Introduction
Environmental fluctuations influence the composition of vegetation and plant species’ coexistence in every region. Understanding these variations’ ecological significance and hierarchy is crucial for conserving and managing plant resources. Floristic diversity and its biological patterns are dependent on topography and elevation. Plant characteristics such as life form, leaf size, and phenological traits reflect the prevailing ecological and natural conditions [1, 2]. Phytosociology, which deals with plant communities’ characteristics, classification, relationships, and distribution, aims to describe species diversity within these communities [3]. Understanding how environmental variables affect the spatial distribution of ecological communities is crucial for predicting vegetation responses to various environmental factors. Ecological theory assumes that a variety of environmental factors shape local species communities and influence different aspects of community structure and composition in various ways [4].
The study of vegetation dynamics is a fundamental aspect of taxonomy that provides essential data for advanced research in plant ecology and conservation [1]. Conducting botanical assessments, which include structural studies of vegetation zones and analyses of floristic composition, is crucial for identifying key elements of plant biodiversity. These assessments contribute to protecting endangered and economically significant species and facilitate the monitoring of protected areas [5]. Pakistan harbors a rich biodiversity spanning across different ecosystems, from coastal regions to high alpine mountains [3]. It is crucial to gain insights into aquatic and terrestrial ecosystems’ ecological health, biodiversity, conservation challenges, and management strategies. Ecological traits, such as biological spectra, serve as reference points for assessing current and future phyto-climatic conditions [6]. There are about 300,000 known vascular plant species worldwide [7]. Understanding the floristic composition of a given area is crucial as it provides important information on the diversity and distribution of plant species [8]. This knowledge is key to accurately identifying and systematically conserving plant species. The distribution of plant species provides valuable insights into the environmental factors and ecosystem services within a specific habitat [9]. Plant biodiversity plays a pivotal role in ecosystems, and precise floristic inventories can deepen our understanding of a region’s climatic, topographic, and pedological conditions [10]. In addition, these inventories help us to understand the various factors that directly affect forest structure and composition [11]. However, the pressing challenges of urbanization, population growth, human activities, and environmental degradation highlight the importance of ecological and floristic studies [12]. Disturbances are among the most significant factors influencing forest ecosystems, and their effects vary according to the magnitude, frequency, and intensity of these events [13]. Such disturbances can profoundly affect successional patterns, species composition, and diversity, ultimately reshaping forest structure [14].
Extensive floristic inventories and vegetation analyses were carried out in various regions of Pakistan. Notable studies include the comprehensive survey in Torghar district [15] and detailed botanical assessments in Chail valley in Swat [16], Margalla foothills in Islamabad [17], and the Kotli district in Azad Kashmir [1]. Other research works are on the floristic composition of Kalash Valley, Chitral [18], plant diversity in Bin Dara in the Dir district [19], the vegetation dynamics in Utror and Gabral regions of Kalam [20], and the Liakot forests in the Kalam area of the Swat district [21]. Despite these comprehensive studies, the floristic composition and ecological gradients in the Ashoran forest of the Hindu Raj range within the greater Hindu Kush Mountains in Pakistan have not yet been explored. The Ashoran Mountains lie on a fault line and have particular geological features contributing to unique vegetation patterns [21]. The ecological assessment of the vegetation of the Ashoran Mountains in Kalam, Swat, is still unexplored, mainly due to the difficult climatic conditions and poor accessibility. This study conducts a detailed floristic inventory and examines the vegetation dynamics in Ashoran, located in the Hindukush Mountains. It makes a distinctive contribution to our understanding of plant diversity in this region by highlighting the importance of Sino-Japanese characteristics in the local flora. The study uncovers previously unknown patterns of species distribution and ecological interactions in this species-rich but little-studied area through comprehensive and extensive investigations along environmental gradients. The findings provide important insights for conservation efforts and contribute to our understanding of Himalayan biodiversity and its complex biogeographical relationships. The study has the following objectives:
2) to analyze the biological range of the collected plant species, and 3) to investigate the influence of environmental factors on the distribution of vegetation.
