Assessing Pasture Degradation in the Brazilian Cerrado Based on the Analysis of MODIS NDVI Time-Series

Osvaldo Pereira,Flávia Pinto,Leandro Baumgarten,Laerte Ferreira

doi:10.3390/rs10111761

Abstract

Around 55% of all Brazilian cattle production is located in the Cerrado biome, which also contains the largest pasture area in Brazil. Previous studies indicated that about 60% of these pastures were degraded by 2010. However, up-to-date and more precise estimates are necessary to access the extent and degree of degradation of the Cerrado pastures, since these areas constitute strategic land reserves for both livestock intensification and soybean expansion. Therefore, in this study, we estimated the area of degraded pastures in the Cerrado by analyzing the trends of cumulative NDVI anomalies over time used as a proxy for pasture degradation. The generated slope surface was segmented into two classes, comprising non-degraded and degraded pastures, which were correlated with socio-economic and biophysical variables. According to our study, around 39% of the Cerrado pastures are currently degraded, encompassing 18.2 million hectares, mostly in areas with a cattle carrying capacity below 1.0 AU ha−1. These areas, distributed in the northwest Cerrado, mostly within the Brazilian states of Maranhão, Piauí, and Bahia (i.e., Matopiba region), tend to be associated with decreasing rainfall patterns and low investments in soil conservation practices. The degraded areas also tend to be concentrated in municipalities with low human development indices (HDI).

Highlights

The Food and Agriculture Organization (FAO) defines the process of pasture degradation as a wide range of conditions associated with soil erosion and soil degradation, which reduce the capacity of an ecosystem to provide biological, hydrological, social, and economic related services
We estimated the distribution of pasture degradation in the Cerrado in recent years, by considering Normalized Difference Vegetation Index (NDVI) images derived from MODIS time-series, relating pasture degradation with the accumulation of NDVI negative anomalies
Some deviation was found between sampling points and pixel stack values of observed regions, which is mostly related to the time difference between the final date of the MODIS time-series and the acquisition of field information

Summary

Introduction

The Food and Agriculture Organization (FAO) defines the process of pasture degradation as a wide range of conditions associated with soil erosion and soil degradation, which reduce the capacity of an ecosystem to provide biological, hydrological, social, and economic related services. A more detailed definition describes pasture degradation as the long-term loss of ecosystem function and services caused by disturbances from which the system cannot completely recover [1]. The dedicated literature highlights three major forms of pasture degradation, which are physical (e.g., soil erosion by water), chemical (e.g., acidification, decline in water storage capacity, salinization), and biological (e.g., decline in soil organic matter) [3,4]. The drivers of pasture degradation are widely variable within different countries and are associated mostly with specific social, economic, political, and environmental conditions. Previous studies have demonstrated the relationship between pasture degradation and intensity/frequency of natural disasters, poor income distribution, marginalization of rural populations, land ownership conflicts, concentration of small farms, regional political instability, health problems, and inappropriate land use, when livestock and forest conversion to pasture are used as a mechanism for land speculation [7]

Methods

Results

Discussion

Conclusion