This biome, also known as a broad-leaved evergreen forest, extends from the state of Rio Grande do Norte, at the eastermost tip of South America, as far as Rio Grande do Sul, the southernmost state in Brazil. It had a total area of 1 million square km (385,000 square miles), at the time of the discovery of Brazil (1500) but it is estimated today that there are only 5-7% of the original forest.
It is so rich in plant species and so dense as the Amazon rainforest, although trees appear to be a little lower. The soil, oxisol, is poor in nutrients from geological origin. It is from acid to very acid (pH below 4). However, the large accumulation of necromass (litter) on top 10cm of the soil, creates condition for proliferation of living roots that trap organic matter from decomposition. Symbiosis of most tree roots with endomycorrhizal fungi are effective on absorption of nutrients before leaching occurs.
As pointed out by past investigations (C.F.Jordan and J.L.Monteith), though a tropical forest has a much greater biomass in wood and leaves than its temperate broad-leaved partner, its respiration losses and maintenance costs for leaves are also higher.This suggests that there will not necessarily be a particularly high annual production of wood by tropical trees, in comparison with temperate forests.
But, the figure below shows how important it is to keep the tropical forest standing. The highest concentration of nutrients, better saying all richness of the Atlantic Forest biome occurs in the wood and leaves, i.e. in living parts of the forest.
Access the link below and watch a sequence of slides on the characteristics of the Atlantic Forest.
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