Orchid Diversity, Endemism, and Future Research Needs: A Meta-analysis on the Orchids of Andaman and Nicobar Archipelago, India

Tropical Islands are among the important hotspots of orchid diversity and endemism. The peculiar requirements of orchids, their distribution, and population status in remote Islands like Andaman and Nicobar are largely unknown. Therefore, their conservation and management remain a major challenge. Here, we attempted to analyse the trend in orchid-related research published in the past two decades (2001-2023) pertaining to the orchid diversity, endemism, and population status in the Andaman and Nicobar (hereinafter ANI) archipelago through systematic meta-analysis. A total of 55 orchid-related studies (~2.5 per year) were found in the past two decades, showing an overall modestly decreasing trend (– 0.084x + 3.39) with erratic increases and decreases across the study period. Our findings also compiled a total of 161 orchids (18% endemic) species reported from the islands, representing approximately ~12% of total orchid species found in India (~1300). Furthermore, a total of 47 new orchids were described in the previous two decades, indicating the high potential for many such undescribed orchid species in the archipelago. Despite the high endemism, only nine orchids have their population status evaluated according to IUCN Red List criteria. Island biogeography theory fits well in the ANI system where the orchid species richness (R2 – 0.76, P-value – 0.004) and endemism (R2 – 0.72, P-value – 0.0077) show a high correlation with the size of the island. Among the literature, only four publications concerning the ecology of orchids have been published since 2001, which is far too less considering the high species richness, impact of century-old logging practices, and fragility of the island ecosystem to natural disasters, including the 2004 tsunami. Additionally, increasing human population and the resultant land-use land cover change in ANI are likely to further impact the orchid populations. Therefore, immediate attention is required to understand the population status and to map critical hotspots so that the impact of ever-increasing anthropogenic pressure on orchids can be minimized.