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Climate change and anthropogenic pressures have resulted in a significant shift in the invasion susceptibility and frequency of non-native species in mountain ecosystems. Cirsium arvense (L.) Scop. (Family: Asteraceae) is an invasive species that spreads quickly in mountains, especially in the trans-Himalayan region of Ladakh. The current study used a trait-based approach to evaluate the impact of local habitat heterogeneity (soil physico-chemical properties) on C. arvense. Thirteen plant functional traits (root, shoot, leaf, and reproductive traits) of C. arvense were studied in three different habitat types (agricultural, marshy, and roadside). Functional trait variability in C. arvense was higher between, than within habitats (between different populations). All the functional traits interacted with habitat change, except for leaf count and seed mass. Soil properties strongly affect C. arvense's resource-use strategies across habitats. The plant adapted to a resource-poor environment (roadside habitat) by conserving resources and to a resource-rich environment (agricultural and marshy land habitat) by acquiring them. The ability of C. arvense to use resources differently reflects its persistence in introduced habitats. In summary, our study shows that C. arvense invades different habitats in introduced regions through trait adaptations and resource-use strategies in the trans-Himalayan region. [ABSTRACT FROM AUTHOR]

Alien plant species have captured attention of the scientific community, ecologists, and environmentalists throughout the world. Like other regions, the Himalayan region is also grappling with the disrupting impacts of plant invasions. Based on an extensive review of studies conducted on alien plant species in the Indian Himalayan region, we report 728 alien plant species belonging to 450 genera under 108 families in the state of Uttarakhand, which represents 15% of the state's flora. Fabaceae (89 species under 49 genera) followed by Asteraceae (63 species under 43 genera) and Poaceae (50 species under 35 genera) were the most diverse families amid alien species. Eucalyptus (15 species) followed by Ipomoea and Euphorbia (12 species each) and Pinus (11 species) were the most diverse genera. The maximum numbers of aliens (mostly herbs) in the state were introduced from America, followed by Europe. Owing to relatively high number of alien plant species in Uttarakhand, it is submitted that serious ecological and socio-economic consequences are likely to escalate in the future. [ABSTRACT FROM AUTHOR]

While the link between clonality and species invasiveness has recently been recognized, whether and how clonality vary with different invasion stages remains open questions. Hence, we tested the relationship between clonality and species invasiveness of Kashmir Himalayan aquatic macrophytes vis-à-vis its variability along different stages of invasion. The data on clonality, stage of invasion and growth form were obtained through an extensive survey of literature and database like CLO-PLA and PLADIAS followed by evaluation of the clonal organs through intensive field surveys undertaken over a period of 3 years (2014–2017) in different aquatic habitats of the Kashmir valley. Our results showed that 84% of the studied species and almost 90% of the most invasive species (stage Vsensu Colautti and MacIsaac: Divers Distrib 10(2):135–141, 2004) are clonal. A highly significant positive correlation between clonality and invasiveness was observed, which further substantiates this association at a broad geographical scale representing the whole region. The distinction of clonal growth forms and significant positive correlation between clonality and different clonal growth organs (rhizomes, runners and turions) further affirm the strong nexus of clonality with species invasions. Future studies directed at unraveling the reasons behind clonality need to be undertaken from the genomic perspective, in order to develop better means for proper management of alien aquatic invasive species. [ABSTRACT FROM AUTHOR]

Across the continents, plant invasion is identified as one of the main threats to ecosystem functioning and stability. The main objective of this research was to evaluate the differences in the functional traits between invasive alien (Ageratina adenophora (Spreng.) and Lantana camara L.) and native (Berberis asiatica Roxb. Ex DC., Pyracantha crenulata (D. Don.) M. Roemer and Rubus ellipticus Sm.) shrub species of chir pine (Pinus roxburghii Sarg.) forest in the central Himalaya. Three 0.5 hectare chir pine forest stands were selected and individuals of similar diameter were tagged for comparative studies of leaf traits, growth pattern, and biomass accumulation in structural organs of each invasive alien and native species. Our one-way ANOVA and Tukey's post hoc test results showed that both the invasive alien species have significantly (p < 0.05) higher SLA, LWC, total chlorophyll content, foliar nutrient (N and P), RGR, LMR, SMR, nutrient uptake, and nutrient use efficiencies than native species. Leaf litter decomposition rate and nutrient release were also significantly (p < 0.05) higher in both the invasive alien species. Native species, R. ellipticus, shared some of the traits, such as leaf area, chlorophyll content, RGR, LAR, LMR, and nutrient uptake efficiency with invasive alien species. The majority of traits differed among invasive alien and native species, implying that the success of invasive alien species is best described by being functionally distinct from native species. These findings indicate that invasive alien species had advanced functional traits which may be playing an important role in a rapid spread in the central Himalaya. [ABSTRACT FROM AUTHOR]

