Revegetation with leguminous trees has been used to recover degraded areas. This study aimed to evaluate the physical quality of a Typic Hapludult soil under secondary forest, pasture and three leguminous tree species: Acacia (Acacia auriculiformis), Sabia (Mimosa caesalpiniaefolia) and Inga (Inga spp.), in Conceição de Macabú County, Rio de Janeiro State, Brazil. Soil samples from the 0-0.10 m and 0.10-0.20 m layers were collected and analyzed in July, 2015. Lower bulk density and higher total porosity and macroporosity values occurred under forest. The higher microporosities were associated with higher bulk densities and lower values of total porosity and macroporosity (pasture and Acacia). The soil under pasture, even when compacted, preserved the largest amount of mesopores, perhaps due to the fasciculate root system of these plants. It was concluded that revegetation leads to changes in the soil surface layer so that its physical attributes become similar to those found in the forest and differ from those of pasture, with an increase in quality to support forest ecosystem functioning.

RESUMO:O objetivo deste trabalho foi avaliar as inter-relações entre uso do solo, posição na paisagem (posição na topossequência) e seus efeitos sobre atributos físicos, químicos e microbiológicos em solos sob diferentes sistemas de uso da terra em duas topossequências no Noroeste do Estado do Rio de Janeiro. A primeira topossequência consistiu de vegetação espontânea no terço superior e plantio de pupunha nos terços médio e inferior; a segunda topossequência consistiu de pasto nos três terços. Os atributos edáficos determinados foram: densidade do solo, porosidade total e teor de argila; teores de P, Ca, Mg, K, Al e pH; carbono e nitrogênio da biomassa microbiana, respiração acumulada, C orgânico e N total. A análise de agrupamento de Tocher e análise de componentes principais (ACP) foram realizadas para diferentes grupos de variáveis. Inicialmente utilizaram-se os atributos físicos e alguns atributos químicos e depois os atributos microbiológicos, C orgânico e N total. O conjunto dos atributos físicos e químicos foram mais sensíveis que o COS, Nt e atributos microbiológicos em explicar a similaridade e, ou, dissimilaridade decorrentes tanto da posição na topossequência quanto da substituição na cobertura vegetal. Os atributos microbiológicos, COS e Nt evidenciaram a influência da substituição da cobertura vegetal e práticas (e, ou ausência) de manejo na dissimilaridade entre os sistemas de uso da terra. A relevância de atributos físicos, químicos e, ou, microbiológicos na distinção de sistemas de uso da terra vai depender das fontes de variação dos ambientes em que estes sistemas estão sendo estudados.Palavras-chave: análise de agrupamento; análise de componentes principais; método de Tocher; pastagem; pupunha Physical, chemical and microbiological attributes of soils under different land uses in a toposequence in the northwest fluminense ABSTRACT: The objective of this study was to evaluate the interrelationships between land use, landscape position (position in a toposequence) and its effects on physical, chemical and microbiological attributes in soils under different land use systems in two toposequences in Northwest of Rio de Janeiro State. The toposequence 1 consisted of spontaneous vegetation in the summit and pupunha palm plantation in the backslope and footslope; Toposequence 2 consisted of pasture in the three positions. The following variables were determined: bulk density, total porosity and clay content; P, Ca, Mg, K, Al content and pH; microbial biomass carbon and nitrogen, microbial respiration, organic C and total N. Tocher method and principal component analysis (PCA) were performed for different groups of variables. Initially the physical attributes and some chemical attributes and then the microbiological attributes, organic C and total N were used. The groups formed by the Tocher method for the two sets of variables used were confirmed by the PCA. The set of physical and chemical attributes were more sensitive than COS, Nt and microbiological attributes to explain the similarity and, or, dis...

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The objective of this work was to assess the efficiency of revegetation with forest leguminous species, for the recovery of the physical quality of a Typic Hapludult under degraded pasture, located in a steep-slope tropical landscape in Southeastern Brazil. Soil samples were collected at the 0-0.10 m and 0.10-0.20 m depths, in areas under Acacia auriculiformis (northern black wattle), Mimosa caesalpiniifolia (“sabiá”), Inga edulis (“ingá”), secondary forest (“capoeira”), and degraded pasture. Tensile strength (TS) was evaluated in soil aggregates of the size classes 8.0-12.5 mm and 12.5-19.0 mm, for the variables TS 8 and TS 12.5, respectively. The lowest mean values of both variables always occurred under the pasture cover (TS 8 of 37.1 kPa and TS 12.5 of 22.7 kPa, for the 0-0.10 m soil layer; and TS 8 of 39.2 kPa and TS 12.5 of 22.8 kPa, for the 0.10-0.20 m soil layer). The highest TS mean values were obtained under the “capoeira” cover (TS 8 of 62.2 kPa, for the 0-0.10 m soil layer) and “sabiá” cover (TS 12.5 of 46.0 kPa, for the 0-0.10 m soil layer; and TS 8 of 53.0 kPa and TS 12.5 of 51.4 kPa, for the 0.10-0.20 m soil layer). Land revegetation with leguminous trees recovers the soil physical quality, since the TS values under the evaluated covers are predominantly closer to those of the secondary forest than to those of the degraded pasture.