Intervenção silvicultural e aspectos meteorológicos no processo de restauração no sul do Brasil

Abstract

Establishing native tree species in degraded areas represents a major challenge for forestry. Low species diversity, especially in the later stages of succession, and the presence of adverse ecological filters may compromise the sustainability of ecosystems that are in the process of restoration. Thus, the objective of this research is to characterize how anthropic action and climate affect the development of effective strategies for restoring degraded environments at the southern end of the Atlantic Forest Biome. We discuss these considerations over three chapters. In Chapter I, we try to identify the impacts of removing seedlings under the natural regeneration of a forest community, as well as to characterize the seasonal dynamics of the seedling bank three years after anthropic intervention. To this end, an experiment was conducted using different intensities of the removal of regenerating individuals (0, 25, 50, 75, and 100% removal); in September 2013, an initial evaluation took place, and in November 2013 the seedlings were removed from natural regeneration. After application of the treatments, evaluations were performed every three months for over a period of three years, totaling 12 evaluations. In Chapter II, the morphological and physiological features of nine species native to the Atlantic Forest Biome were plotted under two planting models and three silvicultural practices. The experiment was carried out in an area belonging to the Quarta Colônia State Park in a randomized block design, with four replications in a 3 × 2 factorial scheme, testing three silvicultural practices and two models of planting native species. Evaluations of survival, height, and collection diameter were carried out twice per year, and the photosynthetic pigment content and the chlorophyll fluorescence parameters were determined 24 months after planting. Chapter III identifies the influence of frost on the silvicultural performance of nine native species of the Atlantic Forest Biome. Meteorological data of daily minimum temperatures were recorded between September 2015 and September 2016. We collected data on the occurrence of damage due to frost in the winter of 2016, as well as data on the survival, height, and collection diameter. After three years of study, it was found that climatic seasonality naturally directed the dynamics of the seedling bank in plant communities. However, the removal of regenerating individuals at high intensities (75 and 100% removal) compromised both the recruitment process of new individuals and continuity in the succession process. The use of intensive silviculture reduced the initial environmental stress, providing a positive impact on the establishment and growth of native tree species after 24 months of planting. Climatic seasonality has a strong influence on the success of restoration plantations in degraded areas at the southern end of the Atlantic Forest Biome, and frost compromises the continuity of forest plantations in subtropical climates.