Biodiversity regulates the ecosystem functioning and stability and is essential for human survival and economic wellbeing (Singh, 2002; Htun et al., 2011; Biplab et al., 2017; Baboo et al., 2017). The loss of biodiversity is a major challenge faced by humans in maintaining the stability and functional sustainability of ecosystems (Hua et al., 2022; Bisht et al., 2023). Wetland ecosystems are threatened by anthropogenic activities (Bisht et al., 2022). Among these, poverty, human population, agricultural expansion and intensification, and infrastructure development have been suggested as major threats to biodiversity in the tropics (Davidar et al., 2010; Bargali et al., 2019; Bargali et al., 2022; Bisht et al., 2023). Wetland ecosystem and its vegetation provide a wide range of ecosystem goods and services to the inhabitants (Gosain et al., 2015; Fartyal et al., 2022). Overexploitation of natural resources has created a big gap between the demand and supply of the natural goods (Manral et al., 2020; Pandey et al., 2023).

The biodiversity patterns along environmental gradients are one of the fundamental questions and are the synthetic reflection of all different types of ecological research (Khan S. et al., 2011; Raduła et al., 2020; Yu et al., 2021). The foundation of biodiversity research is based on the patterns of plant species diversity and the ecological variables affecting these patterns (Nogués-Bravo et al., 2008; Johnson et al., 2015; Li et al., 2018). Because of its importance in predicting future community composition and species performance, plant species diversity has received significant attention (Ullah et al., 2022; Khan et al., 2020; Wang et al., 2008; Subedi et al., 2020). The preservation of ecosystem biodiversity is significantly aided by habitat diversity, where topographical factors have multidimensional and multiscale effects on the pattern of species diversity (De Leo et al., 2014). These factors are interconnected and indicators of several abiotic parameters, including geographic, topographic and soil nutrient flow (Twilley and Rivera-Monroy, 2005).

The spatial scale will likely determine how an organism affects its surroundings, including ecosystem services (Ze-Hao and Xin-Shi, 2000; Kremen et al., 2007). In recent research using worldwide field survey data, organism–environment linkages may change with geography (Grace and Anderson, 2016). Abiotic factors at the regional scale determines the species distribution, as the effects of biotic factors (species types) on their environment are typically more localized (van de Koppel et al., 2012). However, direct and indirect interaction of these factors ultimately constitute organism–environment relationship (Grace and Anderson, 2016). The influence of biota may have been overstated in most studies due to the prevalence of statistical techniques (Alsterberg et al., 2013; Grace and Anderson, 2016).

The edaphic and geographical elements are also important for the variety of plant species and their distribution in aquatic emergent (char-land and water channels) plant communities (Schlaepfer et al., 2012). According to Chao et al. (2006), the soil’s physicochemical characteristics and parent materials may impact the plants growing there and the species diversity. Various direct ecological factors at large scales, including soil texture, nutrient level, and soil hydraulic and metal concentration, influence the distribution and structure of plant communities and species biodiversity in emergent plant communities (Stella et al., 2013). However, the altitudinal gradient is the primary factor forming different mountain habitats and is one of the key elements determining the spatial patterns of species diversity in many regions (Bhattarai and Vetaas, 2003; Wang et al., 2003; Zhao et al., 2005; Jiang et al., 2007; Bhattarai et al., 2014; Subedi et al., 2020).

According to Mitsch and Gosselink (1993), the main factor affecting the distribution of plant species at the land–water interface in wetlands is the water regime. In addition, wetland vegetation’s spatial heterogeneity is influenced by several variables, such as soil composition, microclimate, and topography since it controls the water regime (Naiman et al., 2005; Rybicki and Landwehr, 2007; Watt et al., 2007). The ranges of aquatic plants have been estimated using a variety of methods (Mcfarland and Shafer, 2011; Santos et al., 2011; Orellana et al., 2012; Singh et al., 2020). Field observations and large-scale analyses may now be combined with advances in spatial technology like aerial photography and other remote sensing techniques (Vis et al., 2003) and potent geo-statistical tools like plant cover/density estimators (Pepe et al., 2018). However, owing to the biophysical limitations in the environment, it is important to accurately assess aquatic plant species’ spatial distribution and plant community composition and comprehend their interactions.

