Aleatoriedade e tamanho de amostra em mudas de Pinus spp. em viveiro florestal

Abstract

The forest species have been used since the beginning of the times for the most several ends. However, the unrestricted and inadequate use, especially of native examples of great economical value, it is causing great environmental problems. The form, commonly adopted, to reduce the pressure on the native forests it is the use of exotic species. For the importance that those species reached, it exists at the country a vast area planted with homogeneous stands, prevailing the Pinus and Eucalyptus. That demand generates a demand every time larger for more productive forests and of quality, contemplating, this way, in the production of seedlings. However, there is still a lot to be improved in that section, especially in the scientific field. The statistics, if well explored, it can contribute to that. Therefore, this work had as objectives, to verify the distribution of the variables diameter and height of the seedlings of Pinus spp. and to characterize similar behaviors of the variables, in seedlings production trays, as well as, to estimate the sample size for seedlings of Pinus spp. in forest nursery. For the present study data were collected from seedlings of Pinus spp., produced in the Technological Center of Forestry of Santa Maria's Federal University. The data used for the development of the works were coming of experiments with Pinus taeda, accomplished in the first semester of the year of 2005 and other with Pinus elliottii var. elliottii, accomplished in the second semester of the year of 2005. The seedlings were willing in three trays (B1, B2 and B3). The observed variables were diameter and height of the seedling, appraised of 15 in 15 days (B1 and B2) and of 25 in 25 days (B3), where the first evaluation was accomplished to the 50 (B1 and B2) and 25 (B3) days after the emergency of the seedlings and the last to the 140 (B1 and B2) and 175 (B3) days. The statistical analyses were accomplished through application of the Run Test and sample size. The growth in seedlings of Pinus taeda was heterogeneous, being verified the non randomness in the distribution of the observations of the variables height and diameter. Already, for Pinus elliottii var. elliottii the growth of the seedlings was aleatory. The sample size varies in function of the age and randomness of the seedlings for both studied variables, where the number of sample units, for a semi-width of 10%, for Pinus taeda, went from 25 to height and twelve seedlings for the diameter and for Pinus elliottii var. elliottii went of nine seedlings to height and ten for the diameter, when considered the non randomness.