Recovery of biogeochemical processes in restored tropical dry forest on a coal mine spoil in La Guajira, Colombia

Abstract

Open-cast coal mining eliminates vegetation, alters physical and chemical characteristics of soils, and therefore limits the establishment of native vegetation by lack of sufficient moisture, increase bulk density, and low organic matter content. Restoration of extremely degraded areas through plantation of fast growing species is expected to accelerate the recovers of soil organic matter and nutrient cycles. The purposes of this study were to compare intrasystem cycling of C, N, P, and base cations in native and restored forests at an open-cast coal mine in a dry region of Colombia. Leaf-fall, standing leaf litter, and their N, P, Ca, Mg, and K contents were measured for 1 year in native forests and restored forests of various ages (7, 10, and 21 years). The exploitation of coal in La Guajira degraded soil fertility, and although tree planting was sufficient to achieve the partial recovery of soil chemistry and N cycling relative to reference conditions (i.e., native forest), a P deficiency in forest function remained unresolved even 21 years after restoration. The restoration of biogeochemical processes, particularly of critical processes of the P cycle, requires additional human interventions (such as the application of nutrient-rich litterfall from native forests of the region) that favor nutrient dynamics and lead to the recovery of a self-sustaining ecosystem. Thus, multiple efforts are needed for the restoration of these dryland forests to recover ecosystem services (such as soil fertility) that improve C sequestration and help mitigate climate change.

Accelerating soil aggregate formation: a review on microbial processes as the critical step in a post-mining rehabilitation context

“…Open pit coal mining can cause severe damages to microbial communities and alter the nutritional status of the soil in the mined area through excessive leaching and stockpiling (Ram and Masto 2010). In some cases, the coal spoil abiotic conditions are vastly different from the predegradation baseline (unmined topsoil), and the system may not follow the expected rehabilitation projection (Barliza et al 2018). Coal mine spoil or overburden originates from consolidated and unconsolidated materials that cover a coal seam, and its properties may vary significantly over the globe due to variation in soil texture, mineral composition and stock management (Li et al 2014).…”

“…This available nutrient depletion can affect plant density by limiting germination, seedling establishment and longterm survival (Nussbaumer et al 2016;Yuan et al 2020). The re-establishment of these biogeochemical processes, particularly of the nitrogen, carbon and phosphorus cycle, requires additional human intervention that lead to a selfsustaining ecosystem (Barliza et al 2018).…”

Restoration and rehabilitation of degraded land in arid and semiarid environments: Editorial

“…Revegetation efforts generally result in improvement of soil fertility and enhancement of ecosystem services and functions such as carbon sequestration (Gao, Dang, Zhao, Liu, & Liu, 2018), nutrient cycling (Barliza, Peláez, & Campo, 2018;Hu et al, 2018), and soil microbial diversity and activity (Garcia et al, 2018;Liu et al, 2019); nevertheless, it can also lead to adverse effects such as salinity which may affect the success of restoration efforts in the long term (Yu & Wang, 2018) and generally increases plant productivity and carbon sequestration in the medium or long-term, as highlighted by Valdecantos and Fuentes (2018). Also in this issue, Luna, Vignozzi, Miralles, and Solé-Benet (2018) show that woodchip mulch can be effective for trapping runoff and sediment in mine rehabilitation sites, whereas organic amendments formed by composted waste can improve infiltration and reduce water erosion (Figure 2).…”

“…Revegetation has been for many years a conventional strategy for rehabilitation of degrading landscapes (Hobley et al, 2018) and using native plants adapted to drought can facilitate plant establishment in degraded soils under water stress conditions (Bateman et al, 2018). Revegetation efforts generally result in improvement of soil fertility and enhancement of ecosystem services and functions such as carbon sequestration (Gao et al, 2018), nutrient cycling (Barliza et al, 2018Hu et al, 2018 and soil microbial diversity and activity (García et al, 2018;Liu et al, 2019); nevertheless, it can also lead to adverse effects such as salinity which may affect the success of restoration efforts in the long term (Yu and Wang, 2018). Some native plants such as halophytes, may on the other hand assist in the remediation of salt-affected soils (Shaygan et al, 2018) (Figure 1).…”

“…Revegetation efforts generally result in improvement of soil fertility and enhancement of ecosystem services and functions such as carbon sequestration (Gao, Dang, Zhao, Liu, & Liu, 2018), nutrient cycling (Barliza, Peláez, & Campo, 2018;Hu et al, 2018), and soil microbial diversity and activity (Garcia et al, 2018;Liu et al, 2019); nevertheless, it can also lead to adverse effects such as salinity which may affect the success of restoration efforts in the long term (Yu & Wang, 2018). Some native plants such as halophytes, may on the other hand assist in the remediation of salt-affected soils (Shaygan, Mulligan, & Baumgartl, 2018; Figure 1).…”