Monitoring vegetation dynamics with medium resolution MODIS-EVI time series at sub-regional scale in southern Africa

Type Journal Article - International Journal of Applied Earth Observation and Geoinformation
Title Monitoring vegetation dynamics with medium resolution MODIS-EVI time series at sub-regional scale in southern Africa
Author(s)
Volume 38
Publication (Day/Month/Year) 2015
Page numbers 175-183
URL https://www.researchgate.net/profile/Olena_Dubovyk/publication/271274076_Monitoring_vegetation_dynam​ics_with_medium_resolution_MODIS-EVI_time_series_at_sub-regional_scale_in_southern_Africa/links/54c5​edd70cf256ed5a9c2e80.pdf
Abstract
Currently there is a lack of knowledge on spatio-temporal patterns of land surface dynamics at medium
spatial scale in southern Africa, even though this information is essential for better understanding of
ecosystem response to climatic variability and human-induced land transformations. In this study, we
analysed vegetation dynamics across a large area in southern Africa using the 14-years (2000–2013) of
medium spatial resolution (250 m) MODIS-EVI time-series data. Specifically, we investigated temporal
changes in the time series of key phenometrics including overall greenness, peak and timing of annual
greenness over the monitoring period and study region. In order to specifically capture spatial and per
pixel vegetation changes over time, we calculated trends in these phenometrics using a robust trend
analysis method. The results showed that interannual vegetation dynamics followed precipitation patterns
with clearly differentiated seasonality. The earliest peak greenness during 2000–2013 occurred at
the end of January in the year 2000 and the latest peak greenness was observed at the mid of March in
2012. Specifically spatial patterns of long-term vegetation trends allowed mapping areas of (i) decrease
or increase in overall greenness, (ii) decrease or increase of peak greenness, and (iii) shifts in timing of
occurrence of peak greenness over the 14-year monitoring period. The observed vegetation decline in the
study area was mainly attributed to human-induced factors. The obtained information is useful to guide
selection of field sites for detailed vegetation studies and land rehabilitation interventions and serve as
an input for a range of land surface models.

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