Please note, due to essential maintenance online transactions will not be possible between 02:30 and 04:00 BST, on Tuesday 17th September 2019 (22:30-00:00 EDT, 17 Sep, 2019). We apologise for any inconvenience.
To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
The southern Gran Sabana (SE Venezuela) holds a particular type of neotropical savanna characterized by the local occurrence of morichales (Mauritia palm swamps), in a climate apparently more suitable for rain forests. We present a paleoecological analysis of the last millennia of Lake Chonita (4°39′N–61°0′W, 884 m elevation), based on biological and physico-chemical proxies. Savannas dominated the region during the last millennia, but a significant vegetation replacement occurred in recent times. The site was covered by a treeless savanna with nearby rainforests from 3640 to 2180 cal yr BP. Water levels were higher than today until about 2800 cal yr BP. Forests retreated since about 2180 cal yr BP onwards, likely influenced by a higher fire incidence that facilitated a dramatic expansion of morichales. The simultaneous appearance of charcoal particles and Mauritia pollen around 2000 cal yr BP supports the potential pyrophilous nature of this palm and the importance of fire for its recent expansion. The whole picture suggests human settlements similar to today – in which fire is an essential element – since around 2000 yr ago. Therefore, present-day southern Gran Sabana landscapes seem to have been the result of the synergy between biogeographical, climatic and anthropogenic factors, mostly fire.
The pattern and magnitude of glacier equilibrium-line altitude (ELA) lowerings in the tropics during the last glacial maximum (LGM) are topics of current debate. In the northern tropics, paleo-ELA data are particularly limited, inhibiting the ability to make regional and large-scale paleoclimatic inferences. To improve these records, nine paleo-glaciers in the Venezuelan Andes were reconstructed based on field observations, aerial photographs, satellite imagery and high-resolution digital topographic data. Paleo-glacier equilibrium-line altitudes (ELAs) were estimated using the accumulation-area ratio (AAR) and the area-altitude balance ratio (AABR) methods. During the local LGM in Venezuela (∼ 22,750 to 19,960 cal yr BP), ELAs were ∼ 850 to 1420 m lower than present. Local LGM temperatures were are at least 8.8 ± 2°C cooler than today based on a combined energy and mass-balance equation to account for an ELA lowering. This is greater than estimates using an atmospheric lapse rate calculation, which yields a value of 6.4 ± 1°C cooler. The paleo-glacial data from the Venezuelan Andes support other published records that indicate the northern tropics experienced a greater ELA lowering and possibly a greater cooling than the Southern Hemisphere tropics during the LGM.
Email your librarian or administrator to recommend adding this to your organisation's collection.