Can vegetation productivity be derived from greenness in a semi-arid environment? Evidence from ground-based measurements

TY - JOUR

T1 - Can vegetation productivity be derived from greenness in a semi-arid environment? Evidence from ground-based measurements

AU - Mbow, Cheikh

AU - Fensholt, Rasmus

AU - Rasmussen, Kjeld

AU - Diop, Doudou

PY - 2013/10

Y1 - 2013/10

N2 - Trends of biomass production and land processes in the Sahel have been widely studied since the droughts of 1970s. Satellite data have been an important source of information because of limited in situ data. Previous studies relied on the assumed existence of a relationship between vegetation productivity and the NDVI, in particular the annually integrated NDVI (iNDVI). This study examines this assumption and its limitations, based on in situ time series measurements of biomass, species composition, NDVI and soil moisture at the Dahra test site in northern Senegal. It is shown that, there are large differences between the NDVI - vegetation productivity relationships, and these differences can be linked to species composition. There is moderate correlation between NDVI and above-ground net primary productivity (ANPP) at the peak season (r2=0.39). In particular, the species Zornia glochidiata is characterized by high peak NDVI and low ANPP, compared to other common species such as Cenchrus biflorus and Aristida adscensionis. It is concluded that spatial and temporal variations in species dominance is likely to add noise to the relationship between NDVI and biomass. However, the seasonal cyclic fraction of the NDVI - "small seasonal integral" - reduces such noise.

AB - Trends of biomass production and land processes in the Sahel have been widely studied since the droughts of 1970s. Satellite data have been an important source of information because of limited in situ data. Previous studies relied on the assumed existence of a relationship between vegetation productivity and the NDVI, in particular the annually integrated NDVI (iNDVI). This study examines this assumption and its limitations, based on in situ time series measurements of biomass, species composition, NDVI and soil moisture at the Dahra test site in northern Senegal. It is shown that, there are large differences between the NDVI - vegetation productivity relationships, and these differences can be linked to species composition. There is moderate correlation between NDVI and above-ground net primary productivity (ANPP) at the peak season (r2=0.39). In particular, the species Zornia glochidiata is characterized by high peak NDVI and low ANPP, compared to other common species such as Cenchrus biflorus and Aristida adscensionis. It is concluded that spatial and temporal variations in species dominance is likely to add noise to the relationship between NDVI and biomass. However, the seasonal cyclic fraction of the NDVI - "small seasonal integral" - reduces such noise.

U2 - 10.1016/j.jaridenv.2013.05.011

DO - 10.1016/j.jaridenv.2013.05.011

M3 - Journal article

SN - 0140-1963

VL - 97

SP - 56

EP - 65

JO - Journal of Arid Environments

JF - Journal of Arid Environments

ER -