Development and economic growth, coupled with climate change and other environmental shifts, have made the unique and pristine mountainous regions vulnerable to plant invasions. While the effects of exotic plant invasions on community structure have been extensively studied in the lowlands, there is a dearth of such research in the altitudinal ecosystems. The objective of the present study was to investigate the ecological impact of Bidens pilosa (blackjack, Beggars tick; Asteraceae) on vegetation and soil dynamics across the north-western Himalayan landscape. Vegetation and soil sampling were conducted in paired invaded and control quadrats along an altitudinal gradient (300–1500 m asl) in the outer Himalayan region of Kangra, Himachal Pradesh, India. The presence of B. pilosa has a notable impact on reducing alpha diversity, with a more pronounced effect observed above 600 m asl. Pairwise beta diversity indices indicate that the invasion of B. pilosa has changed the natural species composition above 700 m asl, likely due to species turnover (i.e., species replacement). The results of NMDS and PERMANOVA analyses further support the notion that the invasion of B. pilosa has considerably homogenized the species composition along the selected elevational gradient. Further, significant variations in most of the soil parameters between the two invasion classes were observed within the elevation range of 600–1200 m asl. Overall, the results indicate that invasion by B. pilosa reshaped the patterns of floristic composition and soil properties in the north-western Himalayan landscape, leading to biotic and edaphic homogenization across an altitudinal gradient. The most substantial impact was noticed above the altitudinal range of 600 m asl, indicating that B. pilosa prefers mildly temperate climates over tropical ones in the studied area. It is pertinent to monitor and control the spread of B. pilosa in the Himalayan ecosystem to ensure the conservation of its unique biodiversity. [Display omitted] • Alpha diversity was altered by the invasion of Bidens pilosa in northwestern Himalayas. • Invasion by B. pilosa leads to biotic homogenization across an altitudinal gradient. • Soil physiochemical properties were affected in B. pilosa –infested areas. • Most substantial impact was noticed within the altitudinal range of 600–1200 m asl. [ABSTRACT FROM AUTHOR]

In an age of Anthropocene, the urban landscapes are recognised as the ‘hotspots’ of human-mediated alien species introductions. As the cities provide an ideal natural experimental system to investigate the patterns of alien plant diversity in urban landscapes, the present study aimed to unravel the taxonomic, biogeographic and ecological patterns of alien flora of Srinagar—one of the largest urban centres in the Himalayan biodiversity hotspot. The alien flora of Srinagar comprises 325 species, constituting ca.35% of total flora of the city. Out of the 325 alien species documented, 157 species (43%) were recorded to be under cultivation, while 168 species (57%) were growing in the wild (i.e., outside cultivation); those growing in the wild, in turn, comprised 110 cultivation escapes and 58 accidentally introduced plant species. Biogeographically, two-third of the alien plant diversity reported from Srinagar is native to Asia-Temperate. This indicates that climatic similarity between Asia-Temperate and Kashmir Himalayas facilitate in flourishing similar floristic diversity. The study highlights a relatively higher proportion of herbaceous growth form in the aliens growing in the wild (80%) than those under cultivation (43%). Similarly, 82% of the alien species under cultivation had a perennial life span, but those growing in the wild were dominated by annuals (44%). Currently, 45 species are growing as casuals and 124 species are naturalised (including 105 naturalised non-invasive and 19 naturalised invasive). Along the continuum of casual-naturalised-invasive categories, the contribution of cultivation escapes and accidently introduced aliens contrastingly shows decreasing and increasing trends respectively. Interestingly, the results revealed that the human practice of stopping cultivation of alien escapes increased rapidly as we move along the continuum. Thus, the present study has investigated the patterns of alien plant diversity in the urban landscape of Srinagar, and the results obtained offer scientific insights toward better scientific understanding and management of plant invasions in this Himalayan city, with wider policy implications for neighbouring urbanised landscapes in the Himalayas and other mountainous regions across the world. [ABSTRACT FROM AUTHOR]

