A importância da disponibilidade de nutrientes para a dinâmica de carbono abaixo do solo na Amazônia Central
The availability of nutrients is related to primary production in tropical forests and observational evidence demonstrates a range of responses to soil nutrient availability highlighting the need to better understand how soil nutrients determine ecosystem processes. Theory suggests a limitation o...
| Autor principal: | Rosa, Jéssica Schmeisk |
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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/1/23328 http://lattes.cnpq.br/2735890942358191 |
| Resumo: |
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The availability of nutrients is related to primary production in tropical forests and
observational evidence demonstrates a range of responses to soil nutrient availability highlighting
the need to better understand how soil nutrients determine ecosystem processes. Theory suggests
a limitation of tropical forest growth related to low phosphorus availability or even low cation?
availability, raising new questions about how nutrient limitation arises and its various effects on
different compartments of carbon cycling. One ecosystem process related to carbon and nutrient
cycling that is rarely examined is fine root dynamics. The characteristics of the fine roots, including
abundance, functional traits and mycorrhizal symbionts, can be highly sensitive to soil nutritional
changes. Therefore, quantifying the responses of the fine roots and their symbionts to the
alleviation of nutrient limitation can improve our understanding of the effect of low nutrient
availability on the belowground ecosystem processes. In this research, we documented the response
of fine roots, arbuscular mycorrhizal fungi (AMF) and total soil CO2 flux, to the availability of
phosphorus, nitrogen and cations (potassium, magnesium and calcium) during six months of
fertilization in a complete factorial design in one forest land firm in Central Amazonia. We
observed that the addition of nutrients increased both the biomass and the yield of fine roots in the
superficial layers of the soil, where the interaction between phosphorus and cations caused an
increase in the biomass of thin roots in the layer of 10-30 cm, while the increase of productivity of
fine roots in the 0-10 cm layer was caused only by the addition of cations. The morphological
characteristics of the roots did not respond to the addition of the nutrients during the six months of
collection. However, the addition of phosphorus strongly increased the total soil carbon flux as
well as potentially increased the colonization of fine roots by arbuscular mycorrhizal fungi.
Although there was an increase in the yield of fine roots and total soil carbon flux, there was not a
significant relationship between these two factors, suggesting that the increase in the mycorrhizal
community, together with the increase in microbial activity, may have strongly influenced the
increase of the total soil CO2 flux. Together, this research experimentally shows that phosphorus
and cations are the main co-limiting nutrients of belowground ecosystem processes in this Central
Amazonian tropical forest, suggesting that further research is necessary to understand the role
cations and their interactions with other major plant nutrients across tropical forests. |