Fitogeografia de Poaceae do Cerrado: padrões florísticos, filogenéticos e funcionais

Abstract

Grasslands and savannas of the Brazilian “Cerrado” are highly vulnerable to anthropic practices of use and occupation and to the climate crisis. Due to its wide expression in the floristic composition of open formations, we intended to investigate the phytogeographic patterns of the family Poaceae by compiling and analyzing 28 floristic surveys in “Cerrado” areas and associated ecotones. Similarity indexes between sites and species composition with different photosynthetic metabolisms were analyzed, as well as environmental variables that could direct biotic patterns, adding up to 43 variables between climatic, edaphic and landscape features such as shape and surrounding matrix. The results showed strong environmental links with seasonality and temperature as well as soil size and fertility, grouping patterns of similarity between ecotone sites with the Atlantic Rainforest and the core area of the “Cerrado”. Most of the grasses presented in the sites belong to the PACMAD clade, representing 95% of the species. The main subfamilies in the Cerrado areas were Panicoideae, with 255 species (76%), and Chloridoideae, with 47 spp (14%). The presence of C3 species followed the same pattern. Distant sites such as Chaco Mato-grossense and the southernmost “Cerrado” of Paraná have low similarity with the other sites. Parameters related to the conservation of fragments such as extension and surrounding matrix proved to be important in the floristic approach of more preserved areas to the north of the “Cerrado” polygon, showing great fragility of the areas in the southern.