Woody Legumes distribution in Neotropical Dry Forests and past climate changes

PRADO, D.E.; MOGNI, V.Y.; OAKLEY, L.J.

Johannesburgo

Congreso; 6th International Legume Conference; 2013

University of Johannesburg

The Pleistocenic Arc Theory sustains that present day disjunct fragments of dry forests in central tropical South America, give evidence of a previously more continuous expansion of these forests during the Upper Pleistocene, disrupted by dry-cold versus humid-warm climatic cycles. This Arc extends from NE Brazil south to NE Argentina and eastern Paraguay, through the Chiquitania to SW Bolivia and finally dry inter Andean valleys in Peru and Ecuador, with occasional intrusions in the subtropical Great Chaco. The Neotropical Dry Forests are floristically and physiognomically dominated by woody Legumes, mostly deciduous in the dry season. In the last two decades the research on Legume taxa has prospered, both as classical taxonomic revisions and molecular studies and phylogenies, together with paleoclimatic modelling studies. Whereas the distribution patterns of Neotropical legumes are still overall mostly coincidental with the originally found that generated the hypothesis, the published phylogenies either are ambiguous or indicate a much older diversification date than Pleistocene (i.e. Late Miocene-Pliocene). However, molecular population studies seem to confirm the theory. The evidence accumulated for and against the theory is here briefly reviewed. These ecosystems are the most threatened Neotropical forest type due to its frequently fertile soils being suitable for agriculture, and the need for their preservation is emphasized.