Connectivity among Wetlands of EPA of Banhado Grande, RS

Abstract

The Environmental Protection Area (EPA) of Banhado Grande, located in the Metropolitan Region of Porto Alegre, comprises three areas of marshes, the Banhado Chico Lomã, the Banhado Grande and Banhado dos Pachecos. In periods of large flood pulses extensive flooded areas are formed between these wetlands and the river Gravataí floodplain, establishing a connectivity between the Wetlands of EPABG. This connectivity indicates that there is an interaction between these wetlands, such as exchange of nutrients, sediments and living organisms. Thus, this study aims to map extensive floodable areas associated with large flood pulses and to analyze the connectivity areas in EPABG. For this, the work is structured in three steps: i) choice of satellite images between the years 2000 to 2015 to identify largest flood pulses; ii) mapping of floodable areas in large flood pulses using images Normalized Difference Index Water (NDWI); and iii) analysis of the connectivity among wetlands. As the results, in large flood pulses, with precipitation greater than 247 mm, in the 30 days prior to the date of the image, establishing a large area of connectivity between the wetlands, forming on the polygon defined by elevation of 11 metres, two types of connectivity: wetlands-wetlands connectivity, allowing interactions among environments with turf and lagoon deposits; and wetlands-stream connectivity, linking the alluvial and floodplain of the Gravataí River deposits with the background lagoon and paludals deposits. Already, in flood pulses of flooding with rainfall less than or equal to 200 mm, in the last 30 days, the flooded area appears fragmented inside the polygon associated at an elevation of 11 metres, mainly in the corridor between the marshes Grande and the Pachecos, that does not connect by flood, forming just wetlands-stream connectivity. Thus, the characterization of the flood pulses and connectivity become fundamental to the understanding of the dynamic of wetlands, because, make aware of for the need to preserve these areas of importance for flood control, microclimate regulation and maintenance of biodiversity.

Simulation of changes in land-use/land cover on wetlands through CA-Markov model

“…The presence of soybeans and rice is also observed in the central part of the EPABG, in the floodplain of the Gravataí River. Simioni et al (2017) emphasize the importance of preserving this area, which forms a connectivity between the Banhado Grande and Banhado dos Pachecos and the floodplain of the Gravataí River during great floods. Silva (2016) analyzed the dynamics of the environmental fragility in EPABG and pointed out that rice and soybean cultivation contribute to the re lease of organic matter from fertilizers, generating different environmental impacts on water resources.…”

“…When performing a study on the flood pulses in the APABG, Simioni et al (2017) verified that when the rainfall is greater than 247 mm in approximately 30 days, a connectivity among the EPABG wetlands is established, interconnecting the diverse compartments of the BGS. Such connectivity is responsible for several interactions among these wetlands, such as exchange of nutrients, sediments and organisms.…”

“…The EPABG has an area of 136,935 ha ( Figure 01) and is considered one of the most important wetlands of the RS. Its biodiversity is known due to the large variety of birds, especially migratory ones, considered by experts as of relevance for global conservation (Simioni et al, 2017).…”

“…The Environmental Protection Area of the Banhado Grande (EPABG), located in the east region of the State of Rio Grande do Sul (RS), has historically suffered from environmental impacts resulting from agricultural activities (Simioni et al, 2017).…”

Trophic Ecology of Two Sympatric Frogs with Contrasting Morphology and Habitat Use in a Subtropical Wetland

“…Wetlands tend to have high productivity and rapid nutrient cycling that support essential ecosystems services and high biodiversity, including herpetofauna (Zedler 2000). At subtropical and tropical latitudes, wetlands are influenced by rainfall and, to a lesser degree, temperature (Simioni et al 2017), which directly affect environmental conditions, productivity, and community dynamics. During periods of low rainfall, the area of water bodies and flooded zones is reduced and aquatic organism density increases, which might increase predator-prey encounter rates and foraging success of aquatic consumers (Maltchik et al 2007).…”