Materials and Methods
Study Area
The Ashoran Mountains in Kalam, located in the northernmost part of Swat District, are situated between 34° 11’ 27.096” and 35° 55’ 50.0376”N latitude and 72° 25’ 39.972” to 72° 49’ 5.00002”E longitude. This region is characterized by a dry and temperate climate and lies between 1982 m and 3115 m above sea level. As illustrated in Fig. 1, the average maximum temperature in this area is 18.5°C, and the minimum temperature is 3.4°C. The Ashoran Mountains receive an average of 897.7 mm of precipitation annually, and the average annual snowfall is 2834.64 mm. The hottest month is July, with temperatures of up to 26.7°C, while January is the coldest, with temperatures as low as -6.6°C. The amount of precipitation is lowest in September, with an average of 20.6 mm, whereas April has the highest amount of precipitation, with 4056.4 mm.
Data Collection and Analysis
Floristic and ecological assessments were carried out using a phytosociological approach during the reconnaissance trips from 2021 to 2023. Plant species’ quantitative and qualitative characteristics were recorded in 106 quadrats, distributed along different altitudinal transects according to standardized protocols [22]. The quadrats had a size of 1 m for herbs, 5 m for shrubs, and 10 m for trees. Various ecological factors such as slope, orientation, and elevation were documented for each sampling unit using a clinometer, a compass, and a GPS system. The plant specimens were collected, pressed, dried, mounted on standard herbarium sheets, and correctly identified from Pakistan’s flora [22-24] and compared with herbarium specimens and other literature [25, 26]. The voucher specimens were kept in the herbarium of the Botany Department of Islamia College Peshawar. An alphabetically arranged comprehensive floristic list was prepared, which listed the plant families. Each plant species was classified according to life form, leaf size classes, and biological spectra [27- 33]. Data from 106 quadrats were first recorded in Excel software in comma-separated value (CSV) format and then imported into the JUICE program (version 7.0.210), following the recommended methodology [34]. To create realistic species-quadrat associations, the same dataset was organized and processed using a modified version of Two-Way Indicator Species Analysis (TWINSPAN) within the JUICE platform [35]. Five pseudo-species cut levels (0, 2, 5, 10, and 20) were used for the cluster analysis, with Whittaker’s beta diversity serving as the TWINSPAN parameter. Subsequently, Detrended Correspondence Analysis (DCA) was performed using the JUICE program in conjunction with the R program (64-bit version 3.5.2) to examine the relationships between species, quadrats, and environmental variables.
Results
Floristic Composition
A total of 282 plant species were collected, representing 206 genera and 73 families (Table 1). The dominant family was Asteraceae, which had 24 plant species, followed by Poaceae (22 species), Rosaceae (17 species), Fabaceae, and Lamiaceae (14 species). Polygonaceae and Ranunculaceae had 10 species each (Fig. 2). Dicotyledonous species were the most abundant, with 219 species (78% of the total), followed by monocotyledonous species with 39 (13%), pteridophytes with 13 (4.6%), and gymnosperms with 11 (3.9%). Further details are illustrated in Fig. 3. In terms of habitus, herbs formed the majority with 188 species (66.66%), followed by trees with 35 species (12.4%), subshrubs with 24 species (8.5%), shrubs with 23 species (8.1%) (Fig. 4), climbers with 5 species (1.8%), parasites with 4 species (1.4%), and lianas with 3 species (1.06%).
Life Forms
The predominant life forms were therophytes with 85 species (30%), followed by geophytes with 54 species (19%), hemicryptophytes with 52 species (18%), nanophanerophytes with 21 species (7%), mesophanerophytes with 18 species (6%), microphanerophytes with 17 species (6%), chamaephytes with 14 species (5%), cryptophytes with 12 species (4%), and megaphanerophytes with 9 species (3%) (Fig. 5). The prevalence of therophyte life forms indicates their adaptability to adverse environmental conditions and intense anthropogenic disturbances.
