Avaliação ecofisiológica de espécies arbóreas utilizadas para revegetação de áreas degradadas
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Data
2019-08-23
Autores
Mendes, Marcel Merlo
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Universidade Federal do Espírito Santo
Resumo
Diverse anthropic activities over time have dramatically reduced the area occupied by the Atlantic Forest, making it one of the world's biodiversity hotspots. These fragmented habitats are a risk for conservation of several species. Ecological succession processes that would ensure the natural regeneration of degraded areas may be impossible depending on the type and extent of impacts. Mining, for example, leads to loss of vegetation, changes in physical and chemical properties as well as soil compaction. The recovery of these areas through revegetation with planting of native species requires a better knowledge of the soil conditions, as well as the patterns and parameters capable of influencing the growth of the species. The objective of this study was to evaluate the physiological evaluation of tree species of two functional groups (nitrogen fixing and non-fixing species) in different treatments of soil decomposition in the presence and absence of green manuring to determine the best way to plant revegetation projects. The experiment was carried out in an area (720 m2) degraded by clay extraction, with a randomized block design (DBC), 4 replicates (Blocks 1, 2, 3 and 4) and 24 plots of 20 m². Seedlings of four species [Psidium cattleianum and Schinus terebinthifolius (non-nitrogen fixing species) and Dalbergia ecastophyllum and Inga laurina (nitrogen fixing species)] were transplanted with treated soil by scarification, scarification + harrowing, subsoiling + harrowing (T1, T2 and T3, respectively), in two distinct types of plot: i) absence of green manure; ii) presence of green manure, composed of seed mix with grasses, legumes and crucifers (P1 and P2, respectively). After six and twelve months, transient chlorophyll a fluorescence and leaf attributes were evaluated. Chemical analysis and resistance to soil penetration were also performed. In the first evaluation, at 6 months, an increase in the specific energy flows (ABS/RC and DIo/RC) and the photochemical quantum yield for heat dissipation φD0 in the presence of the seed mix (green manure) in Psidium cattleianum and Schinus terebinthifolius, indicating a stress condition, most likely by the competition process exerted by some species that make up the mix. On the other hand, no transient fluorescence parameter of chlorophyll a differed statistically in the same period in Dalbergia ecastophyllum and Inga laurina. However, in the second 12-month evaluation, the seed mix promoted an increase in the energy conservation capacity of the photosynthetic apparatus, that is, it was able to reduce energy losses by maintaining energy transport reactions in the FSII until final acceptors of electrons in FSI in all four species, demonstrating their ability to improve the photochemical performance of tree species over time. This study also demonstrated that the seed mix is able to reduce succulence (SUC), thickness (ESP) and foliar mass per unit area (MFA) in the functional group of nitrogen-fixing species, which availability of water and nutrients in these plots. Leaves with these characteristics, to the senescent, decomposes faster that accelerates and contributes to the process of nutrient cycling of the litter. On the other hand, these characteristics practically did not change in the group of the species N-fixing of nitrogen. Finally, the multivariate analysis (PCA) was used to determine which parameters would explain the growth of the species in the field. Leaves with these characteristics, to the senescent, decomposes faster that accelerates and contributes to the process of nutrient cycling of the litter. On the other hand, these characteristics practically did not change in the group of the species N-fixing of nitrogen. Finally, the multivariate analysis (PCA) was used to determine which parameters would explain the growth of the species in the field. Thus, at six months, a correlation was observed between the height and the active QA reductive reaction centers per cross section in FSII (RC/CSo), which did not vary significantly in any species. It is worth mentioning that all species in the presence of the mix showed better results in these parameters, which would help to explain a greater growth of the individuals of this plot from the twelve months. This study demonstrated that the green fertilization performed through the seed mix is able to promote an improvement in the photosynthetic apparatus in all species over time (twelve months) in the three treatments used in the decompression alone. There were also significant improvements in leaf characteristics (SUC, ESP and MFA), mainly for the group of non-fixing species. Thus, it can be considered that the use of green manuring in revegetation projects, presents a potential of facilitation by benefiting mainly non-fixing species. As this group undergoes a slight stress initially, it is possible to suggest a planting in stages, with the initial insertion of the seed mix, then the nitrogen fixation species and after six months the planting of the non-nitrogen fixing species.
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Revegetação , Ecofisiologia , Plantio direto , Adubo verde , Monitoramento