The current study was conducted in the moist temperate forest ecosystems in the Western Himalayan state of Azad Jammu and Kashmir, which falls between 34.21° latitude and 73.28° longitude in North-East Pakistan (Manzoor et al., 2023). The state’s terrain is hilly and rugged, with deep valleys carved out by numerous streams and rivers and forested mountain sides. Due to its significant elevational gradient, which reaches from 488 m in the southern half of the Punjab Plains to 6,212 m in the north, AJK is a regional biodiversity hotspot, supporting a broad variety of agroclimatic conditions and habitats. This zone is the typical monsoonal type and receives monsoon rainfall due to Himalayan mountainous systems in mostly July to September, with more than 70% more monsoon rainfall as compared to neighboring areas of Pakistan. The average minimum and maximum temperature recorded in July were 15°C to 35°C and in January was −10°C to 22°C. The average annual precipitation in the region is 1,511 mm. The fluctuating relative humidity recorded ranges from 58 to 84%, respectively. The snowfall period is from November to March, with up to 4 meters snow recorded in upper regions and 3 to 6 feet recorded in lower areas of the region. Due to heavy snowfall, winters are cold and prolonged (Shaheen et al., 2024). The main vegetation of the study area includes tree layer (Abies pindrow, A. indica, Taxus wallichiana, Pinus wallichiana, Picea smithiana, and Acer caesium), shrub layer (Viburnum grandiflorum, Parrotiopsis jacquemontiana, Indigofera heterantha, and Rubus fruticosus), and herb layer (Fragaria nubicola, Oxalis corniculata, Dryopteris stewartii, Podophyllum hexandrum, Asplenium trichomanes, and Plantago major).

A total of 14 broad-leaved and mixed-moisture temperate forest sites were sampled in the study area. To find the A. indica populations, a preliminary survey was conducted in the moist temperate forests of the Kashmir region prior to the sampling process. It was followed by selecting 14 moist temperate forest sites in three districts, including Neelum, Muzaffarabad, and Hattian, to ensure the species’ geographic range was covered (Figure 1). The area was surveyed during June to September 2021–2022. A total of 20 quadrats (each of 20 m x 20 m) were taken at each of the 14 study sites for the sampling of vegetation by using the systematic quadrat method. Primary phytosociological parameters of vegetation data comprising density, frequency, and cover were recorded at all sampling sites for A. indica in relation to the associated plant species, following standard protocols (Cox and Larson, 1993). All the associated plant species found in the A. indica populations were recorded and were identified following Flora of Pakistan, and The Plant List (TPL) (Nasir and Ali, 1980–1989).

The biological spectrum of the recorded flora including life form and leaf size, was determined following (Raunkiaer, 1934). Geographical coordinates such as altitude, longitude, and latitude of selected study sites were recorded by using the Global Positioning System (German GPS, Model Oregon 700). ArcGIS 10.8.2 was utilized for geospatial analysis of A. indica populations in AJK. This includes analyzing the spatial distribution of the A. indica populations along with creating digital elevation model (DEM) maps to reveal the altitudinal distribution of the species in the region. GPS data from each of the sampling plots were used to create the map of A. indica sampling locations. PALSAR/ALOS data with a resolution of 12.5 m were used to create the DEM.

Fuelwood properties of A. indica, including moisture contents, ash contents, bulk density, volatile matter, calorific values, and fuelwood value index (FVI), were investigated to analyze the combustion characteristics of this woody plant species following standard protocols (Bhatt and Tomar, 2002). The evaluation of the calorific value of wood based on per unit was investigated by 2 gm oven-dried powdered wood samples in three replicates for each sample. For the determination of calorific value, an oxygen bomb calorimeter was used (Bhatt and Todaria, 1990). The FVI was calculated by the following method (Purohit and Nautiyal, 1987).

Ecological attributes of A. indica-dominated forest communities were calculated using diversity indices. IVI was calculated for all recorded plant species as IVI = Relative density (RD) + relative frequency (RF) + relative cover (RC). Simpson’s diversity index was calculated as D = ⅀ni (ni-1)/N (N-1) (Simpson, 1949), where ni = number of individuals of a single species and N = number of individuals of all species in a community. Shannon’s diversity index was calculated as H′ = −⅀pi log pi (Shannon, 1949), where pi = ni/N; ni = number of individuals of a species and N = number of individuals of all species. Species evenness was calculated as J' = H′/lnS (Pielou, 1969), where H′ = Shannon diversity index and S = Number of species. Species richness was calculated as D = S/√N (Menhinick, 1964), where S = total number of species and N = number of individuals of all species. The community maturity index was calculated as MI = F/S (Pichi-Sermolli, 1948), where F = Frequency of all species and S = total number of species.

