Efeito do uso de diferentes práticas silviculturais e modelos de plantio misto de espécies arbóreas em área degradada no sul do brasil.

Abstract

Areas of native forests are currently in a scenario of intense anthropic pressure. Deforestation and forest degradation pose threats to the preservation of biodiversity and the provision of ecosystem services, with the Atlantic Forest being one of the most threatened forest formations in the world. Forest restoration is one of the sciences that allows the recovery of ecological functions in degraded ecosystems. In this sense, the use of mixed plantations of native and commercial exotic species, combined with the use of intensive silvicultural practices tend to maximize success in establishing forest species, carbon input, as well as enabling social and economic benefits. In this sense, the present study aimed to identify the effect of using models of mixed plantings of native and exotic species, combined with different silvicultural practices, on the survival, growth and physiological aspects of native forest species in a degraded area in the South of the Atlantic Forest Biome. The experiment was installed in September 2020, in a degraded area in the municipality of Dois Irmãos das Missões, northwest of Rio Grande do Sul. The study was carried out in a randomized block design, with 4 replications in a 2×2 factorial arrangement (two models of mixed planting of tree species × two silvicultural practices). The planting models considered the use of 5 native species combined with the use of Eucalyptus dunnii and Acacia mearnsii. Silvicultural practices consisted of the use of intensive and conventional silvicultural practices. Data on survival, growth in height (H), collar diameter (DC) and attributes of chlorophyll a fluorescence (electron transport rate and maximum quantum yield of PSII) were evaluated. There was no significant interaction between planting practices and models for the survival of the studied species. The use of intensive silvicultural practices maximized Cedrela fissilis survival and growth in H and DC for Cordia americana and Vitex megapotamica at 24 months after planting. In general, plants conducted under intensive silviculture showed the highest values of electron transport rate and maximum PSII quantum yield. Among the studied species, C. americana and V. megapotamica were the ones that presented the best performance in the evaluated attributes. The species C. fissilis, on the other hand, proved to be extremely susceptible to the occurrence of low temperatures, with a survival rate of less than 50%. For Araucaria angustifolia, greater development was observed in conventional silviculture, where the presence of shading in the first months of development proved to be essential for its establishment.