Leaf-Form Spectra
In the area studied, nanophylls were the most common leaf size with 105 plant species (37%), followed by microphylls with 73 species (26%), mesophylls with 53 species (19%), leptophylls with 42 species (15%), macrophylls with 4 species (1.4%), aphylloids with 3 species (1%), and megaphylloids with 2 species (0.7%) (Fig. 6).
Plant Communities
A total of five plant communities were identified using the modified TWINSPAN classification, with Whittaker beta diversity as the classification parameter (Fig. 7).
Cedrus-Polygonum-Quercus (CPQ) Community
The Cedrus-Polygonum-Quercus community thrives at altitudes between 2062 m and 2112 m and inhabits the Maidani forest of Cedrus deodara (Roxb. ex D.Don) G.Don and at the base of the Ashoran Mountains, characterized by a dense forest of Quercus dilatata Royle. This community comprised eighteen stems and twenty-five species, with Polygonum aviculare L. dominating the herb layer. The slope in this area was particularly gentle and ranged from 2⁰ to 17⁰. Aspect varied between 84⁰ and 175⁰, latitude ranged from 35° 31’ 30” to 35° 44’ 22.92”, and longitude from 72° 36’ 52.92” to 72° 49’ 4.8”. This community had the highest percentage of tree cover at 48.89 percent, followed by 22.78 percent herbaceous cover. The shrub cover was the lowest, with a value of 3.9. Other predominant associated species were Phleum pratense L., Indigofera heterantha Wall. ex Brandis, Echinochloa crus-galli (L.) P. Beauv., Setaria viridis (L.) P. Beauv., and Pinus wallichiana A.B. Jacks., Phalaris minor Retz., Festuca gigantea (L.) Vill., Calamintha umbrosa (M.Bieb.) Rchb., Polygonum paronychioides Small ex Rydb., Plantago lanceolata L., Dianthus orientalis Adams. Due to its proximity to human settlements, this community has been subject to considerable disturbance in the form of deforestation, overgrazing, and agricultural expansion.
Quercus-Sorberia-Indegofera (QSI) Community
This community thrived at altitudes between 1982 and 2560 m. It comprised 17 sections and harbored 101 species. Slopes in the area ranged from 4⁰ to 55⁰, with an average slope of 28.38⁰. The slope ranged from 113⁰ to 263⁰. The average latitude and longitude were between 34° 54’ 33.48” and 35° 55’ 49.8” and 72° 25’ 21.72” and 72° 41’ 30.84”, respectively. The average proportion of trees, shrubs, and herbs was coverage of 30, 33, and 18.5, respectively. Predominant species in this community included Pennisetum flaccidum Griseb., Parrotiopsis jacquemontiana (Decne.) Rehder, Festuca gigantea (L.) Vill., Leptorhabdos parviflora (Benth.) Benth., Cedrus deodara (Roxb. ex D.Don) G.Don, Origanum vulgare L., Lepidium ruderale L., and others. However, this community is subject to disturbances such as deforestation, overgrazing, and agricultural expansion.
Origanum-Quercus-Seriphedium (OQS) Community
This community lies at an altitude of 2281 to 2756 m and is proof of the resilience of nature. It consists of 21 quadrates and is home to a variety of 146 species. It thrived amidst slopes with gradients from 9° to 66° with aspects from 113° to 273°, offering a panoramic view of the grandeur of nature. Situated at an average latitude and longitude of 34° 11’ 26.88” to 36° 0’ 0” and 72° 34’ 36.84” to 73° 0’ 0”, it was adorned with majestic species such as Pinus gerardiana Wall. ex D.Don, Indigofera heterantha Wall. ex Brandis, Cedrus deodara (Roxb. ex D.Don) G.Don, Lonicera hypoleuca Decne., Rosa webbiana Wall. ex Royle, Prunus jacquemontii Hook.f., Jasminum humile L., Cotoneaster nummularius Fisch. & C.A.Mey., Veronica alpina L., Garcke Garcke, Cotoneaster microphyllus Wall. ex Lindl., Sorbaria tomentosa (Lindl.) Rehder, Hypericum perforatum L., and more. The harmonious coexistence of trees, shrubs, and herbs, with an average cover of 32, 24, and 25, respectively, painted a picture of ecological balance. However, overgrazing threatened the delicate equilibrium despite the high location and conservation efforts.
