Estratégias nutricionais em espécies congenéricas de cerrado e floresta estacional semidecídua
Resumen
The Brazilian cerrado, although is one of the hotspots for the biology conservation, is still under
pressure. One of these is related to restoration practices. This hotspot presents a huge vegetative
diversity, however with predominance of savannas physiognomies. These can be defined as
tropical and subtropical biomes, where the herbaceous layer is almost continuous, interrupted only
by shrubs and trees at varying densities, with growth and reproductive patterns linked to climatic
seasonality and to the occurrence of fires. Since savannas appear in climates that also harbour
forests, only the climate is not enough to explain the occurrence of the former. One of the factors
postulated to explain the occurrence of savannas in areas whose climate allows forests is nutrientpoor
soils, especially regarding nitrogen and phosphorus. We analyzed the strategies presented by
congeneric species, one typical of the cerrado, and the other, seasonal forest through four
treatments in hydroponic system: (1) complete Hoagland solution, (2) Hoagland solution but
nitrogen, (3) Hoagland solution but phosphorus, and (4) Hoagland solution but nitrogen and
phosphorus. We followed the individuals measuring how long cotyledons persist, the time for the
appearance of the first pair of leaves, height, leaf area, specific leaf area, root:shoot ratio,
aboveground biomass and total biomass. All tests were done using variance analyses. Our results
suggest that cerrado and forest species are functionally distinct, already in the early stages of their
development. Both, savanna and forest congeneric seedlings are limited by nitrogen. However,
changes in functional traits due to phosphorus supply evidenced their distinct nutritional strategies.
While the forest species improved their functional traits — evidencing the co-limitation and higher
nutritional demand —, savannas species displayed signs of toxicity, expressed by the decrease of
some attributes.