The recent anthropogenic activities and rapid urbanization have deliberately changed the natural wetland communities in many areas of the world, particularly in developing countries like Pakistan. These activities threatened the communities’ lies at the junction of terrestrial and aquatic ecosystems or on wetlands. For example, recently, Ali et al. (2022) reported different mining operations along the riparian vegetation that adversely affect the community composition and structure. Therefore, this study evaluated Nasturtium officinale (R. Br. In Aiton) communities’ floristic composition and structure along the River Swat using quantitative ecological parameters. The study aims to assess plant communities dominated by N. officinale and associated species, and to provide scientific basis on the following questions: (i) How do these natural bog-plant communities and species diversity at char-land and channels along the Swat River Basin (SRB) respond to ecological factors? (ii) How do different degrees of anthropogenic factors act in the instability perspective of N. officinale at the community-level? By analyzing the ecological data of community composition and structure, we anticipated specifying a valid scientific basis for species assemblage’s distribution and characterization besides its protection and management in the region.

The floristic composition shows a narrow spectrum of vegetation in the aquatic plant communities of N. officinale across the River Swat having 22 species, which are dominated by native species (77%) and non-native species (invasive, naturalized, and cultivated). Similarly, the range of life forms comprises annual herbaceous plants representative of 16 plant families. These spectrums show the physiognomy of the flora and vegetation, which is the result of all living activities combined with the environment, making it vital to comprehend the ecological foundation of vegetation of N. officinale (Amjad et al., 2016). The dominance of annual plant species in communities can bring community homogeneity that favors the invasion of foreign species (Milchunas et al., 1988; Tappeiner et al., 1991; Qian and Guo, 2010). The vegetative reproductive potential of N. officinale may also contribute to community homogenization, resulting in the formation of less diverse vegetation. Similarly, smaller herb species like Xanthium strumarium, Mentha longifolia, Cynodon dactylon, and Cannabis sativa may be advantageous over native species since they can more easily spread across the communities (Timsina et al., 2011). The future vegetation diversity will be at risk, due to this relocation, which ultimately brings communities’ disturbance. These results were contrary to what has been observed in other aquatic ecosystems; non-native species comprise a significant and substantially greater component of submerged aquatic plant communities (Santos et al., 2011; Du Toit et al., 2021), while in this case, N. officinale, a native invasive species, dominated the communities.

The cluster analysis segregated four unique vegetation groups, each dominated by N. officinale and have different co-dominant species. Polygonum glabrum was the co-dominant species in Group I, Cynodon dactylon in Group II, Digitaria sanguinalis in Group III, and Mentha longfolia in Group IV. Similarly, a study was conducted on the phytosociology of Sedum brevifolium and found six plant groups (Nabi et al., 2012), while Ali et al. (2022) reported two plant communities across the wetlands of Panjkora River in district Dir Lower. At the sample sites, N. officinale was often found with several associated species, including Polygonum glabrum, Cynodon dactylon, and Digitaria sanguinalis. The same environmental factors and nutritional requirements might cause their communities’ association, as reported by Khan (2012); Khan et al. (2014); Muhammad et al. (2016); Nasrullah et al. (2015), and Shah and Hussain (2009).

The soil characteristics revealed that the calcareous nature accounted for roughly 99% of the growth of N. officinale. The calcareous soils with high potassium, nitrogen, and low phosphorus concentrations range from sandy loam to loamy silty texture, resulting in gregarious communities, as that reported in the region by Ullah et al. (2021) and Ullah et al. (2022). The smaller communities having high density and cover in terms of species composition may be attributed to two factors, i.e., the communities are new to the region and the potential of N. officinale to regenerate (Ali et al., 2022). Our results were contrasted to that reported by Khan et al. (2020), who reported that seedlings and juvenile plants grow quicker than mature plants, resulting in a decreased density. However, these results complied with Hitimana et al. (2004), where the high density is linked to the plant species’ capacity for regeneration. The community structure and composition may change due to man-made activities, intra- and inter-specific competition, and the pattern of regeneration (Faridah-Hanum et al., 2012). These soils also allow water and air to move through them, letting roots penetrate more readily, providing nutrients and clay aggregation stability (Zimmermann, 1991). Certain invasive generalist species, such as C. sativa, X. strumarium, and C. dactylon, pioneer species of disturbed vegetation, were dominant in the communities (Iqbal et al., 2021). N. officinale probably establishes itself as the dominant species in wetlands in Khyber Pakhtunkhwa due to these environmental factors that favor their propagation and growth. In addition, the vegetation decomposition and microbial activities in the root zone may further add soil nutrients that add to the fertility of soil and resulting in the establishment and propagation of a particular community in an area (Bargali et al., 2018).

