Restoration success in former Amazonian mines is driven by soil amendment and forest proximity

Abstract

Mining contributes importantly to tropical deforestation and land degradation. To mitigate these effects, mining companies are increasingly obliged to restore abandoned mine lands, but factors driving restoration success are hardly evaluated. Here, we investigate the influence of ecological factors (restoration age, soil properties and surrounding forest area) and management factors (diversity and density of planted species, mine zone) on the recovery rate of forest structure and tree diversity on 40 post-mining restoration areas in Southern Amazonia, Brazil, using a 9-year annual monitoring dataset consisting of over 25 000 trees. We found that recovery of forest structure was closely associated with interactions between soil quality and the planted tree communities, and that tree diversity recovery was positively associated with the amount of surrounding forests. We also observed that forest structure and diversity recover more slowly in mine tailings compared to pit surroundings. Our study confirms the complexity of mine land restoration but also reveals that planting design and soil improvement can increase restoration success. For resource-efficient mine restoration, we recommend the focusing of efforts on tailings, which are hardest to restore, and reducing efforts in pit surroundings and areas close to surrounding forest because of their potential for restoration by natural regeneration. This article is part of the theme issue ‘Understanding forest landscape restoration: reinforcing scientific foundations for the UN Decade on Ecosystem Restoration’.

Influence of Distance from Forest Edges on Spontaneous Vegetation Succession Following Small-Scale Gold Mining in the Southeast Peruvian Amazon

“…This would suggest that closer proximity to the remaining reference forest could accelerate the recovery of the vegetation [15]. Because the recovery of biodiversity in tropical forests depends on the recruitment of native species and their accumulation over time [59], the fragmentation of Amazonian forests significantly changes the abundance and richness of species, mainly at distances of less than 500 m [60]. However, our results showed different responses between floristic attributes and distance to the forest edge in a recent study of lands degraded by gold mining in Madre de Dios.…”

Fifteen essential science advances needed for effective restoration of the world's forest landscapes

“…In this theme issue, wind damage in Vietnam is shown to be more detrimental to forest recovery where past disturbance and land-use change have been greatest [ 68 ], while planted seedling survival across Southeast Asian sites was highly variable, but particularly connected to habitat condition at time of planting [ 69 ]. Similarly, new data in the theme issue from Brazil show an increase in forest restoration success with soil quality and proximity to forests [ 70 ].…”

“…Understanding where and how often disturbances occur, and their impact on recovering forests, is essential for informing their management and how, where and when to restore. In this theme issue, new research from Brazil shows that alternative restoration approaches are needed according to the level of disturbance [ 70 ]. The theme issue also reveals that forest plantations in Vietnam are more vulnerable to disturbance than natural forests [ 68 ].…”

“…[ 97 ] demonstrate that root traits of planted trees can be used to predict species success in dry forests. Further new research in this theme issue shows how information on soils is necessary for tailoring restoration and remediation methods to local site conditions [ 70 , 98 ].…”

“…as nurse trees to encourage shade for natives [ 133 ] or to fix soil nitrogen [ 95 ], but further research in this theme issue suggests that exotic tree presence reduces overall biodiversity [ 134 ]. In order for tree-planting to be successful, other research in the theme issue highlights important decisions regarding correct selection of species (for drought tolerance; [ 97 ]) and planting location (for maximizing survival and natural succession; [ 70 ]).…”