigate the combined impacts of climate change and grazing pressures to promote ecosystem stability and resilience.

Seed dispersal through animal ingestion is a critical ecological process that supports the persistence and regeneration of plant populations (Karimi et al., 2018; Pires, 2024; Ghasemi et al., 2024). Large native mammals, in particular, play a crucial role in facilitating seed dispersal, which is essential for maintaining plant diversity and ecosystem functionality. However, these animals are increasingly threatened by anthropogenic pressures such as habitat destruction, poaching, and fragmentation, which can disrupt their dispersal activities and, in turn, impact vegetation dynamics (Gelmi-Candusso and Hämäläinen, 2019; Leclerc et al., 2020; Nield et al., 2020; Draper et al., 2022; Estrada-Villegas et al., 2023). The loss of these ecological services highlights the urgent need for conservation efforts to protect these key species, whose roles in maintaining ecological balance are indispensable.

In contrast, livestock grazing, which is prevalent in northern Iran’s natural pastures, can exert considerable pressure on vegetation, competing with the ecosystem services provided by native herbivores. Livestock grazing has been shown to disrupt plant communities, especially when grazing intensity exceeds the land’s ecological capacity (Gonzalez and Ghermandi, 2021; Shakeri et al., 2021; Salmanpour et al., 2021; Pearson et al., 2022). In many regions, traditional pastoral practices rely heavily on the grazing of livestock in natural meadows, which are often located in areas rich in native plant species. These grazing areas, particularly in the high-altitude pastures on the northern slopes of the Alborz Mountains, are shared by both domestic livestock and native wildlife (Soofi et al., 2018; Hojjati et al., 2021; Savari, 2023; Zandebasiri et al., 2023). Despite the legal framework that permits grazing outside protected zones, few studies have comprehensively examined the long-term impacts of domestic livestock grazing compared to the effects of native artiodactyls, especially in relation to vegetation dynamics and climate change. Understanding these interactions is crucial for informing management strategies aimed at balancing the needs of both livestock and wildlife while mitigating the potential ecological consequences of climate warming.

The findings from this study aim to provide valuable insights into the complex interplay between climate change, grazing pressure, and vegetation dynamics in the Alborz Protected Area. In Zanoos, livestock grazing is carefully managed to prevent entry into the strictly protected Golestanak core zone, where grazing is prohibited under ranger enforcement. This research highlights the importance of such measures in minimizing the impact of grazing on vegetation cover and native herbivore populations. By addressing the effects of climate change alongside varying land-use practices, this study contributes to the growing body of knowledge on ecosystem functioning in diverse landscapes. Ultimately, the outcomes will inform strategies for managing both domestic and wild herbivore populations in the face of climate change and may provide valuable guidance for conservation efforts in similar ecosystems worldwide.

This study sheds valuable light on the complex interplay between climate warming and land-use practices, notably livestock grazing, in shaping vegetation dynamics in the Alborz Protected Area over the past 30 years (1994–2024). The significant upward NDVI trend observed in both study sites, Zānoos and Golestanak, underscores the role of increasing temperatures especially the pronounced June warming and seasonal precipitation in enhancing vegetation productivity in high-altitude ecosystems. However, the slower NDVI growth rate in Zānoos compared to Golestanak highlights the dampening effect of intensive livestock grazing (1–1.2 hectares per head) versus the lighter grazing pressure exerted by native artiodactyls in Golestanak (4.2–4 hectares per individual). This research is crucial, demonstrating that while climate change positively influences vegetation cover, high densities of domestic livestock may offset these gains, which has important implications for conservation and land management. The study provides an essential foundation for understanding how warming and grazing pressures interact, offering insights that could guide policy adjustments aimed at balancing biodiversity conservation with sustainable grazing practices under shifting climate regimes.

The results of this study provide compelling evidence of a significant upward trend in NDVI over the past three decades, with annual increases of 0.7–0.75% in Zānoos and 0.92–0.98% in Golestanak. These findings align with previous studies, including Piao et al. (2006), Pang et al. (2017), Xu et al. (2024), and Tuoku et al. (2024), which identify climate change as a primary driver of increasing NDVI. Furthermore, studies by Eskandari Dameneh et al. (2021) and Ghorbanian et al. (2022) confirm that the NDVI increases observed in Iran are closely linked to climate variability. Our results specifically highlight May and June temperature and precipitation as the most significant climate parameters influencing NDVI, consistent with findings from Kiapasha et al. (2017a, b), Eskandari Dameneh et al. (2021), Ghorbanian et al. (2022), and Zhang et al. (2024). While other studies have indicated that the relative importance of climatic factors can vary by region, with drier habitats showing stronger influences of rainfall on NDVI, our work reinforces the complexity of these interactions. This study underscores the importance of considering both long-term climate trends and short-term climatic fluctuations in understanding vegetation dynamics, particularly in climate-sensitive regions such as Iran, where ongoing climate change is likely to have profound impacts on ecosystem productivity and resilience.

