DYNAMIC VEGETATION ANALYSIS: PHENOLOGICAL BEHAVIOUR AND PHENOLOGICAL PATTERN

GONZÁLEZ LOYARTE , MARGARITA; MASSIMO MENENTI

0257-0521-Proceedings EARSeL Special Interest Group Temporal AnalysisI of Satellite Images

Proceedings EARSeL - www.isn-oldenburg.de

Lugar: Oldenburg; Año: 2012 p. 246 - 253

0257-0521

ABSTRACT The concepts of phenological behaviour (mapping vegetation dynamics), and phenological pattern (actual foliar phenology), both obtained from the time-series analysis of monthly NOAA-AVHRR NDVI GAC images, are illustrated for the vegetation of Mendoza province (Central Western Argentina). A Fast Fourier Transform algorithm was used to decompose the series into dynamic parameters: mean NDVI, amplitude (maximum NDVI variability) and phase (time from start of cycle to maximum NDVI) for different periods. Mean NDVI, amplitude for 9, 3 and 1 year and phase for 1 year were selected. A classification was made based on these five bands with larger information (inter- and intra-annual variability), achieving a map of 18 areas of phenological behaviour. This map is related to ecosystems and vegetation units. The phenological pattern is a modelled monthly NDVI curve that describes the functioning of vegetation (at a pixel level), month by month during an average growth cycle and allows understanding its geographic variations; it is modelled with 11 FFT parameters, five of which are common to classification bands. The phenological pattern was modelled for 17 vegetation units in four extensive ecosystems. The map contributes dynamic elements to the regional study of vegetation, generating a new zonation explained by variables that determine vegetative growth. The overall phenological pattern of Mendoza vegetation responds to an annual cycle with localized weak bimodal patterns. Patterns of low winter-summer contrast correspond to xeric climate conditions, expressing the vegetative peak at the end of the summer; water availability enhances this contrast, shortening the time of maximum vegetative expression.