Table 1.
Floristic diversity, habit, life span, life form, and leaf size in the Ashoran Mountains.
[i] Keys: H: Herb, T: Tree, SS: Sub-shrub, S: Shrub, C: Climber, Pa: Parasite, L: Liana, A: Annual, B: Biennial, P: Perennial, Th: Therophyte, Geo: Geophyte, HemC: Hemicryptophyte, NanP: Nanophyte, MesP: Mesophyte, MicP: Microphyte, ChmP: Chemiphyte, CrP: Cryptophyte, MegP: Megaphyte, Nan: Nanphyll, Mic: Microphyll, Mes: Mesophyll, Lep: Leptophyll, Mac: Macrophyll, Ap: Aphyla, Meg: Megaphyll, W: Wild, C: Cultivated.
Thymus-Rumex-Poa (TRP) Community
The Thymus-Rumex-Poa community thrived in the high alpine regions of the mountain range at an altitude of 2596 m and 3115 m. This community, comprising 17 quadrats and harboring 127 species, had an orientation of 112° to 327° and a slope of 9° to 57°. The geographic coordinates were an average latitude of 35° 31’ 30.72” to 35° 37’ 58.8” and a longitude of 72° 34’ 18.84” to 72° 40’ 45.12”. Trees, shrubs, and herbs covered the area by an average of 5%, 44%, and 45%, respectively. Notable species included Rosa webbiana Wall. ex Royle, Poa alpina L., Phleum alpinum L., Juniperus communis L., Bistorta affinis (D.Don) Greene, Veronica alpina L., Scutellaria petiolata Hemsl. ex Lace & Prain, Piptatherum gracile Mez, Onosma dichroantha Boiss., Ephedra gerardiana Wall. ex Klotzsch & Garcke Garcke, and Colchicum luteum Baker. However, the community was disturbed by overgrazing and the collection of medicinal plants.
Abies-Betula-Picea (ABP) Community
The Abies-Betula-Picea community thrived in subalpine regions with an altitude of 2405 m and 3009 m. With an orientation of 118° to 313° and an inclination of 11° to 68°, the geographical coordinates were between 35° 31’ 0.84” and 35° 47’ 46.68” and between 72° 40’ 21” and 72° 48’ 56.88”. The area was dominated 28% by trees, 17% by shrubs, and 43% by herbs. This community comprised 33 relicts and harbored 170 species. Notable species included Bistorta amplexicaulis (D.Don) Greene, Lindelofia anchusoides (Lindl.) Lehm., Quercus semecarpifolia Sm., Euphorbia wallichii Hook.f., Bergenia stracheyi (Hook.f. & Thomson) Engl., Rosa webbiana Wall. ex Royle, Geranium lamberti Sweet, Aquilegia pubiflora Wall. ex Royle, Onosma dichroantha Boiss., and Rumex hastatus D.Don. This was the best-preserved community, as it was located on steep slopes and away from human settlements, but it was threatened by overgrazing.
Overall, these communities were disturbed to varying degrees by factors such as deforestation, overgrazing, and agricultural expansion, with some being heavily impacted by humans while others remained relatively well preserved. Figs. 8 and 9 represent the locations of the communities without environmental factors and with environmental factors.
Discussion
The flora of the Ashoran Mountains in Kalam consists of 282 plant species from 73 families, as outlined in Table 1. Most of these species are herbaceous, comprising 66.6% of the total flora. Trees constitute 12.4%, followed by subshrubs with 8.5% and shrubs with 8.1%, as depicted in Fig. 4. Similar findings on the dominance of herbaceous plants have been reported by researchers in other regions of Pakistan, e.g., in the Sarban hills of Abbottabad [36] and in Balakot, Mansehra [37]. In the vast mountainous landscapes, herbaceous plants predominate over woody species [38]. This dominance of herbaceous forms can be attributed to these areas’ persistently harsh climatic conditions.
Fig. 7.
