Restoration of forests: Examining tree species diversity and growth for successful ecosystem restoration in Pakistan

Abstract

Restoration of degraded ecosystems is crucial for the conservation of biodiversity and the provision of ecosystem services. In this study, we evaluated the success of forest restoration efforts in Buner District, Pakistan, by assessing tree species diversity and forest structure. The study area was divided into assisted natural regeneration sites and plantations. Altogether thirty sites (by fifteen for assisted natural regeneration and for plantations) were randomly selected, covering the entire area. The result revealed that the assisted natural regeneration sites comprised thirteen diverse species dominated by Pinus roxburghii (54.78%), followed by Dodonaea viscosa (12.14%). In comparison, the plantation sites consisted of sixteen various species dominated by Eucalyptus camaldulensis (77.45%), followed by Robinia pseudoacacia (8.77%). The results further indicated that the average survival rate of the study area was 58.49% with the highest survival rate of 82.45% at the Ambela site and the lowest survival rate of 37.04% at the Budal site. Moreover, the number of exotic species used in plantations was limited; however, their proportion in the study area was much higher (91.15%) than that of the indigenous species (8.85%). A correlation matrix was developed to understand the relationship between seedling density (as a dependent variable) in naturally regenerating sites and influencing factors (as explanatory variables). Results showed that grazing, grass cutting, mean temperature and disturbance negatively correlated with seedling density, whereas elevation and annual precipitation positively correlated. Also, a stepwise linear regression model between seedling density and influencing factors was developed.

Keywords: species composition; Pinus roxburghii; assisted natural regeneration; tree plantations; survival rate; forest disturbance