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Schlagwörter:
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Zusammenfassung:
We investigated the impact of drought on interannual
variability of net primary productivity (NPP) from 1997
to 2009, using the standardized precipitation evapotranspiration
index (SPEI) drought index and satellite-derived vegetation
greenness converted to NPP. SPEI is positive for wet
conditions and negative for dry conditions. We found that
SPEI and NPP were coupled and showed in-phase behaviour
on a global scale. We then used the Köppen climate classification
to study the SPEI–NPP relations regionally and found
that while NPP and SPEI were positively related (high SPEI,
high NPP) in arid and in seasonal dry regions, the opposite
occurs in most boreal regions (high SPEI, low NPP). High
intensity drought events, such as the 2003 drought in Europe
were picked up by our analysis. Our findings suggest
that the strong positive relation between global average moisture
availability and NPP consists of a composite of the positive
relation across dry regions and the coherent NPP decline
during and after intensive drought events in humid regions.
Importantly, we also found that there are many areas on the globe that show no strong correlation between drought and
NPP.