The species abundance data matrix was analyzed using multivariate ordination techniques such as Cluster analysis and Pearson’s correlation test. Principal component analysis (PCA) was also applied to the species dataset to reveal the pattern of dominance and relative abundance of the species in the investigated A. indica populations. Ordination analysis was carried out using PAST Software (Version 4.05) and Origin Software, to find the notable patterns and correlations between structural and diversity parameters of the A. indica populations. Linear bivariate correlation models were used to analyze community attributes with investigated variables. This allowed for observing changes in the indices over time. We used Origin Pro version 10 to conduct the linear regression model.

Deforestation intensity in the A. indica populations was determined by counting the number of stumps/ha. Habitat disturbances, including Grazing intensity and soil erosion, were recorded at all the investigated sites by using visual indicators such as animal droppings, hoof marks, trampling, and browsed vegetation. The indicators were used to classify the studied sites into moderate, low, and overgrazed categories. Furthermore, soil erosion intensity classes were determined as high, moderate, and low-eroded categories (Shaheen et al., 2011).

The investigated A. indica populations showed an average tree density of 435.85 stem/ha, with a maximum value of 1,100 stem/ha at the Pirchanasi site and a minimum of 220 ha at the Bankhora site. An average basal cover value of 356.33 cm was determined for A. indica in the region, varying between a maximum of 1574.5 cm and a minimum of 52.5 cm (Table 1). The populations exhibited a regeneration value varying between 60 seedlings/ha and 340 seedlings/ha averaging, at 174.28 /ha. A deforestation intensity of 135.4 stumps/ha was recorded from the study area.

DEM revealed that A. indica populations were distributed in an altitudinal range of 1,400 m to 2,800 m in the study Most of the A. indica populations (64.29%) were distributed between the elevational range of 2,350 m and 2,850 m, which mainly comprises the upper temperate forest. Three sites (21.43%) were recorded in the 2050 m and 2,100 m ranges, whereas only two sites (14.29%) were recorded below 2000 m elevation in the lower temperate zone.

The floristic inventory revealed that the associated flora of A. indica-dominated forests comprised 168 species belonging to 131 Genera and 51 families. The vegetation communities recorded from Aesculus habitats were largely captivated by herbaceous flora, making a bulk of 89%. A. indica was recorded as the most dominant with an IVI value of 48.81, along with closely associated co-dominant species including Viburnum grandiflorum (23.35), Fragaria nubicola (12.19), Abies pindrow (11.57), Oxalis corniculata (11.06), and Dryopteris stewartii (8.81), respectively.

Results of the biological spectrum showed that Microphylls were the dominant leaf size group in the study area, having 66 plant species with a contribution of 39%, followed by Mesophylls (23%) and Nanophylls (19%) as co-dominant clusters. Leptophylls and Megaphylls comprise 11 and 5% as the least concerned leaf spectra, respectively (Figure 2A). Hemicryptophytes were the dominant life form, with 60 species constituting 38% of the flora, followed bytherophytes (31%) and geophytes (17%). Nanophanerophytes were represented with a share of 0.05%, whereas Megaphanerophytes (0.04%), Mesophanerophytes (0.2%), and Lianas (0.01%) were the least frequent life form classes (Figure 2B).

Phytosociological attributes of Aesculus-dominated vegetation communities showed significant levels of diversity and richness. The recorded plant communities were characterized by an average species number of 35.71 along with an average Simpson’s diversity index of 0.94, fluctuating between 0.97 and 0.81. Average Shannon’s diversity index of 2.90 ranges from 3.64 to 1.02, showing wide variations. The determined values of species richness, species evenness, and maturity index were averaged at 2.89, 0.82, and 47.03, respectively (Table 1).

The average moisture contents determined in the wood of A. indica was recorded as 14.5%, average ash contents were recorded at 9%, and the average volatile matter was recorded as 23.8%. Results revealed that the highest values of ash contents (17%) and volatile matter (40%) were found in the bark of A. indica while moisture contents (21.4%) were present in greater amounts in the branch. Apart from this, A. indica exhibited a calorific value of 30.81 MJ/kg, while the calculated FVI of A. indica was 0.124, respectively.

