Environmental variables drive plant species composition and distribution in the moist temperate forests of Northwestern Himalaya, Pakistan

Synergizing population structure, habitat preferences, and ecological drivers for conservation of Cedrus deodara

BACKGROUND

Climate change is impacting forest tree species adversely and making the ecological system vulnerable. The Himalayan cedar (Cedrus deodara), a keystone species in Western Himalayan forests, plays an important ecological role but is under increasing threats from natural and anthropogenic pressures. The current study analyses the population structure, spatial distribution, environmental factors, and future conservation strategies for Himalayan cedar populations in the Kashmir Himalayas.

METHODS

Field sampling was carried out between 2023 and 2024 in various districts of the Kashmir Himalayas. The quadrat method was used to record the vegetation data across an elevational gradient ranging from 1300 to 2700 m. GIS and spatial analysis were used to map population distribution while, cluster analysis was performed to identify species associations. Canonical Correspondence Analysis (CCA) was applied to identify the influence of environmental factors while, Non-Metric Multidimensional Scaling (NMDS) and SIMPER analysis were used to investigate inter-association dissimilarity.

RESULTS

The populations showed an average stem density of 110.73 trees/ha and low regeneration rates, with just 15 seedlings per ha on average. Stump density (mean: 90.62 stumps/ha) demonstrated human-induced pressures. GIS and spatial analysis revealed that Cedar populations were mostly found at altitudes ranging from 1900 to 2200 m, with a preference for north-facing slopes. Cluster analysis identified four distinct species associations in which each with a different species richness and ecological composition. Association 3 was the most diverse (Shannon index: 3.31 ± 0.05), while Association 4 showed the highest dominance (0.062 ± 0.002). Canonical Correspondence Analysis (CCA) identified altitude and timber extraction as the key drivers of variation, accounting for 16.2% and 15.2% of the distribution variance, respectively. Grazing, erosion, and fire accelerated the degradation of habitat. Cedar density was influenced by various edaphic parameters, with total nitrogen (R2 = 0.11) and soil moisture (R2 = 0.09) demonstrating the strongest association. Soil pH, electrical conductivity, and total phosphorus exhibited minimal or negligible effects. Associations 1 and 2 were associated with increased soil pH and electrical conductivity, but Associations 3 and 4 were influenced more by nutrient-rich and moisture-retentive soils. Non-Metric Multidimensional Scaling (NMDS) and SIMPER analysis identified a 56.99% dissimilarity between associations, mostly driven by species such as Parrotiopsis jacquemontiana and Viburnum grandiflorum.

CONCLUSION

The study reveals that Himalayan cedar populations in the Kashmir Himalayas face low regeneration rates and significant anthropogenic pressure. Their distribution is influenced by various factors, including altitude, timber extraction, soil nitrogen, moisture, grazing, erosion, and fire. These findings highlight the necessity for targeted conservation strategies. Future conservation strategies should encompass controlled grazing, regulated timber extraction, soil conservation measures, anti-logging policies, ecotourism initiatives, and collaboration among local communities and policymakers.

Effects of landscape edge heterogeneity on biodiversity in grassland restoration context

Habitat loss is a major driver of global biodiversity decline, and grassland ecosystems are critical for habitat conservation. In the Loess Plateau of China, prolonged agricultural practices and overgrazing have led to severe degradation of grasslands, causing biodiversity loss and reduced ecological functionality. This study examined the effects of connectivity and edge heterogeneity in three landscape mosaic types-farmland-grassland, river-grassland, and woodland-grassland-on biodiversity restoration. Using seven experimental units in the Ansai District, we assessed species richness, abundance, and community composition of butterflies, carabid beetles, and vascular plants. Our findings showed that connected habitats, particularly in farmland-grassland and river-grassland mosaics, on average increased species richness by over 38% compared to isolated habitats. Rare species were predominantly distributed in river-grassland mosaics, highlighting the importance of edge connectivity in supporting biodiversity. In contrast, biodiversity was lower in connected woodland-grassland mosaics, suggesting taxon-specific responses to connectivity. Vegetation played a key role in regulating biodiversity by providing food and shelter, emphasizing the need to conserve plant diversity for ecosystem recovery. Grazing intensity negatively affected vascular plants and carabid beetles, highlighting the importance of rational grazing management. Our findings highlight principles of connectivity and heterogeneity that are applicable to grassland restoration in arid and semi-arid ecosystems globally. Future research should explore how climate change and extreme weather events may moderate these effects. The results provide actionable recommendations for designing ecological corridors, optimizing landscape mosaics, and integrating sustainable grazing practices to restore degraded grasslands effectively.

