Population structure and regeneration status of Shorea robusta and associated trees in Sal forests of Ranchi, Eastern India

Abstract

The present study was aimed to study the detailed population structure of Shorea robusta and its four dominant associated tree species (Diospyros melanoxylon, Buchanania cochinchinensis, Madhuca longifolia, and Butea monosperma) in Sal forests of Ranchi, Eastern India. In addition, the regeneration status of all recorded tree species and anthropogenic disturbance of Sal forests were also studied. Girth class distribution showed a reverse J-shaped population curve in the present study, and there was a decline in tree density with an increase in girth class, and mature trees with higher girth (> 120 cm) were very few (9.30%), that signifies the ongoing natural regeneration as well as both natural and anthropogenic disturbances within the studied Sal forest stands. Out of the 103 recorded tree species, 50 species (48.54%) had shown the total absence of regeneration (no regeneration), while 23 species each (22.33%) showed poor and good regeneration, and rest 07 species (6.80%) showed fair regeneration in the studied Sal forests stand. On the other hand, the maximum studied Sal forest stands of Ranchi (42.39%) had shown fair regeneration of S. robusta followed by good regenerating forests (36.96%), and 17.39% forests showed no regeneration. Disturbance index had a weak statistically significant negative correlation with density (ind. ha−1) (r = − 0.20; P < 0.05), and tree basal area (m2 ha−1) (r = − 0.19; P < 0.05), while, it had a weak statistically significant positive correlation with Pielou’s evenness index (r = 0.19; P < 0.05). The growth, survival, and reproductive potential of all tree species will be at risk in the near future if the present trend of anthropogenic pressure continues. Thus, it is clear that protection from grazing and other anthropogenic disturbances are the foremost requirements for the conservation and management of Sal forests in Ranchi, Eastern India.