The purpose of this research is to develop a Graded Biodiversity Assessment (GBA) index to provide an estimation of the biodiversity in managed natural forests. In order to facilitate the present project, parameters are performed, confirmed, and annotated for their use as GBA components, notably the wood stock, age, canopy density, regeneration existence, and aspect of the forest under study. These five parameters are easily retrieved from the standard forest management plans. To assist the application of this forest-specific GBA index, data for each of the five index components is coded in three biodiversity levels as per the original description, with group cut-offs of 0, 0.5, and 1. We compute the Consistency Index to quantify the degree of reliability of our selection of GBA components ξ (Ksi) of the Best-Worst Method (BWM). With the proposed GBA index, foresters canhave a new tool at their disposal, which can be used to drive decision making and determineforest regions with low or high biodiversity value, with five parameters that are common in the standard forest management plans.