Environmental Engineering Reference
In-Depth Information
recent decades (see Gordo and Sanz, 2009, for a recent study of plant phenology
in Spain).
Many of the results reported above come from studies at local or regional scale.
However, in the light of current global changes, assessing changes in biodiversity
through time and across large spatial scales is one of the main challenges in the
coming years for a better understanding of the biodiversity-climate relationships
and also the impacts of climate change on ecosystem services. Studying ecosystem
responses to changing climatic conditions could be accomplished using remote-
sensing information and techniques (i.e. the Normalized Difference Vegetation In-
dex, or NDVI; Figure 9.4). The remote-sensing information shows that over the last
20 years vegetation activity increased during spring and autumn but decreased dur-
ing the summer months, suggesting an increase in inter-seasonal deviance (Figure
9.5 and Figure 9.6). These results also suggest that the time period for vegetation
activity starts earlier in spring and finishes later in autumn than 20 years ago. Across
the Mediterranean mountain ranges, the Atlas and Pyrenees encompass more areas
with significant negative trends in vegetation activity, while the Apennines and Pin-
dos are the ones less affected by decreases in vegetation activity (Figure 9.7).
Positive NDVI trends
Negative NDVI trends
Figure 9.4
Trends in vegetation activity in the 25 years from 1982 to 2006. Values of the Nor-
malized Difference Vegetation Index (NDVI) were obtained from the Global Inventory Modelling
and Mapping Studies (GIMMS). (
A full colour version of this figure appears in the colour plate
section
)
