Banca de DEFESA: ANA LUÍSA FARES BIONDI LIMA
Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.DISCENTE : ANA LUÍSA FARES BIONDI LIMA
DATA : 28/02/2019
HORA: 09:00
LOCAL: LM 4 - Instituto de Ciências Biológicas - UFPA
TÍTULO:
"Resisting, nevertheless? Effects of Multiple Land-use on macrophyte communities in Amazonian freshwater ecosystems"
PALAVRAS-CHAVES:
aquatic plants; land-use change; bioindicators; Neotropical freshwaters
Land-use is considered the most severe driver of biodiversity change. Biomes, such as tropical forests, and ecosystems, such as freshwaters, have been damaged by land use, since they are important to global biodiversity maintenance. Aquatic macrophytes are sensitive to changes that occur on their physical habitat, and they respond at different scales to the effects of land use. This study’s main objective was to evaluate the effects of multiple land-use on aquatic macrophyte diversity. Our hypotheses were that: i) macrophyte species richness increases in multiple land-use gradients and ii) macrophyte species composition will change along a multiple land-use gradient. For that, we surveyed, in July 2017, 30 aquatic ecosystems (streams, lakes and ponds) located in Paragominas, Pará, Brazil. Species richness was sampled by taking notes of all species that occurred in a 150m transect of each site. We sampled composition data with a 1m2 quadrat, giving a percentage of cover to each species inside it. The predictive variables consisted of the local environmental variables (water parameters and canopy cover), and the landscape variables, which consisted of the percent of land-use and land cover classes present on each sampling site, that were obtained using geoprocessing techniques. To test hypothesis (i), Generalized Additive Mixed Models were used. To test hypothesis (ii), we used a distance-based redundancy analysis. Additionally, a Threshold Indicator Taxa Analysis was performed to identify which species are indicators of the land-use classes used on this study. We recorded 49 macrophyte species, and one of those was considered invasive. Species richness was affected positively by land-use, and negatively by canopy cover, corroborating hypothesis (i). Altered sites could provide more microhabitats, favoring more species, due to increased light incidence, sediment load, and nutrient input. Species composition was affected negatively by canopy cover, and positively related to pH and land-use, partially corroboration hypothesis (ii). More altered sites can provide habitat heterogeneity and increase life-form diversity. Three species were selected as indicators of land-use change: Cabomba aquatica, Eleocharis interstincta and Utricularia sp. Macrophyte communities could be experiencing an early stage of succession, in which the appearing of invasive species could be the start of a decrease in diversity as the consequences of land-use become abrasive. Those results point macrophytes as indicators of altered conditions, reinforcing their potential to be considered on freshwater assessments on Amazonia. Thus, we conclude that macrophytes are resisting the effects of multiple land use, nevertheless, but how much time (and how much increased impact) will it take to make them disappear completely?
PÁGINAS: 50
GRANDE ÁREA: Ciências Biológicas
ÁREA: Botânica
RESUMO:
Land-use is considered the most severe driver of biodiversity change. Biomes, such as tropical forests, and ecosystems, such as freshwaters, have been damaged by land use, since they are important to global biodiversity maintenance. Aquatic macrophytes are sensitive to changes that occur on their physical habitat, and they respond at different scales to the effects of land use. This study’s main objective was to evaluate the effects of multiple land-use on aquatic macrophyte diversity. Our hypotheses were that: i) macrophyte species richness increases in multiple land-use gradients and ii) macrophyte species composition will change along a multiple land-use gradient. For that, we surveyed, in July 2017, 30 aquatic ecosystems (streams, lakes and ponds) located in Paragominas, Pará, Brazil. Species richness was sampled by taking notes of all species that occurred in a 150m transect of each site. We sampled composition data with a 1m2 quadrat, giving a percentage of cover to each species inside it. The predictive variables consisted of the local environmental variables (water parameters and canopy cover), and the landscape variables, which consisted of the percent of land-use and land cover classes present on each sampling site, that were obtained using geoprocessing techniques. To test hypothesis (i), Generalized Additive Mixed Models were used. To test hypothesis (ii), we used a distance-based redundancy analysis. Additionally, a Threshold Indicator Taxa Analysis was performed to identify which species are indicators of the land-use classes used on this study. We recorded 49 macrophyte species, and one of those was considered invasive. Species richness was affected positively by land-use, and negatively by canopy cover, corroborating hypothesis (i). Altered sites could provide more microhabitats, favoring more species, due to increased light incidence, sediment load, and nutrient input. Species composition was affected negatively by canopy cover, and positively related to pH and land-use, partially corroboration hypothesis (ii). More altered sites can provide habitat heterogeneity and increase life-form diversity. Three species were selected as indicators of land-use change: Cabomba aquatica, Eleocharis interstincta and Utricularia sp. Macrophyte communities could be experiencing an early stage of succession, in which the appearing of invasive species could be the start of a decrease in diversity as the consequences of land-use become abrasive. Those results point macrophytes as indicators of altered conditions, reinforcing their potential to be considered on freshwater assessments on Amazonia. Thus, we conclude that macrophytes are resisting the effects of multiple land use, nevertheless, but how much time (and how much increased impact) will it take to make them disappear completely?
MEMBROS DA BANCA:
Interno - 079.651.076-86 - GRAZIELLE SALES TEODORO - UFPA
Externo à Instituição - LEANDRO JUEN - UFPA
Externo à Instituição - LEANDRO SCHLEMMER BRASIL - UFPA
Presidente - 044.649.569-71 - THAÍSA SALA MICHELAN - UFPA
Externo à Instituição - TIAGO OCTAVIO BEGOT RUFFEIL - UFPA