No abstract

The objective of this work was to evaluate height-diameter, volumetric, and taper models to estimate the height, volume, and bole profile of trees of eucalypt clones (Eucalyptus grandis × Eucalyptus urophylla) in an agrosilvopastoral system. Data were collected from permanent plots in an eight year-old agrosilvopastoral system, composed by three eucalypt clones (VE01, VE06, and VE07), located in the municipality of Coronel Xavier Chaves, in the state of Minas Gerais, Brazil. Two height-diameter, three volumetric, and four taper models were fit to the data of each clone and compared to each other, in order to select the best-fitting one. The equations fitted well to the observed data, and those of the models of Campos, Schumacher-Hall, and Garay stood out as the best ones. In addition, Graybill's F-test showed that the height-diameter and volumetric equations must be fitted separately for each genetic material. The model of Garay was the best taper model to estimate the bole profiles of all clones using a single equation.

The intensive use of agrochemicals has been associated with global human health problems and environmental contamination. Brazil is the world’s largest agrochemical consumer, and this position highlights the growth of agribusiness in the MATOPIBA region (Maranhão, Tocantins, Piauí, and Bahia states). The use of agrochemicals is recurrent in local agricultural practices. However, there is little information on the environmental impacts and risks of contamination regarding river basins in this region. Thus, this study aimed to evaluate the risk of contamination by agrochemicals in the basin area of the Açailândia River in Maranhão. From the multicriteria evaluation, environmental information plans were used to determine the trend of water behavior, infiltration, and runoff, along with agrochemical transportation. The joint evaluation of this information was used to generate the final map of the areas of contamination risk posed by agrochemicals in the region. The hydrographic basin presented high anthropization, with an increase of approximately 27% in land use and occupation by crops in the period from 1984 to 2018. The area of 1087.62 km², corresponding to 35.9% of the basin area, presented a high and extremely high risk of contamination.