Grass pea dual purpose dry matter and seed yields in rainfed conditions across diverse environments

Grass pea (Lathyrus sativus L.) stands out as an excellent choice for sustainable agriculture, thanks to its favorable agronomic characteristics, including a robust root system that penetrates deeply into the soil and its resilience against various biotic and abiotic stressors. In this study, dry-matter yield and seed yield of 16 grass pea genotypes were evaluated in rain-fed conditions at "Gachsaran", "Mehran", "Kuhdasht", and "Shirvan-Chardavol" locations in Iran for three consecutive years. The experimental field trials were carried out using a randomized complete block design, and each experimental setup was replicated three times. The descriptive statistics showed a mean value of 4.030 (ton/ha) and 1.530 (ton/ha), with phenotypic coefficients of 54.77 and 61.56 for dry-matter yield and seed yield, respectively. The projection of geographical, climatic, and edaphic variables into yield measurements depicted remarkable divergence among the four studied environments. Elevation exerts a greater influence on both dry matter and seed yields in the Mehran location as compared to other environments. The climatic factors of rainfall and relative humidity played an important role in "Gachsaran" and "Shirvan-Chardavol", respectively. While for seed yield, the temperature-related attributes were more significant in the "Mehran" location. Low broad-sense heritability was observed, and the R2 for genotype-environment interaction showed the existence of GEI for dry-matter yield (0.126) and seed yield (0.223). Both AMMI1 and AMMI2 could recognize unstable genotypes from other ones, and both AMMI's identified genotypes G10 and G3 as high-yielding and stable genotypes. BLUP-based stability indices revealed G10 and G13 as superior genotypes for seed yield and dry-matter yield, respectively. Three and two mega-environments were identified using a GGE biplot for dry-matter yield and seed yield. For dry-matter-identified mega-environments, the G1, G13, and G2, and for seed-yield-recognized mega-environments, the G10 and G15 can be introduced. "Mehran" and "Gachsaran" out of the studied locations possessed diverse distributions considering dry-matter yield and seed yield and for further GE interaction studies, it is better to establish adaptability trials in these locations. The study concludes that for the promotion of sustainable agriculture in rain-fed regions, taking into account the influence of environmental factors, cultivation of the identified grass pea genotypes holds promise.

Topography and soil variables drive the plant community distribution pattern and species richness in the Arjo-Diga forest in western Ethiopia

Understanding plant community characteristics, distributions, and environmental relationships is crucial for sustainable forest management. Thus, this study examined the relationships between plant community composition and topographic and soil variables within the Arjo-Diga forest. Vegetation data were collected from 72 nested plots (30 × 30 m2 and 2 × 2 m2) systematically laid along nine transects spaced 300 to 700 m apart. Environmental variables, including soil properties and anthropogenic disturbance, were recorded within each main plot. Agglomerative hierarchical cluster analysis and canonical correspondence analysis (CCA) using R software were employed to identify distinct plant community types and examine their relationships with environmental factors. The Shannon‒Wiener diversity index was calculated to quantify and compare species diversity among the identified community types. The analysis revealed five distinct plant community types: 1: Maesa lanceolata-Ehretia cymosa, 2: Trichilia dregeana-Flacourtia indica, 3: Acacia abyssinica-Millettia ferruginea, 4: Combretum collinum-Croton macrostachyus, and 5: Terminalia macroptera-Piliostigma thonningii. The CCA results highlighted the significant influence (p < 0.05) of altitude, CEC, TN, and disturbance on species distribution and plant community formation. The findings indicate that variation in plant communities is closely associated with altitude, TN, and CEC, as well as with disturbance factors such as human interventions, with elevation being the most influential factor. Based on these findings, it is recommended that conservation plans consider the effects of human interventions to address the challenges in conserving forests in the future. Additionally, further research efforts should focus on mitigating disturbance factors and understanding the environmental variables that affect forests to improve their protection.