Significant deforestation pressure was recorded in the A. indica forest stands, with an average value of 135 stumps/ha ranging from a maximum of 435 stumps/ha to a minimum of 41 stumps/ha. Approximately 71% of A. indica populations (10 out of 14) were recorded experiencing moderate to high grazing and trampling pressure, whereas only 4 populations showed non-significant grazing pressure. Six population sites (43%) were recorded with intense soil erosion intensity, followed by four sites each with moderate and low soil erosion.

The PCA was applied to the species data matrix, representing 70% variance in its four axes. PCA illustration identified A. indica as the most dominant species and placed it separately on the x-axis. PCA biplot identified the dominant and most abundant plant taxa within the species dataset and placed them distinctly along the x-axis. Viburnum grandiflorum, Oxalis corniculata, Abies pindrow, Fragaria nubicola, Viola odorata, and Poa alpina, were identified as the most abundant and and closely associated species recorded from the A. indica populations. A second bunch of co-dominant species was also identified by the PCA analysis and placed along the y-axis. These species include Dryopteris stewartii, Indigofera heterantha, Prunus cornuta, Podophyllum hexandrum, Skimmia laureola, Chenopodium album, Asplenium trichomanes, Strobilanthus glutinosus, and Plantago major. The majority of the recorded herbaceous species were characterized by infrequent sporadic distribution and were not significantly associated with any of the sites. These species formed a clump in the center of the PCA biplot, indicating their indifferent behavior (Figure 3).

Linear ordination analysis simplifies complex interactions between variables, providing useful insights into ecological datasets such as vegetation data from mountain regions. Linear ordination analysis offers an organized way to comprehend and demonstrate environmental as well as vegetation pattern gradients, which helps in managing and interpreting forest ecosystems. Pearson’s correlation analysis of diversity index data and structural attributes revealed a significant (p < 0.05) strong positive correlation between the number of species with richness, species evenness with Shannon diversity, and stem density with basal cover. A strong negative correlation (p < 0.05) was recorded between basal cover and species evenness, basal cover and Shannon diversity, stem density, and species evenness, number of species and species maturity, and stem density and Shannon diversity. The rest showed a moderate positive and negative correlation between different data matrix indices (Figure 4).

Generalized linear regression model (GLM) revealed a strong correlation among the structural attributes of the A. indica stands. An increasing trend is reflected in stem density (stem/ha) with the basal cover (cm) values of the species (Figure 5). GLM also revealed a negative correlation of A. indica regeneration and deforestation values, indicating that the disturbed forest stands were showing poor and retarded recruitment. In contrast, a decreasing trend was observed between the variables such as regeneration (seedlings/ha) and deforestation (Stumps/ha) (Figure 6).

The cluster analysis based on Euclidean distance was performed on the phytosociological attributes of the A. indica-dominated vegetation communities. CA successfully separated and classified the investigated populations based on structural and diversity values. The healthiest A. indica populations at Pir Chinasi and Bher Jabser sites were distinctly separated in cluster A from the rest of the populations owing to the highest stem density (<1,000/ha) and basal cover (<1,200 cm) values, along with having the highest number of species (<40). Machiara Behak population separated from Cluster B as an outlier, apparently having higher values of structural attributes among the remaining 12 sites. Cluster B is comprised of nine sites further separated into two subgroups, B-1 having four sites with intermediate values of diversity and structural characteristics, whereas five populations characterized with lower values were grouped in B-2, representing the most disturbed A. indica populations in the region (Figure 7).

Populations of dominant tree species exhibit variations attributed to differences in environmental variables, habitat quality, and land use practices (Ram et al., 2004). Investigated A indica populations showed an average density of 435.85 stems/ha with a very broad range of variation ranging from 1,100 stems/ha to a minimum of 220 stems/ha. More than 50% of the Aesculus populations showed disturbed population structure due to intense cutting pressure and disturbances. Only two sites showed considerably higher tree densities (>1,100/ha) that may be due to the high prevalence of smaller and younger trees (Svenning and Magård, 1999). The basal cover of A. indica was 356.33 cm across the region which is considerably high for a medium-sized deciduous tree. The better cover values suggest that A. indica plays a significant role in the canopy structure and composition of the Himalayan forests (Gairola et al., 2011). The variation in basal cover values could be indicative of differences in stand structure, age distribution, and competitive interactions with other tree species (Sharma and Samant, 2013).

