Tree diversity, growth performance and phytosociological assessment of urban forests in Raipur and Naya Raipur smart city, Chhattisgarh, India

Introduction

Urbanization is rapidly transforming natural ecosystems worldwide, resulting in habitat fragmentation, biodiversity loss, environmental degradation, and increased greenhouse gas emissions. As cities expand, urban forests have become an essential component of sustainable urban development due to their ability to provide ecological, economic, and social benefits (Ostoić & van den Bosch, 2015) [1] . Urban forests, which include roadside plantations, parks, institutional campuses, residential green spaces, and peri-urban forests, contribute significantly to climate regulation, air pollution mitigation, biodiversity conservation, stormwater management, and human well-being (Tiwari et al., 2022) [2] . The ecological sustainability of urban forests largely depends on their tree species composition, structural diversity, and growth performance. Diverse urban forests are generally more resilient to environmental stresses, pests, diseases, and climate change while providing enhanced ecosystem services such as carbon sequestration, temperature regulation, and habitat support for wildlife (Morgenroth et al., 2016; Xie et al., 2024) [3,4] . Therefore, assessment of tree diversity has become a critical component of urban forest management and planning. Tree species inventories provide baseline information on species richness, abundance, distribution, health status, and structural characteristics. Such inventories facilitate the evaluation of ecosystem services and support evidence-based conservation and management strategies. Quantitative assessment of vegetation communities is commonly conducted using phytosociological parameters such as density, frequency, Dominance, relative density, relative frequency, relative dominance, and Importance Value Index (IVI).

In addition, diversity indices including the Shannon-Wiener Diversity Index, Simpson's Dominance Index, Pielou's Evenness Index, and Menhinick's Richness Index are widely used to assess species richness, evenness, and community structure. Growth performance of urban trees, measured through parameters such as diameter at breast height (DBH), girth at breast height (GBH), tree height, basal area, and stem volume, provides valuable information regarding tree health, productivity, biomass accumulation, and carbon storage potential (Nowak & Crane, 2002) [5] . These measurements are essential for understanding urban forest structure and estimating ecosystem services provided by trees. In India, rapid urban expansion has considerably altered urban vegetation patterns, leading to increased environmental challenges such as air pollution, urban heat island effects, and loss of biodiversity (Sharma et al., 2025, Tiwari et al., 2023) [6] . Urban forests have therefore gained importance as nature-based solutions for improving environmental quality and enhancing urban resilience (Maitry et al., 2023; Bherwani et al., 2024) [7][8][9] . Raipur Smart City, one of the fastest-growing cities in Central India, has experienced significant industrial and infrastructural development, resulting in increasing pressure on urban green spaces. Despite the ecological importance of urban trees in the city, comprehensive information regarding tree species composition, diversity, and growth performance remains limited (Humane et al., 2025) [10] .

Therefore, the present study was undertaken to inventory the tree species and assess their growth performance and diversity indices in the Raipur Smart City area. The study aims to generate baseline information on species richness, vegetation structure, and ecological significance of urban trees, which will support sustainable urban forestry, biodiversity conservation, climate-resilient urban planning, and future assessments of carbon sequestration potential.

Materials and Methods

The present study was carried out between March to July 2025 in the interconnected urban ecosystems of Raipur and Naya Raipur (officially Atal Nagar), Chhattisgarh, India, located between 21° 14′ -21° 17′ N latitude and 81° 38′ -81° 47′ E longitude (Fig. 1). Together, these zones form a complex urbanto-peri-urban gradient at an average regional elevation of 298-300 meters above mean sea level. Raipur operates as a highdensity administrative and commercial core with fragmented green spaces, whereas Naya Raipur, located 15-20 km southeast, is a planned satellite smart city featuring extensive, continuous institutional greenbelts. The modern landscape transitions from intensive commercial and residential concrete matrices to developing industrial fringes and structured avenue plantations dominated by species like Neem (Azadirachta indica), Karanj (Pongamia pinnata), Amaltas (Cassia fistula), and Arjun (Terminalia arjuna).