• Floristic Quality Assessment Index (FQAI) is used to evaluate the e health status of the vegetation. • Of the 54 alien species, thirteen species were invasive, 36 were naturalized, and five were casual. • The largest (38%) species pool was observed in natural forest habitats. • Broadleaved forest harbored most alien species (35%) as compared to other types. • FAQI is best for measuring vegetation communities' responses to alien invasions. Evaluations ecosystem health-based field studies can assist decision-makers in formulating more targeted conservation policies to better manage ecosystems and landscape. To analyze forest characteristics in the Zabarwan Mountain Range we used the Floristic Quality Assessment Index (FQAI) technique to evaluate the ecosystem health status of the vegetation. According to our findings, the forest area showed an FQAI rating of 61.41. The FQAI ranked 54 of the plant species growing in the forest region at 0, 30 species at 1–3, 51 species at 4–6, 30 species at 7–8, and 17 species at 9–10. Of the 54 alien species ranking 0, thirteen species were invasive, 36 were naturalized, and five were casual. Amoung the forest types, the Broadleaved forest harbored most alien species (35%) and the scrub forest the least (6%). Based on habitat-wise distribution, the largest (38%) species pool was observed in natural forest habitats, while human-modified habitat types harbord 51% of species. Roadsides exhibited the by far highest alien species number (45%) together with other anthropogenic habitats. The investigation of indicator species revealed a separation between the various ranking groups, as evidenced by high indicator values. Important alien indicator species ranking 0 were i.e., Aesculus indica, Ailanthus altissima, Celtis australis, Daucus carota, Poa bulbosa, Prunus armeniaca, Prunus cerasus, Quercus robur, and Salix alba, which showed a significant p-value for indicator species analysis. The findings of this study provide a method for measuring vegetation communities' responses to alien invasions and as a result can serve for developing management methods to preserve ecosystems, particularly in protected areas, from this biodiversity threat. [ABSTRACT FROM AUTHOR]

Recognizing the array of effects that invasive alien species have, documenting their status from biodiversity rich regions has been much emphasized. Lack of such studies is a major limitation that hampers proper management of alien species. The present paper, therefore, documents the alien flora of the Indian Himalayan state of Himachal Pradesh (HP) based on data obtained from literature and herbarium records. The alien flora of HP comprises of 497 species belonging to 85 families. Majority of them belong to family Asteraceae (59 species), followed by Poaceae (47 species) and Fabaceae (43 species). Amongst the genera, Ipomoea (9 species), Eucalyptus and Euphorbia (7 species each) are the most predominant. Herbs constitute the majority (i.e., 73 %) of alien species and a large percentage of them (i.e., 22.94 %) have South America as their native region. Further, of the total alien species, 248 are intentional introductions and majority (31 % species) have been introduced for ornamental purposes. It was revealed that 34 % species have naturalized while 29 % species have become invasive. Today, in addition to human-disturbed landscapes, alien species have also been reported from dense forests. Himalaya being a biodiversity hotspot and HP being a bio-rich Himalayan state, it is hoped that this inventory and assessment of alien flora will help in designing informed management and monitoring strategies against problematic plant invasions in the state. [ABSTRACT FROM AUTHOR]