The regeneration potential of A. indica assessed by determining the seedling density across the study sites revealed a regeneration value of 174.28 seedlings/ha. The relatively higher seedling density suggests that A. indica has a good regeneration potential in the Himalayan forests, which is crucial for the long-term sustainability of the species (Sharma et al., 2018). However, the variation in seedling density across the study sites could be influenced by factors such as seed availability, microsite conditions, and herbivory (Gairola et al., 2011). Interestingly, the forest stands with significant deforestation pressure also showed better regeneration as open canopies due to low tree density provided better solar insolation which favors seedling growth in A. indica populations mostly occurring on north-facing aspects canopies (Singh and Negi, 2023). The population structure results provide valuable insights into the structure of A. indica forest stands in the western Himalayas. The high variation in structural attributes of the forest stands across the study sites underscores the importance of site-specific management strategies for A. indica.

Floristic analysis revealed that A. indica populations constituted a habitat for a large number of associated floral wealth comprised of 168 plant species indicating its ecological significance as a keystone structural species. The recorded flora revealed overwhelming dominance of five plants, i.e., Asteraceae, Lamiaceae, Rosaceae, Poaceae, and Polygonaceae families, which contributed 50% of the total recorded plant species. These dominant families mainly consisted of herbaceous species that exhibit widespread abundance and unique growth patterns in the Himalayan temperate forests due to morphological and genetic adaptations as well as broader ecological amplitude (Semwal et al., 2010).

Phytosociological investigations of A. indica-dominated temperate forest communities studied from diverse ecological localities showed the dominance of a few representative plant species. A. indica showed the highest IVI value of 48.81 followed by Viburnum grandiflorum, Fragaria nubicola, Abies pindrow, Oxalis corniculata, and Dryopteris stewartii. Similar types of vegetation in temperate forests were also reported by various researchers from the Himalayan region. The present study agreed with Alam et al. (2023), Haq et al. (2023), Haq et al. (2022), and Shaheen et al. (2024). Generally, these species have a wide niche and are distributed across temperate forests. These dominants are the indicators as well as keystone species of the temperate zone’s vegetation (Khan S. M. et al., 2012; Khan W. et al., 2012; Cochard and Dar, 2014). Several studies in the western Himalayas have reported higher abundance values of A. indica which may be due to better conservation of forests (Sharma et al., 2014; Gairola et al., 2011).

Analysis of the biological spectrum of the flora, including leaf size and life form classification, demonstrates how the plants have adapted to the environmental factors and climate of their respective habitats (Khan et al., 2018). Hemicryptophytes were identified as the most prevalent floral life form in the A. indica populations, followed by therophytes and geophytes, respectively. It has been widely documented that the abundance of these life forms serves as a reliable indicator of the harsh environmental and mountainous conditions found in the temperate Himalayan forests (Haq et al., 2023). Microphylls were identified as the most abundant leaf size class in the A. indica-associated flora. Small leaves are reliable indicators of the cold and harsh environmental conditions of mountainous regions, ensuring high moisture retention (Haq et al., 2020). The prevalence of hemicryptophytes and microphylls in the area might be due to broad ecological adaptations to environmental factors, including cold temperatures, abundant rainfall, and short growing seasons (Shaheen et al., 2024).

A. indica populations showed significant levels of diversity and richness in the investigated area. Environmental factors such as aspect, elevation, slope, soil, and microenvironmental habitats strongly influence the patterns of Species Richness and Diversity (Khan S. M. et al., 2012; Khan W. et al., 2012). Species richness values were recorded to be higher on north-facing slopes, attributed to more suitable habitat conditions in terms of higher soil moisture, favorable temperature, and solar insolation (Panthi et al., 2007). The values of Shannon’s diversity recorded for the A. indica populations as 2.89 were in line with values recorded from eastern and middle Himalayan temperate forests of India, Nepal, and Bhutan (Gairola et al., 2011).

Species evenness is an important vegetation attribute that reflects the distribution pattern of plant species in any area ranging from 0 to 1, where the low value means unequal distribution and the highest value indicates uniform and homogenous distribution pattern (Mitchell et al., 2023). Species evenness averaged 0.82 in the A. indica-dominated vegetation communities, reflecting a somewhat uniformly arranged species pattern. Populations showed a high Simpson’s diversity value of 0.94, which reflects the striking dominance of few keystone taxa in the area constituting the majority of the temperate forests (Gairola et al., 2011). Little inter-site variation in Simpson’s diversity values was observed owing to similar habitat conditions as well as species composition of the investigated A. indica populations. The populations exhibited a low value of maturity index (<60), which shows the impacts of anthropogenic disturbances that hinder the communities from developing to ecological climax (Singh et al., 2014). In addition, harsh climatic conditions of the Himalayan Mountain ecosystems, along with climate change impacts, are also exerting persistent pressure on the vegetation, testing its vigor and vitality to reach equilibrium (Panthi et al., 2007).

