Spatial variability of physical and chemical attributes of some forest soils in southeastern of Brazil

Capão Bonito forest soils, São Paulo state, Brazil, have been used for forestry purposes for almost one century. Detailed knowledge about the distribution of soil attributes over the landscape is of fundamental importance for proper management of natural resources. The purpose of this study was to identify the variability and spatial dependence of chemical and physical attributes of Capão Bonito forest soils. A large soil database of regional land was raised and organized. Most of the selected variables were close to the lognormal frequency range. Soil texture presented a higher range in the A horizon, and the nugget effect and sill were greater in the B horizon. These differences are attributed to the parent material of the region (Itararé Geologic Formation), which presents uneven distribution of sediments. Chemical attributes related to soil fertility presented a higher spatial dependence range in the B horizon, probably as a result of more intensive management and erosion history of the superficial soil layer. Maps for some attributes were interpolated. These had specific areas of occurrence and a wide distribution along the perimeter of the Capão Bonito District Forest, allowing a future site-specific soil management

Site evaluation and productivity of a 3-year old stand of Eucalyptus urograndis in São Paulo, Brazil.

No Brasil os plantios florestais ocupam 7 milhões de hectares que correspondem a 1% do território (68% com plantações de Eucalyptus e 25% com Pinus) O objetivo desse trabalho foi avaliar plantios de Eucalyptus urograndis. Estoques elevados de Ca e Mg no solo, sugerem uma lixiviação do calcário. A resistência do solo até os 60 cm de profundidade na linha de plantio foi menor do que na entrelinha, indicando que a subsolagem foi eficiente. Os valores de resistência do solo foram mais altos na entrelinha, distante 1 m da linha de plantio, até os 20 cm de profundidade, provavelmente pelo aumento da compactação na preparação da área. A biomassa da copa das árvores diferiu entre as classes de DAP, justificando o uso de equação para a sua estimativa. A variação observada para área basal não refletiu em diferenças de densidade da madeira. A densidade da madeira de 0,37 g cm-3 foi menor do que a de plantios com 7 anos. A remoção da casca no campo aumentou o suprimento de nutrientes entre 8% e 11%. A colheita da madeira aos 3 anos não resultou numa exportação significativa, indicando que o manejo apropriado dos plantios, pode contribuir para a sustentabilidade florestal.doi: 10.4336/2011.pfb.31.68.331Plantation forests in Brazil cover 7 million hectares, which represents 1% of the country (68% of Eucalyptus and 25% of Pinus plantations). The aim of this study was to evaluate a Eucalyptus urograndis plantation. High levels of Ca and Mg in the soil suggest that limestone had leached into the soil profile. The soil resistance down to 60 cm depth in the row of planting was lower than the inter-row space, indicating that deep tillage had been effective. Soil resistance, down to 20 cm depth at an inter-row distance of 1 m from the planting row, was higher, likely by the increase in soil compaction during the site preparation. The canopy biomass differed amongst the DBH classes, justifying the use of an allometric equation based on a basal area for assessing the canopy biomass. The observed variation in DBH did not correlate with variation in wood density. The wood density of 0.37 g cm-3 was lower than those reported for 7-year-old plantation. The in situ removal of the bark increased nutrient availability by 8-11%. Harvesting of tree bole in 3-year old plantation didn’t result in a large nutrient export, indicating that proper plantation management can contribute to plantation forest sustainability.doi: 10.4336/2011.pfb.31.68.33

Representação e propagação de incertezas em dados de solo: II - Atributos numéricos Representation and propagation of soil data uncertainties: II - Numeric attributes

Este trabalho teve por objetivos utilizar krigagem por indicação para espacializar propriedades de solos expressas por atributos numéricos, gerar uma representação acompanhada de medida espacial de incerteza e modelar a propagação de incerteza por procedimentos fuzzy de álgebra de mapas. Foram estudados os atributos: teores de potássio (K) e de alumínio (Al) trocáveis, saturação por bases (V), soma de bases (S), capacidade de troca catiônica (CTC) e teor de areia total (AT), extraídos de 222 perfis pedológicos e de 219 amostras extras, localizados no estado de Santa Catarina. Quando os atributos foram expressos em classes de fertilidade, a incerteza de Al, S e V aumentou e a de K e CTC diminuiu, considerando intervalos de confiança de 95 % de probabilidade. Constatou-se que um maior número de dados numéricos de K, S e V levou a uma maior incerteza na inferência espacial, enquanto o maior número de dados numéricos de AT e CTC diminuiu o grau de incerteza. A incerteza diminuiu quando diferentes representações numéricas foram integradas.<br>The objectives of this study were to use kriging indicators to generate a representation of soil properties expressed by numeric attributes, to assess the uncertainty in estimates, and to model the uncertainty propagation generated by the fuzzy procedures of map algebra. The studied attributes were exchangeable potassium (K) and aluminum (Al) contents, sum of bases (SB), cationic exchange capacity (CEC), base saturation (V), and total sand content (TST), extracted from 222 pedologic profiles and 219 extra samples, located in Santa Catarina State, Brazil. When the attributes were expressed in fertility classes, the uncertainty of Al, SB, and V increased while the uncertainty of K and CEC decreased, for intervals of confidence of 95% probability. A larger number of numeric data for K, SB, and V provided a larger uncertainty for space inference, while the uncertainty degree decreased for the largest number of numeric data of TS and CEC. There was a decrease of uncertainty when different numeric representations were integrated by fuzzy procedures of map algebra