Tree Inventory and Growth Assessment

Following the establishment of the sampling plots using a stratified random sampling approach, a systematic field survey was carried out during the study period to document the tree flora across the major urban land-use categories of Raipur and Naya Raipur, including roadside plantations, public parks, institutional campuses, residential areas, and other urban green spaces. Within each of the 120 quadrats (31.62m×31.62m), all tree individuals were enumerated and identified to species level using standard regional floras, taxonomic literature, and expert consultation wherever necessary. For each recorded individual, the species name, family, and abundance were documented. To assess the growth performance and structural attributes of the urban tree population, dendrometric parameters including tree height, girth at breast height (GBH; measured at 1.37 m above ground level), and diameter at breast height (DBH) were recorded following standard forestry measurement protocols (Maitry et al., 2025) [11] . The basal area of each tree was subsequently computed from the DBH measurements to characterize stand structure and provide the quantitative data required for subsequent analyses of species composition, growth performance, and diversity within the urban forest ecosystem.

Phytosociological Analysis

The phytosociological parameters, including frequency, density, abundance, basal area, relative frequency (RF), relative density (RD), relative dominance (RDo), and Importance Value Index (IVI), were computed following the standard methods described by Curtis and McIntosh (1950) [12] and Misra (1968) [13] using the following formulae:

Diversity Analysis

Tree diversity was evaluated using standard ecological indices, including the Shannon-Wiener Diversity Index (Shannon & Weaver, 1963) [14] , Simpson's Dominance Index (Simpson, 1949) [15] , Pielou's Evenness Index (Pielou, 1966) [16] , and Menhinick's Species Richness Index (Menhinick, 1964) [17] . These indices were used to assess species richness, diversity, dominance, and evenness of the urban tree community.

Statistical Analysis

The collected data were compiled and analyzed using Microsoft Excel and standard ecological formulae. Descriptive statistical analyses were performed to summarize tree species composition, growth performance, and diversity indices. In addition, Pearson correlation matrix among the different phytosociological parameters was carried out using Origin software to examine the underlying relationships among the variables. The calculated ecological parameters were subsequently interpreted to evaluate the structure, diversity, and ecological stability of the urban forest ecosystem.

Results and Discussion Tree Species Composition and Diversity

The floristic survey conducted in the urban landscapes of Raipur and Naya Raipur Smart City recorded a total of 60 tree species belonging to 26 families, indicating high taxonomic diversity within the urban forest ecosystem (Table 1). The heterogeneous species composition observed in the study area can be attributed to the mosaic of urban habitats and varying environmental conditions that collectively influence species establishment and persistence. Such diversity enhances ecosystem stability and improves the capacity of urban forests to provide ecosystem services, including carbon sequestration, biodiversity conservation, climate regulation, and air pollution mitigation (Nizamani et al., 2021; Nagendra & Gopal, 2010) [18,19] . Among the inventoried species, Azadirachta indica recorded the highest abundance (88 individuals), followed by Pongamia pinnata (84), Albizia lebbeck (77), and Dalbergia sissoo (71). These species also exhibited higher frequency, density, basal area, and Importance Value Index (IVI), indicating their ecological dominance and adaptability under urban environmental conditions. [9] , higher IVI values indicate greater ecological significance due to the combined contribution of density, frequency, and dominance. Similar dominance of Azadirachta indica and Pongamia pinnata has been reported in urban forests because of their adaptability, rapid growth, and tolerance to pollution and drought (Rai, 2016) [20] . Species such as Lagerstroemia speciosa, Bauhinia variegata, Bombax ceiba, Bauhinia malabarica, and Peltophorum pterocarpum recorded comparatively lower IVI values (<2.0), indicating restricted occurrence and relatively poor representation in the study area. Their lower abundance may be associated with species-specific ecological requirements, plantation preferences, or limited adaptability under highly urbanized conditions (Galle et al., 2021) [21] .