Eco-systematic assessment of the spring herbaceous vegetation under edaphic and topographic effects

The distribution and composition of the vegetation are greatly affected by the edaphology and topography of an area. The current study explores the vegetation structure of the herbaceous layer at various habitats of district Kohat for the first time. A survey was conducted during the spring seasons of 2021, 2022 and 2023 selecting 40 sites on the basis of edaphology, topography, altitude, aspect and status. Data was collected via quadrat approach to establish plant communities by species Importance Value (IV), point out dominant species by Total IV (TIV) and dominant families via Total Family IV (TFIV). The quantitative biological spectrum was also calculated. Communities' phytosociological characteristics were analyzed via various diversity indices (Shannon's Index (H), Simpson's Index (D), Species Richness (SR), Evenness (E) and Maturity index (Mi)) while similarity between the communities was calculated by using Sorensen's Index. The findings revealed a total of 253 species belonging to 57 families having the dominant species Cynodon dactylon (L.) Pers. (TIV, 484.3) followed by Saussuria heteromalla (D. Don) Hand. (TIV, 360.4), Anagallis arvensis L. (TIV, 353.2) and Aristida adscensionis L. (TIV, 349.65). Among 40 plant communities, Poaceae (TFIV, 2706.6), Asteraceae (TFIV, 2018.8), Fabaceae (TFIV, 1071.5) and Brassicaceae (TFIV, 825.9) were the dominant families. Therophytes (TIV, 7882) class was the dominant life form class followed by hemicryptophytes (TIV, 2517) while microphylls (TIV, 4669) class was the dominant leaf size class followed by nanophylls (TIV, 5469). Environmental factors i.e. topography and edaphic characteristics, showed significant effects on the diversity of the communities. The study concludes in a diverse pattern of distribution with a rich flora in the area warranting its documentation which will preserve the valuable species opening vistas for future research.

Variations in species diversity patterns and community assembly rules among vegetation types in the karst landscape

The various vegetation types in the karst landscape have been considered the results of heterogeneous habitats. However, the lack of a comprehensive understanding of regional biodiversity patterns and the underlying ecological processes limits further research on ecological management. This study established forest dynamic plots (FDPs) of the dominant vegetation types (shrubland, SL; mixed tree and shrub forest, MTSF; coniferous forest, CF; coniferous broadleaf mixed forest, CBMF; and broadleaf forest, BF) in the karst landscape and quantified the species diversity patterns and potential ecological processes. The results showed that in terms of diversity patterns, the evenness and species richness of the CF community were significantly lower than other vegetation types, while the BF community had the highest species richness. The other three vegetation types showed no significant variation in species richness and evenness. However, when controlling the number of individuals of FDPs, the rarefied species richness showed significant differences and ranked as BF > SL > MTSF > CBMF > CF, highlighting the importance of considering the impacts of abundance. Additionally, the community assembly of climax communities (CF or BF) was dominated by stochastic processes such as species dispersal or species formation, whereas deterministic processes (habitat filtering) dominated the secondary forests (SL, MTSF, and CBMF). These findings proved that community assembly differs mainly between the climax community and other communities. Hence, it is crucial to consider the biodiversity and of the potential underlying ecological processes together when studying regional ecology and management, particularly in heterogeneous ecosystems.

