In semi-arid regions subject to rising temperatures and drought, palaeoecological insights
into past vegetation dynamics under a range of boundary conditions are needed to
develop our understanding of environmental responses to climatic changes. Here, we
present a new high-resolution record of vegetation history and fire activity spanning the
last 12,000 years from Lake Sidi Ali in the southern Middle Atlas Mountains, Morocco.
The record is underpinned by a robust AMS radiocarbon and 210Pb/137Cs chronology
and multi-proxy approach allowing direct comparison of vegetation, hydroclimate, and
catchment tracers. The record reveals the persistence of steppic landscapes until
10,340 cal yr BP, prevailing sclerophyll woodland with evergreen Quercus until 6,300
cal yr BP, predominance of montane conifers (Cedrus and Cupressaceae) until 1,300
cal yr BP with matorralization and increased fire activity from 4,320 cal yr BP, and
major reduction of forest cover after 1,300 cal yr BP. Detailed comparisons between
the pollen record of Lake Sidi Ali (2,080m a.s.l.) and previously published data from
nearby Tigalmamine (1,626m a.s.l.) highlight common patterns of vegetation change in
response to Holocene climatic and anthropogenic drivers, as well as local differences
relating to elevation and bioclimate contrasts between the sites. Variability in evergreen
Quercus and Cedrus at both sites supports a Holocene summer temperature maximum
between 9,000 and 7,000 cal yr BP in contrast with previous large-scale pollen-based
climate reconstructions, and furthermore indicates pervasive millennial temperature
variability. Millennial-scale cooling episodes are inferred from Cedrus expansion around
10,200, 8,200, 6,100, 4,500, 3,000, and 1,700 cal yr BP, and during the Little Ice Age
(400 cal yr BP). A two-part trajectory of Late Holocene forest decline is evident, with
gradual decline from 4,320 cal yr BP linked to synergism between pastoralism, increased
fire and low winter rainfall, and a marked reduction from 1,300 cal yr BP, attributed to
intensification of human activity around the Early Muslim conquest of Morocco. This
trajectory, however, does not mask vegetation responses to millennial climate variability.
The findings reveal the sensitive response ofMiddle Atlas forests to rapid climate changes
and underscore the exposure of the montane forest ecosystems to future warming.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:84555 |
| Date | 04 April 2023 |
| Creators | Campbell, Jennifer F. E., Fletcher, William J., Joannin, Sebastien, Hughes, Philip D., Rhanem, Mustapha, Zielhofer, Christoph |
| Publisher | Frontiers Research Foundation |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:article, info:eu-repo/semantics/article, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 2296-701X, 113 |
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