Our results provide compelling evidence of the differential impacts of grazing by domestic livestock (cattle and sheep) compared to native artiodactyls (Caspian red deer and wild goats) on vegetation dynamics. Despite relatively similar ecological conditions in Zānoos and Golestanak, the response of NDVI to temperature increases exhibited a divergent pattern between the two areas. While Zānoos consistently displayed 0.3 higher NDVI values than Golestanak, the rate of NDVI increase in Golestanak over recent years was 30–32% greater than in Zānoos. This disparity is likely attributed to the higher grazing pressure in Zānoos, where domestic livestock densities are significantly higher (about 4 times denser than Golestanak). The negative effects of livestock grazing on vegetation cover have been well-documented in the literature, with studies by Ndungu et al. (2019), Balata et al. (2022), Li et al. (2022), and Velamazán et al. (2023) highlighting the degradation of plant communities under domestic grazing. These findings emphasize the urgent need for regulating grazing intensity, particularly in areas experiencing both grazing pressure and climate change, to protect ecosystem productivity. Our study underscores the critical importance of sustainable land-use practices to mitigate the combined effects of overgrazing and climate change on vegetation health and ecosystem resilience. Furthermore, our findings align with the results of Skidmore and Ferwerda (2008), Searle et al. (2015), Garroutte et al. (2016), Navarro et al. (2020), and Zhang et al. (2024), which demonstrate the positive influence of protected areas where livestock grazing is prohibited, and only native herbivores are present. This highlights that the distribution of herbivores, particularly native species, is strongly associated with resource availability and reinforces the importance of conservation strategies aimed at promoting native herbivore populations to enhance vegetation regeneration and maintain ecosystem stability.

This study provides compelling evidence for the critical role of effective grazing management in safeguarding Iran’s high-altitude ecosystems, which are increasingly important as climate refuges for vulnerable species (Martin et al., 2018; Peters et al., 2019; Wen et al., 2022; Sayahnia et al., 2024). With rising temperatures, these elevated habitats offer essential seasonal refuge for native large mammals allowing them to escape thermal stress in lower-altitude zones. Research by Millon et al. (2019), Kelt et al. (2019), and Cantor et al. (2021) similarly emphasizes the value of high-altitude habitats for supporting biodiversity under shifting climates, while studies by Teitelbaum and Mueller (2019), Shaw (2020), and Shizuka and Johnson (2020) illustrate how species mobility serves as an adaptive response to dynamic and fragmented environments.

Nevertheless, the encroachment of domestic livestock into these habitats presents a significant challenge, leading to vegetation degradation and reduced habitat availability for native herbivores (Soofi et al., 2018), which are then forced into limited protected areas like Golestanak. This concentration intensifies interspecies competition and risks overgrazing, potentially destabilizing the ecosystem’s delicate balance. In response, adaptive land management strategies that restrict livestock access to critical habitats are essential. Practical measures could include the acquisition of high-pressure grazing lands in areas such as Zānoos and the establishment of ranger stations to reinforce habitat protection. These actions would not only reduce livestock encroachment but also secure habitat corridors essential for the seasonal migrations of native species. Such targeted interventions are crucial for mitigating the compounded impacts of climate change and grazing pressure, ensuring the resilience and long-term sustainability of Iran’s unique biodiversity and high-altitude ecosystems.

This study provides crucial insights into the complex interactions between climate warming and grazing pressures in shaping vegetation dynamics within Iran’s Alborz Protected Area over the past three decades. Our findings demonstrate a significant increase in vegetation cover, driven primarily by temperature increases and seasonal rainfall, with particularly strong responses observed in high-altitude ecosystems. However, the positive effects of climate change on vegetation productivity are tempered by the higher grazing pressures exerted by domestic livestock, as seen in the Zānoos region. In contrast, the more sustainable grazing practices of native herbivores in Golestanak contribute to a stronger and more resilient vegetation response, highlighting the benefits of maintaining native herbivore populations in promoting ecosystem stability. These results underscore the urgent need for sustainable land-use and grazing management strategies, particularly in climate-sensitive regions, to protect ecosystem health and biodiversity. Effective management, including the regulation of grazing intensity and the protection of critical habitats, is essential for mitigating the adverse impacts of climate change and overgrazing. This research provides a foundation for policy adjustments that balance biodiversity conservation with sustainable land-use practices, ensuring the long-term resilience of Iran’s unique high-altitude ecosystems amidst the challenges posed by climate change.