Ecological determinants in plant community structure across dry afromontane forest patches of Northwestern Ethiopia

Ethiopia is a mountainous country with great geographic diversity. The diversified topographic features in Ethiopia made the country have a rich biodiversity forest cover in tropical Africa. This made Ethiopia have the largest floral diversity in tropical Africa. This floral diversity is rich in endemic elements. About 6,027 vascular plant species (including subspecies) with about 10.7% endemism have been documented. Plant community types are primarily influenced by topographic factors, as well as disturbance and environmental factors. The objective of this study is to demonstrate that 1: The forest patches in the study area exhibit distinct plant community types. 2: The composition and structure of these plant communities are influenced by various environmental variables. To achieve this, a total of 76 plots were used to collect vegetation and environmental data. The collected data were then analyzed using the R software, employing agglomerative hierarchical cluster analysis and redundancy analysis (RDA) to identify plant communities and assess the relationship between these communities and environmental variables.R software was used to identify plant communities and analyze the relationship between plant community types and environmental variables using agglomerative hierarchical cluster analysis and redundancy analysis (RDA). Four plant community types were identified. The RDA results highlighted the significant impact (p < 0.005) of altitude, aspect, slope, grazing, and human interference on species distribution and the formation of plant communities. The RDA results highlighted the significant impact (p < 0.005) of altitude, aspect, slope, grazing, and human interference on species distribution and the formation of plant communities.The findings indicate that the variation in plant communities is closely associated with topographic factors such as altitude, slope, aspect, as well as disturbance factors like grazing, and human interference, with altitude being the most influential factor. Based on these findings, it is recommended that conservation plans take into consideration the effects of grazing and human interference in order to address the challenges faced in conserving forest patches in the future.Additionally, further research efforts should focus on mitigating disturbance factors and understanding the environmental variables that affect forest patches to enhance their conservation.

A pathogen's spatial range is not constrained by geographical features in the flax rust pathosystem

Climate change and shifting environmental conditions can allow pathogens to spread into previously unburdened areas. For plant pathogens, this dynamic has the potential to disrupt natural ecosystem equilibria and human agriculture, making predicting plant pathogen range shifts increasingly important. Although such predictions will hinge on an accurate understanding of the determinants of pathogen range-namely the environmental, geographical, and host range characteristics that modulate local pathogen habitation-few studies to date have probed these in natural plant populations. Here, we characterize range determinants for the model system of Lewis flax (Linum lewisii) and its pathogen, flax rust (Melampsora lini), in the Rocky Mountains. Transect surveys were performed to assess three relationships: (i) the effect of geographical features-elevation, slope aspect, slope grade, and land cover-on flax presence and density, (ii) the effect of geographical features on flax rust presence and prevalence, and (iii) the effects of flax's local population density and metapopulation structure on flax rust presence and prevalence. We found that flax population density, but not host metapopulation structure, influences the distribution of flax rust. Additionally, we showed that, while the distribution of flax was broadly constrained to a relatively narrow range of geographical and resulting environmental features, flax rust was evenly distributed across the full range of settings measured. These results indicate that a warming environment, which is expected to modulate such features, may restrict the optimal range of the plant more than that of its pathogen. Importantly, our results also suggest that even if flax shifts its spatial range to escape increasing climatic pressures, flax rust will not face any significant barriers to track this movement.

Diversity of lithophytic moss species in karst regions in response to elevation gradients

