Cristina Aparecida Gonçalves Rodrigues

Efeitos da queima na dinâmica da biomassa aérea de um campo nativo no Pantanal

Resumo – O objetivo deste trabalho foi avaliar os efeitos da queima na dinâmica da biomassa aerea do estrato herbaceo de um campo nativo do Pantanal com predominância de Andropogon bicornis. A area de estudo foi submetida aos tratamentos sem queima e com queima, ambos sem pastejo. Os dados de biomassa aerea e cobertura do solo foram analisados nos onze meses subsequentes a queima. A biomassa aerea das areas com queima apresentou pequeno incremento linear de materia seca, tornando sua biomassa significativamente menor que a obtida nas areas sem queima. Andropogon bicornis, Axonopus purpusii e outras especies apresentaram menor biomassa apos a queima, enquanto Mesosetum chaseae foi favorecido pela queima, apresentando maior producao de materia seca. A acao do fogo removeu praticamente toda a biomassa; a cobertura do solo, trinta dias apos a queima, foi de aproximadamente 35%. Somente sete meses depois, a cobertura do solo foi restabelecida, tornando-se semelhante a area sem queima. Effects of burning on the aerial biomass dynamics of a native field in the Pantanal

Composição e dinâmica da biomassa aérea após a queima em savana gramíneo-lenhosa no Pantanal

The purpose of this work was to evaluate composition and aerial biomass dynamics after burning of a grassy-woody savanna in the Pantanal wetlands, Brazil. During 11 months, data on species frequency, aerial biomass and soil cover were collected in an area with burning (WB) and another free of burning (FB), both not grazed. Burning reduced the frequency of the most predominant grasses and increased the number of dicotyledons and cyperaceae species. The production of total aerial biomass was lower in the WB area, despite an increase tendency that was similar in both areas. Litter production was strongly affected by burnings. After 11 months its production was approximately 25% of the production exhibited by the FB area. Soil cover was also lower in the WB and only after four months it was similar to the FB area.

Modelo multicritério aditivo na geração de mapas de suscetibilidade à erosão em área rural

The objective of this work was to evaluate the construction of an erosion susceptibility map for a rural area of the municipality of Guararapes, SP, Brazil, using a multicriteria additive model. Digital maps on the themes relief (declivity and length of the slopes), pedology (obtained at the field), land use and land cover of the region, and interpretation of the digital elevation model were used. The digital maps were treated in a geographic information system environment using the additive multicriteria method and were validated by the universal soil loss equation (USLE) model. Five erosion susceptibility classes were generated: low, moderate, high, very high, and extremely high. The risk map obtained by additive multicriteria had good correspondence with the USLE model. The erosion susceptibility map can be used for the agricultural and environmental planning of the rural area of the municipality of Guararapes.

Variabilidade espacial do solo e da biomassa epígea de pastagem, identificada por meio de geostatística

O objetivo deste trabalho foi identificar a estrutura de dependencia espacial de atributos do solo e sua interferencia na producao de biomassa epigea de pastagem de capim‑marandu (Urochloa brizantha). Amostras de Latossolo Vermelho‑Amarelo foram coletadas em rede de pontos georreferenciados, para a determinacao de atributos fisicos e quimicos do solo e da producao de biomassa epigea da pastagem, no verao e outono de 2010/2011. Verificou-se dependencia espacial das variaveis, por meio de analise geoestatistica com construcao e ajuste de semivariogramas, interpolacao por krigagem ordinaria e espacializacao em mapas de isolinhas. A dependencia espacial ocorreu para alguns atributos fisicos e quimicos do solo (areia, densidade, resistencia a penetracao, infiltracao, pH, MO, P, K, Ca, Mg, H+Al, Al, CTC e V), e para a biomassa da pastagem medida nas estacoes verao e outono. A analise espacial de atributos fisicos do solo permite identificar areas degradadas da pastagem. A biomassa da pastagem e mais influenciada pelos atributos fisicos do solo do que pelos quimicos.

Dinâmica da vegetação natural no nordeste do estado de São Paulo, entre 1988 e 2003

The images of orbital remote sensing, along with tools available in Geographic Information Systems, have enabled several studies on changes in land cover. This study describes the results of the mapping of land use and cover and changes in a northeastern Sao Paulo state area between 1988 and 2003, specifically regarding the natural vegetation. The evaluation of the dynamics of the areas of remaining natural vegetation and of the riparian vegetation of northeastern Sao Paulo State disclosed a reduction in forests and savannas of 0.14% in comparison to the total area of the counties (51,649.5 km2). However, there was an advance of the riparian vegetation of 0.22% in comparison to the total area. Considering the 125 counties of the researched area, 60.8% had also kept practically the same percentage of natural vegetation cover and riparian vegetation in 2003 regarding to 1988. Considering only the areas with seasonal and secondary forests and savannas, the number of counties increases to 79.2% of the total. The counties that kept the greater percentages of the natural vegetal covering of remainders in the period were: Aguas da Prata, with 39.9% of its total county area, Rifaina (31.7%), Sao Sebastiao da Grama (24.9%) and Pedregulho (24.0%). The occupation of the lands between 1988 and 2003 was characterized by the dynamics of changes between activities that compete for space in the agricultural area, common in the most advanced technical administrative regions in Sao Paulo State.