La cobertura de semillas y los períodos de sequía en la temporada de lluvias interfieren con el éxito de la siembra directa en la restauración de áreas mineras en las sabanas tropicales

Abstract

A�������. Among the limitations for the use of direct seeding in the ecological restoration of severely degraded areas in tropical grasslands, the association between dry periods and an inhospitable substrate stands out. This work evaluated whether covering seed with a soil layer and the addition of a thin topsoil layer to the degraded substrate interferes with native plant establishment in degraded areas. The effect of rainfall variations on direct seeding results was also measured. The establishment of seven native species was evaluated under four different conditions: 1) seeding on degraded substrate, 2) seeding covered by 1 cm degraded substrate layer, 3) seeding on 1cm topsoil layer, and 4) seeding covered by 1 cm topsoil layer. In general, species with smaller seeds showed higher establishment percentages in treatments in which seeds were deposited on the substrate. Legume species, which have larger seeds, achieved be�er establishment percentage when seeds were covered by the substrate. The addition of topsoil was beneficial for Bulbostylis fimbriata (Cyperaceae), while for the other species, the effect was null or harmful. Data also showed that rainfall amount and distribution affected the establishment rate. Direct seeding is an advantageous alternative for the ecological restoration of tropical grassland degraded by mining. Be�er knowledge on sowing management and behavior of native species can contribute to improving the efficiency of this technique.

Native grass sod and plug production as an alternative technique to restore neotropical rupestrian grassland after mining

“…Eighty days after sowing, the plug‐plants were ready to be planted in the field. The establishment rate during the plug‐plants production (57%) was much higher than the values ​​found in direct seeding experiments with this species, ranging from 6 to 33% (Figueiredo et al 2021 a , 2021 b ). Thereby, this technique optimizes the use of seeds, a very limited resource in rupestrian grasslands and OCBILs in general (Hopper 2009).…”

“…In the last decade, some techniques have been tested for introducing native grasses to restore degraded tropical grasslands such as direct seeding and hay transfer. However, the use of these techniques in dystrophic substrates and subject to water scarcity has often culminated in reduced plant establishment rates (Le Stradic et al 2014; Pilon et al 2018, 2019; Figueiredo et al 2021 a , 2021 b ). Thus, it is necessary to seek planting techniques that are more efficient, financially viable, and that facilitate the use of native grasses in restoration projects of degraded open ecosystems (Buisson et al 2021).…”

A global review on arid zone restoration: approaches and challenges

“…Sowing seeds into the ground rather than leaving them on the surface can help alleviate some of the increased mortality, by providing a lower temperature, higher moisture environment for the seeds and concealment from seed predators (Alem 2020). Another potential issue with direct seeding, is that its success is often highly dependent on rainfall before and after seeding with periods of drought significantly decreasing germination and establishment success (Figueiredo et al 2021). In highly variable rainfall areas, it therefore may be useful to back up direct seeding with other planting methods to buffer against potential project failure (Grantz et al 1998).…”