Floral Calendar of Tree Species associated with Insect Pollinators in Coastal Odisha of India
Abstract
Understanding of temporal patterns of tree flowering is essential for assessing the availability of floral resources to sustain the pollinator population throughout the year. The present study examined the flowering phenology of fifteen tree species used as forage of insect pollinators in coastal Odisha during 2024, documenting variations in early, middle, and late flowering phases. Two species such as Moringa oleifera and Santalum album exhibited biannual flowering, with Moringa oleifera flowering for the longest duration (22 weeks), followed by Santalum album (19 weeks). The overall order of flowering duration revealed that a few species substantially dominated the floral calendar, ensuring prolonged resource availability. Month-wise analysis indicated that February, March, and April supported the highest number of insect species (five species each) in their middle flowering phase, reflecting a spring peak in floral abundance. While most species showed middle-phase flowering for two consecutive months, Peltophorum ferrugineum extended to three months. Moringa oleifera and Santalum album again stood out for flowering twice annually and for more than three months in the middle phase, offering extended forage for pollinators. The floral calendar demonstrated distinct species-specific phenological patterns, with eight tree species flowering mainly in spring during February to March and fewer tree species (three each month) flowering during July to December. January, May, and June recorded moderate flowering activity with five, six, and five tree species respectively. The extended flowering periods of Moringa oleifera, Santalum album, Peltophorum ferrugineum, and Tectona grandis contributed significantly to year-round floral resource availability. These overlapping flowering periods, spanning two to four months for many species, playa crucial role in sustaining diverse insect pollinators.
Keywords
Download Options
Introduction
Floral calendar plays a crucial role in ecosystem conservation by tracking the phenology of native plant species. Floral calendar, which tracks the phenology of flowering in plants, is essential tool for understanding the dynamics between plant species and insect pollinators. The timing and sequence of flowering events playa critical role in sustaining healthy pollinator populations, as they determine the availability of nectar and pollen, two key resources for insects like bees, butterflies, and other pollinators. These calendars are particularly important for identifying periods of abundance and scarcity of floral resources, which can directly impact pollinator health and, consequently, ecosystem stability. Since flowering times often fluctuate annually with weather conditions, floral calendars help identify main blooming and dearth periods, allowing beekeepers to introduce supplemental plants to bridge forage gaps (Onyango et al. 2019). This information can inform strategies for adaptation and mitigation in response to changing environmental conditions. It contributes to biodiversity monitoring by highlighting the presence of different plant species over time. Understanding the timing and sequence of flowering events through floral calendars is crucial for sustainable apiculture, apisilviculture, pollinator management, and ecosystem conservation The timing and sequence of plant flowering events are fundamental to the health and sustainability of pollinator populations and the broader ecosystems they support. Trees serve as a continuous source of forage by offering nectar, pollen, and suitable habitats throughout the year. The type, quantity, and quality of pollen and nectar vary among tree species and influence pollinator preferences (Ahmed et al. 2023). Their extended flowering periods ensure a steady food supply, reducing forage shortages and stabilizing insect populations. In recent years, there has been increasing recognition of the role of trees in sustainable agriculture and pollinator management, particularly in agroforestry systems.
Tracking flowering times helps to understand which species are thriving and which are at risk, providing insights into the overall health of an ecosystem. In recent years, there has been increasing recognition of the pivotal role of trees in supporting biodiversity and ensuring food security, especially within agroforestry systems and natural forests (Garibaldi et al., 2014). Trees that flower at different times can provide year-round resources, such as seeds, fruit, or resin, and also help maintain biodiversity. In agroforestry systems, integrating trees with staggered flowering times can improve productivity by supporting multiple income streams and optimizing the use of land throughout the year. It are therefore essential tools for efficient apiary management, helping to determine periods of abundance and scarcity of forage, and enabling proper colony management of bees. (Singh et al. 2023). They also provide valuable data for future studies on climate change impacts and promote the use of beekeeping as a tool for conserving native flora (Onyango et al. 2019). A floral calendar outlines the approximate timing and duration of flowering for major nectar and pollen-producing plants in a given area (Onyango et al. 2019). The flowering period of plant species varies across different locations and times. Each landscape possesses its own unique composition of honeybee flora and experiences specific periods of floral abundance and scarcity. (Bhattarai et al., 2023).
Such records are valuable for studying plant–pollinator relationships, biodiversity conservation, and the influence of climate change. The systematic monitoring of plant phenology provides critical data for numerous scientific and applied fields, including predicting forest productivity, modeling global carbon cycles, managing agricultural systems and most critically understanding the cascading consequences of climate warming on species interactions (Wolkovich et al.,2017). Coastal Odisha, located along India’seastern coastline, experiences a tropical monsoon climate, characterized by distinct wet and dry seasons, as well as fluctuating temperatures and humidity levels. These climatic conditions significantly influence the phenology of plants, determining the timing of flowering. Despite the acknowledged importance of phenology and the environmental sensitivity of the region, systematic and quantitative data on the floral dynamics of forest tree species in coastal Odisha remain critically limited in published literature This study aims to document the floral calendars of selected tree species in coastal Odisha that are associated with insect pollinators, contributing to the growing body of research on floral phenology in tropical coastal regions. By examining the seasonal flowering patterns of key tree species, this research seeks to identify periods of nectar scarcity, assess their implications for pollinator populations, and propose strategies for enhancing pollinator conservation in both natural and agricultural landscapes. Ultimately, the findings will provide valuable insights into the role of trees in sustaining pollinators, promoting biodiversity, and supporting the livelihoods of local communities dependent on these ecosystems
Conclusion
The flowering phenology of the fifteen tree species examined in coastal Odisha during 2024 revealed clear temporal variation across early, middle, and late flowering phases, contributing to a diverse and extended floral resource base. Species such as Moringa oleifera and Santalum album demonstrated biannual and prolonged flowering durations, making them particularly important for sustaining pollinator activity overextended periods. The concentration of middle-phase flowering during February to April, along with multi-month flowering in several species, highlights a strong spring peak supported by the region’stropical climate. At the same time, the presence of at least a few flowering species in all months of the year indicates a continuous, though variable, supply of nectar and pollen vital for insect pollinators. The floral calendar constructed from these observations underscores the ecological significance of flowering overlap among species, which enhances pollinator survival and stabilizes ecosystem functioning throughout the year. Future studies should explore how climate variability and long-term climate change may further influence flowering patterns and pollinator dynamics, enabling better conservation planning and adaptive management. ETHICAL STANDARDS All authors declare that the submission is original, unpublished, and not under consideration elsewhere. Explanation of any issue relating to journal policies There is no issue relating to journal policies.
Declaration of any competing interest There is no competing interest.
Confirmation that all authors have approved the manuscript for submission All authors declare that they have approved the manuscript for submission.
Data availability Data will be made available on request.
Funding Authors have not received fund for this work from any source.
AUTHOR CONTRIBUTIONS Sushree Rojalina Mahapatra made data collection, analysis, review of literature and writing of manuscript. Nirakar Bhol designed the research work, guided manuscript writing and made critical review of the manuscript. Pravasini Behera identified insect pollinators and guided insect related studies. Prajnashree Mallick assisted in data collection, analysis of data and collected reviews of works done. Subhasmita Parida guided in data collection, contributed to manuscript writing and made critical review of the manuscript.
CONFLICT OF INTEREST The authors declare no conflict of interest.