Growth performance of tree species Marked variation was observed in growth characteristics among the recorded tree species. Mean tree height varied from approximately 6.03 to 15.70 m, whereas mean girth at breast height (GBH) ranged from 25.31 to 111.93 cm, demonstrating considerable interspecific variation in growth performance. Among all species, Dalbergia sissoo recorded the highest mean GBH (111.93 cm), followed by Azadirachta indica (101.60 cm), Ficus benghalensis (83.45 cm), and Tamarindus indica (81.70 cm). Likewise, Azadirachta indica exhibited the highest basal area (0.602 m² ha ¹), followed by ⁻ Dalbergia sissoo (0.590 m² ha ¹), ⁻ Pongamia pinnata (0.306m²ha⁻¹), and Albizia lebbeck (0.247 m² ha ¹). These species contribute⁻ substantially to above-ground biomass accumulation and long-term carbon storage because basal area is directly related to tree biomass and productivity (Thakur et al., 2019) [22] . The superior growth performance of these species may be attributed to their high adaptability to tropical climatic conditions, tolerance to urban pollution, efficient nutrient utilization, and drought resistance (Yadav et al., 2024) [23] . Similar findings have been reported by Behera et al., (2022) [24] , who observed that Azadirachta indica, Dalbergia sissoo, and Albizia lebbeck possess excellent biomass production and carbon sequestration potential under Indian urban conditions. The correlogram shows Pearson correlations among twelve phytosociological parameters, with circle size/colour indicating strength and direction, and asterisks marking significance (p≤0.05). Growth and structural attributes including height, girth, basal area, density, frequency, and dominance are strongly, significantly, and positively intercorrelated (r =0.50-0.98), with pairs like density-relative density (RD), frequencyrelative frequency (RF), and total basal cover (BC)-relative dominance (RDo) approaching unity since relative measures are mathematically derived from their absolute counterparts. IVI, as the sum of RD, RF, and RDo, correlates very highly with these variables (r = 0.96 -0.97), confirming its role as an integrative dominance index (Negi et al., 2022) [25] . Conversely, abundance and A/F are negatively correlated with dominance-related parameters (r = -0.42 to -0.65) despite being positively correlated with each other (r = 0.84), reflecting that clumped distribution does not equate to structural dominance, echoing findings that basal area, density, and diversity, while generally linked, can diverge under disturbance (Sagar & Singh, 2006) [26] . Height alone shows weak, nonsignificant links with abundance and A/F.

Diversity Indices

The calculated ecological diversity indices revealed that the urban forests of Raipur Smart City possess a diverse and ecologically stable tree community (Table 2). Based on the total abundance data (n=1304) across all 60 species, here are the calculated values: [27] . The Simpson Dominance Index (D) was 0.0286, indicating very low dominance by any single species. Low Simpson values reflect balanced species composition and lower ecological vulnerability to pest outbreaks, diseases, or environmental disturbances (Kumar, 2025) [28] . Such findings suggest that no single species monopolizes the urban vegetation of Raipur Smart City. The Pielou's Evenness Index (J′) was 0.9338, indicating a remarkably uniform distribution of individuals among the recorded species. High evenness values close to one are generally associated with stable ecosystems where species are evenly represented (Joshi and Garkoti 2025) [29] . The Menhinick Richness Index was 1.6615, demonstrating relatively high species richness after standardizing for sample size (Joshi and Dhyani, 2019) [30] . The richness observed in the present investigation reflects the success of urban greening initiatives and plantation programmes implemented within the Smart City area.

Ecological implications

The dominance of Azadirachta indica, Dalbergia sissoo, Pongamia pinnata, Albizia lebbeck, and Ficus religiosa demonstrates that these species are highly suitable for urban afforestation and green infrastructure development because of their superior growth performance, ecological importance, and greater biomass accumulation. Simultaneously, the presence of numerous indigenous and moderately abundant species contributes to maintaining biodiversity and ecosystem stability (Xess et al., 2026) [4] . The present findings indicate that the urban forests of Raipur Smart City constitute a diverse and wellstructured ecosystem capable of delivering important ecosystem services, including carbon sequestration, air pollution mitigation, urban heat island reduction, biodiversity conservation, and climate resilience. Therefore, continued protection of existing green spaces, coupled with enrichment planting of native tree species, will further strengthen the ecological sustainability of the city's urban landscape.

