Anéis de crescimento e radiocarbono nas análises de incremento e variações celulares em árvores exploradas de florestas em segundo ciclo de corte no sul da Amazônia
Many forests in southern Amazonia are reaching the second cycle of cutting (CC), which raises concerns about these forest’s sustainability. Current forest management criteria may not be suitable primarily for these forests and lead on to an over or under exploitation of timber resources. Allied t...
| Autor principal: | Miranda, Dirceu Lucio Carneiro 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/1/4986 http://lattes.cnpq.br/0710461808576270 |
| Resumo: |
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Many forests in southern Amazonia are reaching the second cycle of cutting (CC), which
raises concerns about these forest’s sustainability. Current forest management criteria may not
be suitable primarily for these forests and lead on to an over or under exploitation of timber
resources. Allied to this, it is not known if the impact of the forest management would trigger
radial variations in the anatomy of the logged trees and influence the quality of the wood
extracted in these forests. In this study, the performed analyzes were concentrated in two
species: Qualea paraensis Duke and Parkia pendula (Willd.) Benth. Ex Walp. All samples
analyzed come from tree trunk discs, destructively collected in a tropical moist terrafirme forest managed in southern Amazonia. In chapter 1, an annual periodicity of rings growth
was investigated, in addition to describing their growth and estimating the minimum logging
diameter (MLD) and the CC for such species. For this purpose, techiniques of
dendrochronological and radiocarbon analyzes were combined and equation adjustments were
used to estimate MLD and CC. In both species the rings were considered anual and are delimited
by density difference in Q. paraensis and by marginal parenchyma band and fibrous zone in P.
pendula. However, without radiocarbon analysis, it was observed that approximately 10%
errors can occur in the delineation and ring count in P. pendula. The mean growth was 0.93
cm.year-1 ± 0.201 in Q. paraensis and 0.63 cm.year-1 ± 0.221 in P. pendula. It can be affirmed
that the area’s logging history promoted an increase in the growth rate only in Q. paraensis.
The MLD estimative was 53 cm in Q. paraensis and 42 cm in P. pendula with 11 and 17 years
of CC, respectively. In chapter 2, it was analyzed the variations in density and in the cellular
dimensions of fibers and vessels in the medulla-cambial direction and an influence of the forest
management on the variations of Q. paraensis and P. pendula wood. The disks were prepared
for an annual identification of the growth rings and removal of 10 predefined samples along the
radius for fiber and vessel measurement. The density was obtained by x-ray densitometry.
Graphical and comparative analyzes were performed between samples in different radial
positions. X-ray densitometry detected variations in density due to forest management in Q.
paraensis and in juvenile wood it was up to 8 cm of radius in P. pendula. There was an increase
in vessel diameter and a decrease in vessel frequency in Q. paraensis. In addition to the vessel
diameter, in P. pendula there was a lengh and thickeness increase of the fibers’ wall and a
decrease in the total thickness of the fibers. The influence of forest management was more
evident in the area occupied by vessels due to the increase in vessel diameter and / or vessel
frequency. The results presented in this thesis allow to conclude: i) the criteria of forest
management in Brazil do not apply to the studied species; ii) errors in growth ring analysis may
occur when no radiocarbon dating is applied; iii) the studied species of logged wood have
important radial variations in the anatomical elements, especially due to this practice of forest
management, which could alter the quality of the logged wood from these forests. |