Soil functioning in a toposequence under rainforest in São Paulo, Brazil

Abstract

Studies of soil-water dynamics using toposequences are essential to improve the understanding of soil-water-vegetation relationships. This study assessed the hydro-physical and morphological characteristics of soils of Atlantic Rainforest in the Parque Estadual de Carlos Botelho, state of São Paulo, Brazil. The study area of 10.24 ha (320 x 320 m) was covered by dense tropical rainforest (Atlantic Rainforest). Based on soil maps and topographic maps of the area, a representative transect of the soil in this plot was chosen and five soil trenches were opened to determine morphological properties. To evaluate the soil hydro-physical functioning, soil particle size distribution, bulk density (r), particle density (r s), soil water retention curves (SWRC), field saturated hydraulic conductivity (Ks), macroporosity (macro), and microporosity (micro) and total porosity (TP) were determined. Undisturbed samples were collected for micromorphometric image analysis, to determine pore size, shape, and connectivity. The soils in the study area were predominantly Inceptisols, and secondly Entisols and Epiaquic Haplustult. In the soil hydro-physical characterization of the selected transect, a change was observed in Ks between the surface and subsurface layers, from high/intermediate to intermediate/low permeability. This variation in soil-water dynamics was also observed in the SWRC, with higher water retention in the subsurface horizons. The soil hydro-physical behavior was influenced by the morphogenetic characteristics of the soils.

Previous Land Use Affects the Recovery of Soil Hydraulic Properties after Forest Restoration

“…The soil attributes and K s values in remnant forest sites could be explained by the longer time that these forests have remained undisturbed, which allows a better soil structure to develop and the storage of more soil carbon [19,66]. These findings are in agreement with those reported by several other studies in the Atlantic Forest [63,65]. Additionally, the K s spatial variability observed in both remnant forests is in line with previous work by Hassler et al [7], who attributed the K s variability in Panama forest soils to overland flows that result in erosion [19].…”

“…In general, important differences were observed in the soil attributes and K s between land-cover classes. These differences could be related to many factors such as intensity of past land use [4,23], spatial and topographic variations in soil types along the toposequences [63,64], density and diversity of plants, root system, vegetation type, canopy cover and soil faunal activity, among others [19]. Unfortunately, the influence of these factors on soil attributes and K s after forest restoration is poorly understood and needs to be included in future studies.…”

Assessing Water Infiltration and Soil Water Repellency in Brazilian Atlantic Forest Soils

“…The highest ρb values were observed in the restored forest R4, where the exposure of the soil and trampling pressure during the land-use history was greater in comparison with restored forest R3. Forest soils were characterized by the lowest ρb values, which can be related to the heterogeneous soil structure and higher soil macroporosity in this cover [51,52]. At the time of sampling, the θi ranged from 0.12 to 0.32 cm 3 cm −3 and the soil was significantly wetter in plots P1U, P2M, R4S, R4M, and F5I ( Figure S1).…”

Hydro-physical characterization of soils under the Restinga Forest

“…Soil hydraulic properties (SHP) have been recognized as important abiotic factors in the attempt to better understand the heterogeneity of these systems (Budke et al, 2007;Cooper et al, 2013). A knowledge of SHP is essential to understanding water flow and solute transport in both saturated and unsaturated soils.…”