Conclusion

The present study provides a comprehensive assessment of the tree diversity, growth performance, and phytosociological characteristics of the urban forests in the study area. The inventory revealed a rich and heterogeneous assemblage of tree species distributed across various urban green spaces, reflecting the ecological significance of urban forests in sustaining biodiversity within a rapidly urbanizing landscape. Phytosociological analysis identified clear differences in the ecological importance and distribution of individual species, highlighting the dominance of a few well-adapted species while demonstrating the substantial contribution of several others to the overall community structure. Variations in growth attributes among species further indicated differences in their adaptability, growth potential, and structural contribution to the urban forest ecosystem. The observed composition and structure of the urban tree community indicate a resilient and functionally stable ecosystem capable of supporting biodiversity conservation and sustaining key ecosystem services. Maintaining such diverse urban forests will be essential for enhancing ecological resilience and environmental sustainability in the context of ongoing urbanization. The findings emphasize the importance of conserving and promoting diverse native and well-adapted tree species to enhance the ecological sustainability of urban landscapes. The comprehensive database generated through this study provides valuable baseline information for urban forest planning, species selection, biodiversity conservation, and long-term ecological monitoring. Furthermore, the study contributes to evidencebased decision-making for the development and management of green infrastructure, supporting climate change mitigation, environmental quality improvement, and the creation of sustainable and resilient urban ecosystems under the Smart Cities Mission. Future urban greening initiatives should prioritize species diversity and ecological suitability to ensure the continued delivery of ecosystem services and strengthen the long-term resilience of urban forests.

