Fodder biomass monitoring in Sahelian Rangelands using phenological metrics from FAPAR time series
Diouf, Abdoul Aziz (Centre de Suivi Ecologique (Dakar, Senegal))
Brandt, Martin (University of Copenhagen. Department of Geosciences and Natural Resource Management)
Verger, Aleixandre (Centre de Recerca Ecològica i d'Aplicacions Forestals)
El Jarroudi, Moussa (Université de Liege. Water, Environment and Development Unit)
Djaby, Bakary (Centre Regional AGRHYMET (Niamey, Niger))
Fensholt, Rasmus (University of Copenhagen. Department of Geosciences and Natural Resource Management)
Ndione, Jacques André (Centre de Suivi Ecologique (Dakar, Senegal))
Tychon, Bernard (Université de Liege. Water, Environment and Development Unit)

Date:	2015
Abstract:	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 OPEN ACCESS 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.
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Fodder biomass ; FAPAR ; Phenological metrics ; Ecoregion ; Food security ; Models ; Sahel
Published in:	Remote sensing (Basel), Vol. 7 (2015) , p. 9122-9148, ISSN 2072-4292

DOI: 10.3390/rs70709122

27 p, 1.5 MB

The record appears in these collections:
Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > CREAF (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Articles > Research articles
Articles > Published articles