A influência exercida pelo relevo no efluxo de co2 do solo na Floresta Nacional de Caxiuanã - Pará.

Abstract

The Amazon Basin is formed by plateaus and depressions. We know that soil respiration in the plateaus and slopes is different from that in the lowlands (Hanson et al., 1993) due to different moisture and temperature conditions depending on topographic position (Silver et al., 1999). Aiming to complement the studies carried out by the Carbo-Pará Project - Conditioning the Carbon Sequestration in the Amazon Forest, an integral part of LBA - Large Scale Biosphere-Atmosphere Experiment in the Amazon, the present work aimed to determine the influence of relief on soil CO2 efflux. The experiment was developed in the Ferreira Penna Scientific Station, located in the Caxiuanã National Forest, 400 km from Belém in Pará State, where four slopes were identified in the forest under yellow medium textured Latosolo, in which four plots were established, composed of four treatments: plateau, high slope, low slope and lowland. Measurements of soil C02 efflux, soil moisture, and soil temperature were taken every three months to account for seasonal changes during the period from April 2002 to April 2003. During the research period, the mean efflux was 3.27±0.20 urnol CO2 .m2 .s- 1 on the plateau; 3.49±0.30 urnol CO2 .m2 .s-1 on the high slope; 3.68 ±0.30 urnol CO2 .m2 .s-1 on the low slope and 3.44±0.30 urnol CO2 .m2 .s-1 on the lowland. There was no significant difference in soil C02 efflux between landform positions (P>0.05, n=5). The fluxes from April 2002 and April 2003 were different, thus indicating greater influence of climatic conditions on soil C02 efflux than the analyzed relief positions different, thus indicating greater influence of climatic conditions on soil C02 efflux than the analyzed relief positions.