Characterization of species structure and regeneration patterns under different density gradients in a tropical Sal forest of Achanakmar-Amarkantak biosphere reserve in Central India

Understanding disturbances that are of significant significance requires a critical focus on preventing forest degradation and addressing problems related to vegetation loss. Hence, the primary objective of this work was to examine the structure of species and the patterns of regeneration at various density gradients within the Achanakmar-Amarkantak Biosphere Reserve in India. This study involved the selection of one closed site (CS) and one open site (OS) from both the Mixed Sal Forest (MSF) and the Pure Sal Forest (PSF). In order to ascertain population structure and regeneration status, plants were classified into seedlings, saplings, and adults based on their Girth at breast height (GBH). The results of our study revealed that the population density of seedlings, saplings, and trees was higher in MSFCS (49250, 980, and 920 ind/ha) compared to PSFCS (41500, 740, 890 ind/ha), MSFOS (16750, 580, and 370 individuals ind/ha), and PSFOS (9750, 180, and 334 ind/ha). Both forests exhibited a reverse-J shaped curve in the CS and an interrupted reverse-J shaped curve in the OS of overall tree species. Nevertheless, the distribution curve at the species level displayed diverse patterns. For instance, Shorea robusta displayed irregular shapes in the OS of both forests, while Terminalia tomentosa displayed a bell-shaped GBH density distribution population curve across all the sites. Differences in regeneration status were observed among different tree species. At the four sites, 18.75% of the species showed good regeneration, 21.87% showed fair regeneration, and a substantial portion, 35.94%, displayed poor to no regeneration. Additionally, 23.44% of the species showed new regeneration. Among these species, Diospyros melanoxylon and Syzygium cumini showed strong regeneration capabilities, while Shorea robusta shown moderate regeneration potential. In the future, the population structure, dominance, and richness of the present tree community may undergo changes. Hence, it is imperative to conduct study on the survival of seedlings and use appropriate management techniques in order to guarantee the long-term viability of the forests.