Respostas nutricionais e características fotossintéticas de espécies pioneiras submetidas a diferentes tratamentos de adubação em pastagens abandonadas na Amazônia central
The expansion of lands used for agriculture and cattle ranching is growing at an exponential rate in the Amazon, in turn, contributing significantly to the increase deforestation in the region. In the case of ranching, large areas once transformed into pastures have shown advanced stages of degra...
| Autor principal: | Silva, Carlos Eduardo Moura da |
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| Grau: | Dissertação |
| 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/1/5131 http://lattes.cnpq.br/1016638921761687 |
| Resumo: |
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The expansion of lands used for agriculture and cattle ranching is growing at an
exponential rate in the Amazon, in turn, contributing significantly to the increase
deforestation in the region. In the case of ranching, large areas once transformed into
pastures have shown advanced stages of degradation, such to the point of abandonment. In
these abandoned areas, there is an emerging secondary succession composed mainly of
pioneer species like those of genus Vismia, Bellucia, and Laetia. With the objective of
investigating the processes of the pioneer species that are revegetating these lands, the
hypothesis was formulated that the improvement of the edafic environment would produce
appropriate conditions for understanding the different strategies for capture and utilization
of primary resources for the three species most common to these degraded environments:
Vismia japurensis, Bullucia grossularioides, and Laetia procera. The study was carried out
in an area of secondary succession that was abandoned for 6 years, located at Embrapa’s
Experimental Station at kilometer 54 of highway BR-174 (2° 34’ S, 60° 02’ W), in the
municipalitie of Manaus, AM, Brazil. The experiment was structured with four treatments:
control treatment (C); treatment with phosphate applied (P); treatment with phosphate and
soil acid correction applied (P+Cal); and treatment with phosphate, soil acid correction,
and agricultural gypsum applied (P+Cal+G). Once the treatments were established, the
following variables were identified: nutrient concentrations in both the soils and the plants;
specific leaf area; leaf water potential; and parameters related to gas exchange and
photochemical efficiency in the photosynthetic mechanism. The results showed greater
concentrations of P, Ca, and Mg in the surface layers of the treatments that received
phosphate fertilizer and soil acid correction. In relation to leaf nutrient levels, the species
showed a varied behavior between treatments and periods of precipitation. The nutrient P
did not seem to limit the success of the species growing in the degraded soils, however,
even despite the fact that the fertilizer elevated the nutrient concentrations in the surfaces
layers of the soil, this was not reflected in the nutrient levels for the leaves. In addition, it
was observed that B. grosularioides was very dependent on N and L. procera accumulated
more Ca and Mn in its leaves when compared with the other species. In regards to the
results of the gas exchange and photosystem II photochemical efficiency, the species that
showed the best and worst responses were V. japurensis and L. procera, respectively. From
this data it can be concluded that these species showed varied strategies for capture and use
of primary resources, with V. japurensis proving to be the most efficient in its use of the
resources, which may be confirmed by the fact that it is the species most frequently found
in such degraded areas. |