Abordagem de floresta de precisão para qualidade silvicultural em plantio comercial de Eucalyptus sp.

Abstract

Precision Forestry (PF) involves activities that can be considered as solutions to maintain the balance between sustainable development and the environmental benefits obtained through its adoption. Equipment and techniques used in this approach aim to use the spatial variability of forests through the collection of georeferenced data and information management in geographic information systems (GIS), to enable the differentiated management of specific areas, according to the requirements of each forest site to increase the productivity. This study aimed to apply spatial analysis to quality data of a commercial plantation of Eucalyptus sp. and distinguish zones of final density of plants. The planting of the study, with about 100 days, is located in a forest garden in the municipality of Butiá-RS, containing about 145 ha (fraction of a forest project), where there were randomly installed 36 sample units (su) of 299.87 m2, georeferenced with GPS navigation receiver. The number of plants attacked by cutter ants, broken, planting failures (dead trees), dead plants, forked plants, replanted plants and total number of plants per sample unit were measured. These variables were tabulated in a spreadsheet in Microsoft Excel® together with the coordinates of the sample units used to create point shapefile in the GIS ArcMap® 10. The spatial analysis was made by interpolation of data by the inverse distance weighted (IDW). Subsequently, survival, survival problems and final planting density were obtained by map algebra in the GIS. The survival or density classes were obtained by reclassification of the interpolated data, of the survival obtained, with reference to the quality parameters defined by the management of the forest garden. The area of influence of each sample unit was determined by Voronoi polygon, to verify the existence of areas with low sample intensity. With these variables, thematic maps were elaborated to better visualize, analyze and interpret the quality of planting. The survival areas or planting density obtained (quality) were named suboptimal, optimal and above the ideal, when observed, respectively, the density <38, among 38 and 42 (desired value ± 5%), and above 42 plants per sampling unit. The reference parameter was 40 plants per sample unit, corresponding to 1333 plants per ha. For these three classes, respectively, areas of 9.64; 42.43 and 93.40 ha. Failure number and survival related problems showed high correlation with plant survival, being 40 and 49% respectively, p 0.05. The number of failures and the amount of post-harvest residues changed the mean plant density in the sample units, which was above ideal in most areas. Survival, total number of plants and number of plants attacked by ants differentiated the zones of planting density. It is concluded that the precision forestry approach applied in the initial phase of the process of implantation and/or reforestation of a forest can provide a more adequate density of plants, since it indicates areas where the planting does not meet the silvicultural quality parameters, which may allow the intervention of the forest manager in specific areas of the forest at varying rates.