A Look at Amazon Basin Seasonal Dynamics with the Biophysical ...

Litter decomposition rate estimation by mass balance model in a transitional tropical forest –savannain Mato Grosso - BrazilNicolau Priante Filho (nicolaup@terra.com.br), Fernando Raiter, Wander Hoeger, Clóvis LastaFritzen, Eduardo Jacusiel Miranda, José de Souza Nogueira, Moacir LacerdaUniversidade Federal de Mato Grosso, Depto. De Física/ICET - Av. Fernando Correa da Costa s/n78060-900-Cuiabá-MT-BRAZILGeorge Louis VourlitisIn the present study we measured the litter production and decomposition in a transition forest todetermine the role played by the litter decomposition in the overall carbon emission. The experimentswere carried out near the city of Sinop in northern Mato Grosso, Brazil, a region of transition betweenthe Amazon rainforest and the savanna (“cerrado”). That region presents an average rainfall of 2000mm, with a dry season from June to September, and a very wet season in the period betweenDecember-February, when approximately a half of the total rainfall is received. Decompositionstudies follow a common procedure, using 20-1m 2 litter traps installed in a 1 ha plot. Fallen litter wascollected monthly sorted and dry mass of leaves, twigs, flowers and fruits determined. We used amass balance model proposed by Wieder and Wright, 1995 to quantify litter decomposition. In thiswork we show preliminary results for the period between January and February 2002. For the fallenlitter, the exponential decay k value for January in Sinop was around 0.02 d -1 . This value was similarto the wet season value obtained in Panama by Wieder and Wright, 1995 and is substantially largerthan the annual average value 0.0089d -1 . The Sinop average litterfall was 13 g m -2 wk -1 to January and9 g m -2 wk -1 to February. In the same area an experiment using the litterbag method have beenconducting to estimate the litter decomposition rate. We continue collecting data until June 2002 andthe results of both methods will be compared and showed.