Seedling dynamics of the critically endangered tree legume Gymnocladus assamicus in northeast India

Gymnocladus assamicus is a critically endangered tree species in northeast region of India having very few or no regenerating populations. Conservation and management is an urgent need to protect the species from extinction. We studied seedling dynamics in in-situ and ex-situ conditions to develop suitable conservation strategies and artificial regeneration in different ecological conditions. For in-situ experiments, tagged seedlings were monitored periodically in natural conditions, while for ex-situ experiments, nursery grown seedlings were transplanted in different environmental conditions and studied for their survival and growth performances. The study revealed that G. assamicus seedlings were light-dependent and express optimum growth and survival under moderate exposure to sunlight. Sapling population was recorded exclusively beyond the canopy of the mother tree. However, lack of seed dispersal was identified as a major constraint for natural regeneration of the species. Seedling mortality was mainly due to water stress along with some degree of chilling affect of the cold winter in its native range. Ex-situ experiments demonstrated that survival and establishment of G. assamicus seedlings beyond its natural distribution range is extremely poor. Therefore, any initiative to reintroduce the species should be practiced in its home range with special emphasis to prevent water stress during dry season.