References

1. Ostoić SK, van den Bosch CCK. Exploring global scientific discourses on urban forestry. Urban Forestry & Urban Greening. 2015;14(1):129-138.
2. Tiwari G, Shukla A, Anthony FM. Air pollution level declines the bird species diversity in an urban area: a case study of Bilaspur, Chhattisgarh during the summer season. International Journal of Agricultural and Applied Sciences. 2022;3(2):29-34.
3. Morgenroth J, Östberg J, Konijnendijk van den Bosch C, Nielsen AB, Hauer R, Sjöman H, et al. Urban tree diversityTaking stock and looking ahead. Urban Forestry & Urban Greening. 2016; 15:1-5.
4. Xess P, Shukla A, Tiwari G. Forest Livelihoods in Transition: An Analysis of NTFP Utilization and Income Differentials in Katghora Forest Division. Journal of Scientific Research and Reports. 2026;32(7):336-344.
5. Nowak DJ, Crane DE. Carbon storage and sequestration by urban trees in the USA. Environmental Pollution. 2002;116(3):381-389.
6. Sharma A, Chauhan A, Parkar V. Planning eco-sensitive zones for promoting tree diversity and ecosystem services in urban academic landscapes: A case study from the Northwestern Indo-Gangetic Plain. Arboricultural Journal. 2025;47(1):1-22.
7. Maitry A, Chandrakar S, Shukla A, Chandra A. Quantitative assessment of macrophytes diversity and their status in wetlands of Guru Ghasidas Vishwavidyalaya, Bilaspur, Chhattisgarh (India). International Journal of Agricultural and Applied Sciences. 2023;4(2):120-127.
8. Bherwani H, Banerji T, Menon R. Role and value of urban forests in carbon sequestration: Review and assessment in Indian context. Environment, Development and Sustainability. 2024;26:603-626.
9. Maitry A, Sharma D, Shah P, Baretha G, Patil G. Assessment of wetland ecosystem services (RAWES approach) in urban settlement area: A case study of Bilaspur, Chhattisgarh, India. Indian Journal of Ecology. 2023;50(4):954-962.
10. Humane PT, Patle CK, Naqvi N. Distribution, diversity and composition of tree species in Nagpur City (M.S.), India. Ecology, Environment and Conservation. 2025;31(Supplement):S42-S50.
11. Maitry A, Patil G, Dubey P. Quantitative Assessment of Vegetation Dynamics through Species Composition and Diversity Indices in Restoring Nandini Limestone Mines, Chhattisgarh. International Journal of Bio-Resource & Stress Management. 2025;16(4).
12. Curtis JT, McIntosh RP. The interrelations of certain analytic and synthetic phytosociological characters. Ecology. 1950;31(3):434-455.
13. Misra R. Ecology Work Book. Calcutta: Oxford and IBH Publishing Company; 1968.
14. Shannon CE, Weaver W. The Mathematical Theory of Communication. University of Illinois Press; 1963.
15. Simpson EH. Measurement of diversity. Nature. 1949;163:688.
16. Pielou EC. The measurement of diversity in different types of biological collections. Journal of Theoretical Biology. 1966;13:131-144.
17. Menhinick EF. A comparison of some species-individuals diversity indices applied to samples of field insects. Ecology. 1964;45(4):859-861.
18. Nizamani MM, Harris AJ, Cheng XL, Zhu ZX, Jim CY, Wang HF. Positive relationships among aboveground biomass, tree species diversity, and urban greening management in tropical coastal city of Haikou. Ecology and Evolution. 2021;11(15):10011-10025.
19. Nagendra H, Gopal D. Street trees in Bangalore: Density, diversity, composition and distribution. Urban Forestry & Urban Greening. 2010;9(2):129-137.
20. Rai PK. Biodiversity of roadside plants and their response to air pollution in an Indo-Burma hotspot region: Implications for urban ecosystem restoration. Journal of Asia-Pacific Biodiversity. 2016;9(1):47-55.
21. Galle N, Halpern D, Nitoslawski S, Duarte F, Ratti C, Pilla F. Mapping the diversity of street tree inventories across eight cities internationally using open data. Urban Forestry & Urban Greening. 2021;61:127081.
22. Thakur T, Padwar GK, Patel DK. Monitoring land use, species composition and diversity of dry tropical environ in AABR, India using satellite data. Biodiversity International Journal. 2019;3(4):162-172.
23. Yadav H, Sasaki T. Afforestation schemes are driven by urbanisation and trees outside forests: A case study of India. Anthropocene Science. 2024;3(1):150-156.
24. Behera SK, Mishra S, Sahu N, Manika N, Singh SN, Anto S, et al. Assessment of carbon sequestration potential of tropical tree species for urban forestry in India. Ecological Engineering. 2022;181:106692.
25. Negi V, Bhardwaj DR, Sharma P, Pala NA. Tree species composition and diversity in natural temperate forests of the North-Western Himalayas. Acta Ecologica Sinica. 2022;42(6):653-660.
26. Sagar R, Singh JS. Tree density, basal area and species diversity in a disturbed dry tropical forest of northern India: implications for conservation. Environmental Conservation. 2006;33(3):256-262.
27. Naidu MT, Kumar OA. Tree diversity, stand structure, and community composition of tropical forests in Eastern Ghats of Andhra Pradesh, India. Journal of Asia-Pacific Biodiversity. 2016;9(3):328-334.
28. Kumar A, Panwar M, Mina U. Roadside green spaces: role of tree diversity in carbon storage and thermal comfort. Discover Cities. 2025;2(1):132.
29. Joshi RK, Garkoti SC. Quantifying ecosystem carbon storage, tree diversity, and carbon credit potential in the urban semi-arid forests of Delhi, India. Environmental Development. 2025;101300.
30. Joshi RK, Dhyani S. Biomass, carbon density and diversity of tree species in tropical dry deciduous forests in Central India. Acta Ecologica Sinica. 2019;39(4):289-299.
31. Tiwari G, Shukla A. Green zones in urban area as potential sites for bird diversity conservation. Int. J. Biosci. 2023;22(5):35-45.