Seasonal pattern of nutrient cycling in the Atlantic forest across a topographic gradient.

Litter layer is the layer of organic detritus accumulated on the soil in forest ecosystems and can be influenced by biologic, edaphic, and climatic factors, increasing from boreal forest to the tropics, and being highly related with the net primary production of forest. In the present study litter was analyzed in three topographic positions; the effect of weather on the litterfall and litter layer amount, the amount of nutrients deposited, accumulated, and released from the litter layer to the soil and C stocks in the forest floor. No differences were found in the amount of litterfall deposited in the plots from the top, middle, and bottom of the hill. There was a large variation in the litterfall throughout the year. The highest litterfall rate was found at the end of the dry season. During the months of very low rainfall, greater litterfall and litter layer were found in the top hill plots. Litterfall is an important mechanism of the transference of nutrients from plants to soil, especially in the non-mobile nutrients and N, due to the high N concentration in the leaves and to the high dominance of Fabaceae trees. In 17 months, around 6.7 Mg ha(-1) of C was deposited on the soil and a mean 2.6 Mg ha(-1) were stored in the litter layer. In the year 2010, in the 12 months, the annual decomposition rate was 1.68.