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| Author(s): |
Luiz Felippe Salemi
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Piracicaba. , ilustrações. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2009-06-16 |
| Examining board members: |
Luiz Antonio Martinelli;
Marcelo Corrêa Bernardes;
Klaus Reichardt
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| Advisor: | Luiz Antonio Martinelli |
| Field of knowledge: | Biological Sciences - Ecology |
| Indexed in: | Banco de Dados Bibliográficos da USP-DEDALUS; Biblioteca Digital de Teses e Dissertações - USP |
| Location: | Universidade de São Paulo. Biblioteca Central da Escola Superior de Agricultura Luiz de Queiroz; ESALQ-BC/t551.483; S163b |
| Abstract | |
The Atlantic forest is the most endangered biome of Brazil. Its significant destruction has taken place since the arrival of Europeans settlers in the country. These Europeans destructed most part of it by changing land use and also due to forest exploitation. In this way, very little information is known about the hydrological and biogeochemical consequences of land use change in the region of this once huge ecosystem. In this context, small catchments have being used to assess these cited consequences of land use change due to their high sensitivity of hydrological and biogeochemical process that occur within them. In the present study, the annual water budget of a small watershed covered by grass (pasture) located in the north coast of the Sao Paulo State, Brazil has been calculated. Additionally, (1) stream water, (2) surface runoff, (3) soil solution (at 30, 50 and 90 cm depth), (4) groundwater and (5) precipitation were sampled weekly and, afterwards, due to analytical reasons, (2) and (3) were sampled biweekly, to determine the concentration of inorganic nitrogen (N-NH4 + and N-NO3 -) by FIA. Moreover, aiming to clarify the possible hydrological process of stormflow, the soil saturated hydraulic conductivity was measured at various depths (15, 30, 50 and 90 cm). The results obtained are: the evapotranspiration of the watershed vegetation, calculated for the study period, was 697 mm (annual precipitation and annual water yield, respectively, de 1433 mm e 736 mm). By the flow duration curve, the baseflow was inferred as the main hydrological pathway that contributes to the total annual water yield. The surface runoff was not very expressive for the reason that 77% of rain intensity was sited in the class of 0 - 5 mm h-1 that is lower than the median of soil saturated hydraulic conductivity at 15 cm depth (22 mm h-1). The low runoff coefficient (0,01) calculated from the runoff plots assures this result. Although soil physical degradation is present, it is not expected an expressive increment of direct runoff generation for the reason that low intensity rainfall predominates and does not exceed Ksat at 15 cm. Little inorganic nitrogen is found in the hydrological processes and pools. The majority of the samples had their inorganic nitrogen concentration below detection limits (0,71 µM e 0,35 µM for N-NH4 + e N-NO3 - respectively). In most pools and hydrological pathways the ammonium predominates against nitrate. For soil solution, it is notable that more inorganic nitrogen was found when the soil gets less wet. The observation of inorganic nitrogen balance dissolved in the water of rain and streamflow exhibits a net gain (0,95 kg N ha-1 year-1) of inorganic nitrogen because the input was 1,10 kg N ha-1 year-1 and the output was 0,15 kg N ha-1 year-1. If the results of nitrogen in the pools are compared to other similar catchment studies with land uses of forest and also pasture in Brazil and elsewhere, it is possible to conclude that the pasture presented here is poorer than forests and even some pastures. This fact may be a consequence of the land use clearing method, the lack of fertilization, the high stocking rates and also due to the pasture age. (AU) | |
| FAPESP's process: | 06/54292-9 - Study of the hydric balance and the biogeochemical balance of nitrogen in a first order microbasin with pasture cover on the north coast of the State of São Paulo |
| Grantee: | Luiz Felippe Salemi |
| Support Opportunities: | Scholarships in Brazil - Master |