Evaluation of the potential of native remnants as propagules sources for restoration of grassland savanas

Abstract

The cerrado grasslands have had their areas of occurrence reduced by several factors, including the conversion to agricultural production, biological invasions and even natural encroachment due to fire suppression. Actions to ensure the conservation of the diversity that has been lost should comprise ceasing land conversion, and development of management practices and restoration techniques for grassland physiognomies. The transfer of topsoil, plant material or even direct seeding have proven effective in restoring grassland vegetation in different regions of the world. The research proposed here aims to evaluate the viability of these techniques for the restoration of grassland savannas in dry and wet environments. The success of different techniques for each physiognomy, and also the resilience of natural ecosystems used as source of top soil and plant material will be evaluated. The study will be conducted in Santa Barbara Ecological Station - EEcSB by collecting material in areas where the ecosystems are intact, to restore areas where native vegetation was completely destroyed by invasion by Pinus elliottii and there is no potential for natural regeneration. Five treatments will be compared for dry grassland restoration: 1- transfer of topsoil; 2- direct seeding; 3-transfer of topsoil + direct seeding; 4-transplantation of plant material and 5- control (no intervention). Three treatments to restore wet grasslandswill be compared: 1- transplantation of plant material; 2- direct seeding; 3- control (no intervention). For each physiognomy, ten replicas per treatment will be installed in ten blocks with randomization of treatments within each block. We will also verify the resilience of the source ecosystems, by removing top soil and plant material from plots (gaps) of three different sizes (treatments) randomized inside ten blocks (ten replicates). Our expectation is that the restoration techniques can bring at least vegetation cover and part of the native flora, and that the source ecosystems are resilient to the removal of top soil and plant material, so enabling these restoration techniques for cerrado grasslands. (AU)