Diversity and carbon sequestration capacity of naturally growth vegetation in ex-nickel mining area in Kolaka, Southeast Sulawesi, Indonesia

Abstract

Abstract. Purnomo DW, Prasetyo LB, Widyatmoko D, Rushayati SB, Supriyatna I, Yani A. 2022. Diversity and carbon sequestration capacity of naturally growth vegetation in ex-nickel mining area in Kolaka, Southeast Sulawesi, Indonesia. Biodiversitas 23: 1433-1442. Efforts to restore forest integrity on ex-mining lands are essential to improve environmental quality and sequester carbon. One such effort is through revegetation of post-mined land including in ex-nickel mining in Southeast Sulawesi. This research analyzes the diversity of naturally regenerating plant species in the ex-nickel mining area in Kolaka, Southeast Sulawesi and determines several local tree species with the potential for carbon sequestration. Vegetation survey was conducted using a systematic nested sampling method at the post-mined site with three vegetation types: secondary forest, shrubs and bushes, and a reference/control site (i.e., natural forest in the nearby Lamedai Nature Reserve). Different types of vegetation were analyzed based on factors using Discriminant Analysis. Vegetation composition was analyzed using the Importance Value Index. Furthermore, biodiversity indicators were analyzed using Shannon-Wiener Diversity Index, Species Evenness Index, and Sorensen Similarity Index. Carbon absorption was measured using the leaf sample method and carbohydrate test. The results showed that the condition of the research site had been disturbed, and the succession process was still ongoing. The species diversity at all plant levels was classified as moderate category and the distribution of the community was unstable. At the tree level, the undisturbed areas had higher diversity. Eradication of Chromolaena odorata was needed to preserve the native vegetation and accelerate forest succession. Tree species recommended for restoring the ex-nickel mining area and carbon sequestration as core plants include Vitex glabrata R.Br., Alstonia macrophylla Wall. ex G.Don, Lithocarpus celebicus (Miq.) Rehder, Callicarpa pentandra Roxb., Dacryodes rugosa (Blume) H.J.Lam, Cananga odorata (Lam.) Hook.f. & Thomson, Glochidion rubrum Blume, Terminalia bellirica (Gaertn.) Roxb., and Psychotria calocarpa Ruiz & Pav., and other pioneer plants of Mallotus paniculatus (Lam.) Müll.Arg., Macaranga peltata (Roxb.) Müll.Arg., and Macaranga hispida (Blume) Müll.Arg.