As expected, the anthropogenic variables substantially disrupted the communities’ structure, favoring non-native species invasion (Geiger and McPherson, 2005; Bhattarai et al., 2014). The study assessed mining factor, grazing pressure, cultivated fields, and over-harvesting to determine how these factors relate to the disturbance of N. officinale communities. However, these factors vary significantly along IVI gradients, showing that they are linked to invasive species and community disturbance. The sites of Group II had greater grazing intensity, agricultural activities or areas occupied by cultivated fields, and mining factors, making the populations more susceptible to invasion, as reported by Chhogyel et al. (2021) and Pretto et al. (2010). This could be due to the easy transportation of the alien species propagules in such areas. According to McDougall et al. (2005) and Sjödin et al. (2008), grazing pressure and mining factor disturbed communities by generating unoccupied niches for alien propagules, enabling the plant to invade the vacant habitats. Similarly, sand extraction from aquatic environments, like rivers and coasts, provides an ecosystem service (Grizzetti et al., 2019). Sand is primarily used in construction because concrete contains 75% sand (Jnr et al., 2018). All this equates to approximately 200 tons of sand for a home, 30,000 tons for every kilometer of roadway, and an astounding 12 million tons of sand for a nuclear power station (Ludacer, 2018; Rentier, and Cammeraat, 2022). This tremendous sand demand has made mining a global environmental concern that disturbed community structure (Asabonga et al., 2017). This mining operation caused habitat fragmentation that continuously disturbed these communities in the river bed and char-land areas.

RDA of vegetation–soil interactions revealed that organic matter, silt, sand, clay, phosphorus, potassium, pH, latitude, longitude, aspect degree, wilting point, field capacity, and available water were the key factors controlling the distribution of vegetation in the region. The role of organic carbon in soil fertility is well known and reported by many authors like Kononova (2013) and Rao et al. (2017). Similarly, increase in soil organic matter content results from the breakdown of plant residues, lower salt toxicity from dissolved potassium and calcium brought by rainwater (Taiz and Zeiger, 2002), and increasing vegetation diversity (Lyons et al., 2005). Moreover, many studies like Ali et al. (2022); Ullah et al. (2022), and Ullah et al. (2021) in the same region reported the significance of soil organic matter, nitrogen, and soil texture in sustaining plant communities. Similar research on the influence of surface sediment percentages of various size classes on the geographical distribution of soil moisture was reported by Dasti and Agnew (1994). In addition, many other factors, such as precipitation, rain, and flood, increase the percentages of silt and clay in the soil texture that play an important role in shaping plant communities (Duniway et al., 2010). The most significant factors closely related to the dispersion of vegetation communities are nutritional status, electrical conductivity, soil texture, slope, and aspect (Tavili and Jafari, 2009). Our results were also in agreement with those of Zare et al. (2011), who reported that the distribution of plants is influenced by slope, aspect elevation, soil texture, lime content, soil moisture, available nitrogen, potassium, and organic matter, and Bargali et al. (2018), revealing the importance of soil organic matter and nitrogen in maintaining plant communities.

The study concluded that topography and spatial variability influenced the N. officinale vegetation’s distribution in the area. In addition, the anthropogenic factors qualitative and quantitative intensity have the most prominent role in disturbing the communities. In addition, it has been shown that the spread of N. officinale vegetation is more strongly correlated with physical environmental factors and substrate characteristics that affect water availability. The disturbance in communities can be minimized by land use to change the water conditions in wetlands directly or indirectly by draining them to make the surface drier and by introducing plant species like N. officinale that are tolerant to flooding and produce more crops and feed. In addition, non-wetland species swiftly builds up peaty soils in the wetlands, elevating the surface above the water building diverse communities. However, the presence of non-native species may subject the communities to unexpected changes in vegetation; therefore, proper management of non-native invasive species should be considered for future perspective.

The original contributions presented in the study are included in the article/ Supplementary Material . Further inquiries can be directed to the corresponding author.

NK and RU conceptualized this research, conducted the field and laboratory experiments, and compiled and analyzed the data; NK and RU wrote the original draft of the manuscript; MO and MA-M supervised the experiments; IS, H-AH, and TA contributed to data analysis; and HA helped in the review and edited the initial draft of the manuscript; all authors read and approved the manuscript.