TWINSPAN (modified after Roleček et al., 2009) classification hierarchy of the five (5) plant associations in the research area (number of relevés are shown as subscripts and number of species are shown as superscripts corresponding with each vegetation unit).
Accurate sampling and analysis are essential for a comprehensive understanding of vegetation and the key factors influencing it in each region. In our study of the Ashoran Mountains, we examined 73 plant families and found that Asteraceae and Poaceae had the highest species richness. These were followed by Rosaceae, Fabaceae, Lamiaceae, and Polygonaceae. These results are consistent with previous studies [6, 39]. Asteraceae, Poaceae, Rosaceae, and Lamiaceae are distributed worldwide and thrive particularly well in temperate forest microhabitats, which emphasizes their broad ecological adaptability. The diverse habitat occurrence of Asteraceae in different habitats is attributed to their high ecological tolerance [40]. Other researchers also observed this pattern in Karak [41] and Malakand [22], where Asteraceae were most abundant in floristic diversity.
Biological spectra, which represent essential botanical characteristics, are often used in vegetation analysis to show how plants adapt to certain climatic conditions. These spectra include various life forms and leaf size categories, which have been extensively documented in Pakistan [40, 42]. In our study in the Ashoran Mountains, a remarkable dominance of therophytes was observed, indicating a significant impact on human activities such as deforestation and grazing. This observation aligns with other ecological studies that state that therophytes often predominate in areas of high disturbance [43]. Our findings are consistent with those of other studies [16, 43], which also reported a similar dominance of therophytes in their study areas.
The resistance of therophytes to extreme ecological conditions, whether at low or high altitudes and in open canopies, probably contributes to their distribution in our study area [44]. The short growing season in this area favors the rapid life cycle of therophytes, allowing them to maximize their growth during the limited favorable periods [45]. With increasing altitude, the harsher climatic conditions restrict the growth of shrubs and trees to lower altitudes and agricultural lands. However, at higher elevations, shrubs such as Salix species, Juniperus communis, Rosa webbiana, and Rosa canina are able to withstand severe conditions such as snowfall, circadian environmental changes, ice slides, and avalanches.
When examining the leaf size spectra, our study revealed that nanophylls are the most abundant, followed by microphylls. This pattern is consistent with the known ecological distribution of leaf sizes, where microphylls are typically associated with steppe environments, while leptophylls and nanophylls are common in hot desert regions [14]. Plants with larger leaves are generally adapted to warmer, wetter environments, while smaller leaves are more likely to be found in cold, dry climates. Species with large leaves thrive in moist and warm conditions, while the presence of smaller leaves suggests adaptation to drier conditions, lower rainfall, and higher temperatures. Similar observations have been made in other studies [42, 46-49], where nanophilous species were found to occur primarily at lower altitudes with reduced rainfall, and microphyllous species were more common at higher altitudes. These patterns emphasize the relationship between leaf size and climatic conditions at different altitudes.
Fig. 8.
Ordination diagrams of DCA analysis, showing the species distribution without environmental variables.
Fig. 9.
DCA analysis depicting the species distribution under the impact of different environmental factors operating in the study area.
In the phytosociological study, five plant communities were identified in the study area using a modified TWINSPAN classification [50, 51]. Canonical Correspondence Analysis (CCA) and Detrended Correspondence Analysis (DCA) are widely used ordination methods in community ecology. These techniques are useful in accurately identifying different ecological units, mapping out ecological gradients, and elucidating the relationships between environmental variables and floristic composition [50, 51].
Conclusions
The Ashoran region in the Hindukush Mountains, with its varied topography and pronounced altitudinal differences, is home to a rich diversity of plant species influenced primarily by Sino-Japanese elements. In this study, 282 plant species were identified, most of which are herbaceous, with the Asteraceae family being particularly well represented. The diverse edapho-climatic conditions support a range of life forms, particularly therophytes and nanophylls. The unique phenology of these species offers insights into their responses to climate change, highlighting the importance of effective forest management and species conservation. However, grazing, deforestation, forest fires, and unplanned development severely threaten the region’s biodiversity. Immediate conservation measures are needed to preserve this valuable and diverse ecosystem.