The geographic variables, including altitude, slope, and aspect, significantly influence the distribution and habitat preference of A. indica in the western Himalayas (Duguid and Ashton, 2013). The combination of moderate to highly steep mountain slopes in the altitudinal range of 1,400–2,800 m located on north-facing aspects constituted the most preferred habitats for A. indica in the western Himalayas. This specific habitat preference can be attributed to the species’ ecological requirements, including soil moisture, nutrient availability, and microclimate conditions (Singh and Negi, 2023).

The DEM analysis revealed that A. indica populations in the western Himalayas are primarily distributed in an altitudinal range of 1,400 m to 2,800 m. This altitudinal distribution is consistent with the species’ preference for temperate climatic conditions and is indicative of its ecological niche in the Himalayan region (Singh and Negi, 2023). Most of the A. indica populations (64.29%) were found to be concentrated between the elevational range of 2,350 m and 2,850 m, which corresponds to the upper temperate forest zone. This finding aligns with previous studies indicating that A. indica predominantly occurs in the temperate regions of the Himalayas (Das et al., 2021; Shaheen et al., 2024).

The upper temperate forest zone, with its unique environmental conditions, appears to offer an optimal habitat for A. indica populations in the study region. The results of the current study revealed a clear preference for A. indica for north-facing aspects, with 90% of the populations recorded exclusively from north-facing slopes. This aspect preference suggests that A. indica exhibits specific adaptive strategies to optimize light interception, temperature regulation, and moisture retention, which are crucial for its growth and survival (Sharma and Samant, 2013). Aspects have a strong influence on the temperature as the north-facing slopes have dense canopy cover and less exposure to sunlight, the temperature is lower and remains shaded. Due to low temperatures and less intensity of light, north-facing areas have high moisture availability, making them suitable for A. indica growth (Bennie et al., 2008). The detailed analysis of geographic variables influencing A. indica distribution provides valuable insights for its conservation and management in the western Himalayas.

A current study has revealed significant pressure on A. indica forests due to various disturbances such as the felling of trees for fuel and fodder, fire, extensive grazing, and soil erosion. These disturbances significantly alter the structure, composition, and abundance of A. indica, as well as associated floral diversity. Habitat loss is widely affecting the ecological functioning of temperate forest ecosystems in the Himalayas (Tiwari et al., 2019). A significant deforestation intensity has been recorded in the A. indica-dominated forests averaging 135 stumps/ha in the study area. Approximately 50% of sites showed higher values of deforestation intensity exceeding 300 stumps/ha. Local Himalayan rural populations heavily rely on forest stands for fuel and timber wood due to the unavailability of alternate fuel, electricity, and poverty, leading to devastated forest structure (Haq et al., 2021).

Overgrazing and trampling were also recorded as major threat to the A. indica seedlings in the region, as approximately 65% of investigated sites showed significant grazing disturbance. Seedlings are very vulnerable and grow only a few centimeters per year, prone to the damage caused by grazing and trampling (Aziz et al., 2019). Forest land encroachment for housing and cultivation also threatens the A. indica populations in the study area due to the scarcity of available space in the rugged mountain terraces (Shaheen et al., 2023).

It is feared that if these activities continue in temperate broad-leaved forests, it can lead to a potential loss of many other species found as associated flora along with A. indica (Pawar and Rothkar, 2015).

Climate change and anthropogenic disturbances pose serious threats to the viability of A. indica populations in the region. Conservation strategies should focus on a strict ban on deforestation, community-based conservation initiatives, a ban on road construction, educating communities to foster awareness, controlled grazing practices, restoration of degraded habitats, controlling invasive species, promoting reforestation initiatives, sustainable harvesting policies, and promoting alternative livelihoods that support local communities in the region. Additionally, the AJK Forest Department and local NGOs engage local communities to create awareness about temperate forest ecosystems through seminars, social media, and cultural events, which help in safeguarding temperate forest ecosystems. Monitoring programs that track A. indica population trends and their associated flora can inform adaptive management strategies. Conservation strategies should prioritize the protection and restoration of A. indica habitats, especially the upper temperate forest zones with north-facing slopes, to ensure the long-term sustainability of the species. The study emphasizes the urgent need for effective conservation measures to safeguard A. indica and its associated floral diversity in the western Himalayan region.