Impacto antrópico na dinâmica de uma floresta nebular do planalto catarinense

The objective of this research was to investigate the dynamics of the adult and regenerating tree community in a Cloud Forest fragment in Urubici, Santa Catarina, subject to livestock impact. Inventories of adult tree individuals were carried out in 2011, 2015, and 2019, and of regenerative trees, in 2013, 2015, 2017, and 2019. For the adult component, sampling was performed within 25 20 x 20 m systematically allocated plots. Within each plot, soil and topographic variables were also collected. The regenerative component was evaluated in subplots according to plant size classes (class 1: plants with a height from 0.15 cm to 1 m in 5 m 2 ; class 2: plants with height above 1 m and up to 3 m in 10 m 2 ; and class 3: plants with height above 3 m and DAP < 5 cm in 20 m 2 ). The demographic rates for the community of adult and regenerating individuals were determined. Regression Trees (RT) were used to test the influence of environmental variables on the dynamics rates of the regenerative component, and Principal Component Analysis (PCA) was performed to synthesize the population dynamics rates. In the last period, 2015-2019, the forest showed a loss of individuals and basal area, which suggests a de-structuring process. For regenerating individuals, the most influential variables in the dynamics were soil fertility, H+Al levels, altitudinal quota, and soil compaction. For the conservation of the area, measures such as fencing to prevent cattle from entering are essential for the maintenance of the forest over time.