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(MBL-GEM) model, can allow quantification and improve our understanding
of the changes in C storage, C exchange, and nutrient dynamics (Williams
et al. 2002 ). Field results indicate that NEE fluxes during deforestation
cause the switch from net sinks to net sources with emission totals reaching
1.6 kg C m 2 y 1 , a flux magnitude equivalent to 10 years of undisturbed
CO 2 sink fluxes in Amazonia (Potter et al. 2001 ).
3.5.4 Conclusions
LULC features and changes in feature patterns can be determined with useable
accuracy for relatively large areas using analysis of medium-resolution (e.g.
TM) remotely sensed data. The information derived through remote sensing of
LULC contains insights to C/CO 2 exchanges primarily in qualitative and semi-
quantitative forms. However, modeling utilizing spectral data, field data, and a
host of improved remote sensing and GIS techniques is beginning to estimate
ABG with improving accuracy that soon will be become an important quanti-
tative data source for scientists engaged in studying components of atmosphere
and ecosystem. Links exist between remote sensing scientists whose focus is on
exploring LULC and LULC changes and scientists with atmospheric/climato-
logical interests. These links need to be strengthened through better under-
standing of where terrestrial and atmospheric interests overlap in order to most
effectively address issues of mutual concern.
3.6 Chapter summary
The tropical climates of the world are providing the climatologist with an
endless set of research questions. In this chapter a number of components have
been emphasized. First, in his highly informative essay, Cerveny provides the
essence of the complexities associated with low-latitude teleconnections.
Thereafter, the discussion relates to the relative roles of climate variability and
human activities in tropical climates. In the case of the desert boundaries, it is
clear that over time there have been changes induced by long-lasting drought. At
the same time, it is shown that degradation of the surface plays a highly
significant role in desertification. The various arguments presented are placed
within the global framework as represented by the United Nations. Continued
research and meaningful discussion are clearly called for.
The same is true of the other example presented, that of deforestation in the
Amazon. The impacts here are a result of government policies, human migration
resulting from drought and poverty in other regions, and the ready availability of an
export market for a product. Needless to say, the changing of any forested region,
especially one in the tropics, has long-term consequences in local and regional
climates. These changes may, too, influence the global climate in ways not totally
 
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