 |
| Titel |
Integrating field surveys and MODIS data to evaluate the effects of the 2005 drought in Amazonia |
| VerfasserIn |
Liana O. Anderson, Oliver Phillips, Luiz Aragao, Yadvinder Malhi, Egidio Arai |
| Konferenz |
EGU General Assembly 2011
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250045737
|
|
|
|
|
|
| Zusammenfassung |
| In 2005, large areas of the Amazon Basin experienced one of the most intense droughts of the
past 100 years, driven by the elevation in temperature of the tropical North Atlantic sea
surface. Contrasting results have emerged in the literature between studies based solely on
remote-sensing data and studies based on field surveys. The evaluation of the enhanced
vegetation index (EVI) from the Terra satellite’s Moderate Resolution Imaging
Spectroradiometer (MODIS) showed a large-scale photosynthetic green-up in intact
evergreen forests during the drought period. On the other hand, multiple long-term
monitoring plots showed that forests experiencing the most elevated moisture stress exhibited
an increase in tree mortality. In this study, we integrated MODIS data with field ecological
data in order to generate the first large scale evaluation of the impacts of the 2005 drought on
Amazonian primary forests from a remote sensing perspective based on multiple
field data sites. To achieve this objective, two datasets were used. The first one
encompasses interval-corrected data on the 2005 tree mortality derived from the
pan-Amazonian RAINFOR database. The second database encompasses the MODIS
MOD13A3 c5 monthly images product, with 1 km spatial resolution, for the 2005
drought period (June to September). In addition to the EVI, shade (S), vegetation
(V) and non-photosynthetic vegetation (NPV) fraction images (F) derived from a
linear spectral mixture model were generated. Samples were acquired from the
MODIS-derived dataset for 17 sites, aggregated based on the clusters of 42 field
plots, to reduce the influence of spatial-autocorrelation. The preliminary analysis
showed a positive relationship between the EVI and VF from June 2005 with the
number of dead trees (R2= 0.67 and R2= 0.68, respectively, p |
|
|
|
|
|
|