Bharat Babu Shrestha

The number of species introduced outside of their historical ranges by human activity continues to rise ¹ . A subset of these species establishes, form self-sustaining populations, and some – invasive alien species – go on to cause substantial harm to biodiversity and ecosystems ² . Preventing new invasive alien species from establishing is the key focus of interventions, because post-establishment management is costly and often fails ^3,4 . However, it remains unclear how effective multilateral efforts have been in curbing the rise. Here we show that the emergence of new invasive alien species across countries is slowing, and trends are similarly negative across geographically diverse countries. Using data and modelling advances, we find a 35% reduction in the establishment of new invasive alien species over a policy-relevant 50-year time frame. The findings directly inform the assessment of progress for the invasive alien species target of the Kunming-Montreal Global Biodiversity Framework ⁵ , and provide a global baseline for monitoring rates of invasive alien species establishment. Furthermore, the slowdown suggests that policy and investment over recent decades to prevent invasive alien species from entering and establishing in countries have had a positive effect.

Protected areas are vital for preserving native biodiversity, yet invasive alien plant species (IAPS) pose significant threats to their conservation. This study investigates how IAPS diversity varies across their dispersal corridors, such as road verges, riversides, seasonal springs, fire lines, and trekking trails, and examines the relationship between tree canopy openness and IAPS richness. We sampled 156 plots (2 m × 5 m) along these corridors in Parsa National Park (PNP), ensuring a minimum distance of 100 m between plots. Out of 10 IAPS recorded during the study, road verges and riversides were invaded by 70% of the recorded species, while the walking trail had the lowest number of IAPS (30%). The most prevalent IAPS was Chromolaena odorata , followed by Mikania micrantha and Ageratum conyzoides . One‐way ANOVA indicated significant differences in IAPS richness among dispersal corridors ( p < 0.001). Furthermore, IAPS richness increased with increasing tree canopy openness ( R = 0.8, p < 0.001). Given that road verges and riversides appeared to be the major dispersal corridors of IAPS in the context of PNP, it is imperative to prioritize these corridors for IAPS monitoring, early detection, eradication, and control. Such efforts can reduce the establishment probability of new IAPS and mitigate the impacts of the widespread IAPS on the native species and ecosystems.

Invasive alien species are major driver of socio-ecological changes, and pose threats to protected areas (PAs) and native biodiversity globally. To reduce their impacts, management effort should be timely, and guided through stakeholder engagement. This study investigated the level of community awareness, and documented perceptions and stakeholder participation in management of invasive alien plant species (IAPS) in ten of Nepal’s twenty PAs (five from each Tarai-Siwalik and Mountain regions). It draws on focus group discussions (n = 60) and key informant interviews (n = 47). We found that people had substantial local knowledge of IAPS and had been substantially impacted by them without having knowledge of their exotic nature. Reported impacts included native species loss, increased weeding time, crop loss, reduced forage availability, and reduced forest regeneration. Lantana camara, Mikania micrantha, Ageratina adenophora and Ageratum houstonianum were the most problematic IAPS causing both ecological and socio-economic impacts. Management efforts were sporadic, inadequate and rarely guided by formal plans or programs. Regional analysis showed that the PAs located in the Tarai-Siwalik regions (southern lowland) experienced greater invasion impacts but received marginally more management than the mountain PAs. While efforts have been made to control IAPS both by local communities and PA authorities at few locations in the Tarai-Siwalik region, the lack of such efforts despite growing problems in the mountain PAs with unique biodiversity is a matter of great conservation concern. Overall, limited participation among stakeholders, along with very low resource mobilization are the key barriers to effective management of IAPS in Nepal’s PAs.

Climate change is a major driver influencing species survival and distribution, particularly for species endemic to mountainous regions. The Hindu Kush Himalaya (HKH), which is a global biodiversity hotspot and the world's youngest mountain system with a high level of endemism, is particularly vulnerable to climate change impacts. This study investigates how future climate change may affect the potential distribution of two congeneric species, Aconitum spicatum and Aconitum naviculare , both endemic to the HKH and occupying habitats with contrasting moisture regimes. Using machine learning‐based ecological niche modeling, we assessed projected changes in climatically suitable habitats under moderate (SSP2‐4.5) and high (SSP5‐8.5) emissions scenarios for two future epochs. Our results indicate that A. spicatum , which prefers moist environments, is projected to experience a decline in suitable habitats across much of its current range without a shift of projected elevation range, particularly in China, India, and Myanmar, due to warming and altered precipitation patterns. Conversely, A. naviculare , which inhabits semi‐arid regions, is expected to exhibit an overall expansion of suitable habitats with a shift of projected elevation range, particularly in China and, to a lesser extent, Nepal, suggesting potential emergence of new ecological niches under future climate conditions. These contrasting responses highlight the species‐specific nature of climate change impacts. Additionally, the overlapped suitable habitat areas of these two species are predicted to decline in future. While future climate change may offer new opportunities for range expansion of the currently range‐restricted A. naviculare , it may simultaneously shrink the habitat range of the more widely distributed A. spicatum . Suitable habitat overlaps under current and future climate scenarios of congeneric but allopatric species that we report can have ecological and evolutionary implications. These insights are critical for designing adaptive, species‐specific conservation strategies that integrate both climate projections and socioecological pressures, such as overharvesting.

