Effects of conversion of native cerrado vegetation to pasture on soil hydro-physical properties, evapotranspiration and streamflow on the Amazonian agricultural frontier.

Rodolfo L B Nóbrega,Gabriele Lamparter,Kristof Kovacs,Gilmar N Torres,Eduardo Couto,Alphonce C Guzha,Ricardo S S Amorim,Gerhard Gerold,Julia A Jones

doi:10.1371/journal.pone.0179414

Rodolfo L B Nóbrega, Gabriele Lamparter + Show 7 more

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https://doi.org/10.1371/journal.pone.0179414

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Abstract

Understanding the impacts of land-use change on landscape-hydrological dynamics is one of the main challenges in the Northern Brazilian Cerrado biome, where the Amazon agricultural frontier is located. Motivated by the gap in literature assessing these impacts, we characterized the soil hydro-physical properties and quantified surface water fluxes from catchments under contrasting land-use in this region. We used data from field measurements in two headwater micro-catchments with similar physical characteristics and different land use, i.e. cerrado sensu stricto vegetation and pasture for extensive cattle ranching. We determined hydraulic and physical properties of the soils, applied ground-based remote sensing techniques to estimate evapotranspiration, and monitored streamflow from October 2012 to September 2014. Our results show significant differences in soil hydro-physical properties between the catchments, with greater bulk density and smaller total porosity in the pasture catchment. We found that evapotranspiration is smaller in the pasture (639 ± 31% mm yr-1) than in the cerrado catchment (1,004 ± 24% mm yr-1), and that streamflow from the pasture catchment is greater with runoff coefficients of 0.40 for the pasture and 0.27 for the cerrado catchment. Overall, our results confirm that conversion of cerrado vegetation to pasture causes soil hydro-physical properties deterioration, reduction in evapotranspiration reduction, and increased streamflow.

Highlights

IntroductionDespite accounting for nearly half of all tropical forests and approximately 6% of the Earth’s land surface, tropical dry forests are underrepresented in the literature on tropical forest
Our study aims to aid filling the gap in the understanding of soil degradation and hydrological processes in active deforestation zones on the Amazonian agricultural frontier in Brazil
In both catchments over 95% of the area shows Compound Topographic Index (CTI) values ranging between 5 and 12, and areas with CTI over 10 have linear form extending from the crest to the outlet of the catchments, which indicates the surface flow pathways

Summary

Introduction

Despite accounting for nearly half of all tropical forests and approximately 6% of the Earth’s land surface, tropical dry forests are underrepresented in the literature on tropical forest. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

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