The distribution pattern of species diversity along various elevation gradients reflects the biological and ecological characteristics of species, distribution status and adaptability to the environment. Altitude, a comprehensive ecological factor, affects the spatial distribution of species diversity in plant communities by causing integrated changes in light, temperature, water and soil factors. In Guiyang City, we studied the species diversity of lithophytic mosses and the relationships between species and environmental factors. The results showed that: (1) There were 52 species of bryophytes in 26 genera and 13 families within the study area. The dominant families were Brachytheciaceae, Hypnaceae and Thuidiaceae. The dominant genera were Brachythecium, Hypnum, Eurhynchium, Thuidium, Anomodon and Plagiomnium; The dominant species were Eurohypnum leptothallum, Brachythecium salebrosum, Brachythecium pendulum etc. The number of family species and dominant family genera increased first and then decreased with the increase of altitude, and their distribution in elevation gradient III (1334-1515m) was the largest, with 8 families, 13 genera and 21 species. The elevation gradient I (970-1151m) was the least species distributed, with 5 families, 10 genera and 14 species. The dominant species with the largest number in each elevational gradient were Eurohypnum leptothallum, Brachythecium pendulum, Brachythecium salebrosum and Entodon prorepens; (2) There were five kinds of life forms in different elevation gradients, including Wefts, Turfs, Mat, Pendants and Tail. Among them, wefts and turfs appeared in all elevations, while a small amount of Pendants appeared in the area of elevational gradient I (970-1151m), and the most abundant life form was found in the range of elevational gradient III (1334-1515m); (3) Patrick richness index and Shannon-Wiener diversity index were highly significantly (p<0.01) positively correlated, both of which increased and then decreased with elevation, reaching a maximum at elevation gradient III (1334-1515m); The Simpson dominance index had a highly significant (p<0.01) negative correlation with the Patrick richness index and the Shannon-Wiener diversity index, which showed a decreasing and then increasing trend with increasing altitude; Pielou evenness index showed no discernible trend; (4) β diversity study revealed that while the similarity coefficient tended to decrease with increasing altitude, the species composition of bryophytes increased. The elevation gradient II (1151-1332m) and elevation gradient I (970-1151m) shared the most similarities, whereas elevation gradient III (1515-1694m) and elevation gradient I shared the least similarities (970-1151m). The findings can enrich the theory of the distribution pattern of lithophytic moss species diversity at distinct elevation gradients in karst regions, and serve a scientific and reasonable reference for restoring rocky desertification and protecting biodiversity there.

Invasive Species Change Plant Community Composition of Preserved Prairie Pothole Wetlands

Plant communities in North American prairie pothole wetlands vary depending on hydrology, salinity, and anthropogenic disturbance in and around the wetland. We assessed prairie pothole conditions on United States Fish and Wildlife Service fee-title lands in North Dakota and South Dakota to improve our understanding of current conditions and plant community composition. Species-level data were collected at 200 randomly chosen temporary and seasonal wetland sites located on native prairie remnants (n = 48) and previously cultivated lands that were reseeded into perennial grassland (n = 152). The majority of species surveyed appeared infrequently and were low in relative cover. The four most frequently observed species were introduced invasive species common to the Prairie Pothole Region of North America. Our results suggested relative cover of a few invasive species (i.e., Bromus inermis Leyss., Phalaris arundinacea L., and Typha ×glauca Godr. (pro sp.) [angustifolia or domingensis × latifolia]) affect patterns of plant community composition. Wetlands in native and reseeded grasslands possessed distinct plant community composition related to invasive species' relative cover. Invasive species continue to be prevalent throughout the region and pose a major threat to biological diversity, even in protected native prairie remnants. Despite efforts to convert past agricultural land into biologically diverse, productive ecosystems, invasive species continue to dominate these landscapes and are becoming prominent in prairie potholes located in native areas.

Tree species composition along environmental and disturbance gradients in tropical sub-montane forests, Tanzania

