Native remnants can be sources of plants and topsoil to restore dry and wet cerrado grasslands

Abstract

Neotropical grasslands have undergone intensive degradation by land conversion or biological invasion, but their restoration is still challenging. Here, we integrated two approaches to (1) assess the resilience of pristine dry and wet cerrado grasslands after removal of plants and topsoil and (2) evaluate the effectiveness of different treatments based on the material extracted from pristine grasslands to restore degraded dry and wet grasslands after pine invasion. We used old-growth cerrado grasslands in southeastern Brazil as donor ecosystems and assessed their resilience after the removal of all plants and the upper 5-cm soil layer. To restore both wet and dry grasslands, we tested topsoil translocation, plant transplantation, direct seeding, topsoil translocation + direct seeding, and needle layer removal. Both wet and dry grasslands were resilient to plants and topsoil removal, as evidenced by their fast recovery. The major mechanisms promoting resilience were seed germination in the wet grasslands and resprouting from underground organs in the dry grasslands. Transplantation was the most successful treatment to restore vegetation cover, species richness, and composition in both wet and dry grasslands, especially for herbaceous species. Restoration of the herbaceous layer of cerrado grasslands can be successful using natural ecosystems as donor sites without impairing their resilience in the studied scale. Improving the resilience of degraded dry and wet cerrado grasslands depends on reestablishing the condition to seed germination in the wet grasslands and reintroducing species with the ability to resprout after disturbance in the dry grasslands, attributes that explained the quick recovery of the donor ecosystems. Implications for Practice• Donor ecosystems can quickly recover from uprooting plants and removing topsoil at a small scale in both dry and wet grasslands. • As topsoil translocation and transplantation of mature grasses and forbs proved to be viable techniques to restore dry and wet cerrado grasslands, once restored these grasslands can be turned into sources of material for grassland restoration elsewhere. • Transplantation during the rainy season is a promising way to quickly recover the ground layer of degraded dry and wet grasslands with low potential for natural regeneration in the Cerrado. • Reestablishing the ground cover, plant species richness, and species composition is much faster and easier in wet than in dry degraded grasslands. • Removal of the pine needle layer is mandatory before the application of restoration techniques in either dry or wet grasslands.

Long‐term Pinus plantations reduce the bud bank in Cerrado areas

“…Furthermore, the accumulation of a thick layer of pine needles may have suppressed species from the herbaceous layer, also preventing germination from a seed bank and inhibiting the establishment and survival of seedlings, which are unable to survive under shaded conditions (Hoffmann et al, 2004;Abreu et al, 2017;Pilon et al, 2018;Durigan et al, 2020). When seedling recruitment is incapable of sustaining population maintenance, the persistence of native species after disturbances relies on recruitment from the below-ground bud bank (Ott et al, 2019).…”

Shade alters savanna grass layer structure and function along a gradient of canopy cover

“…Rather, competition is likely to be for space and light through times of high water availability, and both tall and large grasses with dense canopies and high annual production of biomass (such as Paspalum lachneum) can exclude smaller and more slender grasses (such as Agenium leptocladum or Eragrostis leucosticta) in the absence of fire (Figure 5b). The higher diversity observed in high light conditions may well be mediated by fire, which reduces the overall grass biomass creating space and conditions for the small grasses to propagate (Coutinho, 1990;Fidelis et al, 2012;Pilon et al, 2019). We do not interpret the positive associations between species (Figure 5b) as a trend towards facilitation processes.…”

Quantifying Long-Term Urban Grassland Dynamics: Biotic Homogenization and Extinction Debts

“…In dryland ecosystems, seeding often fails because managers do not account for seed dormancy and germination traits [79]. Whereas, in neotropical grasslands, the translocation of topsoil and transplantation of mature forbs and grasses proved to be the most successful restoration technique [80].…”