Aporte, transporte e decomposição de liteira em igarapés da bacia amazônica
The allochthnous organic matter (OM) is the main energy source in aquatic forested ecosystems. When entering streams it can be retained and be kept stored. And it is in its retention and afterwards decomposition that it will occur the chain between primary consumers and its food source. The geolo...
| Autor principal: | Paula, Joana D’Arc de |
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| Grau: | Tese |
| Idioma: | por |
| Publicado em: |
Instituto Nacional de Pesquisas da Amazônia - INPA
2020
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| Assuntos: | |
| Acesso em linha: |
https://repositorio.inpa.gov.br/handle/1/12262 http://lattes.cnpq.br/9379172063617836 |
| Resumo: |
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The allochthnous organic matter (OM) is the main energy source in aquatic forested
ecosystems. When entering streams it can be retained and be kept stored. And it is in its
retention and afterwards decomposition that it will occur the chain between primary
consumers and its food source. The geological structure of the Amazon Basin results in a
mosaic of distinct geochemical formations, which determines differences that allows the
occurrence of soil fertility gradients and rainfall at the forest. But, these gradients will be also
reflected into the contribution, transport and decomposition of the organic matter in headwater
streams of Amazon Basin? Based on this it was formulated the following hypothesis: is the
dynamics of organic matter in headwater streams of the Amazon Basin influenced by the soil
fertility gradients and rainfall. To test the hypothesis there were collected samples from OM
lateral contribution, experiments of leaf transportation and leaf decomposition and it was
performed samples of storage organic matter and Dissolved organic carbon (DOC) in
transport, simultaneously there were collected soil and water samples to characterize the
streams and their soil fertility. Experiments and samples were collected along 90 days, in 16
headwater streams distributed in a soil fertility gradient and rainfall. The thesis was formatted
in 4 chapters. In each one, the following hypothesis were tested: chapter 1) Differences into
the soil characteristics and rainfall reflect into differences in quantity and quality of the input
litter the low order streams of Amazon Basin; chapter 2) Headwater streams of Amazon Basin
present high retentiveness influenced by local factors as well as local rainfall and soil fertility;
3) The concentration of dissolved nutrients into the headwater streams water throughout
Amazon Basin is distinct reflecting into the soil fertility gradients and rainfall, resulting in
different decomposition times; and chapter 4) The fertility of the soil and rainfall of Amazon
Basin promote distinction of the fractions distribution of organic matter coarse particulate,
fine particulate and dissolved (DOC). The quality and quantity of litter that enter laterally into
the low order streams of Amazon Basin showed been influenced by soil fertility, soil texture
and rainfall. The streams presented high retentiveness that was explained by the channel
characteristics as obstacles frequency and free water column, factors influenced by rainfall
patterns. The decomposition time between the studied species was distinct, and it was due to
the characteristics of the species and location; differences between locations were due to the
soil fertility patterns and rainfall. It was observed a high stock of OM on the streambed and
also that less than 50% of carbon has been really computed when considered only the fraction
of fine particulate organic and DOC, and that studies that include the coarse particulate carbon
storage into the streambed of the streams allow more accurate estimates of the carbon
concentration in aquatic ecosystems, enabling the extrapolation of results obtained in terms of
the global carbon balance. Therefore the rainfall and soil fertility gradients explain not only
the dynamic diversity of arboreal species but also the dynamic of the dead organic matter in
headwater streams at the Basin. However, it is important to highlight that these results are stillxiii
preliminary, and more studies that provide even better verification of seasonality are needed
in the region. Still, in view of the extensive drainage network and high input values of organic
matter in headwaters streams, the high retention capacity of these streams, as well as the
different stages of decomposition, promoting high concentrations of carbon stored in fractions
streambed, we can say that the maintenance of the integrity of the water bodies of low-order
has fundamental source importance to these ecosystems, allowing the maintenance of long
food webs present in them. |