Rhododendron species in the Indian Eastern Himalayas: New approaches to understanding rare plant species' distributions

Abstract

Rhododendrons are an important, dominant, and primitive group of flow-ering plants with considerable ecological and economic importance found in the temperate, subalpine and alpine regions of western Arunachal Pradesh, India. In addition to aesthetic, sacred, and ethno-medicinal values, several species have commercial and social importance. Rhododendrons are one of the preferred plant species used by local inhabitants in the region. Anthropogenic disturbance associated with deforestation, unsustainable extraction, over-exploitation, and agricultural practices have collectively put pressure on Rhododendron species; as a result many species have become endangered, rare, or threatened. Knowledge of the specifics of a species' distribution is essential for its in situ conservation and management. We focused, in this study, on four rare Rhododendron species (R. edgeworthii, R. kendrickii, R. keysii, and R. maddenii). We recorded geographic locations of the selected species through extensive field surveys, and obtained additional occurrences from secondary sources. We used a NASA-MODIS/Terra data set to summarize environmental characteristics. We incorporated location and environmental data into evolutionary-computing approaches to develop ecological niche model predictions of the likelihood of occurrence of these species. Seven new populations of the studied species were encountered in subsequent field surveys of the predicted sites. Ecological niche modeling can thus serve an important role in various in situ as well as ex situ measures for establishment of arboreta, sanctuaries, parks and reserve forests, protected areas through community management, botanical gardens, and also for in vitro research activities for species conservation.