Understanding the ecological impacts of livestock grazing on rangeland conditions is essential for developing sustainable rangeland management strategies that balance livestock production and ecosystem health. However, there is a paucity of field experiments measuring the impacts of grazing on rangeland health in the Himalayan region. This study assessed the impacts of four grazing intensities—non‐grazed (NG), lightly grazed (LG), moderately grazed (MG), and highly grazed (HG)—on plant species diversity, community composition, plant height, biomass production, and soil physicochemical properties across three sub‐alpine rangelands in Jumla district, western Nepal. A total of 113 plant species were recorded, dominated by forbs (87.6%), with fewer graminoids, pteridophytes, and shrubs. Species richness increased along the grazing gradient from HG to NG, with MG plots supporting high diversity and productivity. Non‐metric multidimensional scaling (NMDS) ordination revealed distinct species assemblages under NG, while MG and LG showed overlapping plant communities. Plant height and biomass were the highest in NG plots and declined with increased grazing intensity, with elevation exerting a negative effect on both. Soil organic carbon and nitrogen were generally higher under NG and MG, although responses varied across sites. Our results support the intermediate disturbance hypothesis and highlight the ecological benefits of moderate grazing, although these effects are largely site‐specific. The complex interaction between grazing pressure and environmental conditions underscores the importance of site‐specific and adaptive management strategies to sustain rangeland health. Our findings provide valuable evidence for designing evidence‐based sustainable rangeland management strategies in Nepal and comparable high‐altitude regions.

Invasive alien species pose significant threats to biodiversity and ecosystem functioning in protected areas (PAs) worldwide. This study examines ecological impacts of invasive weeds Lantana camara and Mesosphaerum suaveolens on plant species diversity, community composition and soil chemical properties in Parsa and Shuklaphanta National Parks (NPs), Nepal. In total, we sampled 180 pairs of 5 m × 5 m plots, comprising 45 pairs (3 sites × 15 pairs) for each invasive species in each NP. Across all sampling sites, these weeds consistently reduced species diversity (Shannon, Simpson indices), despite the species- and site-specific variations in species richness and soil characteristics. Non-metric multidimensional scaling and Canonical correspondence analysis revealed substantial modifications in plant species composition, along with shifts in indicator species and an increase in the relative cover of established alien plants in invaded plots. While the effects of invasions on soil properties were inconsistent, L. camara significantly increased soil organic carbon and total nitrogen in Parsa, whereas M. suaveolens had no measurable impact on soil parameters except soil pH in either PA. These results suggest that species diversity indices and changes in species composition serve as reliable ecological indicators for assessing impacts of invasive weeds and monitoring ecological restorations. The decline in species diversity and alterations in plant community composition can have cascading effects on ecosystem processes and livelihoods of local communities. Given the increasing threats of plant invasions in Nepal’s PAs, urgent and effective management interventions are needed to prevent further spread, mitigate ecological and socio-economic impacts, and restore invaded habitats.

Protected areas are vital for preserving native biodiversity, yet invasive alien plant species (IAPS) pose significant threats to their conservation. This study investigates how IAPS diversity varies across their dispersal corridors, such as road verges, riversides, seasonal springs, fire lines, and trekking trails, and examines the relationship between tree canopy openness and IAPS richness. We sampled 156 plots (2m  5m) along these corridors, ensuring a minimum distance of 100 meters between plots. Out of 10 IAPS recorded during the study, road verges and riversides were invaded by 70% of the recorded species, while the walking trail had the lowest number of IAPS (30%). The most prevalent IAPS was Chromolaena odorata, followed by Mikania micrantha and Ageratum conyzoides. One-way ANOVA indicated significant differences in IAPS richness among dispersal corridors (p<0.001). Furthermore, IAPS richness increased with increasing tree canopy openness (R=0.8, p<0.001). Given that road verges and riversides appeared to be the major dispersal corridors of IAPS, it is imperative to prioritize these corridors for IAPS monitoring, early detection, eradication, and control. Such efforts can reduce the establishment probability of new IAPS and mitigate the impacts of the widespread IAPS on the native species and ecosystems.