Understanding the environmental and disturbance determinants of tree species dominance and community composition in an ecosystem, is important for informing management and conservation decisions, through maintaining or improving the existing forest composition and structure. This study was carried out to quantify the relationship between forest tree composition structure and environmental and disturbance gradients, in a tropical sub-montane forest of Eastern Usambara. Vegetation, environmental, and anthropogenic disturbance data for 58 plots across Amani and Nilo nature forest reserves were obtained. Agglomerative hierarchical cluster analysis and canonical correspondence analysis (CCA) were used to identify plant communities and analyze the influence of environmental variables and anthropogenic disturbances on tree species and community composition respectively. Four communities were identified and CCA results showed that the variation was significantly related to elevation, pH, Annual mean temperature, temperature seasonality, phosphorus nutrients and pressures from adjacent villages and roads. Likewise, environmental factors (climate, soil and topography) explained the most variation (14.5%) of tree and community composition in relation to disturbance pressure (2.5%). The large and significant variation in tree species and community patterns explained by environmental factors suggests a need for site-specific assessment of environmental properties for biodiversity conservation plans. Similarly, the intensification of human activities and associated impacts on natural environment should be minimized to maintain forest species composition patterns and communities. The findings are useful in guiding in policy interventions that focus on minimizing human disturbances in the forests and could aid in preserving and restoring the functional organization and tree species composition of the sub-tropical montane forests.

Differences and spatial variations of plant leaf calorific value in deserts of the Hexi Corridor, Northwestern China

The leaf calorific value (LCV) is an important trait that indicates how efficiently a plant utilizes natural resources to capture energy. However, little is known about the LCV characteristics of plants in arid and hyper-arid environments. To investigate the spatial patterns and variations in LCV of desert plants and their possible causes, we collected 343 leaf samples of 52 species along a 1000-km transect in the desert area of northwestern China. We analyzed the gross calorific value (GCV), ash-free calorific value (AFCV), carbon content (CC), nitrogen content (NC), and ash content (AC) of the leaves. The mean leaf GCV and AC were 16.2 kJ g^-1 (range from 8.9 to 20.1 kJ g^-1), and 189.8 mg g^-1 (range from 61.5 to 495.1 mg g^-1) respectively, which differ significantly from the values for plants growing in more humid areas of China. Succulence was the dominant trait that drove the differences in leaf GCV and AFCV among plant functional groups. Succulent plants had significantly lower leaf GCV and AFCV, and significantly higher AC, than non-succulent plants, indicating that the investment of energy for succulent plants in response to drought stress may be lower than that for non-succulent plants. Among the biological factors that affected LCV, the CC and AC were the main determinants of leaf GCV, whereas CC and NC were the main determinants of leaf AFCV. Drought stress is an environmental constraint that has a direct negative effect on both leaf GCV and AFCV, but its contribution may be weaker than phylogenetic effects. Our results suggest that LCV is a useful leaf trait that can be used to evaluate plant-environment interactions from an energy perspective.

Influence of Edaphic Properties in Determining Forest Community Patterns of the Zabarwan Mountain Range in the Kashmir Himalayas

The significance of edaphic factors in describing forest vegetation patterns is becoming more well acknowledged, with significant implications for the description of biogeographical regions and biome classification, as well as abundance and growth patterns at regional levels. The current study examines the vegetation association in the Zabarwan mountain range of the Western Himalayas and its association with edaphic factors. To collect data on forest types, we employed a systematic random sampling strategy in 60 plots (0.1 ha) across five forest types. We investigated data using ordination and cluster analysis approaches after calculating the important value index (henceforth IVI) for each plant species and edaphic data from forests. In total, 76 plant species from 39 different families were found in the area. The Rosaceae family was the most numerous, followed by Fabaceae and Asteraceae. Scrub forest types have lower diversity indices, while broad-leaved forest types have greater diversity indices. Two-way cluster analyses classified the forest vegetation of the Zabarwan mountain range into two plant communities on the basis of indicator plant species. The ordination analysis (canonical correspondence analysis) indicated that vegetation association tended to be influenced differently by distinct levels of soil parameters. The soil pH and calcium content were the main factors influencing the species distribution in the different forest types. The phytosociological features (basal area) were higher in coniferous forest type (74.49 m2ha−1) compared to broad-leaved (58.63 m2ha−1) and scrub forest type (15.4 m2ha−1). Overall, the goal of this research is to gain a better understanding of the impact of soil elements on forest composition and associations in order to develop scientifically based management options for forest ecosystem protection in the Himalayan region.