La Selva Marginal de Punta Lara, ¿relicto o colonización reciente?

T he association called marginal forest of Punta Lara is located southeast from La Plata city, in the municipality of Ensenada, at 34 ° 47 '31' 'South and 57 ° 59' 51 '' West. It includes tree species such as Blepharocalyx salicifolius , Allophylus edulis , Ocotea acutifolia , Pouteria salicifolia and Lonchocarpus nitidus , accompanied by numerous vines, epiphytes, herbs and shrubs typical of the forests of southern Brazil and northeastern Argentina. At the end of the first half of the 20th century, the contributions of Cabrera & Dawson in 1944 and Cabrera in 1949 established a theoretical framework that the scientific community followed to recognize the "primitive" status of this coastal area of the Rio de la Plata. From then on, the notion of the marginal forest of Punta Lara as a “relict” took strong roots in the scientific, technical and popular literature. The goal of this work is to challenge this theoretical framework, which constitutes at present the basis for some of the main conservationist practices in Buenos Aires province. Five sources of information were used for this purpose: 1) cartography from the 18 th and X19th centuries, 2) reports of travelers from that period, obtained from various bibliographical sources, 3) databases of vascular plants herborized before the 20 th century, 4) the xylophilous fungi collected in the late 19 th century from the coast of La Plata and 5) the recent paleoclimatic record. As a result, a new hypothesis is proposed: the marginal forest of Punta Lara is not a relict but a recent installation, established in the mid-nineteenth century when the climate of the Rio de la Plata region presented increases in rainfall and minimum temperature, a trend that continues to the present.