Influence of forest gaps on the density of cedar population in Silveira Martins-RS

The objective of this study is to analyze the influence of gaps on the density of cedar population ( Cedrela fissilis Vell.) and characterize the total diameter distribution and size class of this species. The study area is located in the municipality of Silveira Martins (state of Rio Grande do Sul), where a census was conducted by walking through 5.54 hectares. The area was divided and characterized into A (0.36 ha), more intensive use of soil; B (0.10 ha), gap with a radius of approximately 17.5 m; C (0.08 ha), gap with radius of approximately 16 m; and D (5.0 ha), intermediate regeneration. All cedar individuals with a total height greater than 15 cm were measured and classified as adults (diameter at breast height - DBH > 10 cm), young (0 < DBH <10 cm), and seedlings (total height - Ht < 1.30 m). The density per area and the Chi-square test for the different areas were calculated. In addi­tion, a diameter distribution histogram was constructed for each size class and area. The negative exponential shape of diametric distribution histograms evidences that the areas with gaps present a higher frequency of young individuals and seedlings; however, there was no difference between the gaps (areas B and C) and the area at an initial regeneration stage (area D).