Ecological succession in areas degraded by bauxite mining indicates successful use of topsoil

Abstract

Brazilian ironstone outcrops (cangas) are nutrient‐poor stressful habitat dominated by slow‐growing woody species with high biodiversity and unique evolutionary history. Mining has produced great impacts on this ecosystem. Spontaneous regeneration of abandoned canga mined areas has not been observed. One of the active methods most widely used for ecological restoration in environments where soil has been lost or severely degraded is topsoil transposition due to the physical, chemical, and microbiological improvement of the substrate, in addition to the seed bank. Thus, plant succession was monitored for 40 months after topsoil transposition in a canga area degraded by aluminum mining, without any other type of management. A completely randomized design with 70 permanent plots (1 × 1 m) was used. Annual phytosociological surveys were carried out and floristic and vegetational spectra were constructed with the life‐forms proposed by Raunkiaer. Floristic composition was compared with a reference site. Overall, 105 species were identified. Both flora and vegetation changed over time, increasing resemblance to the reference areas. The floristic and vegetational spectra after 4 years of topsoil deposition are similar to pristine ones. The vegetation spectrum showed an increase in the dominance of phanerophytes and hemicryptophytes, while therophytes reduced their proportion. The early successional stage is dominated by weeds, like in other canga restoration studies, but did not impede the native species regeneration. Cangas's species recruited well from transposed topsoil. Unlike other studies with fertilized topsoil, our findings show the efficiency of topsoil transposition to provide initial conditions for the ecological restoration of this ecosystem.

Effects of topsoil transposition on the taxonomic and functional diversity of macrofauna of highly degraded soil

“…2013; Ferreira & Vieira 2017, Onésimo et al . 2021). The topsoil contributes to improving the characteristics of the ecosystem and collaborates significantly to increase its resilience and the production of environmental services, such as the acceleration of ecological succession and the expression of mechanisms for the natural restoration of the environment (Bechara et al .…”

Canary in the coal mine: Lessons from the Jarrah Forest suggest long-term negative effects of phosphorus fertilizer on biodiverse restoration after surface mining

“…Since research on Jarrah Forest restoration after bauxite mining is more advanced than restoration after bauxite mining in other regions further studies of fertilizer impacts on responses in a broader range of plant community-types are warranted. In a recent study of bauxite mine restoration in Brazil, Onésimo et al (2021) ascribed their relative success, compared with earlier studies in the region, to not applying fertilizer, although this remains to be tested experimentally. Mineral sands mining also often occurs in regions with nutrient-poor soils (Section "Surface mining often occurs in nutrient-poor, biodiverse landscapes") and high plant diversity, and there is emerging evidence that restoration of these environments may also be sensitive to P-application.…”

Review of global trends in meeting the ecological challenges of the mining industry. Part I: International research

“…After composing and applying a mix of soil and aboriginal vegetation seeds, a positive result was obtained in 4 years in the form of eumorphic herbosa. Ecologists revealed no difference of the new ecosystem from the natural landscape [14].…”