Fodder Biomass Monitoring in Sahelian Rangelands Using Phenological Metrics from FAPAR Time Series

Remote Sensing

Abdoul Aziz Diouf³  Martin Brandt⁵  Aleixandre Verger⁶  Moussa El Jarroudi¹  Bakary Djaby⁴  Rasmus Fensholt⁵  Jacques André Ndione³  Bernard Tychon¹  Alfredo R. Huete² 

[1] Water, Environment and Development Unit, University of Liege, Avenue de Longwy B6700, Arlon, Belgium; E-Mails:;Centre de Suivi Ecologique, Rue Aimé Césaire x Leon Gontran Damas, BP 15532 Fann-Dakar, Senegal; E-Mail;Centre de Suivi Ecologique, Rue Aimé Césaire x Leon Gontran Damas, BP 15532 Fann-Dakar, Senegal; E-Mail:;Centre Regional AGRHYMET, BP 11011 Niamey, Niger; E-Mail:;Department of Geosciences and Natural Resource Management, University of Copenhagen, 1350 Copenhagen, Denmark; E-Mails:;CREAF, Cerdanyola del Vallès 08193, Catalonia, Spain; E-Mail:

关键词: fodder biomass;    FAPAR;    phenological metrics;    ecoregion;    food security;    models;    Sahel;   

DOI  :  10.3390/rs70709122

来源: mdpi

【 摘 要 】

Timely monitoring of plant biomass is critical for the management of forage resources in Sahelian rangelands. The estimation of annual biomass production in the Sahel is based on a simple relationship between satellite annual Normalized Difference Vegetation Index (NDVI) and in situ biomass data. This study proposes a new methodology using multi-linear models between phenological metrics from the SPOT-VEGETATION time series of Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) and in situ biomass. A model with three variables—large seasonal integral (LINTG), length of growing season, and end of season decreasing rate—performed best (MAE = 605 kg·DM/ha; R² = 0.68) across Sahelian ecosystems in Senegal (data for the period 1999–2013). A model with annual maximum (PEAK) and start date of season showed similar performances (MAE = 625 kg·DM/ha; R² = 0.64), allowing a timely estimation of forage availability. The subdivision of the study area in ecoregions increased overall accuracy (MAE = 489.21 kg·DM/ha; R² = 0.77), indicating that a relation between metrics and ecosystem properties exists. LINTG was the main explanatory variable for woody rangelands with high leaf biomass, whereas for areas dominated by herbaceous vegetation, it was the PEAK metric. The proposed approach outperformed the established biomass NDVI-based product (MAE = 818 kg·DM/ha and R² = 0.51) and should improve the operational monitoring of forage resources in Sahelian rangelands.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.