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| Titel |
Disentangling the effects of climate and people on Sahel vegetation dynamics |
| VerfasserIn |
J. W. Seaquist, T. Hickler, L. Eklundh, J. Ardö, B. W. Heumann |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 6, no. 3 ; Nr. 6, no. 3 (2009-03-26), S.469-477 |
| Datensatznummer |
250003539
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| Publikation (Nr.) |
 copernicus.org/bg-6-469-2009.pdf |
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| Zusammenfassung |
| The Sahel belt of Africa has been the focus of intensive scientific research
since the 1960s, spurred on by the chronic vulnerability of its population to
recurring drought and the threat of long-term land degradation. But satellite
sensors have recently shown that much of the region has experienced
significant increases in photosynthetic activity since the early 1980s, thus
re-energizing long-standing debates about the role that people play in
shaping land surface status, and thus climate at regional scales. In this
paper, we test the hypothesis that people have had a measurable impact on
vegetation dynamics in the Sahel for the period 1982–2002. We compare
potential natural vegetation dynamics predicted by a process-based ecosystem
model with satellite-derived greenness observations, and map the agreement
between the two across a geographic grid at a spatial resolution of
0.5°. As aggregated data-model agreement is very good, any local
differences between the two could be due to human impact. We then relate this
agreement metric to state-of-the-art data sets on demographics, pasture, and
cropping. Our findings suggest that demographic and agricultural pressures in
the Sahel are unable to account for differences between simulated and
observed vegetation dynamics, even for the most densely populated areas. But
we do identify a weak, positive correlation between data-model agreement and
pasture intensity at the Sahel-wide level. This indicates that herding or
grazing does not appreciably affect vegetation dynamics in the region. Either
people have not had a significant impact on vegetation dynamics in the Sahel
or the identification of a human "footprint" is precluded by inconsistent
or subtle vegetation response to complex socio-environmental interactions,
and/or limitations in the data used for this study. We do not exclude the
possibility of a greater human influence on vegetation dynamics over the
coming decades with changing land use. |
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