Diversity, Distribution, and Ethnobotanical Uses of Ornamental Plants in a Bangladeshi University Campus

Technical Summary: Diversity, Distribution, and Ethnobotanical Uses of Ornamental Plants in a Bangladeshi University Campus

Problem Statement
While ornamental plants are recognized as vital components of urban green infrastructure contributing to biodiversity and ecological resilience, the ethnobotanical knowledge embedded within the ornamental flora of university campuses in Bangladesh remains largely undocumented. Previous scientific investigations in the region have predominantly focused on botanical gardens or rural home gardens, leaving institutional green spaces underrepresented in the literature. This study addresses the gap in systematic documentation regarding the taxonomic diversity, spatial distribution, and traditional uses of ornamental plants within the Daffodil International University (DIU) campus, a significant 360-acre institutional landscape in a rapidly urbanizing context.

Methodology
The research was conducted at the DIU campus in Ashulia, Savar, Dhaka, characterized by a humid subtropical climate and alluvial loam soils. The study employed a mixed-methods approach combining systematic botanical surveys with ethnobotanical data collection:

• Field Surveys: Systematic quadrat sampling was conducted from March 2024 to February 2025. A total of 240 quadrats (5 m × 5 m) were established along transects at 50 m intervals, stratified across seven ecological zones (central gardens, peripheral borders, roadside plantings, water margins, shaded understories, open lawns, and building surrounds). All vascular ornamental taxa were recorded for species identity, frequency, and relative abundance.
• Taxonomic Verification: Specimens were collected, pressed, and identified using standard taxonomic keys and regional floras. Nomenclature was verified against the World Checklist of Selected Plant Families and The Plant List. Voucher specimens (DIU-001 to DIU-068) were deposited in the DIU Herbarium.
• Ethnobotanical Data Collection: Semi-structured interviews were conducted with 103 informants, including campus groundskeeping staff, local residents, faculty with botanical interests, and life science students. Data focused on recognized species and their medicinal, cultural, economic, or nutritional uses.
• Data Analysis: Taxonomic diversity was analyzed by family and genus. Species diversity was quantified using the Shannon–Wiener index ($H'$) and Simpson's diversity index ($1-D$). The Importance Value Index (IVI) was calculated for dominant trees and shrubs. Ethnobotanical significance was evaluated using Use Value (UV) and the Informant Consensus Factor (ICF). All statistical analyses were performed using R version 4.3.2.

Key Contributions and Results
The study documented 68 ornamental plant species belonging to 38 families and 63 genera.

• Taxonomic Composition: The family Arecaceae was the most species-rich (10 species, 14.71%), followed by Poaceae (5 species) and Asparagaceae (4 species). The life form spectrum was dominated by herbs (25.0%) and shrubs (23.53%), with trees comprising 17.65% and palms 14.71%.
• Diversity Indices: The campus flora exhibited high species diversity, with a Shannon–Wiener index ($H'$) of 3.42 and a Simpson's index ($1-D$) of 0.94. These values indicate high species evenness and richness, comparable to managed botanical gardens in Bangladesh and exceeding previous reports from other university campuses in the region.
• Dominant Species: The Importance Value Index (IVI) identified Polyalthia longifolia (IVI = 52.5) as the dominant ornamental tree, followed by Ficus benjamina (IVI = 44.4) and Borassus flabellifer (IVI = 39.5).
• Ethnobotanical Uses: Six major use categories were identified:
  1. Aesthetic/Ornamental: Recorded for all 68 species (ICF = 0.81; Mean UV = 2.41).
  2. Medicinal: 28 species (41.2% of total) were cited for medicinal uses (ICF = 0.62; Mean UV = 1.92), including treatments for fever, skin diseases, and digestive issues. Notable species included Catharanthus roseus (cited for diabetes management and anticancer properties) and Hibiscus rosa-sinensis (hair growth, wound healing, and fever management).
  3. Environmental: 32 species (47.1%) were recognized for environmental services such as air purification and windbreaks.
  4. Cultural/Ritual: 14 species (20.6%) were used in religious ceremonies and festive decorations.
  5. Economic: 19 species (27.9%) had economic value (e.g., timber, essential oils).
  6. Nutritional: 11 species (16.2%) provided edible fruits, seeds, or leaves.

Significance and Claims
The paper asserts that the DIU campus harbors a rich and culturally significant ornamental flora that functions as a repository of traditional ethnobotanical knowledge. The study claims that the high diversity indices confirm the campus sustains a well-distributed plant assemblage, likely due to deliberate landscaping initiatives.

The authors highlight that while the taxonomic richness is impressive for an institutional setting, it is characterized by a dominance of exotic species, with only 31 of the 68 species being indigenous or naturalized in Bangladesh. Consequently, the paper concludes that the documented ethnobotanical knowledge, particularly regarding medicinal species, should be preserved through campus botanical trails with interpretive signage. The authors recommend that future landscaping strategies prioritize native taxa to enhance ecological connectivity and pollinator support, rather than relying solely on the current mix of exotic ornamentals. The study serves as a baseline for monitoring temporal changes in plant diversity and suggests further research into the invertebrate and avian communities supported by this flora.