• Plant invasion alters the physico-chemical and microbial properties of soil, primarily in the surface (0–10 cm) layer. • L. camara and A. adenophora invasion increase soil Moisture, Porosity, OC, N, K, MBC and MBN in chir pine forests. • Soil MBC and MBN are significantly influenced by seasonal changes and followed the pattern of rainy > summer > winter in all the sites. • Plant invasion develops nutrients and microbial biomass rich substratum which enhanced the soil nutrient cycling process in microsites of chir pine forest. Plant invasion has been considered as one of the most influential forces that change the soil physico-chemical and biological properties of forest ecosystems. We have investigated the impact of two invasive alien plants, Lantana camara and Ageratina adenophora on soil physico-chemical and microbial properties in three different pine forests (Chanfi, Matial and Mehra) in the central Himalaya. Three subsites viz., non-invaded (NI), L. camara invaded (LI) and A. adenophora invaded (AI), were identified in each forest. Soil samples were collected seasonally in triplicate from the surface (0–10 cm) and subsurface (10–20 and 20–30 cm) depths and processed in the laboratory. PCA and correlation analysis were conducted to explore the relationship between soil properties, status (invaded and non-invaded) and soil depths. The soil variables were further compared between status and depth using linear mixed-effect model (LMM) and Tukey's HSD test. It was found that in LI and AI sites, soil properties such as moisture (Mo), porosity (Po), organic carbon (OC), total nitrogen (N), potassium (K), microbial biomass carbon (MBC) and nitrogen (MBN) were significantly (p < 0.05) higher and bulk density (BD) was lower in the surface soil (0–10 cm) than NI site but the difference was less prominent in subsurface (10–20 and 20–30 cm) depths. The MBC and MBN showed similar seasonal variations among LI, AI and NI sites following the trend of rainy > summer > winter. The results indicated that L. camara and A. adenophora invasion alter the soil properties and develop nutrient-rich substratum which may further promote the invasiveness in chir pine forest. The present findings would be helpful to develop appropriate management strategies for minimizing the impact of these invasive species on the soil characteristics including nutrient cycling processes of chir pine forests in the central Himalaya. [ABSTRACT FROM AUTHOR]

Litter decomposition, a key biogeochemical cycling process regulating carbon and other nutrient balances, is driven by several factors including vegetation composition, litter quality and local environmental conditions. However, the relative role of these drivers on decomposition process in the context of plant invasions has been little investigated, particularly in the Himalaya. In this study, we investigated the effect of plant invasion, litter quality and altitude on decomposition rate at multiple sites along an elevational gradient in Kashmir Himalaya. We used the standard litterbag incubation experiment to compare decomposition rates among the plots with- and without global plant invader Leucanthemum vulgare , using both standard (cellulosic filter papers) and local (pine needles) litter types. Our results show that invasion had a significant effect on decomposition rates of both the litter types with relatively higher decomposability in case of invaded plots than the uninvaded ones. Litter quality was the predominant factor in controlling the decomposition rate as evidenced from much higher decomposability (about eight times) of filter papers as compared to pine needles. Also, altitude had a significantly negative effect on decomposition rate of both the litter types, possibly through the influence on abiotic conditions (temperature and precipitation in particular). Our results highlight that, although multiple factors are affecting the litter decomposition at the regional scale, the litter quality exerted the stronger influence. Our study suggests that invasive L. vulgare by altering the litter decomposition rates could greatly influence the cycling of nutrients in the invaded landscapes. • Understanding the main drivers of litter decomposition is a key issue in ecology. • Effect of plant invasion, litter quality and altitude on decomposition was studied. • Plant invasion significantly increased decomposition rates in invaded landscapes. • Litter quality was the dominant factor in controlling rate of litter decomposition. [ABSTRACT FROM AUTHOR]

• Our results support a positive relationship between ploidy status and species invasiveness. • Invaders are largely polyploids while endemics tend to be diploids. • However, early stage (stage II) invaders and endemics show similar levels of diploidy. • The ploidy status of invasive species can yield useful insights for biodiversity managers. Despite the recently recognized link between ploidy level and species invasiveness, disentangling ploidy variations throughout the various stages of invasion still is an open question. Therefore, our aim was to investigate the variations in the ploidy level of alien Kashmir Himalayan plant throughout different stages of invasion and to compare those variations with the ploidy levels of 112 rare endemics. Ploidy level data was derived from an extensive literature review and web-based sources. The equality of proportions test was used to assess the relationship between ploidy status and species invasiveness or rarity/endemicity. We used Pearson's product-moment correlation coefficient to test the relationship between ploidy level and diversification among some of the most widespread alien plant families. Results showed a greater preponderance of polyploidy in invasive than in rare endemic species, which were mostly diploid. Regression analysis of 309 alien plant species showed that the proportion of polyploids increases with the stage of invasion, from stage II to stage V. Our results suggest a positive relationship between ploidy status and invasiveness. We emphasize the predictive value of these variations, as our model suggests that the 32 stage II alien polyploids seem more likely to become future invaders in Kashmir Himalaya than the 46 stage II diploids. Appropriate management strategies could be put in place early enough to prevent further damage from these potentially dangerous species. [ABSTRACT FROM AUTHOR]