We have recently published a scientific paper (here) on rare tree species in the Western Ghats of India with colleagues belonging to different institutions.
In general, rarity is of interest to conservation biologists because rare species tend to be at greater risk of extinction than common species. The Western Ghats rain forests have a high proportion of endemic trees (around 64% of evergreen trees ≥10 cm girth at breast height), found only in this biogeographic region. Therefore rare species that are endemic are doubly vulnerable. We estimated that around 48% of 514 species were rare, of which 28 endemics were found in only one site. Rare species had narrower ecological amplitudes, being restricted to particular regions such as the southern Western Ghats and montane forests. Rare species with broader geographical distributions tended to be both wide ranging and locally sparse and narrow ranging and locally dense, and some from single species families could be relictual. Rare species were more likely to be threatened, although 39% have not been evaluated by IUCN. Rarity and endemism increased with increasing family size, indicating that the Western Ghats wet forests are both a cradle of new species (which are rare) and a museum of disappearing species (which are also rare). These forests have been the source of major crops (mango, jackfruit, pepper, cardamon) and should be properly protected because of their unique evolutionary history and biodiversity.