ABSTRACT
Savannas and grasslands have lost almost 50% of their original cover worldwide. Therefore, the development of methods and information on open-canopy ecosystem restoration is urgent for the inclusion of these ecosystems into global and regional priorities. In the Brazilian savanna, the most diverse savanna in the world, restoration efforts focused on open ecosystems have been virtually absent, but have increased in the last 10 years. Such efforts are frequently threatened by invasive exotic grasses (IEG) that invade and dominate areas excluding native species, oftentimes aided by altered soil conditions. Long-term studies of savanna restoration trajectories are rare. In this study, we surveyed 22 savanna restoration areas established two to ten years before the study with similar restoration methods to assess their current status. We show that the current restoration methods are successful in establishing native species and allowing species turnover but they are threatened by IEG. Restoration success varies and is affected by soil conditions, IEG landscape cover and post-sowing weeding. Despite that, the simultaneous introduction of different plant functional groups allows turnover from fast to slow-growing plants. Establishing savanna native species is possible at an operational scale with current knowledge and techniques. However, native species establishment fails to prevent IEG reinfestation, which needs to be managed in restoration efforts in the Brazilian savanna.
ABSTRACT
Estacas de Euplassa inaequalis foram avaliadas em casa de vegetação, por 180 dias, para: 1) identificar efeitos de métodos de aplicação e concentrações de ácido indolbutírico (AIB) e Benlate no enraizamento; 2) verificar presença de amido nos tecidos caulinares para relacionar com a capacidade rizogênica; e 3) verificar presença de barreiras à emissão de raízes. Estacas apicais com 20 cm de comprimento e duas folhas foram coletadas no início e final da época seca e no meio da chuvosa. Estacas foram tratadas por imersão rápida e via palito embebido com doses de AIB (2000, 4000 e 8000 ppm) e Benlate 0,25g/250ml de água por imersão rápida. Fragmentos das estacas foram utilizados para identificação de amido e barreiras anatômicas. Concluiu-se que AIB, Benlate e vias de aplicação não favoreceram o enraizamento, enquanto a coleta no fim da seca se mostrou favorável ao enraizamento, sobrevivência e formação de calos. Ocorrência e distribuição de amido nos tecidos caulinares variaram sazonalmente, com maior presença no final da seca, sugerindo que a quantidade de amido seria um dos fatores que estariam favorecendo a maior capacidade de enraizamento e sobrevivência nessa época. Não foi observado tecido lignificado que possa funcionar como barreira à emissão de raiz adventícia.
Cuttings of Euplassa inaequalis were evaluated at greenhouse, for 180 days for: 1) to identify effects methods of application and indolbutiric acid (IBA) and Benlate; 2) verify presence of starch to relate with rooting capacity; and 3) check the presence of barriers against rooting. Apical cuttings (20 cm long with two leaves) collected at the beginning and end of the dry season and at the middle of the rainy season were tested. Cuttings were treated by rapid immersion and via toothpick soaked with IBA doses (2000, 4000 and 8000 ppm) and 0, water 25g/250ml Benlate fast dipping. Fragments were also collected for identification of starch and anatomical barriers. It was concluded that IBA, and routes of Benlate application do not favored rooting, while collecting during the dry season were favourable to rooting, survival and the formation of calus. Presence and starch distribution varied seasonally, with greater presence at the end of the dry season, suggesting that this feature would be one of the factors of higher rooting capacity and survival at this period. Unlignified parenchyma tissue was not observed as a barrier to presence of adventitious roots.
