Newton P. U. Barbosa

Distribution of non-native invasive species and soil properties in proximity to paved roads and unpaved roads in a quartzitic mountainous grassland of southeastern Brazil (rupestrian fields)

One of the most important disturbances of roads is the facilitation of the increase of non-native invasive species into adjacent plant communities. The rupestrian fields of Serra do Cipó, a montane grassland ecosystem in southeastern Brazil, are recognized for their enormous richness of species and endemism rates. The presence of non-native invasive species in this ecosystem could threaten the existence of the native flora and its associated organisms. The aim of this study is to understand how non-native invasive species and native species are distributed along paved and unpaved roads, in a montaneous grassland ecosystem such as the Brazilian rupestrian fields. The two road surfaces provide differing gradients from their edges with respect to nutrients, soil chemical aspects and plant species diversity. High content of calcium at the roadside in the paved road resulted from the paving process, in which limestone gravel is used in one of the several paving phases. In these newly created habitats the toxicity of aluminum is drastically reduced and nutrient enriched, hence representing favorable sites from where non-native invasive species are capable to colonize and grow for undetermined period waiting the chance to invade the adjacent pristine habitats. Disturbances provoked by any natural or human-caused event can provide the opportunity for the non-native invasive species to colonize new plant communities.

Seedling growth of the invader Calotropis procera in ironstone rupestrian field and seasonally dry forest soils

The present study evaluated the growth, biomass allocation and nutrient content in seedlings of the invasive and exotic especies Calotropis procera (Aiton) W.T. Aiton (Apocynaceae), cultured in greenhouse, in soils from two different ecosystems: ironstone rupestrian . elds (Canga) of Brumadinho, Minas Gerais; and seasonally dry forest (Caatinga), of Serra Talhada, Pernambuco. Seedlings from the Canga treatment were signi. cantly higher in concern to stem length, leaf biomass and total biomass. In respect to nutrient content there were higher phosphorus, iron and zinc levels in the seedlings from the Canga treatment. The iron accumulation indicates the capacity of C. procera to tolerate high levels of iron, which is characteristic of Canga soils. In the Caatinga treatment there was a higher root/ shoot ratio and a higher potassium accumulation in the plant tissues. The obtained results suggest that C. procera displays a good adaptation to the edaphic conditions of the Canga treatment, which indicates an invasive potential towards the Canga ecosystem.

Rupestrian Grassland: Past, Present and Future Distribution

Despite the existing evidence about climate change in South America during the Pleistocene, ancient climate and vegetation data for the mountainous regions of eastern Brazil are still scarce. Thus, little is known about the possible changes that took place in the distribution of mountainous ecosystems, such as the rupestrian grasslands. Additionally, the extent of the Rupestrian Grassland has not yet been completely mapped. The main objective of this chapter is to present the results of distribution modeling to investigate the potential distribution of the Rupestrian Grassland for the present (1950–2001), for the last glacial maximum (~21,000 years B.P.), and for the middle Holocene (~6000 years B.P.). Since we expect that mountainous ecosystems should be more sensitive to climate change than other ecosystems, we also investigated the potential distribution of the Rupestrian Grassland into the future (for the decades of 2020, 2050, and 2080), under two different scenarios (pessimistic and optimistic). We also identify historically stable areas of the Rupestrian Grassland from a paleohistorical viewpoint and also from predictions based on general circulation models of the future. According to our results, there was no significant expansion of the Rupestrian Grassland during the middle Holocene and during the last glacial maximum, probably due to the strong edaphic specificity of this ecosystem. The historically stable areas for the rupestrian grasslands were basically the mountains of Espinhaco and Canastra, some isolated mountains in southern/southeastern Minas Gerais State, and central Brazil. The future models indicate a large loss of areas environmentally suitable for rupestrian grasslands into the 2080s, which is linked to various human impacts already existing in these regions and which may lead to unpredictable catastrophic results.