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| Titel |
Effects of past climate variability on fire and vegetation in the cerrãdo savanna of the Huanchaca Mesetta, NE Bolivia |
| VerfasserIn |
S. Y. Maezumi, M. J. Power, F. E. Mayle, K. K. McLauchlan, J. Iriarte |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 11, no. 6 ; Nr. 11, no. 6 (2015-06-08), S.835-853 |
| Datensatznummer |
250117317
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| Publikation (Nr.) |
 copernicus.org/cp-11-835-2015.pdf |
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| Zusammenfassung |
| Cerrãdo savannas have the greatest fire activity of all major global land-cover
types and play a significant role in the global carbon cycle. During the
21st century, temperatures are projected to increase by ~ 3 °C coupled with a precipitation decrease of
~ 20%. Although these conditions could potentially
intensify drought stress, it is unknown how that might alter vegetation
composition and fire regimes. To assess how Neotropical savannas responded
to past climate changes, a 14 500-year, high-resolution, sedimentary record
from Huanchaca Mesetta, a palm swamp located in the cerrãdo savanna in northeastern
Bolivia, was analyzed with phytoliths, stable isotopes, and charcoal. A
non-analogue, cold-adapted vegetation community dominated the
Lateglacial–early Holocene period (14 500–9000 cal yr BP, which included trees and
C3 Pooideae and C4 Panicoideae grasses. The Lateglacial
vegetation was fire-sensitive and fire activity during this period was low,
likely responding to fuel availability and limitation. Although similar
vegetation characterized the early Holocene, the warming conditions
associated with the onset of the Holocene led to an initial increase in fire
activity. Huanchaca Mesetta became increasingly fire-dependent during the
middle Holocene with the expansion of C4 fire-adapted grasses. However,
as warm, dry conditions, characterized by increased length and severity of
the dry season, continued, fuel availability decreased. The establishment of
the modern palm swamp vegetation occurred at 5000 cal yr BP. Edaphic factors
are the first-order control on vegetation on the rocky quartzite mesetta.
Where soils are sufficiently thick, climate is the second-order control of
vegetation on the mesetta. The presence of the modern palm swamp is
attributed to two factors: (1) increased precipitation that increased water
table levels and (2) decreased frequency and duration of surazos (cold wind
incursions from Patagonia) leading to increased temperature minima. Natural
(soil, climate, fire) drivers rather than anthropogenic drivers control the
vegetation and fire activity at Huanchaca Mesetta. Thus the cerrãdo savanna
ecosystem of the Huanchaca Plateau has exhibited ecosystem resilience to
major climatic changes in both temperature and precipitation since the
Lateglacial period. |
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