Savannah Phenological Dynamics Reveal Spatio-Temporal Landscape Heterogeneity in Karamoja Sub-region, Uganda
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Date
2020
Journal Title
Journal ISSN
Volume Title
Publisher
Frontiers in Sustainable Food Systems
Abstract
Phenological properties are critical in understanding global environmental change
patterns. This study analyzed phenological dynamics in a savannah dominated semi-arid
environment of Uganda. We used moderate-resolution imaging spectroradiometer
normalized difference vegetation index (MODIS NDVI) imagery. TIMESAT program was
used to analyse the imagery to determine key phenological metrics; onset of greenness
(OGT), onset of greenness value, end of greenness time (EGT), end of greenness value,
maximum NDVI, time of maximum NDVI, duration of greenup (DOG) and range of
normalized difference vegetation index (RNDVI). Results showed that thicket and shrubs
had the earliest OGT on day 85 ± 14, EGT on day 244 ± 32 and a DOG of 158 ± 25
days. Woodland had the highest NDVI value for maximum NDVI, OGT, EGT, and RNDVI.
In the bushland, OGT occurs on average around day 90 ± 11, EGT on day 255 ± 33
with a DOG of 163 ± 36 days. The grassland showed that OGT occurs on day 96 ± 13,
EGT on day 252 ± 36 with a total DOG of 156 ± 33 days. Early photosynthesis activity
was observed in central to eastern Karamoja in the districts of Moroto and Kotido. There
was a positive relationship between rainfall and NDVI across all vegetation cover types as
well as between phenological parameters and season dynamics. Vegetation senescence
in the sub-region occurs around August to mid-September (day 244–253). The varied
phenophases observed in the sub-region reveal an inherent landscape heterogeneity
that is beneficial to extensive pastoral livestock production. Continuous monitoring of
savannah phenological patterns in the sub-region is required to decipher landscape
ecosystem processes and functioning.
Description
Keywords
Conflict, Drylands, Grazing, Mobility, Pastoral
Citation
Egeru A, Magaya JP, Kuule DA, Siya A, Gidudu A, Barasa B and Namaalwa JJ (2020) Savannah Phenological Dynamics Reveal Spatio-Temporal Landscape Heterogeneity in Karamoja Sub-region, Uganda. Front. Sustain. Food Syst. 4:541170. doi: 10.3389/fsufs.2020.541170