Late Holocene phytolith and carbon-isotope record from a latosol at Salitre, south-central Brazil

The reliability of paleovegetation records inferred from soil phytolith ass emblages and SOM (soil organic matter) carbon isotope analysis was examined in light of previous pollen and charcoal reconstructions. The sampled lato sol is located in southcentral Brazil (Salitre), at a boundary between fore st and cerrado. The derived mean age of phytoliths and SOM at each level is the result of a balance between continuous translocation and selective dis solution. It increases with depth in a regular, quantifiable fashion that a llows paleoenvironmental interpretation. Phytoliths and SOM tracers first r ecord a savanna phase, associated with the last Holocene long dry period oc curring between ca, 5500 and 4500 yr B.P. Two periods of tree community dev elopment followed, between ca, 4000 and 3000 and after ca, 970 yr, B.P. lea ding to the present cerrado/forest association, The dry spell interrupted t his trend about 970 +/- 60 yr B.P. The second development of woody elements was contemporaneous with an increase in anthropogenic fires, Therefore, cl imate was more important than fires and human activities in constraining th e growth of vegetation during the last nine centuries at Salitre, More gene rally, despite pedogenic pro processes, soil phytoliths and delta(13)C valu es of the SOM may be accurate tracers of vegetation changes. (C) 1999 Unive rsity of Washington.